Original Standard - DIN 32876-1-198604

8/20/2019 Original Standard - DIN 32876-1-198604

http://slidepdf.com/reader/full/original-standard-din-32876-1-198604 1/6

"'

;

.;

01

c:

:::1

e -

z . ,

>

= ~

~ ~

,_

c: :::1

; '

.

.<= <=

-

(/) (/)

:; '

,,

c .,

z:i

c

- 0

0 ()

c: . ,

o.c

'U,i-g

- ~ : ;

E

o

~ < =

(/)

C.

0 c:

~ : ~

., 0

.<=.,

-" '

£ ~

i i i ~

, c:

D OS

g E

,

,_

.c .c

,_::>

' 0

E ,

,c ;

~ ~

tiE:

( / )

0

c.

0

z

UDC

389:531.71:621.317.39:001.4:620.1

DEUTSCHE NORM

April1986

Electrical length measurement

with analogue data acquisition

Concepts, requirements, testing

DIN

32876

Part 1

Elektrische Uingenmessung mit analoger Erfassung der MeBgroBe; Begriffe, Anforderungen, Prufung

1 Field

of

application

This standard applies

to

electrical length measurement

with analogue data acquisition and either mechanically

contacting or non-contacting detection of the meas

urand.

It specifies

the

main characteristics of such instruments

and gives details as to how they may be tested.

The auxiliary measuring devices specified in

DIN

2257

Part 1 are

not

integral

to the

present standard .

2 General principles

1

)

Electrical length measurement is based on the principle

that

the change in the value of

the

measurand as detect

ed by the sensor effects a change in the electric quanti

ties utilized in the method applied, namely inductance,

capacitance, resistance

Changes in these electric quantities in the course of

measurement are generally converted into a change in

voltage and indicated by means of a voltmeter.

This form of analogue data acquisition is characterized

particularly by the direct correlation between measurand

and measuring signal.

Contact measuring systems may be operated

as

complete

systems without adjustment.

Non-contacting measuring systems shall be calibrated or

adjusted for

the

task in hand in

all

cases where the given

conditions differ from the reference conditions, because,

depending

on

the electric quantity utilized, the measure

ment result

is

influenced by the material and geometry

of the object to be measured or the dielcectric between

the object and the sensor,

as

the case may be.

Note. The selection of sensors for non-contacting length

measuring systems must take account of the mate·

rial

of the

object

to

be measured; depending

on

the electric quantity utilized for conversion pur

poses, measurements may be made

on

ferro

magnetic, electrically conducting, and non-con

ducting materials.

3 Concepts

Unless defined below, the metrological concepts and

instrument-related terminology used

in

this standard are

to be understood as defined in

DIN

2257 Parts 1 and 2

and

DIN

1319 Part 2.

1

)

See also Supplement 1

to

DIN

32 876

Part 1.

3.1 Measuring system

Electrical length measuring systems generally consist of

a sensor and a measuring instrument which are electri

cally connected and require for the ir operation an elec

tric power supply.

3.2

Family of instruments

A family of instruments signifies a group of sensors and

measuring instruments which function on the basis of

the same physical principle and which evince the same

characteristic properties

at

their interface .

3.3

Sensor

The sensors of contacting and non-contacting electrical

length measuring systems acquire the measurement data

and convert them into electric signals.

3.4 Stylus

Stylus

is

a sensor designed to acquire measurement data

through mechanical contact with

the

surface to be meas

ured.

3.4.1 Axial stylus

An axial stylus is a sensor defined by the measuring pin

and measuring transducer being in alignment; the Abbe

principle

is

observed.

The

measuring pin

is

rigidly

attached to the moving

component

of the transducer

3.4.2 Parallel stylus

A parallel stylus is a sensor defined by the measuring pin

being moved parallel

to

the transducer,

to

which the

measurand thus detected

is

transferred. Its sensitivity

(cf. DIN 2257 Part

1)

is independent of the length of the

measuring pin .

