IEC 60393-5:2015

Potentiometers for use in electronic equipment - Part 5: Sectional specification - Single-turn rotary low-power wirewound and non-wirewound potentiometers

IEC 60393-5:2015 applies to single-turn rotary low-power wirewound and non-wirewound potentiometers, with a rated dissipation less than to 10 W. These potentiometers are primarily intended for use in electronic equipment. This part of IEC 60393 prescribes preferred ratings and characteristics and selects from IEC 60393-1, appropriate quality assessment procedures, tests and measuring methods. It provides general performance requirements for this type of potentiometer. This standard gives the minimum performance requirements and test severities. This edition includes the following significant technical changes with respect to the previous edition:
a) revision of the information on the assessment level EZ and FZ (zero nonconforming);
b) complete editorial revision.
This publication is to be read in conjunction with IEC 60393-1:2008.

Potentiomètres utilisés dans les équipements électroniques - Partie 5: Spécification intermédiaire - Potentiomètres de faible puissance, bobinés et non bobinés, rotatifs, monotour

L'IEC 60393-5:2015 s'applique aux potentiomètres de faible puissance, bobinés et non bobinés, rotatifs, monotour avec une dissipation assignée inférieure à 10 W. Ces potentiomètres sont principalement conçus pour être utilisés dans des équipements électroniques. La présente partie de l'IEC 60393 prescrit des valeurs assignées et des caractéristiques préférentielles et sélectionne dans l'IEC 60393-1 des procédures d'assurance de la qualité, des essais et des méthodes de mesure appropriés. Elle donne les exigences de performances générales pour ce type de potentiomètre. La présente norme donne les exigences de performances et les sévérités d'essais minimales. Cette édition inclut les modifications techniques majeures suivantes par rapport à l'édition précédente:
a) révision des informations sur les niveaux d'assurance EZ et FZ (zéro non-conformité);
b) révision éditoriale complète.
Cette publication doit être lue conjointement avec la IEC 60393-1:2008.

General Information

• Status: Published
• Publication Date: 13-Dec-2015
• ICS: 31.040.20 - Potentiometers, variable resistors
• Technical Committee: TC 40 - Capacitors and resistors for electronic equipment
• Drafting Committee: MT 60393-5 - TC 40/MT 60393-5
• Current Stage: PPUB - Publication issued
• Start Date: 14-Dec-2015
• Completion Date: 31-Dec-2015

Standards Content (Sample)

IEC 60393-5 ®
Edition 3.0 2015-12
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Potentiometers for use in electronic equipment –
Part 5: Sectional specification – Single-turn rotary low-power wirewound and
non-wirewound potentiometers
Potentiomètres utilisés dans les équipements électroniques –
Partie 5: Spécification intermédiaire – Potentiomètres de faible puissance,
bobinés et non bobinés, rotatifs, monotour

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IEC 60393-5 ®
Edition 3.0 2015-12
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Potentiometers for use in electronic equipment –

Part 5: Sectional specification – Single-turn rotary low-power wirewound and

non-wirewound potentiometers
Potentiomètres utilisés dans les équipements électroniques –

Partie 5: Spécification intermédiaire – Potentiomètres de faible puissance,

bobinés et non bobinés, rotatifs, monotour

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 31.040.20 ISBN 978-2-8322-3059-6

