SIST EN 60523:2000

SLOVENSKI STANDARD
SIST EN 60523:2000
01-september-2000
Potenciometri za enosmerni tok (IEC 60523:1975 + A1:1979 + corrigendum dec.
1980)
Direct-current potentiometers
Gleichspannungs-Kompensatoren
Potentiomètres à courant continu
Ta slovenski standard je istoveten z: EN 60523:1993
ICS:
17.220.20 0HUMHQMHHOHNWULþQLKLQ Measurement of electrical
PDJQHWQLKYHOLþLQ and magnetic quantities
SIST EN 60523:2000 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN 60523:2000

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SIST EN 60523:2000

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SIST EN 60523:2000

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SIST EN 60523:2000
NORME
CEI
INTERNATIONALE
IEC
60523
INTERNATIONAL
Première édition
STANDARD
First edition
1975-01
Potentiomètres
à courant continu
Direct-current potentiometers
© IEC 1975 Droits de reproduction réservés —
Copyright - all rights reserved
Aucune partie de cette
publication ne peut être reproduite ni No part of this publication may be reproduced or utilized in
utilisée sous
quelque forme que ce soit et par aucun any form or by any means, electronic or mechanical,
procédé, électronique ou mécanique,
y compris la photo- including photocopying and microfilm, without permission in
copie et les
microfilms, sans l'accord écrit de l'éditeur. writing from the publisher.
International Electrotechnical Commission 3, rue de Varembé Geneva, Switzerland
Telefax: +41 22 919 0300 e-mail: inmail@iec.ch IEC web site http: //www.iec.ch
CODE PRIX
Commission Electrotechnique Internationale
N
PRICE CODE
International Electrotechnical Commission
IEC
MemayHapogHaR 3JIeKTpOTexH144eCHap KOMHCCHR
Pour prix, voir catalogue en vigueur
• • For price, see current catalogue

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SIST EN 60523:2000
- 3 -
CONTENTS
Page
5
FOREWORD
PREFACE 5
Clause
7
1. Scope
2. Terms and definitions 7
7
2.1 D.C. potentiometer (hereinafter designated "potentiometer")
2.2 Measuring dials 7
2.3 Effective range 7
7
2.4 Range-changing device
7
2.5 Standardization of a potentiometer
7
2.6 Dial setting
2.7 Auxiliary equipment 7
7
2.8 Resolution
9
2.9 Circuit insulation voltage (nominal circuit voltage)
2.10 Ripple content 9
9
2.11 Leakage current screen (circuit)
9
2.12 Electrostatic screen
9
2.13 Measuring terminals
9
2.14 Measuring circuit
2.15 Measured quantity circuit selector switch 9
2.16 Residual e.m.f. of a potentiometer 9
9
2.17 Incremental linearity
2.18 Influence quantity 9
9
2.19 Common mode voltage
2.20 Variation with influence quantity 9
2.21 Reference conditions 11
11
2.22 Reference value
2.23 Reference range 11
11
2.24 Nominal range of use
2.25 Limiting values of an influence quantity 11
2.26 Fiducial value 11
11
2.27 Error
2.28 Intrinsic error 11
11
2.29 Accuracy
I1
2.30 Accuracy class
11
2.31 Class index
13
Classification 3.
13
4. Limits of intrinsic error
13
4.1 Permissible limits of intrinsic error
4.2 Incremental linearity 13
13
4.3 Resolution
15
4.4 Range-changing device
4.5 Independent circuit for standardization of a potentiometer 15
Conditions for the determination of intrinsic errors 15
5.
17
6. Permissible variations
17
6.1 Limits of variation
17
6.2 Conditions for the determination of the variations
17
6.3 Determination of the effect of a common mode voltage
Additional electrical and mechanical requirements 19
7.
19
7.1 Voltage test and other safety requirements
19
7.2 Insulation resistance test
7.3 Measured quantity circuit selector switches 19
19
7.4 Rheostats for standardization of the potentiometer
7.5 Limiting temperature for storage, transport and use 19
21
8. Information, markings and symbols
21
8.1 Information
21
8.2 Markings, symbols and their locations
8.3 Documentation 23
23
8.4 Example of the marking of a potentiomter
27
APPENDIX A - Determination of the effect of common mode voltage. Direct method
29
APPENDIX B - Determination of the effect of common mode voltage. Indirect method (Superposition method)