3.4.3

Lever stylus

A lever stylus

is

a sensor defined by

the

measurand being

detected by a lever and transferred to the transducer. Its

sensitivity

(cf.

DIN 2257 Part

1) is

a function of the

length of the lever.

3.5

Measuring inst rument

In

electrical length measuring systems, the analogue

measurement signal proceeding from

the

sensor

is

con

verted and displayed

in

the measuring instrument. Ana

logue measurement signals can also be converted into

digital signals and displayed

in digital form.

These instruments may be equipped with signal

outputs

and data processing facilities.

Continued on pages 2 to 6

Beuth Verlag GmbH, Berlin. has

the exclusive

right of sale for German Standards DIN·Normen).

02.88

DIN 32

876 Part 1

Engf.

Price group 7

Sales No. 0107



Page 2 DIN

32 876

Part 1

3.6

Basic clearance

The

basic clearance,

LG

indicates,

in

the

case of non

contacting detection

of the

measurand,

the

minimum

distance between sensor and object, from which

point

the

measuring system may be used for taking measure

ments (lower limit

of

measuring range).

3.

7 Effective area

The effective area,

A

indicates,

in

the

case of non-con

tacting detection

of the

measurand,

the

area

of the

sen

sor actually effective

in the

acquisition of measurement

data.

Note.

The

object

to ·be

measured should

at

no point

be

smaller

than

this area.

3.8

Sensor displacement

For sensors as specified

in

subclause

3.4,

the

displace

ment,

L is

that part of the

measuring pin or lever dis

placement used for measurement purposes

in

which

the

permissible spans of error are

not to

be exceeded.

3.9

Sensor zero

Sensor zero

is

the

position of

the

measuring pin or lever

at

wich

the

signal from

the

sensor

is

zero (zero signal).

3.10

Temperature coefficient

The temperature

coefficient defines

the

maximum influ

ence

of the

temperature on

the

signal or

the

indication

within

the

working temperatu re range,

ftT

being

the temperature

coefficient

of the

sensor,

in

~ m / ° C , and

ftG

being

the

temperature coefficient

of the

measuring

instrument,

in

%/°C, relative to

the

span.

3.11

Working

temperature

range

The working tempera ture range defines

the

temperature

limits between which

the

specified spans

of

error are

not

to

be exceeded.

3.12

Operating

temperature

range

The

operating temperature range defines

the

tempera

ture

limits between which sensor

or

measuring instrument

may be operated

without

risk of damage.

3.13

Storage

temperature

range

The

storage temperature range defines the temperature

limits between which sensor

or

measuring device may be

stored or transported

without

risk

of

damage.

3.14

Mechanical limiting frequency

of

stylus

The mechanical limiting frequency o f

the

stylus,

VTm·

defines, for sinusoidal movement,

the

maximum number

of measuring pin

or

lever strokes per second,

at

which

the

mechanical

contact

with

the

object

to

be measured

is

just

maintained.

The

mechanical limiting frequency

is

essentially a function of

the

displacement,

the

mass

moved and

the

measuring force.

3.15

Limiting frequency

of

non-contacting sensors

The

limiting frequency

of

non-contacting sensors,

VTb•

defines

the

frequency

up

to

which a sinusoidal change

in

the

measurand

is

acquired

without the

specified spans

of

error being exceeded.

3.16

Limiting frequency

of

measuring

instrument

The limiting frequency of

the

measuring instrument,

VG

defines

the

frequency up to which an analogue sinus

oidal signal

is

transferred

to

the

measuring instrument

without the

specified spans of error being exceeded.

3.17

Self-adjustment

time

The

self-adjustment time

is

the

period elapsing from

the

moment

when there

is

a

jump in the

signal amounting to

the

value of half

the

span

to

the moment

at

which

the

indication

or the

signals remain within

the

limits given

by

the

specified spans

of

error.

3.18

Hold

time

of

digital display

The

hold time

of

a digital display

is the

time available

for taking a reading between

the

change from one digit

to

the

next.

