IEC TS 60815-3:2025
(Main)Selection and dimensioning of high-voltage insulators intended for use in polluted conditions - Part 3: Polymer insulators for AC systems
Selection and dimensioning of high-voltage insulators intended for use in polluted conditions - Part 3: Polymer insulators for AC systems
IEC TS 60815-3:2025, which is a technical specification, is applicable for the selection of polymeric insulators for AC systems, and the determination of their relevant dimensions, to be used in high voltage systems with respect to pollution. The specification applies to insulators for outdoor installation only.
This document gives specific guidelines and principles to arrive at an informed judgement on the probable behaviour of a given insulator in certain pollution environment.
The contents of this document are based on CIGRE TB 158 and CIGRE TB 361, which form a useful complement to this document for those wishing to study in greater depth the performance of insulators under pollution.
This document does not deal with the effects of snow or ice on polluted insulators. Although this subject is dealt with by CIGRE TB 158, current knowledge is very limited and practice is too diverse.
The objective of this document is to give the user means to
- determine the reference unified specific creepage distance (RUSCD) from site pollution severity (SPS) value or class,
- choose appropriate profiles,
- apply correction factors for altitude, insulator shape, size and position, etc. to the RUSCD.
This second edition of IEC TS 60815-3, together with IEC TS 60815-1, cancels and replaces the first edition of IEC TS 60815-3:2008. This edition constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous edition:
a) Terms and definitions are modified or introduced in this document;
b) From RUSCD of reference insulator to USCD of candidate insulator, the correction factors are introduced and revised, such as altitude correction, diameter correction, shed profile correction and - parallel insulator number correction;
d) The general guidance on materials is revised. The concept of hydrophobicity transfer and hydrophobicity transfer material (HTM) are introduced, recognising that a reduced creepage distance may be used for HTM insulators.
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Standards Content (Sample)
IEC TS 60815-3 ®
Edition 2.0 2025-12
TECHNICAL
SPECIFICATION
Selection and dimensioning of high-voltage insulators intended for use in
polluted conditions -
Part 3: Polymer insulators for AC systems
ICS 29.080.10 ISBN 978-2-8327-0746-3
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CONTENTS
FOREWORD . 3
1 Scope . 5
2 Normative references . 5
3 Terms, definitions and abbreviated terms . 5
3.1 Terms and definitions . 5
3.2 Abbreviated terms. 7
4 Principles . 7
5 Materials. 8
5.1 General information on common polymer housing materials . 8
5.2 Issues specific to polymer housing materials under pollution . 9
5.2.1 Reduction of creepage distance. 9
5.2.2 Extreme pollution . 9
6 Site pollution severity class. 10
7 Determination of the RUSCD . 10
8 General recommendations for polymer profiles . 11
9 Checking of profile parameters . 12
9.1 General remark . 12
9.2 Alternating sheds and shed overhang . 12
9.3 Spacing versus shed overhang . 13
9.4 Minimum distance between sheds . 14
9.5 Creepage distance versus clearance . 15
9.6 Shed angle . 15
9.7 Creepage factor. 16
10 Determining USCD by correcting RUSCD . 16
10.1 Introductory remark . 16
10.2 Correction for altitude K . 17
a
10.3 Correction for insulator diameter K . 17
d
10.4 Correction for profile K . 18
s
10.5 Correction for the number of similar insulators in parallel K . 18
p
11 Determination of the final minimum creepage distance . 19
12 Confirmation by testing. 19
Annex A (informative) Background information on pollution induced degradation of
polymers . 20
Bibliography . 23
Figure 1 – RUSCD as a function of SPS class . 10
Figure 2 – Typical “open” profile. 11
Figure 3 – Typical steep polymer profile . 11
Figure 4 – Typical shallow under-ribs on open profile . 11
Figure 5 – Typical deep under-rib profile . 12
Figure 6 – Typical “alternating” profiles . 12
Figure 7 – Illustration and typical values of shed overhang . 12
Figure 8 – Spacing versus shed overhang for uniform and alternating sheds . 13
Figure 9 – Minimum distance between adjacent sheds of the same diameter for uniform
and alternating sheds. 14
Figure 10 – Creepage distance versus clearance for different sheds . 15
Figure 11 – Illustrations of shed angle . 15
Figure 12 – Correction for insulator diameter . 18
Figure A.1 – Operating areas as a function of pollution severity and USCD (for a fixed
insulating length) . 22
Table 1 – Classification of profiles based on the values of shed overhang . 13
Table 2 – Deviations for s/p for sheds with and without under-ribs with trunk diameter
≤ 110 mm . 13
Table 3 – Deviations for s/p for sheds with and without under-ribs with trunk diameter
> 110 mm . 13
Table 4 – Deviations for c for uniform and alternating sheds . 14
Table 5 – Deviations for l/d for different sheds . 15
Table 6 – Deviations for shed angle . 16
Table 7 – Deviations for creepage factor . 16
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
Selection and dimensioning of high-voltage insulators
intended for use in polluted conditions -
Part 3: Polymer insulators for AC systems
FOREWORD
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IEC TS 60815-3 has been prepared by IEC technical committee 36: Insulators. It is a Technical
Specification.
This second edition of IEC TS 60815-3, together with IEC TS 60815-1, cancels and replaces
the first edition of IEC TS 60815-3:2008. This edition constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) Terms and definitions are modified or introduced in this document;
b) From RUSCD of reference insulator to USCD of candidate insulator, the correction factors
are introduced and revised, such as altitude correction, diameter correction, shed profile
correction and parallel insulator number correction;
c) The general guidance on materials is revised. The concept of hydrophobicity transfer and
hydrophobicity transfer material (HTM) are introduced, recognising that a reduced creepage
distance may be used for HTM insulators.
The text of this Technical Specification is based on the following documents:
Draft Report on voting
36/613/DTS 36/636/RVDTS
Full information on the voting for its approval can be found in the report on voting indicated in
the above table.
The language used for the development of this Technical Specification is English.
This document was drafted in accordance with I
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