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SIST EN 60523:2000
INTERNATIONAL ELECTROTECHNICAL COMMISSION
DIRECT-CURRENT POTENTIOMETERS
FOREWORD
1)
The formal decisions or agreements of the IEC on technical matters, prepared by Technical Committees on which all the National
Committees having a special interest therein are represented, express, as nearly as possible, an inte rn
ational consensus of opinion
on the subjects dealt with.
2) They have the form of recommendations for international use and they are accepted by the National Committees in that sense.
3) In order to promote international unification, the I EC expresses the wish that all National Committees should adopt the text of
the IEC recommendation for their national rules in so far as national conditions will permit. Any divergence between the IEC
recommendation and the corresponding national rules should, as far as possible, be clearly indicated in the latter.
PREFACE
This standard has been prepared by Sub-Committee 13B, Indicating Instruments, of I EC Technical Committee
No. 13, Measuring Instruments.
Drafts were discussed at the meetings held in Toronto in 1972 and in Copenhagen in 1973. The draft,
Document 13B(Central Office)44, was submitted to the National Committees for approval under the Six Months'
Rule in May 1974.
The following countries voted explicitly in favour of publication:
Argentina Japan
Austria Poland
Belgium Portugal
Brazil Romania
Canada South Africa (Republic of)
Denmark Sweden
Finland Turkey
France United Kingdom
Germany United States of America
Hungary Yugoslavia
Israel

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SIST EN 60523:2000
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DIRECT-CURRENT POTENTIOMETERS
1. Scope
This standard applies to d.c. potentiometers assembled from resistors and switches and operating entirely on
direct current, having accuracy classes of 0.0005 . 0.1 (5 ppM . 1 000 ppM (parts per million)). It applies
also to auxiliary equipment which is a built-in part of the potentiometer.
This standard does not apply to potentiometers which are set automatically or semi-automatically nor to those
which also employ graduations on the null detector to obtain a part of the indicated value, nor to external
auxiliary equipment used with the potentiometer.
2. Terms and definitions
For the purposes of this standard, the following definitions apply.
2.1 D.C. potentiometer (hereinafter designated "potentiometer")
A voltage-measuring instrument in which the voltage to be measured is balanced against a known voltage
obtained by passing a fixed current through an adjustable resistor or an adjustable current through a fixed resistor,
or any combination thereof.
2.2 Measuring dials
The dials from which, taking into account the range factor, if any, the value of the measured quantity is
determined.
2.3 Effective range
For a specified range factor, the range of dial settings for which the potentiometer can measure with the stated
accuracy.
2.4
Range-changing device
A device whereby the effective range may be multiplied by a factor (e.g. 0.1) which is known as the range
factor.
2.5 Standardization of a potentiometer
Adjustment(s) necessary to ensure that a potentiometer is set correctly for measurement.
2.6 Dial setting
The setting of the measuring dials after balancing the potentiometer, multiplied by the range factor, if
applicable, when determining a measured voltage, after standardization of the potentiometer.
2.7 Auxiliary equipment
Additional equipment, which is or is not an integral part of the potentiometer, necessary to enable the poten-
tiometer to operate accurately and safely as specified.
2.8 Resolution
The voltage corresponding to either one step or the smallest division on the measuring dial of lowest value.

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SIST EN 60523:2000
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2.9 Circuit insulation voltage (nominal circuit voltage)
The highest voltage with respect to earth which may be applied to a circuit(s) of the potentiometer so that the
potentiometer is unlikely to become dangerous to touch.
Nole. — Auxiliary circuit(s) (if any) may have different value(s) of circuit insulation voltage (nominal circuit voltage).
2.10 Ripple content
The ripple content of a d.c. supply expressed as a percentage of the d.c. component is:
r.m.s. voltage of the fluctuating component
x 100
d.c. voltage
2.11 Leakage current screen (circuit)
A conductive path which prevents leakage currents from affecting the results of measurements.
2.12 Electrostatic screen
An electrically conductive enclosure or coating intended to protect the enclosed space from external electrostatic
influences.
2.13 Measuring terminals
The terminals to which the circuit of the voltage to be measured is intended to be connected.
2.14 Measuring circuit
The internal circuit of the potentiometer which is (or can be) conductively connected to the measuring terminals.
2.15 Measured quantity circuit selector switch
The switch which selects the set of measuring terminals to be connected to the measuring circuit.
2.16 Residual e.m.f of a potentiometer
The open circuit voltage present at the measuring terminals due to the potentiometer itself when it is operational
and its measuring dials are set to zero.
2.17 Incremental linearity
The overall linearity of a potentiometer is characterized by both of the following aspects:
constancy of the developed voltage for any two different settings of the measuring dials, each setting
a)
indicating the same value.
b) constancy of incremental voltage developed between adjacent settings of any one measuring dial.
2.18 Influence quantity
A quantity, other than the measured quantity, which is liable to cause unwanted variation in the dial setting.
2.19 Common mode voltage
A voltage which exists between one of the measuring terminals (called the reference terminal of common mode
voltage) and the earth terminal, or the leakage current screen terminal, or the electrostatic screen terminal,
separately or collectively (as specified).
2.20 Variation with influence quantity
The difference between two measured values for the same measured quantity when an influence quantity assumes
successively two different specified values.