3.19

Computation

of

measured value

The computation

of

the

measured value refers

to the

mathematical processing (e.

g.

finding totals

or

differ

ences)

of

measured values (instantaneous values or stored

values).

3.20

Storage

of

measured values

Storage of measured values refers to

the

storage

of

char

acteristic values (e.g. minimum and maximum values).

3.21

Classification

of

measured values

Classification

of

measured values refers

to the

grading

of

measured values into classes (e.

g.

with

the

aid of limit

switches). A separate signal

is

assigned to each class.

3.22

Switching uncertainty

The switching uncertainty,fgw,

is

the

difference between

the

greatest and

the

smallest value for which

the

class

change

is

signalized for

the

same limit value during meas

urement in

one direction.

3.23

Switching hysteresis error

The

switching hysteresis error, ff JJ.,

is

the

difference

between

the

greatest and

the

smallest value for which

the

class change

is

signalized for

the

same limit value

during measurement

in both

directions.

3.24

Span

of

error

The

span

of

error, fe,

is the

distance between

the

ordi

nates of

the

highest and lowest

point

in

the

deviation

diagram

2

), the following spans being distinguished:

feT

-

span

of

error

of

sensors;

feA -span

of error

of

analogue indication;

fea -span

of error

of

analogue

output;

feo -span

of error

of

digital indication;

fed -span

of error

of

digital

output.

3.25

Span

of

error

of the

measuring system

The span of error of the measuring system,

feM,

is the

sum of

the

individual spans of error of one

or

more sen

sors toge ther with

that of the

measuring ins trument.

2

)

For examples of deviation diagrams, see DIN

878,

DIN 879 Part 2 and DIN 2270.



DIN 32

876

Part 1

Page

3

Table

1.

Technical details of sensors

No.

Parameters

Units

Meehan cally Non-

contacting

contacting

1

Measurement method

-

X

X

2 Design

-

X X

3

Dimensions mm X X

4

Degree of protection as specified in

DIN

40 050

-

X X

5

Lift-off system

-

X

-

6

Cable length m

X X

7

Maximum cable extension without the spans of error m

X

X

being exceeded

8

Bearing application of measuring pin

or

lever

-

X

-

9

Mass

moved

1

)

g

X

-

Sensitivity

at

supply voltage

mV/[J.m2)

10

Carrier frequency

v X X

Hz

11

Displacement, L and span

1-Lm or

mm X X

12

Basic clearance

LG

[J.m

or

mm

-

X

13

Effective area

A

mm

2

-

X

Clearance between stops and zero

14 upper stop

1-Lm or

mm

X

-

lower stop

15

Measuring force

3)

4)

N

X -

16

Increase in measuring force

3)

4

)

N/mm X

-

17

Hysteresis error of measuring force 3)

4

)

fk

N X

-

18

Hysteresis error

4

)

fuT

[J.m

X

X

19

Repeatability

4

)

fw

~ J . m

X

X

20


ftT

[J.m 'C X X

21

Working temperature range

oc

X

X

22 Operating temperature range

oc

X

X

23

Storage temperature range

oc

X

X

24

Reference material

-

-

X

25

Chemical resistance area

-

X X

1)

Not applicable for lever gauges.

2

)

For

example only; the relevant data are a function of the system concerned.

3)

Applies

to

axial styl i and parallel styli installed perpendicularly

with

the measuring pin pointing downwards, and

to

lever styli

with

their

case

and lever axis in the horizontal position.

4)

For static measurements only.



Page

4 DIN 32 876 Part 1

4.3 Measuring instruments

The manufacturer shall include in the relevant data sheets the parameters given in table 1, and the measuring instruments

concerned shall comply with the values there specified.

Table 2. Technical details

of

measuring instruments

No.

