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AS 4024.2—1998
Australian Standard®
Safeguarding of machinery
Part 2: Installation andcommissioning requirementsfor electro-sensitive systems—Optoelectronic devices
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This Australian Standard was prepared by Committee SF/41, General Principles forthe Guarding of Machinery. It was approved on behalf of the Council of StandardsAustralia on 31 December 1997 and published on 5 April 1998.
The following interests are represented on Committee SF/41:
Australian Chamber of Commerce and Industry
Australian Manufacturing Workers Union
Department for Industrial Affairs S.A.
Department of Training and Industrial Relations, Qld
Electricity Supply Association of Australia
Ergonomics Society of Australia
Federal Chamber of Automotive Industries
Metal Trades Industry Association of Australia
National Safety Council of Australia
Safety Institute of Australia
Tractor and Machinery Association of Australia
University of Melbourne
Victorian WorkCover Authority
WorkCover N.S.W.
WorkSafe Western Australia
Additional interests participating in preparation of Standard:
Optoelectronic protective equipment manufacturers
Review of Australian Standards.To keep abreast of progress in industry, Australian Standards aresubject to periodic review and are kept up to date by the issue of amendments or new editions asnecessary. It is important therefore that Standards users ensure that they are in possession of the latestedition, and any amendments thereto.Full details of all Australian Standards and related publications will be found in the Standards AustraliaCatalogue of Publications; this information is supplemented each month by the magazine ‘TheAustralian Standard’, which subscribing members receive, and which gives details of new publications,new editions and amendments, and of withdrawn Standards.Suggestions for improvements to Australian Standards, addressed to the head office of StandardsAustralia, are welcomed. Notification of any inaccuracy or ambiguity found in an Australian Standardshould be made without delay in order that the matter may be investigated and appropriate action taken.
This Standard was issued in draft form for comment as DR 97242.
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AS 4024.2—1998
Australian Standard®
Safeguarding of machinery
Part 2: Installation andcommissioning requirementsfor electro-sensitive systems—Optoelectronic devices
Originated as part of AS 4024.2(Int)—1992.Revised and redesignated in part as AS 4024.2—1998.
PUBLISHED BY STANDARDS AUSTRALIA(STANDARDS ASSOCIATION OF AUSTRALIA)1 THE CRESCENT, HOMEBUSH, NSW 2140
ISBN 0 7337 1814 0
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AS 4024.2 — 1998 2
PREFACE
This Standard was prepared by the Standards Australia Committee SF/41, GeneralPrinciples for the Guarding of Machinery, as a revision, in part, of AS 4024.2(Int)—1992,Safeguarding of machinery,Part 2: Presence sensing systems.
During the preparation of this Standard the Committee considered work emanating fromthe European Community (CEN). Since many European Standards are becoming de factointernational Standards, or are being adopted as International Standards by ISO, theCommittee decided to use the draft European Standard as the basis for this revision.
This Standard has been developed because of the increasing use within industry ofelectro-sensitive protective equipment for safeguarding both cyclic and continuouslyrunning machinery, which has led to a demand for a Standard embracing a range ofelectro-sensitive protective equipment.
The terms ‘normative’ and ‘informative’ have been used in this Standard to define theapplication of the appendix to which they apply. A ‘normative’ appendix is an integralpart of a Standard, whereas an ‘informative’ appendix is only for information andguidance.
© Copyright STANDARDS AUSTRALIA
Users of Standards are reminded that copyright subsists in all Standards Australia publications and software. Except where theCopyright Act allows and except where provided for below no publications or software produced by Standards Australia may bereproduced, stored in a retrieval system in any form or transmitted by any means without prior permission in writing fromStandards Australia. Permission may be conditional on an appropriate royalty payment. Requests for permission and informationon commercial software royalties should be directed to the head office of Standards Australia.
Standards Australia will permit up to 10 percent of the technical content pages of a Standard to be copied for useexclusively in-house by purchasers of the Standard without payment of a royalty or advice to Standards Australia.
Standards Australia will also permit the inclusion of its copyright material in computer software programs for no royaltypayment provided such programs are used exclusively in-house by the creators of the programs.
Care should be taken to ensure that material used is from the current edition of the Standard and that it is updated whenever theStandard is amended or revised. The number and date of the Standard should therefore be clearly identified.
The use of material in print form or in computer software programs to be used commercially, with or without payment, or incommercial contracts is subject to the payment of a royalty. This policy may be varied by Standards Australia at any time.
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3 AS 4024.2 — 1998
CONTENTS
PageSECTION 1 SCOPE AND GENERAL
1.1 SCOPE. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51.2 OBJECTIVE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51.3 APPLICATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51.4 REFERENCED DOCUMENT. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51.5 DEFINITIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51.6 GENERAL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
SECTION 2 RISK ASSESSMENT2.1 GENERAL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82.2 RISK ASSESSMENT. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82.3 DOCUMENTATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
SECTION 3 SAFETY DISTANCES3.1 GENERAL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113.2 SAFETY DISTANCE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113.3 LOCATION OF ELECTRO-SENSITIVE PROTECTIVE EQUIPMENT. . . . 123.4 METHODOLOGY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123.5 GENERAL EQUATION FOR CALCULATING MINIMUM DISTANCES . . 143.6 CALCULATING MINIMUM DISTANCES FOR ELECTRO-SENSITIVE
PROTECTIVE EQUIPMENT EMPLOYING ACTIVEOPTOELECTRONIC PROTECTIVE DEVICES. . . . . . . . . . . . . . . . . . . . 14
3.7 CALCULATING SAFETY DISTANCES FOR FLOOR LEVELELECTRO-SENSITIVE PROTECTIVE EQUIPMENT. . . . . . . . . . . . . . . . 27
3.8 BLANKING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
SECTION 4 SAFETY-RELATED CONTROL SYSTEMS4.1 SAFETY-RELATED CONTROL SYSTEMS FITTED WITH
ELECTRO-SENSITIVE PROTECTIVE EQUIPMENT. . . . . . . . . . . . . . . . 294.2 ELECTRO-SENSITIVE PROTECTIVE EQUIPMENT USED AS
A MACHINE-START INTERLOCK . . . . . . . . . . . . . . . . . . . . . . . . . . . . 294.3 NORMAL START OPERATION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 304.4 MUTING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
SECTION 5 FUNCTIONAL REQUIREMENTS OF ADDITIONALSAFETY-RELATED CONTROL SYSTEMS
5.1 GENERAL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 325.2 SAFETY MONITORING DEVICES. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 325.3 STOPPING PERFORMANCE MONITOR. . . . . . . . . . . . . . . . . . . . . . . 355.4 SECONDARY SWITCHING DEVICE. . . . . . . . . . . . . . . . . . . . . . . . . . . 365.5 START INTERLOCK . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 365.6 RESTART INTERLOCK . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 365.7 MUTING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 375.8 ELECTRO-SENSITIVE PROTECTIVE EQUIPMENT USED
AS A MACHINE-RESTART DEVICE . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
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AS 4024.2 — 1998 4
PageSECTION 6 COMMISSIONING AND TESTING
6.1 SCOPE OF SECTION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 396.2 DOCUMENTATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 396.3 FREQUENCY OF TESTING. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 396.4 COMMISSIONING EXAMINATION AND TESTS . . . . . . . . . . . . . . . . . . 396.5 SIX- OR TWELVE-MONTHLY EXAMINATION, INSPECTION
AND TEST PROCEDURE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 406.6 TESTS TO BE CARRIED OUT DAILY AND AFTER SETTING. . . . . . . . 416.7 TESTING OF OPTIONAL REQUIREMENTS. . . . . . . . . . . . . . . . . . . . . . 41
APPENDICESA WORKED EXAMPLES OF SAFETY DISTANCES. . . . . . . . . . . . . . . . . . . 44B GUIDANCE FOR THE SELECTION OF CATEGORIES. . . . . . . . . . . . . . . 51C SAFETY DISTANCES FOR ANGLED OR NORMAL APPROACH. . . . . . . 58
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5 AS 4024.2 — 1998
STANDARDS AUSTRALIA
Australian Standard
Safeguarding of machinery
Part 2: Installation and commissioning requirementsfor electro-sensitive systems—Optoelectronic devices
S E C T I O N 1 S C O P E A N D G E N E R A L
1.1 SCOPE This Standard specifies the installation and commissioning requirementsfor electro-sensitive protective equipment using optoelectronic devices specifically relatedto machinery safety.
Requirements for the manufacture and testing of electro-sensitive systems usingoptoelectronic devices may be found in AS 4024.3.
1.2 OBJECTIVE The objective of this Standard is to enable designers, manufacturers,suppliers, employers and users of machinery to minimize the risks to health and safety ofemployees and others working with or otherwise near machinery.
1.3 APPLICATION This Standard is intended for use by those who design,manufacture, supply, install or use machinery guarding or safety devices. It applies tooptoelectronic protective devices employing radiation of wavelength within the range of400 nm to 1500 nm.
Alternative methods of providing safety to those given may be used provided that thelevel of safety offered by the alternative is at least equivalent to that provided by themethods given in this Standard.
Some regulatory authorities have specific requirements relating to the forms that guardingmay take and to the order in which guarding techniques may be considered. Users of thisStandard should therefore make themselves aware of any specific requirements in thejurisdiction where the machinery will be used.
This Standard may still be used in these jurisdictions to identify the most appropriatelevel of system integrity required, and to provide guidance in other aspects of machinesystem safety.
1.4 REFERENCED DOCUMENT The following document is referred to in thisStandard:
AS4024 Safeguarding of machinery4024.1 Part 1: General principles4024.3 Part 3:Manufacturing and testing requirements for electro-sensitive
systems—Optoelectric devices
AS/NZS4360 Risk management
1.5 DEFINITIONS For the purpose of this Standard the definitions given inAS 4024.1 and those below apply.
1.5.1 Actuation (of protective equipment)—physical initiation of the protectiveequipment when it detects the presence or intrusion of a person or a part of a person.
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AS 4024.2 — 1998 6
1.5.2 Approach
1.5.2.1 Angled approach—where the direction of approach makes an angle to thedetection zone.
1.5.2.2 Normal approach—where the direction of approach makes a right angle to thedetection zone.
1.5.2.3 Parallel approach—where the direction of approach is parallel to the detectionzone.
1.5.3 Blanking—a facility to disable an area of the electro-sensitive protectiveequipment, while leaving the remaining area(s) fully active.
1.5.4 Detection capability—the sensing function parameter limit specified by themanufacturers which, when exceeded, will cause actuation of the electro-sensitiveprotective equipment.
1.5.5 Detection zone—the sensing field which is capable of detecting the presence orintrusion of a person or part of a person.
1.5.6 Direction of approach—the direction of movement of the body or part of thebody toward the danger zone.
1.5.7 Electro-sensitive protective equipment (ESPE)—a protection trip or presence-sensing system comprising as a minimum—
(a) a sensing function;
(b) a system control function; and
(c) an output signal switching device.
1.5.8 Hazardous area—any area within or around machinery which provides access tothe danger zone.
1.5.9 Muting—a facility (subject to specified conditions) for automatically switchingthe protective equipment system into a condition where the final switching devices do notresponse to an interruption of the sensing unit.
1.5.10 Overall system stopping performance—the time occurring from the actuationof the sensing function to the cessation of hazardous motion, or to the removal of the risk.
NOTE: The overall system stopping performance comprises a minimum of two phases asfollows:
T = t1 + t2
where
T = overall system stopping performance
t1 = the maximum time in seconds, between the actuation of the sensing functionand the output signal switching devices being in the ‘off’ state.
t2 = the response time of the machine, in seconds, i.e. the time required to stop themachine or remove the risk after receiving the output signal from the protectiveequipment.
The relationship betweent1 and t2 is defined in Figure 1.1. It is a function of the protectiveequipment and the machine respectively and is determined by design.
1.5.11 Residual risk—any risk remaining after safety measures have been taken.
1.5.12 Safety distance—the minimum distance(s) from the detection zone to the dangerzone that ensures that the risk of exposure to any hazard is eliminated.
1.5.13 Safety measure—a means that eliminates or minimizes a hazard or a risk.
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7 AS 4024.2 — 1998
FIGURE 1.1 RELATIONSHIP BETWEEN t1 AND t2
1.6 GENERAL Electro-sensitive protective equipment is applied to machinery thatpresents a risk of personal injury. It provides protection by causing the machine to revertto a safe condition before a person can be placed in a hazardous situation.
