IEC TS 62993:2017

IEC TS 62993 ®
Edition 1.0 2017-07
TECHNICAL
SPECIFICATION
Guidance for determination of clearances, creepage distances and requirements
for solid insulation for equipment with a rated voltage above 1 000 V AC and
1 500 V DC, and up to 2 000 V AC and 3 000 V DC

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IEC TS 62993 ®
Edition 1.0 2017-07
TECHNICAL
SPECIFICATION
Guidance for determination of clearances, creepage distances and requirements

for solid insulation for equipment with a rated voltage above 1 000 V AC and

1 500 V DC, and up to 2 000 V AC and 3 000 V DC

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 29.080.30 ISBN 978-2-8322-4501-9

– 2 – IEC TS 62993:2017 © IEC 2017
CONTENTS
FOREWORD . 4
INTRODUCTION . 6
1 Scope . 7
2 Normative references . 7
3 Terms and definitions . 8
4 Basic information for the determination of INSULATION requirements . 11
4.1 General . 11
4.2 Voltages . 12
4.2.1 General . 12
4.2.2 Determination of RECURRING PEAK VOLTAGE . 12
4.3 OVERVOLTAGE categories. 12
4.4 Material groups . 13
4.5 POLLUTION DEGREES . 14
4.5.1 General . 14
4.5.2 Degrees of POLLUTION in the MICRO-ENVIRONMENT . 14
4.5.3 Conditions of conductive POLLUTION . 14
4.5.4 Clearances . 14
5 Dimensioning rules . 15
5.1 Clearances . 15
5.2 CREEPAGE DISTANCES . 17
5.2.1 General . 17
5.2.2 Voltage . 17
5.2.3 POLLUTION. 17
5.2.4 Shape of insulating surface . 17
5.2.5 Relationship to CLEARANCE . 18
5.2.6 CREEPAGE DISTANCES where more than one material is used or more
than one POLLUTION DEGREE occurs . 18
5.2.7 CREEPAGE DISTANCES split by floating conductive part . 18
5.2.8 Dimensioning of CREEPAGE DISTANCES of BASIC INSULATION,
SUPPLEMENTARY INSULATION and REINFORCED INSULATION . 19
5.2.9 CREEPAGE DISTANCES for DC applications . 20
5.3 SOLID INSULATION . 21
5.3.1 General . 21
5.3.2 Withstand of voltage stresses . 21
6 Tests and measurements . 21
6.1 Tests . 21
6.1.1 General . 21
6.1.2 Test for verification of CLEARANCES . 22
6.1.3 Tests for the verification of SOLID INSULATION . 24
6.2 Measuring CLEARANCES and CREEPAGE DISTANCES . 27
Bibliography . 28

Figure 1 – RECURRING PEAK VOLTAGE . 12
Figure 2 – Determination of the width (W) and height (H) of a rib . 18

Table 1 – RATED IMPULSE VOLTAGES according to OVERVOLTAGE CATEGORIES . 13

Table 2 – Clearances to withstand TRANSIENT OVERVOLTAGES . 15
Table 3 – Dimensioning of clearances to WORKING VOLTAGES, TEMPORARY
OVERVOLTAGES or RECURRING PEAK VOLTAGES . 16
Table 4 – Altitude correction factors . 17
Table 5 – CREEPAGE DISTANCES to avoid failure due to tracking . 20
Table 6 – Test voltages based on CLEARANCES and a test site altitude of 2 000 m
above sea level . 23
Table 7 – Correction factors according to test site altitude for test voltages for
CLEARANCES . 24
Table 8 – Severities for conditioning of SOLID INSULATION . 26

– 4 – IEC TS 62993:2017 © IEC 2017
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
GUIDANCE FOR DETERMINATION OF CLEARANCES, CREEPAGE
DISTANCES AND REQUIREMENTS FOR SOLID INSULATION
FOR EQUIPMENT WITH A RATED VOLTAGE ABOVE 1 000 V AC
AND 1 500 V DC, AND UP TO 2 000 V AC AND 3 000 V DC

FOREWORD
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Technical specifications are subject to review within three years of publication to decide
whether they can be transformed into International Standards.
IEC TS 62993, which is a technical specification, has been prepared by IEC technical
committee 109: Insulation co-ordination for low-voltage equipment.

The text of this technical specification is based on the following documents:
Enquiry draft Report on voting
109/158A/DTS 109/162/RVDTS
Full information on the voting for the approval of this technical specification can be found in
the report on voting indicated in the above table.
This
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