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SIST EN 60523:2000
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2.21 Reference conditions
The specified conditions under which the potentiometer meets the requirements concerning intrinsic errors.
2.22 Reference value
A specified single value of an influence quantity at which, within the stated tolerance, the potentiometer meets
the requirements concerning intrinsic errors.
2.23 Reference range
A specified range of values of an influence quantity within which the potentiometer meets the requirements
concerning intrinsic errors.
2.24 Nominal range of use
A specified range of values which each influence quantity can assume without causing a variation exceeding
the specified limits.
2.25 Limiting values of an influence quantity
Extreme values which an influence quantity may assume without the potentiometer being damaged or perma-
nently altered in such a way that it no longer satisfies the requirements of its accuracy class.
2.26 Fiducial value
A single value for each effective range to which reference is made in order to specify the accuracy of a poten-
tiometer.
Unless otherwise stated by the manufacturer, the fiducial value of a given effective range is the highest integral
power of 10 within that range.
A potentiometer having a maximum dial setting of 1.8 V and range factors of 1, 0.1 and 0.01 will have
Example:
fiducial values of 1.0 V, 0.1 V and 0.01 V respectively.
2.27 Error
Value obtained by subtracting the true value of the measured quantity from the dial setting.
Since the true value cannot be determined by measurement, a value obtained under specified test conditions and
at a specified time is used instead. This value is traceable to national measurement standards or to measurement
standards agreed upon by manufacturer and user.
Note. — The error due to any auxiliary equipment which is not built-in to the potentiometer is not included in the error of the poten-
tiometer.
2.28 Intrinsic error
An error determined under reference conditions.
2.29 Accuracy
The accuracy of a potentiometer is defined by the limits of intrinsic error and the limits of variations due to
influence quantities.
2.30 Accuracy class
A class of potentiometers the accuracy of all of which can be designated by the same number if they comply
with all the requirements of this standard.
2.31 Class index
The number which designates the accuracy class.

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SIST EN 60523:2000
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3. Classification
Potentiometers specified in this standard are classified according to their accuracy classes as defined in
Sub-clause 2.30 as follows:
a) 0.0005, 0.001, 0.002, 0.005, 0.01, 0.02, 0.05, 0.1
b) 5 ppM, 10 ppM, 20 ppM, 50 ppM, 100 ppM, 200 ppM, 500 ppM, 1 000 ppM.
The class index of a potentiometer may be expressed either in percentage using a) or in ppM using b) or both.
If a potentiometer has several measuring ranges, each range may have its own class index.
4. Limits of intrinsic error
Potentiometers shall comply with the relevant limits of intrinsic error specified for their respective accuracy
classes for the duration of one year from the date of certification associated with delivery or another date to be
agreed upon by the manufacturer (or responsible supplier) and the user, provided that the conditions of use, trans-
port and storage specified by the manufacturer are complied with.
Note. — For potentiometers, stability with regard to time is an essential characteristic. Here, it is specified only for the duration of
one year, but experience has shown that the rate of change due to ageing effects decreases with time.
4.1 Permissible limits of intrinsic error
The permissible limits of error of a potentiometer are composed of two parts:
— constant term related to the fiducial value,
— variable term proportional to the dial setting.
The two limits are given by the positive and negative values, respectively, of the binomial formula:
Ettm
100 (1 0
+ X/
where:
Elim is the permissible limit value of the error, expressed in volts,
Un is the fiducial value, expressed in volts,
X is the dial setting, expressed in volts,
c is the class index, expressed as a percentage.
When the class index c is expressed in ppM, the formula given below should be used:
C Un
Eitm = ^
1 000 000 10 + X
4.2 Incremental linearity
4.2.1 The difference in error corresponding to the same value of the measured quantity obtained by any two
dial settings shall not exceed half of the permissible limit of intrinsic error.
4.2.2 The difference in error between any two adjacent dial settings on any one measuring dial shall not exceed
half of the average of the permissible limit of intrinsic error of the same sign for these settings.
4.3 Resolution
The resolution shall not have a value exceeding:
0.5 Un if the class index c is expressed in percentage.
100
or:
0.5 Un if the class index
c is expressed in ppM.
1 000 000