The equipment incorporates at least one sensing device that employs one or more types ofdetection by means of electromagnetic radiation. This radiation can be either self-generated by the device or supplied from an external source.
Each type of machine presents its own particular hazards. The treatment of applications ofthe electro-sensitive protective equipment should be a matter for agreement between theequipment supplier and the machine user and in this context attention is drawn to therelevant guidance given in AS 4024.1.
Some types of electro-sensitive protective equipment fitted to certain machines have thefacility of muting the equipment during certain parts of the machine cycle. There alsoexists an additional feature used to blank out a part of the detection zone, for example topermit strip to be fed to a press. Unlike muting, this facility is functional during the entiremachine cycle, and particular care is necessary to prevent access being gained to thedanger zone through the blanked section of the equipment.
Electro-sensitive protective equipment for a machine shall be selected and used inaccordance with the appropriate Standard for that particular machine. If no Standardexists, a risk assessment shall be undertaken according to AS 4024.1 prior to selecting theappropriate device.
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AS 4024.2 — 1998 8
S E C T I O N 2 R I S K A S S E S S M E N T
2.1 GENERAL This Section describes the procedure known as risk assessment bywhich the knowledge and experience of the design, use, incidents, accidents and harmrelated to machinery is brought together in order to assess the risks during the life of themachinery (see also AS 4024.1 and AS/NZS 4360).
This Standard is not intended to provide a detailed account of methods for analysinghazards and estimating risks as this is dealt with elsewhere (e.g. textbooks and otherreference documents).
2.2 RISK ASSESSMENT Risk assessment is a series of logical steps to enable theexamination in a systematic way of the hazards associated with machinery. Riskassessment is followed, whenever necessary, by risk reduction as described in AS 4024.1.When this process is repeated it forms the iterative process for eliminating hazards as faras possible and implementing safety measures according to the state of the art.
Risk assessment includes (see Figure 2.1) the following:
(a) Risk analysis Risk analysis consists of—
(i) determination of the limits of the machinery;
(ii) hazard identification; and
(iii) risk estimation.
(b) Risk evaluation Risk analysis provides the information required for the riskevaluation, which in turn allows judgements to be made on the safety of machinery.
Risk assessment relies on judgemental decisions. These decisions shall be supported byqualitative methods, complemented as far as possible by quantitative methods.Quantitative methods are particularly appropriate when the foreseeable severity and extentof harm are high.
Quantitative methods are useful to assess alternative safety measures and to determinewhich gives better protection.
NOTE: The application of quantitative methods is restricted by the amount of useful data whichare available. Therefore, in many applications only qualitative risk assessment will be possible.
The risk assessment procedure shall be conducted in such a manner that it is possible todocument—
(i) the intended use of the machinery for which the assessment has been made,(e.g. specifications or limits);
(ii) the hazards, hazardous situations and hazardous events identified;
(iii) pertinent information used (e.g. accident histories and experience gained from riskreduction applied to similar machines);
(iv) the objectives to be achieved by the risk control measures;
(v) the safety measures implemented to eliminate identified hazards or reduce risks; and
(vi) the residual risk to the individual hazards by specifying any relevant assumptionsthat have been made (loads and safety factors).
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9 AS 4024.2 — 1998
NOTE: Risk reduction and selection of appropriate risk control measures are not part of the risk assessmentprocess.
FIGURE 2.1 THE ITERATIVE PROCESS TO ACHIEVE SAFETY
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AS 4024.2 — 1998 10
2.3 DOCUMENTATION Documenting the risk assessment is a means of describingthe hazards identified and the safety measures implemented. The documentation shouldcontain information on—
(a) the information on which risk assessment was based;
(b) the machinery for which the assessment has been made (specifications or limits);
(c) any relevant assumptions which have been made, such as loads, strengths, or safetyfactors;
(d) the hazard identified;
(e) the hazardous situations identified;
(f) the hazardous events considered in the assessment;
(g) the data used and the sources;
(h) any uncertainty associated with the data used and the impact on the risk assessment;
(i) the objectives to be achieved by the risk control method;
(j) any requirements implemented (e.g. Standards or other specifications used);
(k) the information regarding residual risks; and
(l) the results of the final risk evaluation.
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11 AS 4024.2 — 1998
S E C T I O N 3 S A F E T Y D I S T A N C E S
3.1 GENERAL The effectiveness of this type of protective equipment in minimizingrisk relies, in part, on the relevant parts of the equipment being correctly positioned inrelation to the hazardous area. In deciding on the positions a number of aspects will needto be taken into account including—
(a) a need for the identification of hazards and an assessment of all the risks;
(b) existing Standards;
(c) possible future technical developments;
(d) the type of equipment to be used;
(e) the response times of protective equipment used;
(f) the time taken to ensure the safe condition of the machine following operation ofthe protective equipment, e.g. to stop the machine;
(g) biomechanical and anthropometric data for body parts;
(h) the path taken by a body part when moving from the sensing or actuating meanstowards the hazardous area;
(i) the possible presence of a person between the device and the hazardous area; and
(j) the possibility of undetected access to the danger zone.
Parameters are provided and are based on values for hand/arm and approach speeds. Themethodology to determine the minimum distances from specific sensing or actuatingdevices of protective equipment to a hazardous area are also provided.
The specific devices are trip devices (see AS 4024.1), specifically electro-sensitiveprotective equipment, including those trip devices used additionally to initiate operation.
Guidance is based on the assumption that the correct device has been chosen by carryingout a risk assessment in accordance with AS 4024.1.
The calculated distances, when implemented, will provide sufficient protection for personsagainst the risks caused by approaching a hazardous area which generates potential riskssuch as crushing, shearing, cutting or severing, entanglement, drawing-in or trapping,friction or abrasion, stabbing or puncture and impact.
Protection against the risks from mechanical hazards arising from the ejection of solid orfluid materials and non-mechanical hazards such as toxic emissions, electricity orradiation, are not covered by the Standard.
The distances are derived from data that take into account population groups likely to befound in European countries. Users should take into account the population to be foundwithin their workplace.
NOTES:
1 If this Standard is to be used for non-industrial purposes then the designer should take intoaccount the fact that this data is based on industrial experience.
2 Until specific data is available for approach speeds for children this Standard uses adultspeeds and lower detection factors where relevant should be used to calculate the distancesthat could be within the reach of children in those areas where it is foreseen that childrenmay be present.
3.2 SAFETY DISTANCE The safety distance between the detection zone and thedanger zone shall ensure that a risk of exposure to any hazard does not occur.
In each instance, the worst case should be taken as the basis for determining the safetydistance, using the stopping time of the power driven machinery.
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AS 4024.2 — 1998 12
There should be no risk of injury if the maximum value of the stopping time isconsistently maintained. When calculating the safety distance, the maximum value of handapproach speed should be used.
The safety distance and the maximum value of the stopping time should be clearly markedand permanently indicated on a label near the detection zone. This does not apply to areaguarding.
If the position of the detection zone is adjustable, it should be provided with means forlocking in any position.
3.3 LOCATION OF ELECTRO-SENSITIVE PROTECTIVE EQUIPMENT Electro-sensitive protective equipment shall be fitted so that—
(a) the danger zone can be reached only through the detection zone; and
(b) it is impossible for the operator to stand between the detection zone and the dangerzone.
This includes walking through the detection zone into a hazardous area.
Where reaching over, reaching under or reaching round the electro-sensitiveprotective equipment is possible, additional safeguarding measures shall beprovided.
If certain parts of the detection zone can be rendered ineffective by special means e.g.muting or blanking, the parts no longer protected by the electro-sensitive protectiveequipment shall be safeguarded by other protective devices.
The detection zone shall be adjustable only to such an extent that the additional safetydevices are effective, and the safety distance is maintained.
3.4 METHODOLOGY Figure 3.1 provides a schematic representation of themethodology for determining the correct position of sensing or actuating devices ofprotective equipment using this Standard, which is as follows:
(a) Identify the hazards and assess the risks. (See AS 4024.1.)
(b) If a machine-specific Standard exists for the machine, select one of the specifiedtypes of protective equipment from that machine-specific Standard, and then use thedistance specified by that Standard.
(c) If there is no machine-specific Standard or if the Standard does not specify anyminimum distances, then use the equations in this Standard to calculate theminimum distance for the protective equipment selected. The selection of theappropriate type of protective equipment should be made in accordance with therequirements of AS 4024.1.
(d) Incorporate the distance in the machine design.
(e) Check if the determined position will allow persons to be between the sensingdevices of the protective equipment and the hazardous area without being detected.In this case supplementary measures may be required, depending on the risk.
(f) Ensure the device has been installed in such a manner that access to the hazardousarea will not be possible without detection by the device.
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FIGURE 3.1 SCHEMATIC OF METHODOLOGY
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AS 4024.2 — 1998 14
3.5 GENERAL EQUATION FOR CALCULATING MINIMUM DISTANCES Theminimum distance from the danger zone shall be calculated by using the following generalEquation 3(1):
S = (K × T) + C . . . 3(1)
where
S = the minimum distance from the danger zone to the detection zone, inmillimetres
K = a parameter derived from data on approach speeds of the body or parts of thebody, in millimetres per second
T = the overall system stopping performance, in seconds
C = the intrusion distance of the body or part of the body towards the danger zonebefore actuation of the protective equipment, in millimetres.
NOTE: For worked examples see Appendix A.
3.6 CALCULATING MINIMUM DISTANCES FOR ELECTRO-SENSITIVEPROTECTIVE EQUIPMENT EMPLOYING ACTIVE OPTOELECTRONICPROTECTIVE DEVICES
3.6.1 General This Clause considers three main applications based on the direction ofapproach to the detection zone, which are—
(a) normal approach (at right angles) to the detection zone;
(b) parallel approach to the detection zone; and
(c) angled approach to the detection zone.
Where it is foreseeable that any gaps adjacent to or within the detection zone of theelectro-sensitive protective equipment will allow access to the hazardous area then thisshall be taken into account in the correct positioning of the protective equipment andadditional safeguards shall be considered. See AS 4024.1 for guidance on safety distancesfor non-electro-sensitive systems.
3.6.2 Direction of approach normal to the detection zone(See also Figure 3.2)
3.6.2.1 Electro-sensitive protective equipment with a maximum detection capability of40 mm diameter The minimum distance from the detection zone to the danger zone shallbe not less than that calculated using the following equation:
S = (K × T) + C . . . 3(1)
where
S = the minimum distance from the danger zone to the detection zone, inmillimetres
K = approach speed of the body or part of the body, in millimetres per second
= 2000 mm/s
T = the overall system stopping performance, in seconds
C = the intrusion distance of the body or part of the body towards the danger zonebefore actuations of the particular equipment, in millimetres
= 8(d − 14 mm) but not less than 0
d is the detection capability of the device in millimetres
then
S = (2000 mm/s ×T) + 8(d − 14 mm) . . . 3(2)
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This equation applies for all minimum distances ofS up to and including 500 mm. Theminimum value ofS shall be not less than 100 mm.
If S is found to be greater than 500 mm the following equation may be used:
S = (K × T) + C . . . 3(1)
where
S = the minimum distance from the danger zone to the detection zone, inmillimetres
K = approach speed of the body or part of the body, in millimetres per second
= 1600 mm/s
T = the overall system stopping performance, in seconds
C = the intrusion distance of the body or part of the body towards the danger zonebefore actuation of the particular equipment, in millimetres
= 8(d − 14 mm) but not less than 0
then
S = (1600 mm/s ×T) + 8(d − 14 mm) . . . 3(3)
The value ofS shall be not less than 500 mm.
The relationship between safety distance and overall response time is depicted inFigure 3.3.
Access to the danger zone by reaching over or around the electro-sensitive protectiveequipment (and any other protective equipment) shall be prevented using the values ofsafety distances given in the table of guard distance within AS 4024.1 where applicable.The minimum height of the electrosensitive protective equipment shall be not less than300 mm.
Where it is foreseeable that electro-sensitive protective equipment will be used in non-industrial applications (e.g in the presence of children), the minimum distanceScalculated using Equation 3(2) shall be increased by at least 75 mm. In such cases,Equation 3(3) is not applicable.