– 2 – IEC 60393-5:2015  IEC 2015
CONTENTS
FOREWORD . 4
1 General . 6
1.1 Scope . 6
1.2 Normative references . 6
1.3 Information to be given in a detail specification . 6
1.3.1 General . 6
1.3.2 Outline drawing and dimensions . 7
1.3.3 Mounting . 7
1.3.4 Style . 8
1.3.5 Resistance law . 8
1.3.6 Ratings and characteristics . 8
1.3.7 Marking . 8
1.3.8 Ordering information . 8
1.3.9 Additional information . 8
1.4 Marking . 9
1.4.1 General . 9
1.4.2 Marking for potentiometers . 9
1.4.3 Marking for packaging . 9
1.4.4 Additional marking . 9
2 Preferred ratings, characteristics and test severities . 9
2.1 Preferred characteristics . 9
2.1.1 General . 9
2.1.2 Preferred climatic categories . 9
2.1.3 Temperature coefficients and temperature characteristics of resistance . 10
2.1.4 Limits for change in resistance or output voltage ratio . 11
2.1.5 Limits for insulation resistance . 12
2.1.6 Limits for resistance law . 12
2.1.7 Limits for starting torque . 13
2.1.8 Limits for switch torque . 13
2.2 Preferred values of ratings . 13
2.2.1 General . 13
2.2.2 Nominal total resistance . 14
2.2.3 Tolerances on nominal total resistance . 14
2.2.4 Rated dissipation . 14
2.2.5 Limiting element voltage . 15
2.2.6 Insulation voltage . 15
2.2.7 Switch rating (if applicable) . 15
2.3 Preferred test severities . 15
2.3.1 General . 15
2.3.2 Drying . 16
2.3.3 Vibration . 16
2.3.4 Shock . 16
3 Quality assessment procedures . 16
3.1 General . 16
3.2 Definitions. 16
3.2.1 Primary stage of manufacture . 16

3.2.2 Structurally similar components . 16
3.2.3 Assessment levels EZ and FZ (zero non-conforming) . 17
3.3 Qualification approval . 17
3.3.1 General . 17
3.3.2 Qualification approval on the basis of the fixed sample size procedure . 17
3.3.3 Tests . 17
3.4 Quality conformance inspection . 27
3.4.1 Formation of inspection lots . 27
3.4.2 Test schedule . 27
3.4.3 Assessment levels . 27
3.5 Delayed delivery . 31
Annex A (normative) Test methods for sealing . 32
A.1 Container sealing test for container sealed styles only . 32
A.2 Shaft and panel sealing test for all styles . 32
Bibliography . 33

Figure 1 – Outline drawing and dimensions . 7
Figure 2 – Rated dissipation curve . 14
Figure 3 – Rated dissipation curve (examples of smaller area). 15
Figure A.1 – Component under test. 32

Table 1 – Temperature coefficients and temperature characteristics of resistance for
non-wirewound potentiometers . 10
Table 2 – Temperature coefficients and temperature characteristics of resistance for
wirewound potentiometers . 11
Table 3 – Preferred combination of limits . 12
Table 4 – Preferred measuring points and values of output ratio for non-wirewound
potentiometers . 13
Table 5 – Preferred measuring points and values of output ratio for wirewound
potentiometers . 13
Table 6 – Fixed sample size test schedule for qualification approval (1 of 8) . 19
Table 7 – Quality conformance inspection: Lot-by-lot (1 of 2) . 27
Table 8 – Quality conformance inspection: Periodic testing (1 of 3). 29

– 4 – IEC 60393-5:2015  IEC 2015
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
POTENTIOMETERS FOR USE IN ELECTRONIC EQUIPMENT –

Part 5: Sectional specification – Single-turn rotary low-power
wirewound and non-wirewound potentiometers

FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote
international co-operation on all questions concerning standardization in the electrical and electronic fields. To
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agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
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3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
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assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any
services carried out by independent certification bodies.
6) All users should ensure that they have the latest edition of this publication.
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8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of
patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 60393-5 has been prepared by IEC technical committee 40:
Capacitors and resistors for electronic equipment.
This third edition cancels and replaces the second edition published in 1992 and constitutes a
technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) revision of the information on the assessment level EZ and FZ (zero nonconforming);
b) complete editorial revision.