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SIST EN 60523:2000
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Range-changing device
4.4
The manufacturer shall specify if re-standardization of the potentiometer is necessary on changing the range.
Independent circuit for standardization of a potentiometer
4.5
If a potentiometer can be standardized on any range by means of an independent circuit without the use of the
measurin g dials, the additional error introduced by such standardization shall not exceed half of the permissible
intrinsic error.
Conditions for the determination of intrinsic errors
5.
5.1 The reference values relative to each of the influence quantities are shown in Table I.
5.2 Before any measurement, sufficient time shall elapse for the potentiometer to reach a stable state and to be
in equilibrium with the reference values of the influence quantities.
5.3 The leakage current screen and the electrostatic screen, if any, shall be connected in accordance with the
manufacturer's instructions.
TABLE I
Reference conditions and tolerances of the influence quantities
Reference conditions
Class index
Influence Tolerance permitted
unless otherwise
quantity indicated by for testing purposes 1)
the manufacturer % ppM
0.0005.0.001 5.10 ± 0.5 °C
Ambient temperature 20 °C 2)
0.002 .0.01 20.100 ± 1 °C
200.1 000 2 °C
0.02 . .0.1 ±
Relative humidity 40% to 60%
Position
Any
Ripple content 3)
Less than 0.1%
0.0005.0.1 5 .1 000 ± 0.1 of the
Common mode voltage Zero
fiducial value
Period of connection At least 5 min
to auxiliary supplies
prior to measurement
4)
1)
For a reference range, no tolerance is allowed.
2)
If another temperature is indicated, it should be chosen from IEC Publication 160, that is 23 °C or 27 °C.
3)
This relates to the ripple content of each associated external d.c. supply to the ripple of the external voltage reference source (if any)
and to the ripple superimposed on the measured quantity.
4)
The effects of changes in the d.c. supply(ies) are not taken into account. They are normally removed by the process of standardization.

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SIST EN 60523:2000
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6. Permissible variations
6.1 Limits of variation
gle influence quantity is
When the potentiometer is under the reference conditions given in Table I and a sin
varied in accordance with Sub-clause 6.2, the variation shall not exceed the values specified in Table II and
Sub-clause 6.3.
TABLE 11
Limits of the nominal range of use and permissible variations
Class index
Limits of nominal range of use unless
Permissible
Influence
otherwise indicated by the
variation 1)
quantity
manufacturer
% ppM
20
0.0005.0.001 5.10 Reference value ± 2 °C
Ambient temperature
Reference value ± 5 °C 50
0.002 .0.01 20.100
200.1 000 Reference value ± 10 °C 100
0.02 .0.1
0.0005.0.1 5.1 000 25% and 75% 30
Relative humidity
2>
50
d.c. common mode 0.0005.0.1 5.1 000 10 V
voltage
1) Expressed as a percentage of the permissible intrinsic error.
2)
The resistance of the external circuit, that is the resistance seen from the two terminals between which the measured quantity is applied,
shall not exceed 10 kS2.
6.2
Conditions for the determination of the variations
6.2.1 Variations shall be determined for each influence quantity. During each determination, all other influence
quantities shall be maintained at their reference conditions.
6.2.2 The variation is assessed as follows:
6.2.2.1 When a reference value is assigned to the potentiometer, the influence quantity shall be varied between
that value and any value within the limits of the nominal range of use as given in Table IL
6.2.2.2 When a reference range and a nominal range of use are assigned to the potentiometer, the influence
quantity shall be varied between each of the limits of the reference range and any value in that part of the nominal
range of use adjacent to the chosen limit of the reference range.
6.3
Determination of the effect of a common mode voltage
The effect of a common mode voltage may depend on the resistance of the external circuit of the measured
quantity.
The effect of a common mode voltage may be determined:
— either by the direct method given in Appendix A or,
— by the indirect method given in Appendix B.
If the potentiometer enclosure is made of insulating material, a conductive supporting plate is used instead
of the earth terminal.
Tests to determine the effect of a common mode voltage are to be carried out only by agreement betweeri
man
ufacturer and user.