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AS 4024.2 — 1998 16
FIGURE 3.2 APPROACH NORMAL TO THE LIGHT CURTAIN
FIGURE 3.3 SAFETY DISTANCE Vs RESPONSE TIME FOR NORMAL APPROACH
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17 AS 4024.2 — 1998
3.6.2.2 Electro-sensitive protective equipment used for the initiation of machineoperation Electro-sensitive protective equipment used for the initiation of machineoperation shall have a detection capability equal to or less than 30 mm. In this caseEquation 3(1) shall apply and the minimum distanceS shall be greater than 150 mm. Therelationship between safety distance and response time for this application is depicted inFigure 3.4.
Where the electro-sensitive protective equipment is intended to detect fingers or hands,machine initiation is allowed only when the detection capability of the electro-sensitiveprotective equipment does not exceed 14 mm.
Where it is foreseeable that the work will consist of rapid repetitive operations, e.g. wherethe operator is sitting close to the machine during work, the workpieces are small, of lowweight, easy to grip and handle with one hand and the cycle time is short, then theminimum distance shall be calculated using the following equation:
S = (K × T) + C . . . 3(1)
where
S = the minimum distance from the danger zone to the detection zone, inmillimetres
K = the approach speed of the body or part of the body, in millimetres per second
= 2500 mm/s
T = the overall system stopping performance, in seconds
C = the intrusion distance of the body or part of the body towards the danger zonebefore actuation of the particular equipment, in millimetres
= 8(d − 14 mm) but not less than 0
then
S = (2500 mm/s ×T) + 8(d − 14 mm) . . . 3(4)
The minimum distanceS shall be greater than 150 mm and the detection capability ofdshall be less than 30 mm.
FIGURE 3.4 MINIMUM DISTANCE Vs OVERALL RESPONSE TIMEFOR DEVICES USED FOR MACHINE INITIATION
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AS 4024.2 — 1998 18
3.6.2.3 Electro-sensitive protective equipment with detection capability greater than40 mm and less than or equal to 70 mmSuch pieces of equipment are considered by thisStandard to be sets of multiple beams. They will not detect intrusion of the hands andshall only be used where the risk assessment indicates that the need for detection of thehands is not foreseeable.
This equipment shall be installed in accordance with the parameters set out in this Clause.
The minimum distance from the detection zone to the danger zone is in part dependent onthe part of body to be detected and shall be calculated using the following equation:
S = (K × T) + C . . . 3(1)
where
S = the minimum distance from the danger zone to the detection zone, inmillimetres
K = the approach speed of the body or part of the body, in millimetres
= 1600 mm/s
T = the overall system stopping performance, in seconds
C = the intrusion distance of the body or part of the body, towards the danger zonebefore actuation of the protective equipment, in millimetres
= 850 mm
then
S = (1600 mm/s ×T) + 850 mm . . . 3(5)
The relationship between minimum distance and response time for devices having adetection capability of between 40 mm and 70 mm is given in Figure 3.5.
The risk of inadvertent access shall be taken into account during the risk assessment stagebut in all cases the height of the uppermost beam shall be not less than 900 mm and theheight of the lowest beam shall be not greater than 300 mm.
Where it is foreseeable that electro-sensitive protective equipment will be used in areaswhere children may be present, the height of the lowest beam shall be not greater than200 mm.
FIGURE 3.5 MINIMUM DISTANCE FOR DEVICES HAVING 40 mm TO 70 mmDETECTION CAPABILITY
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19 AS 4024.2 — 1998
3.6.2.4 Multiple separate beamsMultiple separate beams shall only be used to detectintrusion of the whole body rather than parts of the body.
If the risk assessment indicates that separate beams are appropriate, they shall bepositioned at a minimum distance from the danger zone in accordance with Clause 3.6.2.3.
During risk assessment, methods which can possibly be used to bypass such equipmentshall be taken into account, for example—
(a) crawling below the lowest beam;
(b) reaching over the top beam;
(c) reaching between two of the beams; or
(d) gaining bodily access by passing between two beams.
Where the risk assessment indicates that access to the danger zone can be gained by anyof the methods indicated above, then denial of access shall be provided in accordancewith Clause 3.6.2.3 or by use of physical barriers in accordance with AS 4024.1.
The heights for multiple beams given in Table 3.1 have been found to be the mostpractical in application.
TABLE 3.1
HEIGHT OF MULTIPLE BEAMSmillimetres
No. of beams Heights above reference plane, e.g. floor or conveyor
4 300, 600, 900, 1200
3 300, 700, 1100
2 300, 800
3.6.2.5 Single beams Single beams shall only be used for low risk or secondarysafeguarding applications.
Where the risk assessment supports the use of a single beam to detect the intrusion of aperson’s body, then the minimum safety distance shall be calculated using the followingequation:
S = (1600 mm/s ×T) + 1200 mm . . . 3(6)
The relationship between minimum distance and system response time is shown inFigure 3.6 and examples of using single beams in Figure 3.7.
3.6.2.6 Summary of detection capabilityThe relationship between detection capabilityand permitted applications when used in a normal approach to the detection zone is givenin Figure 3.8.
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AS 4024.2 — 1998 20
FIGURE 3.6 MINIMUM DISTANCE FOR SINGLE BEAMS
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21 AS 4024.2 — 1998
FIGURE 3.7 EXAMPLES OF USING SINGLE BEAMS
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AS 4024.2 — 1998 22
FIGURE 3.8 DETECTION CAPABILITY AND USE IN NORMAL APPROACH
3.6.3 Direction of approach parallel to the detection zone (see Figure 3.9)Thisminimum distance shall be calculated using the following equation:
S = (K × T) + C . . . 3(1)
where
S = the minimum distance from the danger zone to the outermost edge of thedetection zone, in millimetres
K = the approach speed of the body or part of the body, in millimetres
= 1600 mm/s
T = the overall system stopping performance, in seconds
C = 1200 mm − 0.4H, but not less than 850 mm, whereH is the height of thedetection zone above the reference plane, e.g. floor, in millimetres
then
S = (1600 mm/s ×T) + (1200 mm − 0.4H) . . . 3(7)
For this type of protective equipment the heightH of the detection zone shall be amaximum of 1000 mm. However, ifH is greater than 300 mm (200 mm for non-industrialapplications, e.g. where children may be present), there is a risk of inadvertent undetectedaccess beneath the detection zone. This shall be taken into account in the risk assessment.
Where such access is foreseeable, it should be denied through the use of physical barriersin accordance with AS 4024.1. Alternatively, the direction of approach from beneath thedetection zone may be considered an angled approach and the safety distance calculated inaccordance with Clause 3.6.4.
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23 AS 4024.2 — 1998
The lowest allowable height of the detection zone shall be calculated using the followingequation:
H = 15(d − 40 mm) . . . 3(8)
where
H = height of the detection zone, in millimetres
d = detection capability of the device, in millimetres
Thus, for a given height of the detection zone, the corresponding detection capabilitydshall be calculated using the following equation:
. . . 3(9)d H15
40 mm
This means that, where the height of the detection zone is known or fixed, a maximumdetection capability can be calculated, e.g. when calculating the horizontal section ofstand-in electro-sensitive protective equipment; or if a detection capability is known orfixed, a minimum height can be calculated, up to the allowable maximum of 1000 mm(see Figure 3.10).
Where such access is foreseeable, it should be denied through the use of physical barriersin accordance with AS 4024.1, or the direction of approach from beneath the detectionzone be considered an angled approach and the safety distance calculated in accordancewith Clause 3.6.4.
NOTE: Safe distanceS = 1.6 × T + (1200 − 0.4H) where the lowest allowable heightH = 15(d − 40) up to amaximum of 1000 mm
where
T is in milliseconds
d is in mm
and safe distanceS is in mm.
FIGURE 3.9 APPROACH PARALLEL TO THE PLANE OF THE LIGHT CURTAIN
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AS 4024.2 — 1998 24
FIGURE 3.10 DETECTION CAPABILITY Vs MINIMUM HEIGHTABOVE FLOOR
3.6.4 Direction of approach angled to the detection zone (see Figure 3.11)If theprotective equipment has been installed so that the direction of approach to the detectionzone is within ±5° of their design approach (either normal or parallel), then it need not beconsidered as an angled approach detection zone and the relevant equations will apply(see Clauses 3.6.2, 3.6.3 and 3.6.5).For detection zones which are positioned in angles greater than ±5° to the direction ofapproach, account shall be taken of the risks associated with the foreseeable directions ofapproach and the most appropriate equation used.Foreseeable directions of approach greater than 30° should be considered normal approach(see Clause 3.6.2 and Figure 3.11(a)) and foreseeable angles of approach less than 30°should be considered as a parallel approach when calculating the safety distances from thedetection zone to the danger zone (see Clause 3.6.3 and Figure 3.11(b)).When angled approach detection zones are considered as parallel approach then Equation3(8) linking H and d (see Clause 3.6.3) shall apply to the lowest beam or the beam closestto the working surface (seeH in Figure 3.11). In the case of parallel approach, theequation to derive the minimum distanceS shall apply to the beam furthest from thedanger zone. This beam may be used up to a maximum height of the detection zone of1000 mm (see Clause 3.6.3).Detection zones which are positioned at angles between 5° and 30° to the direction ofapproach increase the risk of access to the danger zone, either from beneath the detectionzone, or by leaning over the detection zone from above. Where the risk assessmentconsiders these directions of approach to be foreseeable, they shall be considered as anormal approach and the safety distance calculated in accordance with Clause 3.6.2, oraccess shall be denied through the use of physical barriers in accordance with AS 4024.1.Where denial of access is not practicable, the installation shall satisfy the safety distancerequirements of both normal and parallel approaches.
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FIGURE 3.11 APPROACH ANGLED TO THE PLANE OF THE LIGHT CURTAIN
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AS 4024.2 — 1998 26
3.6.5 Dual position equipment
3.6.5.1 Dual position equipment When the detection zone can be readily converted to aposition either normal or parallel to the direction of approach then the minimum distancesfor both directions of approach shall be applied (see Paragraph A4, Appendix A, andFigure 3.12).
The axis of rotation of the detection zone shall be at a point where both requirements canbe achieved. This need not necessarily be the last beam.
When in position normal to the direction of approach (vertical detection zone) theminimum distance S shall be calculated using Equation 3(2) and a value ofK = 2000 mm/s up to a maximum value ofS = 500 mm.
If S is found to be greater than 500 mm then a value ofK = 1600 mm/s may be used, butwith a minimum distance ofS = 500 mm.
When in position parallel to the direction of approach (horizontal detection zone) theminimum distanceS shall be calculated using Equations 3(7), 3(8) and 3(9) up to amaximum height of 1000 mm.
3.6.5.2 Combined detection zonesWhere the detection zone comprises a combinationof two or more discrete detection zones installed such that they form two detection zonesparallel and normal to the direction of approach, the minimum safety distance for thenormal detection zone, which is usually furthest from the danger zone, shall be calculatedusing Equation 3(2) and a value ofK = 2000 mm/s up to a maximum value ofS = 500 mm. If S is found to be greater than 500 mm then the value ofK = 1600 mm/smay be used, but with a minimum safety distance ofS = 500 mm.
The detection zone parallel to the direction of approach, which is often used to detectpersons standing between the normal detection zone and the danger zone, should betreated as a set of multiple separate beams. The detection capability of the beams isdependent upon the height of the detection zone above the working surface, which willusually be the floor, and shall be calculated using Equation 3(8). (See also Clause 3.6.3).
FIGURE 3.12 DUAL POSITION EQUIPMENT
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3.7 CALCULATING SAFETY DISTANCES FOR FLOOR LEVEL ELECTRO-SENSITIVE PROTECTIVE EQUIPMENT
3.7.1 General method The selection and use of electro-sensitive protective equipmentintended for detection of the feet is dependent on the result of a risk assessment inaccordance with AS 4024.1.
Its use shall be restricted to applications whereH is less than 300 mm above the floor orreference plane, i.e. the maximum acceptable height for a person to step whenapproaching the hazardous area for example a walkway or platform.
The safety distances derived in this Clause assume that the speed of movement towardsthe hazardous area will be a normal walking speed. Additional allowance should be madewhere it is foreseeable that this speed could be greater, as in walking quickly, or running,or where there is the likelihood of tripping and stumbling towards the hazardous area. Therisk of stepping over the detection zone is addressed in Clause 3.7.2.