The text of this standard is based on the following documents:
FDIS Report on voting
40/2408/FDIS 40/2423/RVD
Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.
This International Standard is to be used in conjunction with IEC 60393-1:2008.
A list of all parts in the IEC 60363 series, published under the general title Potentiometers for
use in electronic equipment, can be found on the IEC website.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
The committee has decided that the contents of this publication will remain unchanged until
the stability date indicated on the IEC web site under "http://webstore.iec.ch" in the data
related to the specific publication. At this date, the publication will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
– 6 – IEC 60393-5:2015  IEC 2015
POTENTIOMETERS FOR USE IN ELECTRONIC EQUIPMENT –

Part 5: Sectional specification – Single-turn rotary low-power
wirewound and non-wirewound potentiometers

1 General
1.1 Scope
This part of IEC 60393 applies to single-turn rotary low-power wirewound and non-wirewound
potentiometers, with a rated dissipation less than to 10 W. These potentiometers are primarily
intended for use in electronic equipment.
This part of IEC 60393 prescribes preferred ratings and characteristics and selects from
IEC 60393-1, appropriate quality assessment procedures, tests and measuring methods. It
provides general performance requirements for this type of potentiometer.
This standard gives the minimum performance requirements and test severities.
1.2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and
are indispensable for its application. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any
amendments) applies.
IEC 60062, Marking codes for resistors and capacitors
IEC 60068-1:2013, Environmental testing – Part 1: General and guidance
IEC 60068-2-1:2007, Environmental testing – Part 2-1: Tests – Test A: Cold
IEC 60068-2-2:2007, Environmental testing – Part 2-2: Tests – Test B: Dry heat
IEC 60393-1:2008, Potentiometers for use in electronic equipment – Part 1: Generic
specification
IEC 60915, Capacitors and resistors for use in electronic equipment – Preferred dimensions
of shaft ends, bushes and for the mounting of single-hole, bush-mounted, shaft-operated
electronic components
IEC 61193-2:2007, Quality assessment systems – Part 2: Selection and use of sampling
plans for inspection of electronic components and packages
1.3 Information to be given in a detail specification
1.3.1 General
Detail specifications shall be derived from the relevant blank detail specification.
Detail specifications shall not specify requirements inferior to those of the generic, sectional
or blank detail specification. When more severe requirements are included, they shall be
listed in a subclause of the detail specification and indicated in the test schedules, for
example by an asterisk.
The information given in 1.3.3 and 1.3.4 may, for convenience, be presented in tabular form.
The following information shall be given in each detail specification and the values quoted
shall preferably be selected from those given in the appropriate clause of this sectional
specification.
1.3.2 Outline drawing and dimensions
The detail specification shall incorporate an illustration of the potentiometer being specified.
Where space is insufficient to show the detail dimensions required for inspection purposes,
such dimensions shall appear on a drawing forming an annex to the detail specification, as
shown in Figure 1.
IEC
Figure 1 – Outline drawing and dimensions
The drawing shall give the following details:
– the dimensions of the shaft and bush. These may be given either on the outline drawing or
by reference to IEC 60915;
– any locating devices;
– the total mechanical travel;
– the effective electrical travel;
– the angle of ineffective mechanical travel;
– the switch angle (if applicable);
– the dimensions of the switch, if fitted, and the location of terminations;
– the dimensions which shall be measured in accordance with IEC 60393-1:2008, 4.4.2;
– any other dimensional information which will adequately describe the potentiometer.
All dimensions shall preferably be stated in millimetres, however, when the original
dimensions are given in inches, the converted metric dimensions in millimetres shall be added.
When the potentiometer is not designed for use on printed boards, this shall be clearly
indicated in the detail specification.
1.3.3 Mounting
The detail specification shall specify the method of mounting to be applied for the voltage
proof and the insulation resistance tests and for the application of the vibration and shock
tests. The potentiometers shall be mounted by their normal means, but the design may be
such that special mounting fixtures are required. In this case, the detail specification shall
describe the mounting fixtures that shall be used for the voltage proof and the insulation