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SIST EN 60523:2000
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7. Additional electrical and mechanical requirements
7.1 Voltage test and other safety requirements
The requirements for the voltage test and other safety requirements are included in IEC Publication 414, Safety
Requirements for Indicating and Recording Electrical Measuring Instruments and their Accessories, to which
reference shall be made.
7.2 Insulation resistance test
The values of d.c. insulation resistance, measured at 500 V d.c. ± 10% between any two points which are not
intended to have any connection between them, shall not be less than the values given in Table III.
The measurement shall be made between 1 min and 2 min after the application of the voltage.
TABLE III
Minimum values of insulation resistance
Class index
Minimum value of
insulation resistance
ppM
0.0005.0.001 5.10 10 GS
0.002 .0.01 20.100 1 GS/
0.02 .0.1 200.1 000 100 M52
7.3 Measured quantity circuit selector switches
Measured quantity circuit selector switches, if any, shall switch all poles of all measured quantity circuits. The
several measured quantity circuits shall not be connected together, even momentarily, during operation of the
switch.
7.4 Rheostats for standardization of the potentiometer
If internal rheostats are provided, they shall be smooth and continuous in operation and shall have a fineness
of adjustment such that the potentiometer current can be set with a resolution less than or equal to 10% of the
value corresponding to the class index.
7.5 Limiting temperature for storage, transport and use
Unless otherwise stated by the manufacturer, potentiometers shall be capable of withstanding, without damage,
exposure to ambient temperatures within the range —10 °C to +50 °C. After returning to reference conditions,
the potentiometers shall meet the requirements of this standard.
Notes 1.— If potentiometers are installed in racks or test desks, care should be taken to ensure that the ventilation required for their
operation is not impeded.
2. — If the potentiometer incorporates a standard cell or other devices which could be damaged by temperature, the manufacturer
may state other values.

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SIST EN 60523:2000
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8.
Information, markings and symbols
8.1 Information
8.1.1 The following information shall be given by the manufacturer:
a) Manufacturer's name or mark or that of the responsible supplier.
b) Type reference given by the manufacturer or responsible supplier.
c) Serial number.
d) Effective range, resolution and measuring range factor(s).
e) Class index (indices).
f) Reference value and nominal range of use for temperature if different from those given in Tables I and II.
g) Where relevant, reference position and nominal range of use for position.
h) Where relevant, essential parameters of the auxiliary equipment, in particular those of the voltage reference
source and current supply apparatus.
i)
Procedure for standardization and use of the potentiometer.
j) Circuit diagram, values of components and list of replaceable parts.
k) Reference value (range) and nominal range of use for other influence quantities (see
f) and g)), if different
from those given in Tables I and II.
1) Test voltage.
8.1.2 If a certificate is supplied by agreement between the manufacturer or responsible supplier and the user,
it shall contain the following information:
m)
Certified values together with their uncertainties.
n) Date of certification.
o) Designation of certifying authority.
8.2 Markings, symbols and their locations
The markings and symbols shall be legible and indelible.
The symbols specified in Table IV shall be used.
8.2.1 The following information shall be marked on a nameplate or on the case:
a), b), c),
e) using symbol E-7 or E-8.
g)
using symbols D-1 to D-6.
I) using symbols C-1 to C-3.
In addition, the following markings shall be made:
"d.c. potentiometer" or this term in another language.
Where relevant, symbol F-33, showing that some other essential information is given in a separate document.
If the reference value or the reference range is marked, it shall be identified by underlining.
8.2.2 All terminals shall be marked to show polarity (where relevant), function and characteristics of the supply
source.
In particular, the following terminals shall be identified by a marking adjacent to the terminal:
— measuring terminals;
terminals for connection to auxiliary equipment;
— earth terminal, if any (using symbol F-31);
—
terminal(s) of the leakage current screen (circuit), if any;
terminal of the electrostatic screen, if any.
8.2.3 The following information shall be given either on the nameplate or on the case or in a separate document:
— d), f), k)

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SIST EN 60523:2000
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8.3 Documentation
8.3.1 Documentation shall state:
a), b), c), i j);
h), ),
d), f), k), if these are not marked on the nameplate or on the case. (See Sub-clause 8.2.3.)
8.3.2 The certificate referred to in Sub-clause 8.1.2, when supplied, shall state:
n
m), ), o).
8.4 Example of the marking of a potentiometer
(0.1.1 V/10 µV) x 1/0.1
13.23.33 °C
In this example, the markings provide the following information:
d.c. potentiometer, type A.B.C.D., serial number 12345, manufactured by N.N.
1)
2) The class index: 0.01 or 100 ppM
3) — range factor 1:
effective range (0.1.1 V) x 1. Resolution 10 µV;
— range factor 0.1:
effective range (0.1.1 V) x 0.1. Resolution 1 RV.
4)
Reference value of temperature: 23 °C.
Nominal range of use: from 13 °C to 33 °C.
(These values are shown because they are different from those specified in Tables I and II.)
5) Further essential information is given in a separate document.
6)
The test voltage is 500 V.

