Presenters:

Dan Alecu & Lovenah Galchoolah

Hazardous Area Requirements(with a case study)

Infernal triangle The process of combustion can be represented by the fire

triangle.

Three factors are always needed to cause an explosion:

1. A source of ignition e.g. hot surface, arc or spark

2. Oxygen

3. Flammable material

A hazardous area is an area in which an explosive gasmixture is present or may be present in sufficient quantitiesto require special precautions in the life cycle of theequipment that could create an ignition source.

Electrical equipment in hazardousareas (EEHA) If any side of the triangle is removed, a fire cannot be

started or an existing fire cannot continue to burn.

This forms the basis of design of electrical equipment inhazardous areas.

Various protection techniques exist:

Ex d, flameproof-explosion containment

Ex e, increased safety-exclusion of arcs or sparks or hotsurface

Ex n, non sparking-avoidance of ignition source

Ex i, intrinsic safety- Energy limitation

Hazardous area classification Zone depends the probability of the explosive gas atmosphere

being present Zone 0-present continuously (>1000hr per annum)

Zone 1-likely to occur in normal operation (between 10 and 1000hrper annum)

Zone 2-not likely to occur in normal operation (less than 10hr perannum)

Gas Group depends on ignition energy of the gas present IIA-Representative gas: propane

IIB-Representative gas: ethylene

IIC-Representative gas: hydrogen

Temperature class (T1-T6) depends on auto ignition temperatureof the gas present

Australian Standards AS 3000 is mandatory and mentioned in Regulations of

numerous Acts of Parliament.

AS 3000 calls up AS2381 with regards to the design,selection and installation of electrical equipment in hazardousareas.

AS 2381 makes reference to various other standards forexample AS 60079 series and AS 2380 and hence thesestandards become mandatory.

All Ex inspections to be carried out by competent people asper AS 2381 clause 1.7.

Ex inspections Flowchart to determine periodic inspection interval:

Exd inspection findings Ex d enclosure works on explosion containment

Common issues are:

Extra unauthorised entries in enclosure

Missing or damaged bolts

Corroded junction box

Damaged box along flamepath

Exe inspection findings Exe works on ignition avoidance

Common issues are:

Non certified terminals inside JB

Absence of IP washer

Loose conductor terminations create

hot spots

IP54 (min) enclosure

CASE STUDY ON MOTORS

CASE STUDY ON MOTORS It is strongly recommended that the relevant IEC, Australian

Standards and Statutory Authorities be consulted prior to finalselection of the motor including:

Ex d Group I - Combination of Gas & Dust Ex d Group IIA , IIB & IIC - Combination of Gas & Dust Ex d Single Phase 240Volt Ex d HighVoltage EX d Brake &Two Speed Ex tD ( Formerly DIP) -Dust Excluding Ignition Proof Ex d Forced Cooled Inverter Duty Ex e - Increased Safety Motors EX nA - Non Sparking Motors

CASE STUDY ON MOTORS It is strongly recommended that the relevant IEC, Australian

Standards and Statutory Authorities be consulted prior to finalselection of the motor including:

Ex d Group I - Combination of Gas & Dust Ex d Group IIA , IIB & IIC - Combination of Gas & Dust Ex d Single Phase 240Volt Ex d HighVoltage EX d Brake &Two Speed Ex tD ( Formerly DIP) -Dust Excluding Ignition Proof Ex d Forced Cooled Inverter Duty Ex e - Increased Safety Motors EX nA - Non Sparking Motors

CASE STUDY ON MOTORS

CASE STUDY ON MOTORS

CASE STUDY ON MOTORS

CASE STUDY ON MOTORS

CASE STUDY ON MOTORS

CASE STUDY ON MOTORS

CASE STUDY ON MOTORS

CASE STUDY ON MOTORS

CASE STUDY ON MOTORS

Temperature

Tolerance

Class

Maximum Operation

Temperature Allowed

Allowable

Temperature

Rise at full

load

1.0 service

factor motor 1)

Allowable

Temperature

Rise

1.15 service

factor motor 1)

oC oF oC oC

A 105 221 60 70

B 130 266 80 90

F 155 311 105 115

H 180 356 125 -

CASE STUDY ON MOTORS