– 8 – IEC 60393-5:2015  IEC 2015
resistance tests and for the application of the vibration and shock tests. For the latter tests
the mounting shall be such that there shall be no parasitic vibration.
1.3.4 Style
See IEC 60393-1:2008, 2.2.2.
The style shall be presented by a double-letter code, e.g. AB, which is arbitrarily chosen for
each detail specification.
The style designation, therefore, has no meaning unless the number of the detail specification
is also given.
1.3.5 Resistance law
See 2.1.6.
1.3.6 Ratings and characteristics
1.3.6.1 General
The ratings and characteristics shall be in accordance with the relevant clauses of this
specification together with the following:
1.3.6.2 Nominal total resistance range
See IEC 60393-1:2008, 2.3.2
When products approved according to the detail specification have different ranges, the
following statement should be added:
“The range of values available in each style is given in the register of approvals, available for
www.iecq.org”.
example on the website http://
The qualified products list “QPL” style is given in the register of approvals, available for
example on the website stated above.
1.3.7 Marking
The detail specification shall specify the content of the marking on the potentiometer and on
the package. Deviations from 1.4 of this sectional specification shall be specifically stated.
1.3.8 Ordering information
The detail specification shall indicate that the following information, in clear or in coded form,
is required when ordering:
a) nominal total resistance and tolerance on nominal total resistance;
b) resistance law (if other than linear);
c) number and issue reference of the detail specification and style reference;
d) shaft and bush dimensions, if not implicit in the style reference.
1.3.9 Additional information
The detail specification may include information which is not required to be verified by the
inspection procedure, such as circuit diagrams, curves, drawings and notes needed for the
clarification of the detail specification.

1.4 Marking
1.4.1 General
When coding is used for nominal resistance, tolerance and date of manufacture, the method
shall be selected from those given in IEC 60062.
The information given in the marking is normally selected from the following list; the relative
importance of each item is indicated by its position in the list:
a) nominal total resistance;
b) tolerance on nominal total resistance;
c) resistance law (if other than linear);
d) detail specification and style reference;
e) year and month (or week) of manufacture;
f) details of shaft and bush (if not implicit in d) above). This may be in code form;
g) manufacturer's name and/or trademark;
h) switch rated voltage (a.c. and d.c. ratings when appropriate);
i) switch rated current (a.c. and d.c. ratings when appropriate);
j) corresponding terminals (in the case of double pole switches), and terminals for
connection to the mains supply;
k) manufacturer’s type and designation.
1.4.2 Marking for potentiometers
The potentiometer shall be clearly marked with a) and b) of 1.4.1 and with as many of the
remaining items as is practicable. Any duplication of information in the marking of the
potentiometer should be avoided.
The switch, if fitted, shall be clearly marked with h), i) and j) of 1.4.1.
1.4.3 Marking for packaging
The package containing the potentiometer(s) shall be clearly marked with a) to g) and, if a
switch is fitted to the potentiometer, with h) and i) of 1.4.1, and with the information below.
a) quantity
b) country origin
1.4.4 Additional marking
Any additional marking shall be so applied that no confusion can arise.
2 Preferred ratings, characteristics and test severities
2.1 Preferred characteristics
2.1.1 General
The values given in the detail specification shall preferably be selected from the following:
2.1.2 Preferred climatic categories
The potentiometers covered by this specification are classified into climatic categories
according to the general rules given in IEC 60068-1:2013, Annex A.