The safety distance shall be calculated using the following Equation (see Clause 3.6.3):
S = (1600 mm/s ×T) + (1200 mm − 0.4H) . . . 3(7)
where
S = the safety distance (the minimum distance in a horizontal plane from thehazardous area to the outermost beam of the detection zone), in millimetres
T = the overall system stopping performance, in seconds
H = the distance above the reference plane, in millimetres
The lowest allowable height of the detection zone shall be calculated using the followingequation:
H = 15(d − 40 mm) . . . 3(8)
where
H = height of the detection zone, in millimetres
d = detection capability of the device, in millimetres
Thus, for a given height of the detection zone, the corresponding detection capabilitydshall be calculated using the following equation:
. . . 3(9)d H15
40 mm
This means that, where the height of the detection zone is known or fixed, a maximumdetection capability can be calculated, or if a detection capability is known or fixed, aminimum height can be calculated, up to the allowable maximum of 300 mm. (SeeFigure 3.9).
3.7.2 Walking speeds and stride lengths The positioning of equipment which isintended to be activated by a person walking into the detection zone, is affected by speedof approach and stride length.
The walking speed and stride length depend on the physical and anthropometric data ofthe population as follows:
(a) Speed of approachThis Standard assumes that the approach of persons towards thedanger zone will be at normal walking speed.
(b) Stride length Available research data has shown that the 95th percentile of twosteps (i.e. starting and finishing with the same foot) measured from heel contact atwalking speed is approximately 1900 mm. By dividing by 2 and subtracting the 5thpercentile female shoe length this gives a stride length of 700 mm. If it is assumedthat an allowance has to be made, for example, between the detection zone and thestride length of, e.g. 50 mm, this gives a minimum width of 750 mm for thedetection zone.
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AS 4024.2 — 1998 28
3.7.3 Floor mounting In situations where the electro-sensitive protective equipment isfitted directly onto the floor,H will approach zero. Therefore the safety distance shall becalculated using Equation 3(10) derived from Equation 3(7) (see Clause 3.6.3), as follows:
S = (1600 mm/s ×T) + 1200 mm . . . 3(10)
3.7.4 Step mounting If the trip device is mounted onto a step or raised platform thenthe minimum distance may be reduced by 0.4H, where H is the height of the step inmillimetres.
3.8 BLANKING
3.8.1 General Blanking may be used if it is essential to both the process and themachine. Where blanking is not necessary for a machine the facility should not beavailable.
Situations where blanking may be acceptable include those where material beingprocessed would actuate the electro-sensitive protective equipment during part or all ofthe operation cycle and where arrangements for differentiating between material and theoperator are considered impractical. Examples include feeding strip into a press.
3.8.2 Requirements Where blanking is provided the following requirements shall bemet:
(a) Where it is possible to select the blanking facility, selection shall be by meanswhich do not allow indiscriminate use of the facility e.g. by means of a key-operated switch or password access to the software.
(b) Access to the danger zone through the blanked portion of the electro-sensitiveprotective equipment shall be prevented by barriers in accordance with AS 4024.1.
(c) Blanking shall be effective across the full width of the electro-sensitive protectiveequipment.
(d) A label indicating that a blanking facility is fitted to the electro-sensitive protectiveequipment shall be provided.
3.8.3 Blanking techniques Blanking is normally achieved by using one of thefollowing techniques:
(a) Physically removing a transmitter(s) and receiver(s) from the equipment.
(b) Disabling a transmitter(s) and receiver(s) in the equipment by switching them off.
(c) Blanking off part of the equipment.
3.8.4 Visual indicators One or more visual indicators shall be provided whichilluminate when the protective equipment is in a blanked condition.
The combined illuminated area of the blanking indicators shall be at least 1 cm2 and havea luminance of not less than 200 cd/m2.
Any fault condition of the blanking indicator which results in a failure to comply with therequirements shall ensure that the protective equipment does not allow a muted condition.
The blanking indicator shall be arranged to be readily visible from any normal operatingposition of the machine to which the device is designed to be applied and from theposition at which any adjustment of the blanking is normally carried out.
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S E C T I O N 4 S A F E T Y - R E L A T E DC O N T R O L S Y S T E M S
4.1 SAFETY-RELATED CONTROL SYSTEMS FITTED WITH ELECTRO-SENSITIVE PROTECTIVE EQUIPMENT When designing the safety-related part ofthe control system interface which is connected to the electro-sensitive protectiveequipment, the level of safety integrity of the device should be maintained and careshould be taken that the switching commands are appropriately processed. Seeinterlocking considerations of AS 4024.1.
Where practicable, agreement on the safety-related part of the control system and itsinterface to the electro-sensitive protective equipment should be obtained between themanufacturers of the electro-sensitive protective equipment and of the control system.
A piece of electro-sensitive protective equipment may be fitted to a machine only if thesafety-related control system is so designed that—
(a) a dangerous situation cannot arise when the equipment is in the ‘off’ state;
(b) a dangerous situation is removed when the equipment changes to the ‘off’ state,except where the equipment is used exclusively as a machine-start interlock; and
(c) when Category 2 electro-sensitive protective equipment is used, the system testshould be initiated by the safety-related machine control system, and an evaluationof the results of the system tests should take place in the control system.
It is recommended that the test is made at switch-on and at intervals determined by therisk assessment.
When more than one piece of electro-sensitive protective equipment has been installed atone location, then a start interlock and restart interlock should be provided for eachelectro-sensitive protective device.
When several pieces of electro-sensitive protective equipment are used to form a detectionzone a common start interlock and reset interlock is allowed.
The initiation of the first cycle after—
(i) switching on;
(ii) changing the operating mode of the machine; or
(iii) changing the type of operation of the electro-sensitive protective equipment;
shall be possible only after actuation of the operating element of the machine-startinterlock.
Following an entry into the detection zone, a further machine cycle shall be possible onlyafter the detection zone has been cleared, or the hazardous area has been vacated and afteroperation of the reset actuator.
The operating element of the restart interlock may be the same actuator as the operatingelement of the start interlock.
4.2 ELECTRO-SENSITIVE PROTECTIVE EQUIPMENT USED AS A MACHINE-START INTERLOCK The requirements of Clause 3.2 do not apply when theequipment exclusively operates as a machine-start interlock since this application wouldalways be used in conjunction with another form of guarding. A typical application iswhere electro-sensitive protective equipment is provided inside physical barrier guardsinstalled in accordance with AS 4024.1 to detect the presence of a person within thedanger zone. In these applications, the risk assessment must take account of allforeseeable postures and positions of the person, and the electro-sensitive equipment
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installed in such a way that it detects all foreseeable conditions, e.g. climbing on part ofthe machine so that the person is above the detection zone. Electro-sensitive protectiveequipment used exclusively as a machine-start interlock offers no protection during theworking cycle of power-driven machinery.
4.3 NORMAL START OPERATION
4.3.1 General The operating elements in the start interlock and in the restart interlockshall not be capable of being operated from inside the detection zone. It shall not bepossible to initiate a normal operation after switching off the electro-sensitive protectiveequipment.
Normal start operation means a machine cycle associated with the designed productionintent of the machine. It includes loading and unloading of components, but does notencompass activities such as machine setting or adjustments which shall be protected byother safety measures.
4.3.2 Position Control devices shall be positioned and spaced so as to provide safe andeasy operation and there should be ample clearance between each control and other partsof the machinery. Control devices should be so placed that the operator can reach themeasily without stretching or moving from a normal working position. The controls mostfrequently used should be placed in the most accessible positions.
4.3.3 Warning signals On installations where the main operating station or startcontrol is in a position from which the people in the vicinity of dangerous parts of themachinery cannot be seen clearly, audible and visual warnings shall be operated through asuitable interlock for a predetermined time before the machinery starts to operate. Wherepracticable, start-up should result in a progressive speed increase to full running speed.Adjacent machines should be provided with distinguishable audible signals.
Where malfunction of the machinery creates a hazard, suitable warning signals shall begiven. These signals should be given automatically and shall be both auditory and visual.
Auditory and visual warnings may be provided in addition to, but not as substitution for,physical safeguards.
Auditory and visual warnings shall be either monitored or shall fail to safety.
4.4 MUTING
4.4.1 General Muting may be used if it is essential to the process currently beingundertaken on the machine. When muting is not required on a particular machine, thefacility should not be available.
Situations where a mute condition may be acceptable include those—
(a) where material being processed would actuate the sensing system during part of thecycle of operations, and where arrangements for differentiating between the materialand the operator are impracticable; or
(b) where close observation of the process requires the operator to stand in a positionthat may cause interruption to the sensing system.
Muting should be used only during the time in the operating cycle or sequence, whensafety is maintained by alternative means. The position at which muting occurs should beindependent of the overall system response time and also of operator intervention. Themute may be adjusted automatically when the operator adjusts other machine operatingparameters, e.g. to accommodate different material thicknesses. If the position at whichmuting occurs can be adjusted, the means of adjustment shall be provided with a lockingfacility so that adjustment is restricted to competent persons designated within anappropriate system of work.
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NOTE: When used in conjunction with the control system of a power press, e.g. press brake,‘mute’ refers to the position in the final closing portion of the press stroke where the pressautomatically stops at a distance of 10 mm from the bottom of the stroke, or 3 mm above thethickness of the material to be processed. This latter mute setting is only where the 10 mmbottom stop is not practicable to achieve, for example when deep drawing dies are in use.
At this point the sensing unit of the electro-sensitive protective equipment device may be mutedfor the remainder of the closing stroke and, if there are no danger points, for all of the openingstroke.
4.4.2 Requirements Where muting is provided the following requirements shall bemet:
(a) Selection of the muting facility (for example, to set or for maintenancerequirements) shall be by means of a key-operated switch.
(b) The device or system used to control the mute position should be automaticallymonitored to ensure that its effective function cannot be circumvented. Thiscondition can be met by checking for the change-over state of the muting switchduring the return stroke before the next cycle.
(c) The signals necessary for muting if occurring in an invalid combination shall, atleast, ensure that the protective equipment device does not allow a muted condition.
4.4.3 Visual indicators One or more visual indicators shall be provided whichilluminate when the protective equipment is in a muted condition.
The combined illuminated area of the mute indicators shall be at least 1 cm2 and have aluminance of not less than 200 cd/m2.
Any fault condition of the mute indicator which results in a failure to comply with therequirements shall ensure that the protective equipment does not allow a muted condition.
The mute indicator shall be arranged to be readily visible from any normal operatingposition of the machine to which the device is designed to be applied and from theposition at which any adjustment of the muting is normally carried out.
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S E C T I O N 5 F U N C T I O N A L R E Q U I R E M E N T SO F A D D I T I O N A L S A F E T Y - R E L A T E D
C O N T R O L S Y S T E M S
5.1 GENERAL Electro-sensitive protective equipment may provide additional devicesor functions, arranged to perform optional functions within the safety-related controlsystem. The selection and utilization of such devices or functions depend on the categoryof control and application.
The electro-sensitive protective equipment together with the optional functions shall meetthe requirements of this Standard.
NOTE: To assist in the understanding of electro-sensitive protective equipment, block schematicdiagrams are shown in Figures 5.1 and 5.2.
Optional safeguarding devices or functions are as follows:
(a) Safety monitoring devices (see Clause 5.2).
(b) Stopping performance monitor (see Clause 5.3).
(c) Secondary switching device (see Clause 5.4).
(d) Start interlock (see Clause 5.5).
(e) Restart interlock (see Clause 5.6).
The following have elements which are not safeguarding functions or devices:
(i) Muting (see Clause 5.7).
(ii) Electro-sensitive protective equipment used as a machine-restart device (seeClause 5.8).
5.2 SAFETY MONITORING DEVICES
5.2.1 Functional requirements When connected to the electro-sensitive protectiveequipment, the safety monitoring devices shall provide electrical signals that correspondunambiguously to the output states of the device to which it is applied.
The safety monitoring devices shall monitor at least—
(a) the state of the output from each signal switching device;
(b) the state of the output from the secondary switching device; and
(c) the state of machine primary control elements to ensure that each machine primarycontrol element is responding correctly to the output from the corresponding outputsignal switching device.
When provision is made for connection of external safety monitoring devices, the controlmonitoring function shall provide a test signal proving that, at every change of state of amonitored element, the corresponding signal is received from its safety monitoring means.