Parameters

Unit

1 Dimensions (length x breadth x height)

mm

2

Mass

kg

3

Supply voltage

v

4

Permissible variation in supply voltage

%

5

Frequency range for supply voltage

Hz

6

Power input

w

7

Operating hours per set

of

batteries or per charge

h

8

Protective system

as

specified in DIN 40 050

-

9

Adjustable measuring

ranges

1-1m or mm

10

Excitation voltage

v

11

Carrier frequency

Hz

Self-adjustment time

-

of analogue indication

12 -

of digital indication

s

- of analogue

output

- of digital output

13

Hold time of digital display

s

Span of

error (relative

to

the

span)

-

of analogue indication

feA

14

-

of digital indication

fen

%

-

of

analogue

output

fe

- of digital output

fed

15

Hysteresis error of the analogue indication

fuA

%

(relative

to

the span)

16


ftG

o;orc

(relative

to

the span)

Maximum number of sensors that may be connected without the

spans

of error

-

17

being exceeded

18

Working temperature range

oc

19

Operating temperature range

oc

20

Storage temperature

range

oc

Analogue output

- voltage range

v

- cur rent

range

mA

21 - sensitivity

V /mV or

mA/mV

1)

-permissible

load resistance

kQ

-residual ripple (relative

to

the span)

%

- reference potential

-

- l imit ing frequency

va

Hz

22

Digital output

Interface

as

specified in

DIN

...

;

e. g.

DIN 66 349

1

) For example only; the relevant data

are

a function of the system connected.



3.26

Repeatability

Repeatability in electrical length measurements

is

a char·

acteristic for fluctuations

in

the measured value over a

number of measurements of the same measurand from

the

same direction and within

the

nominal range.

4 Requirements

4.1 Measuring system

Sensors and measuring instruments belonging to the

same family of instruments shall be interchangeable.

4.2 Sensors

The manufactorer shall include in the relevant data sheets

the parameters given in table 1, and

the

sensors con

cerned shall comply with

the

values there specified.

The mating dimensions of the styli shall correspond to

those specified for dial gauges in DIN

878,

for dial indi

cators

in DIN

879 Part

1,

or for lever gauges

in DIN

2270.

The span of error feT and, as far as possible, the limiting

frequencies VTm and vTb shall be specified for the sensor

as a function of different parts of the displacement or

measuring range in a table or diagram.

4.3

Measuring instruments

See page 4.

5 Characteristics of measuring system

Users will generally only be able

to

assess the measuring

system as a whole.

It is recommended that the characteristics of the meas

uring system be calculated from its components

sensor

and measuring instrument in accordance with the

square law

of

error propagation (see DIN 2257 Part 2);

for examples, see Supplement 1 to this standard.

Note. A reduction in the uncertainty of measurement

may be achieved by calibrating the measuring

system. Systematic error proportions contained

in

the

characteristics (cf. DIN

1319

Part 3) may

then be corrected by way of the systematic devi

ations (errors)

that

have been established.

DIN 32 876 Part 1 Page 5

6 Testing

Users will generally only be able to test the measuring

system as a whole. The components shall be combined

as specified in clause 5.

Only those parameters which affect the uncertainty of

measurement shall be tested.

6.1 Span

of

error and hysteresis error of measuring

system

To determine the span of error, feM· and the hysteresis

error, fuM of the measuring system, a deviation diagram

shall be plotted for

the

measuring range

to

be tested.

In

the case of non-contacting systems, the specified refer

ence material shall be used.

The tes t may be carried

out

down to an uncertainty

of

measurement of ± 0,5 f.Lm with the aid of parallel gauge

blocks or test devices having a correspondingly smaller

uncertainty of measurement. To achieve

yet

smaller

uncertainties of measurement, special test devices or sen

sors are to be used.

The parameters referred

to

above shall be read off from

the completed diagram, which shall comprise

not

less

than ten points of measurement distributed equally over

the measuring range.

6.2

Repeatability

Repeatability shall be checked at any point in the meas

uring range

on

the strength of not less than ten measure

ments. The maximum difference between the values thus

obtained shall

not

exceed

the

values specified by

the

manufacturer.

6 ~ 3

Measuring force, increase in measuring force ,

hysteresis error of measuring force

Measuring

force, increase in measuring force and hys

teresis error of measuring force may be de termined with

the aid

of

a force transducer

or

a spring balance.