– 10 – IEC 60393-5:2015  IEC 2015
The lower and upper category temperature and the duration of the damp heat, steady state
test shall be chosen from the following:
Lower category temperature: –65 °C, –55 °C, –40 °C, –25 °C and –10 °C.
Upper category temperature +70 °C, +85°C, +100 °C, +125 °C and +155 °C.
Duration of the damp heat, steady state test: 4, 10, 21 and 56 days.
The severities for the cold and dry heat tests are the lower and upper category temperatures
respectively. Because of the construction of some potentiometers these temperatures will
occur between two of the preferred temperatures given in IEC 60068-2-1:2007 and
IEC 60068-2-2:2007. In this case the nearest preferred temperature within the actual
temperature range of the potentiometer shall be chosen for this severity.
2.1.3 Temperature coefficients and temperature characteristics of resistance
The limits of change in resistance for the temperature characteristics of resistance test are
given in Table 1 (for non-wirewound potentiometers) and in Table 2 (for wirewound
potentiometers).
Each line in the table gives the preferred temperature coefficients and corresponding
temperature characteristics for 20 °C to 70 °C and limits of resistance change in resistance
for the measurement of the temperature characteristics of resistance (see IEC 60393-1:2008,
4.14) on the basis of the category temperature ranges of 2.1.2.
Different portions of the resistance range may be covered by different temperature
coefficients (or characteristics) of resistance although they appear in a single detail
specification.
If measurements at additional temperatures are required, they shall be called for in the detail
specification.
Table 1 – Temperature coefficients and temperature characteristics
of resistance for non-wirewound potentiometers
Tempera- Temperature Temperature characteristics of resistance
ture characteristics (limits of resistance change in percentage )
coeffi- of resistance
%
cients of
%
resistance
Reference temperature/ Reference temperature/
–6 Lower category temperature Upper category temperature
10 /K
°C °C
+20/ +20/ +20/ +20/ +20/
a
20 °C/70 °C 20/85 20/100 20/125 20/155
–65 –55 –40 –25 –10
–800/ –4/ –5,2/ –6,4/ –8,4/ –10,8/
+6,8/ +6/ +4,8/ +3,6/ +2,4/
–2 500 –12,5 –16,25 –20 –26,25 –33,75
+21,3 +18,75 +15 +11,3 +7,5
–400/ –2/ –2,6/ –3,2/ –4,2/ –5,4/
+3,4/ +3/ +2,4/ +1,8/ +1,2/
–1 000 –5 –6,5 –8 –10,5 –13,5
+8,5 +7,5 +6 +4,5 +3
–150/ –0,75/ +1,3/ +1,13/ +0,9/ +0,68/ +0,45/ –0,98/ –1,2/ –1,58/ –2,02/
– 600 –3 –3,9 –4,8 –6,3 –8,2
+5,1 +4,5 +3,6 +2,7 +1,8
±1 000 ±5 ±8,5 ±7,5 ±6 ±4,5 ±3 ±6,5 ±8 ±10,5 ±13,5
±500 ±2,5 ±4,3 ±3,75 ±3 ±2,25 ±1,5 ±3,25 ±4 ±5,25 ±6,75
±250 ±1,25 ±2,15 ±1,88 ±1,5 ±1,13 ±0,75 ±1,62 ±2 ±2,62 ±3,38
±150 ±0,75 ±1,3 ±1,15 ±0,9 ±0,68 ±0,45 ±0,98 ±1,2 ±1,6 ±2,05
±100 ±0,5 ±0,85 ±0,75 ±0,6 ±0,45 ±0,3 ±0,65 ±0,8 ±1,05 ±1,35
±50 ±0,25 ±0,43 ±0,375 ±0,3 ±0,23 ±0,15 ±0,325 ±0,4 ±0,525 ±0,675
a
Potentiometers having an upper category temperature of 85 °C need not be measured between 20 °C and
70 °C.
Table 2 – Temperature coefficients and temperature characteristics
of resistance for wirewound potentiometers
Tempera- Tempera- Temperature characteristics of resistance
ture ture (limits of resistance change in percentage )
coeffi- character-
%
cients of istics of
resistance resistance
Reference temperature/ Reference temperature/
–6
Lower category temperature Upper category temperature
10 /K %
°C °C
a
20 °C/70 °C +20/–65 +20/–55 +20/–40 +20/–25 +20/–10 20/85 20/100 20/125 20/155
+600/–200 –1/+3 –5,1/+1,7 –4,5/+1,5 –3,6/+1,2 –2,7/+0,9 –1,8/+0,6 +3,9/–1,3 +4,8/–1,6 +6,3/–2,1 +8,1/–2,7
±250 ±1,25 ±2,15 ±1,88 ±1,5 ±1,13 ±0,75 ±1,62 ±2 ±2,62 ±3,38
±150 ±0,75 ±1,3 ±1,15 ±0,9 ±0,68 ±0,45 ±0,98 ±1,2 ±1,6 ±2,05
±100 ±0,5 ±0,85 ±0,75 ±0,6 ±0,45 ±0,3 ±0,65 ±0,8 ±1,05 ±1,35
±50 ±0,25 ±0,43 ±0,375 ±0,3 ±0,23 ±0,15 ±0,325 ±0,4 ±0,525 ±0,675
±25 ±0,125 ±0,215 ±0,188 ±0,15 ±0,113 ±0,075 ±0,162 ±0,2 ±0,262 ±0,338
a
Potentiometers having an upper category temperature of 85 °C need not be measured between 20 °C and
70 °C.
2.1.4 Limits for change in resistance or output voltage ratio
The preferred combinations of limits for change in resistance or output voltage ratio in each of
the tests listed in the heading of Table 3 are as indicated in the lines of the table.