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FIGURE 5.1 SCHEMATIC EXAMPLE OF INTERFACING CATEGORY 2 ELECTRO-SENSITIVE PROTECTIVE EQUIPMENT TO A MACHINE CONTROL SYSTEM
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FIGURE 5.2 SCHEMATIC EXAMPLE OF INTERFACING CATEGORY 4 ELECTRO-SENSITIVE PROTECTIVE EQUIPMENT TO A MACHINE CONTROL SYSTEM
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5.2.2 Fault condition requirements A safety monitoring device shall be incapable ofcontinuing to change its output signal under failure conditions of the device to which it isapplied.
Failure to achieve the correct response from the safety monitoring device shall result in alock-out condition.
NOTE: This can be achieved by checking current, voltage, mechanical movement of contactors,or other means, to ensure the output is responding correctly to the appropriate control unitsignal.
For Category 2 electro-sensitive protective equipment, the output signal switching device,the final switching device and the machine primary control device where fitted, shall bemonitored by application of the periodic check and if failures are revealed the machinesecondary control element shall go to the ‘off’ state, (see Figure 5.2). More detailedrequirements for the design of safety related parts of control systems for Category 2electro-sensitive protective equipment are given in AS 4024.1.
Advice on the selection of Categories is given in Appendix B.
5.3 STOPPING PERFORMANCE MONITOR
5.3.1 Functional requirements The stopping performance monitor shall providesignals to the electro-sensitive protective equipment related to the time taken by, or theamount of travel of, the dangerous parts of the machine in coming to rest or reverting to asafe condition.
The stopping performance monitor shall apply an automatic stopping performance test tomonitor the overall system stopping performance.
The stopping performance monitor shall be capable of initiating the automatic stoppingperformance test in response to signals derived from one or both of the following sources:
(a) The electro-sensitive protective equipment, immediately upon actual or simulatedactuation of the sensing function.
(b) The stopping performance monitor itself, in response to the machine reaching aspecific point in its operating cycle.
NOTE: The source used and the measurement conditions will be determined by the applicationof the electro-sensitive protective equipment.
For a Category 4 electro-sensitive protective equipment application, the electro-sensitiveprotective equipment shall have two input channels for stopping performance monitoring.If either of these input devices operate incorrectly, the electro-sensitive protective deviceshall go to a lock-out condition. More detailed requirements for the design of safetyrelated parts of control systems is given in AS 4024.1 and Appendix B. Advice on theselection of Categories is given in Appendix B.
Any means by which the present limit(s) within the stopping performance monitor may beadjusted shall be in a lockable enclosure.
Lock-out in this context refers to a lock-out of the electro-sensitive protective equipmentand is not to be confused with the term lock-out in respect of machine lock-out andisolation.
Lock-out of the electro-sensitive protective equipment is a condition of the system whichis automatically attained both when its supply mains are interrupted and restored and inresponse to failure signals. From a lock-out condition, normal operation can be achievedonly by removing the fault which caused the equipment to enter the lock-out conditionand restarting the electro-sensitive protective equipment.
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5.3.2 Fault condition requirements The electro-sensitive protective equipment or themachine safety-related control system shall go to a lock-out condition in response to anyof the following conditions:
(a) When the preset limit of stopping performance is exceeded.
(b) Upon failure to apply, respond to or complete the automatic test.
(c) Upon failure of transmission of motion to the stopping performance monitor orwhere duplicated transmission devices are used, the failure of either one of thosedevices.
(d) Upon disconnection of the stopping performance monitor from the electro-sensitiveprotective equipment.
5.3.3 Marking The supplier shall provide permanently affixed marking to the stoppingperformance monitor, giving the following information:
(a) Name and address of the supplier.
(b) Type or model number and serial number.
(c) The electro-sensitive protective equipment category for which the stoppingperformance monitor is designed.
(d) The parameter monitored, e.g. time, angle, linear displacement.
(e) The accuracy of the unit.
5.4 SECONDARY SWITCHING DEVICE
5.4.1 Functional requirements When the electro-sensitive protective equipment is in alock-out condition, the secondary switching device shall be in the ‘off’ state.
The ability of the secondary switching device to perform its safety related function shallbe checked by an automatic test carried out when machine power is switched on andbefore the machine is operated.
NOTE: The output circuit of the secondary switching device should be adequately protected toprevent failures to danger under overcurrent conditions.
5.4.2 Fault condition requirements If the automatic test referred to in Clause 5.4.1identifies a failure of the secondary switching device to go to the ‘off’ state whenmachine power is switched off, the output signal switching device(s) shall remain in the‘off’ state.
5.5 START INTERLOCK
5.5.1 Functional requirements After a lock-out occurs, when the electro-sensitiveprotective equipment electrical supply is switched on or is interrupted and restored, thestart interlock shall ensure that the lock-out condition is maintained if the sensing zoneremains interrupted or the defined signal range is exceeded.
The lock-out condition shall continue until the start interlock is manually reset to its ‘on’state.
5.5.2 Fault condition requirements A failure of the start interlock which causes it togo to, or remain in, a permanent ‘on’ state shall cause the output signal switching deviceto go to, or remain in, the ‘off’ state.
5.6 RESTART INTERLOCK
5.6.1 Functional requirements The restart interlock shall cause the output signalswitching device to go to the ‘off’ state when—
(a) the start interlock, if fitted, has not been reset to the ‘on’ state;
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(b) the sensing zone is interrupted or the defined signal range is exceeded while themachine movement is at a dangerous part of its operating cycle;
(c) the sensing zone is interrupted or the defined signal range is exceeded while themachine is in automatic or semi-automatic mode;
(d) the periods to next initiation or cycle time referred to in Clause 5.8.2 are exceeded;or
(e) there is a change of the machine operating mode or type of operation.
After initiation, the restart interlock shall ensure that the lock-out condition is maintainedif the sensing zone remains interrupted or the defined signal range is exceeded.
The lock-out condition shall continue until the restart interlock is manually reset.
5.6.2 Fault condition requirements A failure of the restart interlock which causes itto go to, or remain in, a permanent ‘on’ state, shall be automatically revealed and shallcause the output signal switching device to go to the ‘off’ state.
NOTE: This may be achieved by causing the start interlock to go to the ‘off’ state.
5.7 MUTING
5.7.1 Functional requirements One or more visual indicators shall be provided whichshall illuminate when the electro-sensitive protective equipment is in a muted condition.
The combined illuminated area of the mute indicators shall be at least 1 cm2 and have abrightness (luminance) of not less than 200 cd/m2.
The mute indicator(s) shall be arranged to be readily visible from any normal position ofthe operator of the machine to which the electro-sensitive protective equipment isdesigned to be applied, from the position at which any adjustment of the muting isnormally carried out.
In Category 4 electro-sensitive protective equipment, there shall be two independent hard-wired muting signal sources, of the same level of safety integrity as the electro-sensitiveprotective equipment. More detailed requirements for the design of safety related parts ofelectro-sensitive protective equipment are given in AS 4024.1.
Advice on the selection of Categories is given in Appendix B.
If conflicting muting signals occur, the electro-sensitive protective equipment shall notallow a muted condition to occur.
5.7.2 Fault condition requirements Any fault condition of the mute indicator(s)which results in a failure to comply with the requirements of Clause 5.7.1 shall ensurethat the electro-sensitive protective equipment does not allow a muted condition to occur.
In Category 2 electro-sensitive protective equipment, any failure to danger in the mutinginput shall be revealed by the periodic test, and shall at least ensure that the electro-sensitive protective equipment does not allow a muted condition to occur. More detailedrequirements for the design of safety related parts of electro-sensitive protectiveequipment are given in AS 4024.1.
Advice on the selection of the Categories is given in Appendix B.
5.8 ELECTRO-SENSITIVE PROTECTIVE EQUIPMENT USED AS A MACHINE-RESTART DEVICE
5.8.1 General In addition to its function as a protective device, the electro-sensitiveprotective equipment can be used to initiate machine operation.
The following modes of operation can be used:
(a) Single break, where an actuation and de-actuation of the sensing function initiatesmachine movement.
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(b) Double break, where two consecutive actuations and de-actuations of the sensingfunction initiate machine movement.
5.8.2 Functional requirements The function shall be selected only by a key switch.After switch-on or actuation of the sensing function during dangerous motion, it shall notbe possible to use either mode of operation before the operation of the restart interlock.
Successive initiations of machine operation by use of the modes of operation described inClause 5.8.1 shall be possible only within the normal cycle time of the machine.
When a machine can be operated in either single or double break modes the followingconditions shall be fulfilled:
(a) The first cycle shall require a manual start signal.
(b) Effective provision shall be made and maintained to ensure that it is impossible forpersons to pass completely through the detection zone towards the hazard and toallow the electro-sensitive protective equipment to clear behind them. This includesclimbing into the danger zone e.g. die-space or pallet-well.
(c) The electro-sensitive protective equipment shall be effective at all times during thedangerous motion of the machinery.
(d) The automatic machine initiation system shall not reduce the safety integrity of thebasic electro-sensitive protective equipment.
(e) The facility for automatic initiation of machinery motion upon clearing of thecurtain shall be limited to a period of time commensurate with the normal cycletime.
(f) A restart interlock is required for occasions when machinery motion is notautomatically initiated within that limited period.
(g) If the electro-sensitive protective equipment is actuated during hazardous motion itshall not be possible for further motion to be initiated until the safety related controlsystem has been completely restored to its normal condition and the machinecontrols have been manually operated.
Initiation of a further machine start by the electro-sensitive protective equipment shallonly be possible within a period of 30 s, or within the normal cycle time of the machine.If this period is exceeded, it will be necessary to operate the restart interlock in order toinitiate another machine start.
Where the electro-sensitive protective equipment is intended to detect fingers or hands,machine initiation is allowed only when the detection capability of the electro-sensitiveprotective equipment does not exceed 14 mm (see also Clause 3.6.2.2).
5.8.3 Fault condition requirements If the limited restart period referred to in Clause5.8.2 is exceeded, further machine initiation shall not be possible until the restart interlockhas been operated and the device for counting the re-actuations of the sensing zone hasbeen reset.
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S E C T I O N 6 C O M M I S S I O N I N G A N D T E S T I N G
6.1 SCOPE OF SECTION This Section considers the examination, inspection andtesting of the total installation, i.e. the machine and its associated electro-sensitiveprotective equipment.
6.2 DOCUMENTATION The machine supplier and the electro-sensitive protectiveequipment supplier shall ensure that information on the routine maintenance and theexamination requirements for the equipment are available to the user. Details of theserequirements should include lubrication, routine adjustments, routine examination and,where necessary, replacement of mechanical or electrical parts expected to wear or fail.Users should be informed of methods of ascertaining that the machine and the electro-sensitive protective equipment are operating within their specifications.
6.3 FREQUENCY OF TESTING The procedures for examination, inspection andtesting should be carried out at the following times:
(a) When the installation is first commissioned, the total ‘package’ of machine andelectro-sensitive protective equipment shall be examined and tested (see Clause 6.4).
(b) Installations shall be examined every six months by a competent person (see Clause6.5).
(c) Installations shall be tested by a designated person daily and after resetting (seeClause 6.6).
NOTE: Daily testing should be performed only when the machine is scheduled for operationon that day.
6.4 COMMISSIONING EXAMINATION AND TESTS
6.4.1 General The commissioning examination and test shall be carried out bycompetent persons who possess all the information on the machine provided by theelectro-sensitive protective equipment suppliers.
Results of the examination and tests shall be recorded and copies of the record kept by theuser and by the employer(s) of the person(s) carrying out the tests.
6.4.2 Performance The persons carrying out these tests shall ensure that the followingperformance is achieved:
(a) It shall not be possible for the hazardous parts of the machine to be set in motionwhilst any part of a person is in a position to actuate the electro-sensitive protectiveequipment.
(b) Actuation of the electro-sensitive protective equipment shall result in the hazardousparts being arrested or, where appropriate, assuming an otherwise safe conditionbefore any part of any person can reach them. It shall not be possible for thehazardous parts to be set in motion again until the electro-sensitive protectiveequipment has been completely restored to its normal condition.