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SIST EN 60523:2000
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TABLE IV
Symbols for marking potentiometers
The majority of these symbols have been taken from IEC Publication 51, Table XI.
Symbol
Item I Symbol No. Item
No.
D-4 Example for potentio-
meter to be used as D - 1
Principal units and their principal
A
Nominal range of use
multiples and sub-multiples
80°.100°
Ampere A
A-2
80.90.100°
Milliampere mA
A-3 —
A-4 Microampere
uA
D-5 Example for potentio-
meter to be used as D-2
A-5 Kilovolt kV
1
Nominal range of use
—1.0.+1°
—1° .+ 1°
V
A-6 Volt
A-7 Millivolt mV
D-6 Example for potentio-
A8- Microvolt
µV
/
meteomi be used as
Nominal range of usee
A-16 Kilohertz • kHz
45°.75°
45.60.75°
A-17 Hertz Hz
A-18
Megohm MO
E Accuracy class
A-19 Kilohm kf
E-7 Class index with errors
A-20 Ohm 12
expressed as a percentage
(e.g. 0.01) when the per-
A-21 Milliohm
mt2
miscible error is pro-
0.01
portional in part to the
A-24
Degree Celsius `C
fiducial value and in part W
to the dial setting
A-25
Gigohm GS2
C Safety
E-8 Class index with errors
expressed in parts per
C- 1
Test voltage 500 V
million (e.g. 100 ppM)
when the permissible
100
Û
error is proportional in P P M
part to the fiducial value
C-2
Test voltage above 500 V
and in part to the dial
(e.g. 2 kV)
setting
l_-,1
C-3
Apparatus not subjected
/\
to a voltage test
l
F General symbols
LJ
F-27 Electrostatic screen -.\
D Position of use ( )
\\ _i
D-1
Potentiometer to be used
F-31 Earth terminal
with the supporting (
surface vertical
D-2
Potentiometer to be used
F-33 Refer to a separate A
I
with the supporting I
document
surface horizontal
D-3
Potentiometer to be used
F-41 Leakage current screen Under consideration
with the supporting
surface inclined (e.g. 60°)
/60°
from the horizontal plane

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SIST EN 60523:2000
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APPENDIX A
DETERMINATION OF THE EFFECT OF COMMON MODE VOLTAGE
DIRECT METHOD
The effect of a common mode voltage is obtained directly by determining the variation caused in the dial setting
for a given measured quantity when a common mode voltage is applied to one of the measuring terminals.
The specified value of common mode voltage is applied between each of the measuring terminals and the
enclosure of the potentiometer when it is conductive or, when the enclosure is made of insulating material, a
conductive supporting plate.
All precautions should be taken so that the leakage resistances of auxiliary equipment cannot affect the results
of the test. Auxiliary equipment which is not incorporated in the potentiometer, such as:
— standard cell,
— null detector,
— power supply,
as well as the external measuring circuit, should be carefiilly insulated from the enclosure of the potentiometer
(or from the conductive plate).
When it is impossible to avoid the use of external devices or of a measuring circuit having an auxiliary a.c.
source, all precautions should be taken to prevent coupling from a.c. circuits from affecting the results of the
test.
When the potentiometer itself has a leakage current screen, it should be connected in accordance with the
manufacturer's instructions. In the absence of a statement to the contrary by the manufacturer, the electrostatic
screen, if any, should be connected to the enclosure and to earth.
The determination of the effect of the common mode voltage should be carried out:
a)
with substantially zero resistance of the external measuring circuit,
b)
with a resistance of about 10 kS2 of the external measuring circuit, the common mode voltage being applied
in turn to both of the measuring terminals.
This test is carried out using at least three values of the measured quantity spread over the effective range.
Each test is carried out using both polarities of the common mode voltage.
The variation is given by the difference between the values obtained above and those obtained in the absence
of a common mode voltage, all other test conditions remaining unchanged.
The variation shall not exceed the values given in Table II.

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SIST EN 60523:2000
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APPENDIX B
DETERMINATION OF THE
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