– 12 – IEC 60393-5:2015  IEC 2015
Table 3 – Preferred combination of limits
Stability 4.38 4.34 4.30 4.22 4.35
class Climatic sequence Change of Robustness Thrust and Vibration
temperature of terminals pull
% 4.39 4.37
on shaft
Damp heat, steady 4.33 Shock
state Resistance to 4.34
soldering heat Change of
4.40 Mechanical
temperature
endurance 4,35
Vibration
4.43.2 Electrical
endurance at 70 °C 4.37
Shock
4.43.3 Electrical
endurance at upper
category
temperature
U U
ab ab
b a a
∆ ∆
∆R between terminals a and c
U U
ac ac
Non-wirewound potentiometers
20 ±(20 % R + 0,5 Ω) ±(5 % R + 0,1 Ω) ±(5 % R + 0,1 Ω) ±5 % ±5 %
±(15 % R + 0,5 Ω) ±(5 % R + 0,1 Ω) ±(3 % R + 0,1 Ω) ±3 % ±3 %
±(10 % R + 0,5 Ω) ±(3 % R + 0,1 Ω) ±(2 % R + 0,1 Ω) ±2 % ±2 %
±(5 % R + 0,1 Ω) ±(2 % R + 0,1 Ω) ±(1 % R + 0,1 Ω) ±1 % ±1 %
±(2 % R + 0,1 Ω) ±(1 % R + 0,05 Ω) ±(0,5 % R + 0,05 Ω) ±0,5 % ±0,5 %
Wirewound potentiometers
±(5 % R + 0,1 Ω) ±(2 % R + 0,1 Ω) ±(1 % R + 0,1 Ω) ±1 % ±1 %
±(3 % R + 0,1 Ω) ±(2 % R + 0,1 Ω) ±(1 % R + 0,05 Ω) ±1 % ±1 %
±(2 % R + 0,1 Ω) ±(1 % R + 0,1 Ω) ±(0,5 % R + 0,05 Ω) ±0,5 % ±0,5 %

The subclause numbers in the table refer to IEC 60393-1:2008.
U
a ab
The change in the output voltage ratio ∆ shall be expressed in percent of the total applied voltage.
U
ac
b
∆R indicates the value of change in resistance.

2.1.5 Limits for insulation resistance
The preferred limits for insulation resistance shall be 1 GΩ minimum or, after humidity tests,
100 MΩ.
2.1.6 Limits for resistance law
The preferred measuring points and associated values of the output ratio for resistance laws
are as follows:
a) non-wirewound potentiometers, see Table 4.