6.4.3 Additional requirements The persons carrying out the tests shall also—
(a) inspect the position of the electro-sensitive protective equipment to ensure that it isset at the correct distance from the hazardous parts of machinery as recorded on themachine or electro-sensitive protective equipment information label or plate;
(b) ensure that additional safeguarding has been provided where necessary to preventaccess to the hazardous parts of machinery from any direction not protected by theelectro-sensitive protective equipment;
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(c) where appropriate, test the overall system response time using a timing instrumentdesigned for this purpose, and ensure that it is the same or less than the overallsystem response time recorded on the information label or plate;
(d) test that it is not possible for a person to stand between the electro-sensitiveprotective equipment and the hazardous parts of the machinery;
(e) test the detection capability according to the supplier’s recommendations;
(f) examine the machine controls and the connections to the electro-sensitive protectiveequipment to ensure that the machine and electro-sensitive protective equipmentdesign requirements are met;
(g) examine the stopping performance monitor, if fitted, to ensure that it is correctlypositioned and fitted, test that the monitor is working satisfactorily to the supplier’srecommendation, and ensure that the means whereby the stopping performance canbe assessed by the operator is indicating correctly;
(h) test the muting arrangements, if fitted; and
(i) examine any brakes or clutches, if fitted, to the manufacturer’s recommendation.
6.5 SIX- OR TWELVE-MONTHLY EXAMINATION, INSPECTION AND TESTPROCEDURE
6.5.1 General The user shall ensure that when orders or contracts are placed, thepersons competent to carry out these examinations, inspections and test procedures areidentified. Those persons may be representatives from independent inspectingorganizations such as insurance companies, machinery manufacturers or agents, electro-sensitive protective equipment suppliers, or from within the user’s organizations.
The results of the examination, inspection and test shall be recorded and a copy of therecord shall be retained by the user.
6.5.2 Performance The person carrying out the examination shall ensure that thefollowing performance is achieved:
(a) It shall not be possible for the hazardous parts of the machine to be set in motionwhilst any part of a person is in a position to actuate the electro-sensitive protectiveequipment.
(b) Actuation of the electro-sensitive protective equipment shall result in the hazardousparts being arrested or, where appropriate, assuming an otherwise safe conditionbefore any part of any person can reach them. It shall not be possible for thehazardous parts to be set in motion again until the electro-sensitive protectiveequipment has been completely restored to its normal condition.
6.5.3 Additional requirements The person carrying out the tests shall also—
(a) carry out the examination, inspection and tests set out in the commissioningprocedures detailed in Clause 6.4, for stopping performance and for testing aspermissible the alternative means for determining that the overall system responsetime recorded on the information label has not been exceeded;
(b) examine and test the machine primary control elements to ensure that they arefunctioning correctly and are not in need of maintenance or replacement;
(c) inspect the machine to ensure that there are no mechanical or structural aspects thatshould prevent the machine from stopping or assuming an otherwise safe conditionwhen called upon by the electro-sensitive protective equipment to do so; and
(d) examine and inspect the machine controls and connections to the electro-sensitiveprotective equipment to ensure that no modification has been made which couldadversely affect the system, and that suitable modifications have been properlyrecorded.
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6.6 TESTS TO BE CARRIED OUT DAILY AND AFTER SETTING
6.6.1 General Daily tests, and tests after re-setting, shall be carried out by adesignated person appointed by the machine user. A copy of the results shall be kept onor near the machine. Daily testing should be carried out only when the machine isscheduled for operation on that day.
NOTE: Specific regulatory requirements may apply to certain classes of machinery.
6.6.2 Performance The designated person shall—
(a) check that access to the hazardous parts of machinery is not possible from anydirection not protected by the electro-sensitive protective equipment and that anyside and rear guards are in order;
(b) check that the minimum distance from the hazardous parts of machinery to theelectro-sensitive protective equipment is not less than the safety distance stated onthe machine or the electro-sensitive protective equipment information plate; and
(c) check that it is not possible for a person to stand between the electro-sensitiveprotective equipment and hazardous parts of machinery.
6.6.3 Additional requirements The effectiveness of the electro-sensitive protectiveequipment, with power on but with the machine initially at rest, shall be tested as follows:
(a) Establish that the electro-sensitive protective equipment is functioning by checkingthe state of the appropriate indicators, and ensure that the electro-sensitiveprotective equipment is not muted.
(b) Insert the appropriate diameter test piece into the detection zone at an approachangle similar to that used by operator while the machine is in use. The test pieceshould be passed very slowly down the detection zone in three separate places; closeto each transmitter/receiver, and in the middle of the detection zone. The test lightwhich indicates interruption of the detection zone should change state whenever thetest piece enters and leaves the detection zone and should not change state for thewhole time the test piece is in the detection zone.
(c) Initiate machine movement and insert the test piece into the detection zone. Underno circumstances should an attempt be made to insert the test piece into or betweenthe hazardous parts of machinery. Upon insertion of the test piece during motion,the hazardous parts should come to rest without observable delay.
(d) Test that when the mute mode is operative, i.e. the electro-sensitive protectiveequipment is muted, the moving parts of machinery are no longer hazardous. Forexample, the gap between the top and bottom tools at muting on a press brakeshould be just greater than the material thickness. Check that the mute indicator isilluminated when the electro-sensitive protective equipment has been muted.
(e) Check that the stopping performance monitor (where provided) is in use and is setup and functioning in the manner recommended by the manufacturer.
(f) Check that the cabinets housing the electronic apparatus are closed and locked, andthat the key is removed for retention by a designated person.
(g) Check for external signs of damage to equipment or to electrical wiring. Anydamage found should be immediately reported to line management.
6.7 TESTING OF OPTIONAL REQUIREMENTS
6.7.1 Safety monitoring device Verify by inspection and test that—
(a) the safety monitoring device is connected so that it monitors—
(i) the state of the output from each output signal switching device;
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(ii) the state of the output from the secondary switching device; and
(iii) the corresponding state of the machine primary control element(s) and theoutput signal switching device(s);
(b) for an external safety monitoring device, the protective device control unit applies atest to prove that the change of state of the monitored element(s) produces acorresponding signal(s) to the safety monitoring means;
(c) the safety monitoring device cannot continue to change its output signal when thedevice to which it is applied has failed;
(d) when an incorrect response is received from the safety monitoring device, a lock-outcondition is achieved; and
(e) for a Category 2 electro-sensitive protective equipment application, when a failure isrevealed by the external test, an appropriate signal is available to switch a machinesecondary control element to the ‘off’ state.
6.7.2 Stopping performance monitor Verify by inspection that—
(a) the stopping performance monitor initiates an automatic test in response to a signalfrom the electro-sensitive protective equipment or the machine control system;
(b) the stopping performance monitor output signal(s) causes the electro-sensitiveprotective equipment or the machine safety related control system to go to a lock-out condition when the preset limit of stopping performance is exceeded;
(c) the appropriate parameter is being monitored, e.g., time, angle, linear displacement;
(d) for a Category 4 electro-sensitive protective equipment application there are at leasttwo independent signal sources from the stopping performance monitor to theelectro-sensitive protective equipment or the machine safety related control systemand failure of either one of those causes lock-out;
(e) any adjustment means are in a lockable enclosure;
(f) when the automatic test has failed to be applied or completed, a lock-out conditionis achieved;
(g) when any of the transmission of motion means has failed, a lock-out condition isachieved;
(h) when the stopping performance monitor is disconnected from the electro-sensitiveprotective equipment or safety-related control system, a lock-out condition isachieved; and
(i) the markings comply with Clause 5.3.3 and are correct.
6.7.3 Secondary switching device Verify by inspection and test that—
(a) the secondary switching device is in the ‘off’ state under lock-out conditions; and
(b) when the secondary switching device is in the ‘on’ state and machine power isswitched on, the output signal switching device(s) remain(s) in the ‘off’ state, evenwhen a reset is attempted.
6.7.4 Start interlock Verify by inspection and test that—
(a) when the start interlock is in the ‘off’ state, a lock-out condition is initiated;
(b) when the electro-sensitive protective equipment power supply is switched on, thestart interlock remains in the ‘off’ state until the start interlock actuator is manuallyoperated;
(c) if the start interlock fails to an ‘on’ state, the output signal switching device(s) arein the ‘off’ state; and
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(d) after a lock-out condition, the start interlock shall not go to an ‘on’ state if thesensing function remains interrupted or the defined signal range is exceeded.
6.7.5 Restart interlock Verify by inspection and test that—
(a) when the restart interlock is in the ‘off’ state, a lock-out condition is initiated;
(b) the restart interlock will not go to the ‘on’ state when the start interlock is in the‘off’ state;
(c) the restart interlock will not reset to the ‘on’ state while the detection zone isinterrupted during a dangerous machine motion;
(d) should the electro-sensitive protective equipment be used as a machine restartdevice and the times referred to in Clause 5.8.2 are exceeded the restart interlockgoes to the ‘off’ state;
(e) when the machine operating mode or type of operation is changed the rest interlockgoes to the ‘off’ state; and
(f) should the restart interlock fail to an ‘on’ state, movement of dangerous machineparts is prevented.
6.7.6 Muting Verify by inspection and test that—
(a) visual indicators are provided, as required by Clause 5.7.1;
(b) failures of the indicators to comply with Clause 5.7.1 are revealed by preventing amuted condition;
(c) in a Category 4 electro-sensitive protective equipment there are two independenthard wired muting signal sources which—
(i) are automatically checked before starting the operation of the machine;
(ii) are automatically checked at each machine cycle; and
(iii) in the event of (i) and (ii) giving an invalid combination of signals, a mutedcondition is prevented; and
(d) in a Category 2 electro-sensitive protective equipment, any failure which could leadto a dangerous condition is revealed by the periodic test and when such a failure isdetected, a muted condition is prevented.
6.7.7 Electro-sensitive protective equipment used as machine restartVerify byinspection and test that—
(a) after switch-on, machine initiation is possible only following the operation of therestart interlock;
(b) after actuation of the sensing zone during dangerous machine motion, furthermachine initiation is possible only following the operation of the restart interlock;
(c) for a double break application if the second actuation and de-actuation of thesensing function is not consecutive, the machine initiation is prevented and anyfurther machine initiation is possible only after the operation of the restart interlock;and
(d) if a second machine initiation is attempted at an interval greater than the presetinterval between successive breaks, which shall not exceed 30 s, machine movementis prevented and further machine initiation is possible only after the operation of therestart interlock.
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APPENDIX A
WORKED EXAMPLES OF SAFETY DISTANCES
(Informative)
A1 WORKED EXAMPLES The following examples show how this Standard can beused to determine safety distances for electro-sensitive protective equipment.
It is assumed in these examples that either the risk assessment for the relevant machine, orthe machine-specific Standard, will allow the protective equipment chosen for theseexamples.
A2 EXAMPLE 1 A machine has a stopping time of 60 ms. It is to be fitted withelectro-sensitive protective equipment employing a vertical active optoelectronicprotective device having a detection capability of 14 mm and a response time of 30 ms(see Figure A1).
Using Equation 3(2)—
S = (2000 mm/s ×T) + 8(d − 14 mm) . . . 3(2)
where
S = the minimum distance from the danger zone to the detection zone, inmillimetres
T = the overall system stopping performance of (60 + 30) ms = 90 ms
d = 14 mm
then—
S = (2000 mm/s × 0.09 s) + 8(14 − 14) mm
S = 180 mm.
A3 EXAMPLE 2 This example features the same machine as in Paragraph A2 but witha detection capability of 30 mm.
Using Equation 3(2)—
S = (2000 mm/s ×T) + 8(d − 14 mm) . . . 3(2)
where
T = the overall system stopping performance of (60 + 30) ms = 90 ms
d = 30 mm
then—
S = (2000 mm/s × 0.09 s) + 8(30 − 14) mm
S = 180 mm + 128 mm
S = 308 mm.
A4 EXAMPLE 3
A4.1 Introduction A dual position detection zone is required for a machine with atable height of 1000 mm. Overall system stopping performanceT is 100 ms and thedetection capability of the curtaind is 40 mm (see Figure A2).
A4.2 Vertical application Using Equation 3(2)—
S = (2000 mm/s ×T) + 8(d − 14 mm) . . . 3(2)
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where
T = 100 ms
d = 40 mm
then—
S = (2000 mm/s × 0.1 s) + 8(40 − 14) mm
S = 200 mm + 208 mm
S = 408 mm
This determination is not greater than 500 mm so the equation is valid.