The measuring force shall be measured in

the

middle

of

the measuring range, while the other characteristics may

be determined at any point in the range.



Page 6 DIN 32 876 Part 1

Standards and other documents referred t

DIN 878 Dial gauges

DIN 879 Part 1

DIN 1319 Part 2

DIN 1319 Part 3

DIN 2257 Part 1

DIN 2257 Part 2

DIN 2270

DIN 40 050

DIN 66 349

Supplement 1

to

DIN 32 876 Part 1

Dial indicator

with

mechanical indication

Basic concepts in metrology; concepts relating

to

the

use

of measuring instruments

Basic concepts in metrology; concepts relating

to

uncertainty of measurement and the assess-

ment of measuring instruments and systems

Concepts in dimensional metrology; units, procedures, equipment; metrological concepts

Concepts in dimensional metrology; measurement errors and uncertainty

Lever gauges

Degrees of protection provided by enclosures; protection of electrical equipment against con

tact, foreign bodies and ingress of water

Interface for parallel measuring data transmission; BCD interface

Electrical length measurement; general information and examples of application

Other relevant standards and documents

DIN 66 258 Part 1 Interfaces and basic data link control procedures

for

data communication; C-S interface, v_s

interface

IEC 625 Part 1 An interface system

for

programmable measuring instruments (byte serial,

bit

parallel). Part 1:

Functional specifications, electrical specifications, mechanical specifications, system applica

tions and requirements for designer and user

IEC 625 Part 2 An interface system for programmable measuring instruments (byte serial,

bit

parallel). Part 2:

Code and format conventions

VDI/VDE 2600 Part2*) Metrology; basic concepts

VDI/VDE 2600 Part 3

*)

Metrology; concepts relating to instruments

VDIIVDE 2600 Part 4

*)

Metrology; concepts serving to describe the characteristics of measuring systems

VDI VDE 2600 Part 5 *) Metrology; concepts defining the mode of operation of measuring systems

VDI VDE 2600 Part 6 *) Metrology; nomenclature of measuring systems

Explanatory notes

For length measurements in industry, mechanical dial gauges, dial indicators and lever

gauges

are gradually being super

seded

by various types of electrical length measuring systems.

Until now, one problem for the user

was

how

to

decide which system

was

best suited

to

his particular application

because

the specifications provided by the various manufacturers were

not

readily comparable. The aim

of

this standard

has

been to standardize these manufacturer's specifications. However, in order to comprehend the large number of

sys-

tems

with

differing spans and avoid obstructing future developments, it has been decided

initially

not to specify numeri

cal

values for the characteristics detailed in clause 4, the only requirement being that such values

be

specified by the

manufacturer. It is conceivable that in a revision of this first edition of the standard numerical values will have

to

be

supplied

for

the required characteristics. To this end,

users

of the standard

are

requested

to

inform the

NormenausschuB

Lange

und

Gestalt

(Length and Shape Standards Committee) of thei r experiences in its application.

In addition to the

sensors

dealt with in this standard, displacement transducers are available which

differ

from mechani

cally contacting

sensors

in

that

the measuring pin is

not

applied under pressure

but

rigidly coupled

to

the object

to be

measured. This standard may be apppied analogously for

sensors

of this type, though certain specified characteristics

such

as

the measuring force and the mechanical

limiting

frequency are then redundant.

This standard

is

published in conjunction with a supplement containing general information and examples for application

aimed at elucidating the additional possibilities which these systems

offer

in comparison

with

dial indicators, dial gauges

and lever gauges.

International Patent lassification

G01 B

7/02

G01 B 21/02

*) Obtainable from

Beuth Verlag GmbH,

BurggrafenstraBe 6, D-1000 Berlin 30.

Date post:	07-Aug-2018
Category:	Documents
Upload:	tere
View:	219 times
Download:	0 times

Original Standard - DIN 32876-1-198604

Documents