Table 4 – Preferred measuring points and values of output ratio
for non-wirewound potentiometers
Output ratio
% of effective U
Resistance law ab
%
electrical travel
U
ac
linear( B) 47 to 53
R < 0,22 MΩ: 40 to 60
R ≥ 0,22 MΩ: 35 to 65
logarithmic (A) 30 to 36 1,5 to 8
64 to 70 10 to 40
reverse logarithmic ( C ) 30 to 36 60 to 90
64 to 70 92 to 98,5
b) wirewound potentiometers, see Table 5.
Table 5 – Preferred measuring points and values of output ratio
for wirewound potentiometers
Output ratio
% of effective
U
Resistance law electrical travel ab
%
±1°
U
ac
linear (B) 33 1/3 33 1/3 ± 2,5
50 ± 2,5
66 2/3
66 2/3 ± 2,5
logarithmic (A) 25 12,5 ± 5
29 ± 5
reverse logarithmic (C) 25 37,5 ± 5
70,5 ± 5
2.1.7 Limits for starting torque
Limits for starting torque are as follows.
a) At the standard conditions for test:
− without shaft seal: 3,5 mN⋅m to 50 mN⋅m
− with shaft seal: 3,5 mN⋅m to 100 mN⋅m
b) At lower category temperature:
− without shaft seal: 3,5 mN⋅m to 150 mN⋅m
− with shaft seal: 3,5 mN⋅m to 300 mN⋅m
2.1.8 Limits for switch torque
Limits for starting torque are as follows.
a) At the standard conditions for test:
a maximum of 200 mN⋅m.
b) At lower category temperature:
a maximum of 400 mN⋅m.
2.2 Preferred values of ratings
2.2.1 General
The values given in detail specifications shall preferably be selected from the following:

– 14 – IEC 60393-5:2015  IEC 2015
2.2.2 Nominal total resistance
See IEC 60393-1:2008, 2.3.2.
2.2.3 Tolerances on nominal total resistance
The preferred tolerances on nominal total resistance are
− non-wirewound types: ±30 %, ±20 %, ±10 % and ±5 %
− wirewound types: ±10 % and ±5 %.
2.2.4 Rated dissipation
The preferred values of rated dissipation at 70 °C are:
0,063 W, 0,1 W, 0,16 W, 0,25 W, 0,4 W, 0,63 W, 1 W, 1,6 W, 2,5 W, 4 W, 6,3 W and 10 W.
The derated values of dissipation at temperatures in excess of 70 °C shall be as indicated by
the curve as shown in Figure 2.
Percentage of the
Area of recommended
rated dissipation
operation
Upper category
Lower category + 70 °C
temperature
temperature
IEC
Figure 2 – Rated dissipation curve
A smaller (or larger) area of operation may be given in the detail specification. In this event
the detail specification shall state the maximum allowable dissipation at temperatures other
than 70 °C. All break points on the curve shall be verified by test.

An example of derating curve having a smaller area of operation is given in Figure 3.
C.C.
Percentage of the
rated dissipation
W.W.
C.C.
LCT UCT
+ 40 °C  + 50 °C   + 70 °C   + 85 °C   + 100 °C
IEC
Key
LCT lower category temperature
UCT upper category temperature
Resistive elements
C.C. carbon composition
W.W. wire-wound
Figure 3 – Rated dissipation curve (examples of smaller area)
2.2.5 Limiting element voltage
The preferred values of limiting element voltage d.c. or a.c. (r.m.s.) are:
100 V, 125 V, 150 V, 200 V, 250 V and 300 V.
2.2.6 Insulation voltage
The detail specification shall state the value of the insulation voltage, rounded off to the
nearest 10 V. The numerical value of the insulation voltage shall be:
– normal air pressure: ≥1,42 times the limiting element voltage;
– low air pressure (at 8 kPa): ≥two-thirds the value at normal air pressure.
2.2.7 Switch rating (if applicable)
The preferred ratings for a switch are
– for a.c. voltage (r.m.s.):
1 A to 125 V, 1 A to 250 V, 2 A to 250 V, 3 A to 125 V, and 4 A to 250 V
– for d.c. voltage:
1 A to 250 V.
2.3 Preferred test severities
2.3.1 General
Test severities given in the detail specification shall preferably be selected from the following.