A4.3 Horizontal application Using Equation 3(7)—
S = (1600 mm/s ×T) + (1200 mm − 0.4H) . . . 3(7)
where
(1200 mm − 0.4H) is not less than 850 mm
then—
S = (1600 mm/s × 0.1 s) + 850 mm
S = 160 mm + 850 mm
S = 1010 mm
The pivot point will therefore be at a horizontal distance of 408 mm from the dangerzone.
The minimum length of the detection zone will be (1010 − 408) mm = 602 mm.
Risk assessment will indicate if additional safeguarding is required.
A5 EXAMPLE 4 A machine has a stopping time of 200 ms. It is to be fitted withelectro-sensitive protective equipment having a response time of 30 ms. The height of thedanger zoneH above the ground is 1000 mm.
Using Equation 3(5)—
S = (1600 mm/s ×T) + (1200 − 0.4H) . . . 3(5)
where
S = the minimum distance from the danger zone to the outermost edge of thedetection zone, in millimetres.
T = the overall system stopping performance of (200 + 30) ms = 230 ms
then—
S = (1600 mm/s × 0.23 s) + 1200 − (0.4 × 1000) mm
S = 368 mm + 800 mm
S = 1168 mm
However, the value of (1200 − 0.4H) shall be not less than 850 mm;
S = 368 + 850 mm
= 1218 mm
The electro-sensitive protective equipment is now located on an arc of radius 1218 mmcentred on the danger zone. The height above the ground of the uppermost beam is thendetermined. The selection of this height is critical so as to ensure that access to the dangerzone cannot be gained by reaching over the protective equipment. (See also Appendix C.)
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This height is determined as follows:
(a) From Figure C1, locate the height of the danger zoneH, in the leftmost column. Inthis caseH = 1000 mm. IfH lies between two listed values, use the higher value.
(b) Read across to the right to locate the horizontal distance to the danger zoneS. Inthis caseS = 1218 mm. IfS lies between two listed values, use the lower value, thusin this instance use a value ofS = 1000.
(c) Read upwards to the column heading to locate the height of the uppermost beamU.In this caseU = 1200 mm.
The electro-sensitive protective equipment is therefore located on an arc having a radiusof 1218 mm, the uppermost beam being located 1200 mm above the standing surface.
A6 EXAMPLE 5
A6.1 General A machine has a stopping time of 200 ms. It is to be fitted withelectro-sensitive protective equipment having a response time of 20 ms and positioned asshown in Figure A3. The height of the danger zone above the ground is 1000 mm and thedetection capability of the vertically positioned equipment is 30 mm.
A6.2 Safety distance calculation Using Equation 3(2)—
S = (2000 mm/s ×T) + 8(d − 14 mm) . . . 3(2)
where
S = the minimum distance from the danger zone to the detection zone, inmillimetres
T = the overall system stopping performance of (200 + 20) ms = 220 ms
d = 30 mm
then—
S = (2000 mm/s × 0.22s) + 8(30 − 14)
S = 568 mm
BecauseS > 500 mm, the safety distance may be recalculated with a minimum value ofS = 500 mm.
Using Equation 3(3)—
S = (1600 mm/s × 0.22s) + 8(30 − 14)
S = 480 mm
Because the recalculated value forS < 500 mm, the minimum safety distance becomes500 mm.
A6.3 Height determination for equipment normal to approach The height of theuppermost beam above the ground is determined in accordance with Paragraph A5. In thiscase, the heightH is found to be 1600 mm.
A6.4 Height determination for equipment parallel to approach
A6.4.1 General The height of equipment above the standing level and located parallelto the direction of approach is set dependent upon the results of a risk assessment. Thefactor which determines the height is whether it is foreseen that a person will stand in thespace between the danger zone and the detection zone of the equipment positioned normalto the approach or whether a person could attempt to reach up through the equipment toreach the danger zone. These are referred to as whole-body detection and part-bodydetection.
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A6.4.2 Whole body detectionWhere the risk assessment shows that only access by thewhole body need to be considered, the height of the equipment can be determined once adetection capability for the equipment has been chosen. The detection capability shall beappropriate for the body part to be detected. For this example, a detection capability of100 mm has been chosen.
Using Equation 3(8)—
H = 15(d − 40 mm) . . . 3(8)
H = 15(100 − 40 mm)
where—
H = 900 mm
A6.4.3 Part body detection Where the risk assessment shows that a person may attemptto gain access to the danger zone by reaching upwards through the equipment, theapproach may be considered a normal approach.
Using Equation 3(2)—
S = (2000 mm/s ×T) + 8(d − 14 mm) . . . 3(2)
where—
S = minimum distance from the danger zone to the outermost edge of the detectionzone, in millimetres
T = overall system stopping performance, in seconds
= 0.22 s
d = detection capability, in millimetres
= 30 mm
S = (2000 × 0.22 s) + 8(30 mm − 14 mm)
S = 480 mm
BecauseS < 500 mm, the minimum safety distance becomes 500 mm.
The height of the electro-sensitive protective equipment above the standing surfacebecomes—
K = H − S
where—
K = height of electro-sensitive protective equipment above the standing surface, inmillimetres
H = height of danger zone above the standing surface, in millimetres
S = safety distance from the danger zone to the outermost edge of the detectionzone, in millimetres
then—
K = 1000 mm − 500 mm
K = 500 mm
A7 EXAMPLES COMPARING DIFFERENT DEVICES
A7.1 Example 6 Inadvertent access to the danger zone of an automated machinesystem is to be detected by photoelectronic protective equipment.
The risk assessment indicates that a multiple separate individual beam device would beappropriate and a three-beam device is selected.
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The stopping time of the machine system is 300 ms and the response time of theprotective equipment is 35 ms.
From Table 3.1 the beams should be set at 300, 700 and 1100 mm from the floor. Theminimum safety distance is given by Equation 3(5), as follows:
S = (1600 mm/s ×T) + 850 mm . . . 3(5)
where
T = 335 ms
then—
S = (1600 mm/s × 0.335 s) + 850 mm
S = 536 mm + 850 mm
S = 1386 mm.
A7.2 Example 7 This example features the same machine as in Paragraph A5.1 butwith a floor mounted device instead of a three-beam device. Therefore—
S = (1600 mm/s ×T) + 1200 mm . . . 3(10)
then—
S = 1600 mm/s × 0.335 s + 1200 mm
S = 536 mm + 1200 mm
S = 1736 mm.
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FIGURE A1 EXAMPLE 1 VERTICAL DETECTION ZONE
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NOTE: Safe distanceS = 1600 ×T + (1200 − 0.4H) where the lowest allowable heightH = 15(d − 40) up to amaximum of 1000 mm.
FIGURE A2 EXAMPLE 3 DUAL POSITION DETECTION ZONE
FIGURE A3 EXAMPLE 5 TWIN DETECTION ZONES
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APPENDIX B
GUIDANCE FOR THE SELECTION OF CATEGORIES
(Normative)
B1 SCOPE This Appendix describes a simplified method for selecting the appropriatecategories of interlock as reference points for the design of various safety aspects of acontrol system.
To quantify risk is often very difficult and this method is only concerned with thecontribution to risk reduction made by the interlocks within the control system underconsideration and providing it is intended to guide the designer in a choice of categorybased on interlock behaviour in case of a fault. However, this is only one aspect and otherinfluences will also contribute to the assessment that adequate safety has been achieved.These influences include, for example, component reliability, the technology used and theparticular application, and they can indicate a deviation from the expected choice ofcategory.
B2 METHOD The severity of injury (denoted by S) is relatively easy to estimate, e.g.laceration, amputation or fatality. For the frequency of occurrence, auxiliary parametersare used to improve the estimation. These parameters are—
(a) frequency and exposure time to the hazard (F); and
(b) possibility of avoiding it (P).
Experience has shown that these parameters can be combined as shown in Figure B1 togive a range of risk from low to high. It is emphasized that this is a qualitative processwhich gives only an estimation.
In Figure B1, the preferred categories are indicated by a large filled circle. In someapplications the designer can deviate to another category indicated by either a small circleor a large unfilled circle. Other categories than those preferred can be used, but theintended system behaviour in case of faults should be maintained and the reasons fordeviating given. These reasons can include the use of different technologies, such as well-tried hydraulic or electromechanical components (Category 1) in combination with anelectrical or electronic system (Category 3 or 4). When lower categories (small circle inFigure B1) are selected, additional measures can be required, for example, overdimensioning, the use of techniques leading to fault exclusion or the use of dynamicmonitoring.
B3 GUIDANCE IN SELECTING PARAMETERS S, F AND P FOR RISKESTIMATION
B3.1 Severity of injury (S1 and S2) In estimating the risk arising from a fault in thesafety components of a control system only slight injuries (normally reversible) andserious injuries (normally irreversible and those including death) are considered.
To make a decision, the usual consequences of accidents and normal healing processesshould be taken into account in determining S1 and S2, for example, bruising orlacerations without complications would be classified as S1, whereas an amputation ordeath would be classified as S2.
B3.2 Frequency or exposure time to the hazard (F1 and F2) A generally valid timeperiod when parameter F1 or parameter F2 should be selected cannot be specified.However, the explanation below can facilitate making the right decision in cases of doubt.
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F2 should be selected if a person is frequently or continuously exposed to the hazard. It isirrelevant whether one or several persons are exposed to the hazard on successiveexposures. The use of lifts is an example.
The period of exposure to the hazard should be evaluated as a proportion of the total timefor which the machine is used.
The frequency of exposure should be evaluated in terms of the number of times andoperator is exposed to the hazard during machine operation. For example, if it isnecessary to reach regularly between the tools of the machine during cyclic operation inorder to feed and remove workpieces, then F2 should be selected. If access is onlyrequired from time to time, then F1 can be selected.
B3.3 Possibility of avoiding the hazards (P1 and P2) When a hazard arises it isimportant to know if it can be recognized and whether it can be avoided before it leads toan accident. For example, an important consideration is whether the hazard can be directlyidentified by its physical characteristics or whether it can be recognized only by technicalmeans, such as indicators. Other important aspects which influence the selection ofparameter P include—
(a) operation with or without supervision;
(b) operation by experts or non-professionals;
(c) speed with which the hazard arises (e.g. quickly or slowly);
(d) possibilities for hazard avoidance, e.g. by taking flight or by intervention of a thirdparty; and
(e) practical safety experiences relating to the process.
When a hazardous situation occurs P1 should only be selected if there is a realistic chanceof avoiding an accident or of significantly reducing its effect. P2 should be selected ifthere is no realistic chance of avoiding the hazard.
B4 DESIGN OF SAFETY RELATED PARTS OF CONTROL SYSTEMS
B4.1 The safety related parts of control systems These shall be in accordance withthe requirements of one or more of the five categories. (See Paragraph B4.2 andTable B1).
The categories state the required behaviour of safety related parts of a control system inrespect of its resistance to faults.
Category B is the basic category. When a fault occurs, the safety function may not beperformed. In Category 1, improved resistance to faults is achieved predominantly byselection and application of components. In Categories 2, 3 and 4, improved performancein respect to a specified safety function is achieved predominantly by improving thestructure of the safety related part of the control system. In Category 2, this is providedby periodically checking that the specified safety function is being performed. InCategories 3 and 4, this is provided by ensuring that the single fault will not lead to theloss of the safety function. Whenever practicable in Category 3, and in Category 4, suchfaults will be detected and resistance to their accumulation will be specified.
Direct comparisons of capability to resist faults between categories, can only be made ifone parameter at a time is changed. Higher categories can only be interpreted as providinga greater resistance to faults in comparable circumstances, e.g. when using similartechnology, components of comparable reliability, similar maintenance regimes and incomparable applications.
When considering the causes of failures in some components it is possible to excludecertain faults.
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FIGURE B1 POSSIBLE SELECTION OF CATEGORIES
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TABLE B1
CATEGORIES OF SAFETY RELATED PARTS OF CONTROL SYSTEMS
Category Summary of requirements System behaviour*Main principle
toachieve safety
B(see Paragraph
B4.2.1)
Safety related parts of machine controlsystems or their protective equipment, aswell as their components, shall bedesigned, constructed, selected, assembledand combined in accordance with relevantStandards so that they can withstand theexpected influences.
When a fault occurs it canlead to the loss of the safetyfunction.
By selection ofcomponents
1(see Paragraph
B4.2.2)
Requirements of B shall apply.
Use well-tried safety components andsafety principles.
As described for category B,but with higher safety relatedreliability of the safetyfunction.