– 16 – IEC 60393-5:2015  IEC 2015
2.3.2 Drying
See IEC 60393-1:2008, 4.3, procedure 1 shall be used.
2.3.3 Vibration
See IEC 60393-1:2008, 4.35, with the following details:
Frequency range: 10 Hz to 55 Hz, or
10 Hz to 500 Hz, or
10 Hz to 2 000 Hz (non-wirewound potentiometers only).
Amplitude: 0,75 mm or acceleration 100 m/s (whichever is the less severe).
Sweep endurance: total duration: 6 h
The detail specification shall prescribe the mounting method to be used (see 1.3.3).
2.3.4 Shock
See IEC 60393-1:2008, 4.37, with the following details:
Pulse shape: half-sine
Acceleration: 500 m/s
Pulse duration: 11 ms
Severity: 3 successive shocks to be applied in each of the three directions (total
3 shocks)
The detail specification shall prescribe the mounting method to be used (see 1.3.3).
3 Quality assessment procedures
3.1 General
See IEC 60393-1:2008, Clause H.1.
3.2 Definitions
3.2.1 Primary stage of manufacture
For potentiometers, the primary stage of the manufacture is
– for carbon composition types: the process which produces the greatest change
polymerization of the binder;
– for wire-wound types: the winding of the resistance wire (or ribbon) on the mandrel
(insulation or insulated);
– for film types: the deposition of the resistive film on the substrate.
3.2.2 Structurally similar components
Potentiometers are considered as being structurally similar if they are produced with similar
processes and materials, having the same style and construction and also the same or similar
shaft and bush dimensions, though they may have different resistance values and
temperature characteristics (or coefficients) of resistance.

3.2.3 Assessment levels EZ and FZ (zero non-conforming)
Assessment levels EZ and FZ meet the requirements of “zero nonconforming” approach. It
has been introduced to align the assessment procedures and levels with current industry
practices by prescribing the permitted number of nonconforming items (acceptance number) c
as zero.
Therefore the sample size for lot-by-lot testing is determined by IEC 61193-2:2007, Table 1.
3.3 Qualification approval
3.3.1 General
The procedures for qualification approval testing are given in IEC 60393-1:2008, Clause H.5.
The schedule to be used for qualification approval testing on the basis of lot-by-lot and
periodic test is given in 3.4.
The procedure using a fixed sample size schedule is given in 3.3.2 and 3.3.3 below.
3.3.2 Qualification approval on the basis of the fixed sample size procedure
Sampling
The fixed sample size procedure is described in IEC 60393-1:2008, H.5.3 b). The sample
shall be representative of the range of values for which approval is sought. This may or may
not be the complete range covered by the detail specification.
The sample shall consist of specimens having the highest and lowest resistance values for
which approval is being sought. It should also include the specimens having the critical
resistance value, if this is within the range being submitted. When approval is being sought
for more than one temperature coefficient (or characteristics) of resistance, the sample shall
contain specimens representative of the different temperature coefficients (or characteristics)
of resistance. In a similar manner, the sample shall also contain a proportion of specimens of
the different resistance values having the closest tolerance for which approval is being sought.
The proportion of specimens having the different characteristics shall be proposed by the
manufacturers chief inspector and shall be to the satisfaction of a certification body (for
example IECQ CB).
Spare specimens are permitted as follows.
a) One per resistance value and one per each temperature coefficient or temperature
characteristics value which may be used to replace the permitted nonconforming items in
Group 0.
b) One per resistance value and one per each temperature coefficient or temperature
characteristics value which may be used to replace specimens which are nonconforming
because of incidents not attributable to the manufacturer. The number given in Group 0
assume that all groups are applicable.
When additional groups are introduced into the qualification approval test schedule the
number of specimens required for Group 0 shall be increased by the same number as that
required for the additional groups.
3.3.3 Tests
The
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