2(see Paragraph
B4.2.3)
Requirements of B and the use of well-tried safety principles shall apply.
Safety function(s) shall be checked atsuitable intervals by the machine controlsystem.
NOTE: What is suitable depends on theapplication and type of machine.
The occurrence of a fault canlead to the loss of the safetyfunction between thechecking intervals.
The loss of safety function isdetected by the check.
3(see Paragraph
B4.2.4)
Requirements of B and the use of well-tried safety principles shall apply.
Control systems shall be designed, so that —
(a) a single fault in the control does notlead to the loss of the safetyfunction(s), and
(b) whenever reasonably practicable thesingle fault is detected.
When the single fault occursthe safety function is alwaysperformed.
Some but not all faults willbe detected.
Accumulation of undetectedfaults can lead to the loss ofthe safety function.
By structure
4(see Paragraph
B4.2.5
Requirements of B and the use of well-tried safety principles shall apply.
A control system shall be designed, sothat —
(a) a single fault in the control does notlead to a loss of safety function(s),and
(b) the single fault is detected at orbefore the next demand upon thesafety function. If this is not possible,then an accumulation of faults shallnot lead to a loss of safety function.
When the faults occur thesafety function is alwaysperformed.
The faults will be detected intime to prevent the loss ofthe safety functions.
By structure
* The risk assessment will indicate whether the total or partial loss of the safety function(s) arising from faults isacceptable.
B4.2 Category specification
B4.2.1 Category B The safety related parts of control systems shall, as a minimum, bedesigned, constructed, selected, assembled and combined, using basic safety principles forthe specific application so that they can withstand—
(a) the expected operating stresses (e.g. the durability and reliability with respect toswitching capacity and frequency);
(b) the influence of the processed material; and
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55 AS 4024.2 — 1998
(c) other relevant external influences (e.g. mechanical vibrations, external fields, powersupply interruptions or disturbances).
B4.2.2 Category 1 The requirements of Category B and of this Paragraph shall apply.
Safety related parts of control systems complying with Category 1 shall be designed andconstructed using well-tried components and principles.
A well-tried component for a safety related application is a component which has beenwidely used in the past with successful results in similar applications, or made andverified using principles which demonstrate its suitability and reliability for safety relatedapplications.
In some well-tried components certain assessed faults can also be excluded because thefault rate is known to be very low.
The decision to accept a particular component as a well-tried one can depend on theapplication.
Well-tried safety principles include—
(a) the avoidance of certain faults (e.g. avoidance of short circuit by separation);
(b) reducing the probability of faults (e.g. over-dimensioning or underrating ofcomponents);
(c) orientating the mode of a fault (e.g. by ensuring an open circuit when it is vital toremove power in the event of a fault);
(d) detecting faults very early (e.g. earth fault detection); and
(e) restricting the consequences of a fault.
Newly developed components and principles may be considered as equivalent to ‘well-tried’ if they fulfil the above conditions.
NOTES:
1 On the level of single electronic components alone, it is not normally possible to realiseCategory 1.
2 The probability of failure in Category 1 is lower than in Category B. Consequently the lossof the safety function is less likely.
3 When a fault occurs it can lead to the loss of the safety function.
B4.2.3 Category 2 The requirement of Category B, the use of well-tried safetyprinciples and the requirements in this Paragraph shall apply.
The safety function of safety related parts of the control systems complying withCategory 2 shall be checked at suitable intervals by the machine control system. Thecheck of the safety function(s) shall be performed at the machine start-up, prior to theinitiation of any hazardous situation and periodically during operation if the riskassessment and the kind of operation shows that it is necessary.
The initiation of this check may be automatic or manual. Any check of the safety functionshall either—
(a) allow operation if no faults have been detected; or
(b) generate an output which initiates appropriate control action if a fault is detected.Whenever possible this output shall initiate a safe state. When it is not possible toinitiate a safe state (e.g. welding of contacts in the final switching device) theoutput shall provide a warning of the hazard.
The check itself shall not lead to a hazardous situation.
After the detection of a fault, a safe state shall be maintained until the fault is cleared.
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AS 4024.2 — 1998 56
The checking equipment may be integral with, or separate from, the safety related part(s)providing the safety function.
NOTES:
1 In some cases Category 2 is not applicable because the checking of the safety function cannot be applied to all components, e.g. pressure switch or temperature sensor.
2 In general Category 2 can be realised with electronic techniques, e.g. in protectiveequipment and particular control systems.
3 This allows a fault to occur, which can lead to the loss of the safety function between thechecking intervals, however the loss of safety functions is detected by the next check.
B4.2.4 Category 3 The requirements of Category B, the use of well-tried safetyprinciples and the requirements of this Paragraph shall apply.
Safety related parts of control systems complying with Category 3 shall be designed sothat a single fault in any of these parts does not lead to the loss of the safety functions.Common mode failures shall be taken into account. Whenever reasonably practicable thesingle fault shall be detected at or before the next demand upon the safety function.
NOTES:
1 This requirement of single fault detection does not mean that all faults will be detected.Consequently, the accumulation of undetected faults can lead to an unintended output and ahazardous situation at the machine. Typical examples of practicable measures for faultdetection are connected movement of relay contacts or monitoring of redundant electricaloutputs.
2 This system behaviour allows that—
(a) when a single fault occurs the safety function is always performed;
(b) some but not all faults will be detected;
(c) accumulation of undetected faults can lead to the loss of the safety function.
B4.2.5 Category 4 The requirements of Category B, the use of well-tried safetyprinciples and the requirements of this Paragraph shall apply.
Safety related parts of control systems complying with Category 4 shall be designed sothat—
(a) a single fault in any of these safety related parts does not lead to a loss of the safetyfunctions; and
(b) the single fault is detected at or before the next demand upon the safety functions,e.g. immediately, at switching on, and at the end of a machine operating cycle. Ifthis detection is not possible, then an accumulation of faults shall not lead to a lossof safety functions.
If the detection of certain faults is not possible during the first inspection after theoccurrence of the fault, the occurrence of further faults shall be assumed. In this situationthe accumulation of faults shall not lead to the loss of the safety functions. Fault reviewmay be stopped when the probability of occurrence of further faults is considered to besufficiently low. In this case the number of faults in combination which need to be takeninto consideration will depend upon the technology, structure and application, but shall besufficient to meet the detection criteria.
This fault review may be limited to two faults in combination, when—
(i) the fault rates of the components are low;
(ii) the faults in combination are largely independent of each other; and
(iii) the faults have to appear in a certain order to interrupt the safety function.
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57 AS 4024.2 — 1998
If further faults occur as a result of the first single fault the first and all consequent faultsshall be considered as a single fault. Common mode failures shall be taken into account,e.g. by using diversity, or special testing procedures.
NOTES:
1 In practice, the number of faults which need to be considered will vary considerably, e.g. inthe case of complex microprocessor circuits, a large number of faults can exist but in aelectro-hydraulic circuit, the consideration of three (or even two) faults can be sufficient.
2 In the case of the complex circuit structures (e.g. microprocessors, complete redundancies)the review of faults is generally carried out at the structural level, i.e. based on assemblygroups.
3 This allows that even under fault conditions the safety function is always performed and thefaults will be detected in time to prevent the loss of the safety function.
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AS 4024.2 — 1998 58
APPENDIX C
SAFETY DISTANCES FOR ANGLED OR NORMAL APPROACH
(Normative)
C1 GENERAL This Appendix sets out a method for determining the safety distancesto be used when installing electro-sensitive protective equipment using optoelectronicdevices, where the approach direction is angled to the plane of the detection zone or isnormal to the plane of the detection zone.
The process for determining the location of the curtain has two steps. The first involvesdetermining a safety distance from the danger zone to the detection zone to prevent accessbeing gained to the danger zone through the curtain. The second determines the minimumheight of the uppermost element of the curtain, to ensure that access to the danger zonecannot be gained by reaching over the curtain.
C2 METHOD
C2.1 For angled approach
C2.1.1 Determination of safety distanceThe safety distance from the danger zone tothe detection zone shall be determined using the following equation:
S = (K × T) + C . . . 3(1)
where
S = the minimum distance from the danger zone to the outermost edge of thedetection zone, in millimetres
K = the approach speed of the body or part of the body, in millimetres
= 1600 mm/s
T = the overall system stopping performance, in seconds
C = 1200 mm − 0.4H, but not less than 850 mm, where H is the height of thedanger zone above the reference plane, e.g. floor, in millimetres
The safety distance is used to locate the curtain on an arc centred on the danger zone andhaving a radius equal to the safety distance.
C2.1.2 Determination of uppermost beam heightThe height of the uppermost beamabove the working surface shall be determined as follows:
(a) From Figure C1 locate the height of the danger zoneH, in the column headedHeight of danger zone. IfH lies between two values, use the higher of the twovalues.
(b) Read across the row to the right to locate the horizontal distance to the danger zone,which is equal to the safety distanceS. If S lies between two values, use the lowerof the two values.
(c) Read up to the column to determine the height of the uppermost beamU above theworking surface from the heading.
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59 AS 4024.2 — 1998
millimetres
Height ofdangerzone
H
Height of uppermost beam u
1 000 1 200 1 400 1 600 1 800 2 000 2 200 2 400 2 500
HORIZONTAL DISTANCE TO DANGER ZONE S
2 500 — — — — — — — — —
2 400 100 100 100 100 100 100 100 100 —
2 200 600 600 500 500 400 350 250 — —
2 000 1 100 900 700 600 500 350 — — —
1 800 1 100 1 000 900 900 600 — — — —
1 600 1 300 1 000 900 900 500 — — — —
1 400 1 300 1 000 900 800 100 — — — —
1 200 1 400 1 000 900 500 — — — — —
1 000 1 400 1 000 900 300 — — — — —
800 1 300 900 600 — — — — — —
600 1 200 500 — — — — — — —
400 1 200 300 — — — — — — —
200 1 100 200 — — — — — — —
0 1 100 200 — — — — — — —
NOTES:1 There should be no interpolation of the values in the Table.2 A dash in the horizontal distance to danger zone data may be read as 0.
FIGURE C1 GUARD DISTANCES
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AS 4024.2 — 1998 60
C2.2 Approach normal to the detection zone
C2.2.1 Determination of safety distanceThe safety distanceS shall be determinedusing Equation 3(2). If the safety distance is found to be greater than 500 mm, then itmay be recalculated using equation 3(3), however, the safety distance shall be not lessthan 500 mm.
C2.2.2 Determination of uppermost beam heightThe height of the uppermost beamabove the working surface shall be determined as follows:
(a) From Figure C1 locate the height of the danger zoneH, in the column headedHeight of danger zone. IfH lies between two values, use the higher of the twovalues.
(b) Read across the row to the right to locate the horizontal distance to the danger zone,which is equal to the safety distanceS. If S lies between two values, use the lowerof the two values.
(c) Read up to the column to determine the height of the uppermost beamU above theworking surface from the heading.
NOTE: A worked example is given in Appendix A.
C2.2.3 Determination of horizontal curtain height
C2.2.3.1 General In some applications, a second piece of electro-sensitive protectiveequipment is installed parallel to the direction of approach and between the danger zoneand the detection zone. This second piece of equipment may be used to detect a personstanding in the area between the detection and danger zones, or to detect attempts to gainaccess to the danger zone by reaching under the electro-sensitive protective equipment.
C2.2.3.2 Detection of whole body Where detection of a whole body within the spacebetween the danger zone and the detection zone is required, the height of the detectionzone H may be determined using Equation 3(8). The detection capability of the deviceshould be chosen so as to detect the appropriate body part e.g. ankle, thigh or waist.
C.2.2.3.3 Detection of body part Where detection of a part of the body within thespace between the detection zone and the danger zone is required, the approach should beconsidered as an approach normal to the detection zone, and the safety distanceSdetermined using Equation 3(2). If the safety distance is found to be greater than 500 mm,then Equation 3(3) may be used, but the value ofS shall not be less than 500 mm.
NOTE: A worked example is given in Appendix A.
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![Building (Plumbing) Act 1998 - legislation.vic.gov.au€¦ · 1 Building (Plumbing) Act 1998† [Assented to 10 November 1998] The Parliament of Victoria enacts as follows: 1. Purpose](https://static.documents.pub/doc/80x56/5afee3577f8b9a994d8f9e20/building-plumbing-act-1998-1-building-plumbing-act-1998-assented-to.jpg)
