IEC TS 60815-3-2025 PDF

Full title and description

St IEC TS 60815-3-2025 — Selection and dimensioning of high-voltage insulators intended for use in polluted conditions - Part 3: Polymer insulators for AC systems. This technical specification provides guidance to select and size polymer (composite) outdoor insulators for AC high-voltage systems exposed to pollution, including procedures to derive reference and candidate creepage distances, and practical correction factors for site and insulator characteristics.

Abstract

This document (IEC TS 60815-3:2025) gives principles and practical methods to determine the Reference Unified Specific Creepage Distance (RUSCD) from site pollution severity (SPS), to convert RUSCD to a Unified Specific Creepage Distance (USCD) for a candidate polymer insulator using correction factors (altitude, diameter, shed/profile, parallel insulators, mounting, etc.), and to choose suitable shed profiles and materials (including guidance on hydrophobicity transfer materials — HTM). It applies to outdoor polymer insulators for AC systems and explicitly excludes snow or ice effects.

General information

• Status: Published (Technical Specification).
• Publication date: 3 December 2025.
• Publisher: International Electrotechnical Commission (IEC), TC 36 Insulators.
• ICS / categories: 29.080.10.
• Edition / version: Edition 2.0 (second edition, technical revision; cancels and replaces IEC TS 60815-3:2008).
• Number of pages: 23 pages.

(Publication and bibliographic details as recorded by the IEC webstore.)

Scope

Applies to the selection and dimensioning of polymeric outdoor insulators for AC high-voltage systems in polluted environments. The specification provides methods to determine RUSCD from site pollution severity or class, choose appropriate insulator profiles, and apply correction factors to obtain the USCD for a candidate insulator. It is intended for practical use by designers and manufacturers and does not cover snow/ice effects. The guidance is informed by CIGRE technical brochures referenced in the document.

Key topics and requirements

• Definition and use of Reference Unified Specific Creepage Distance (RUSCD) and procedure to derive Unified Specific Creepage Distance (USCD) for candidate polymer insulators.
• Correction factors to modify RUSCD for practical application: altitude, insulator diameter, shed/profile geometry, number of parallel insulators, mounting position and other site/installation factors.
• Material guidance with introduction of hydrophobicity transfer (HTM) concept and allowance for possible reduced creepage for qualified HTM materials, plus cautions about ageing and verification.
• Profile and geometry recommendations (shed shapes, spacing, clearances) and verification steps including laboratory or line trials where appropriate.
• Exclusions and limitations: snow/ice effects are not treated; final dimensioning should be confirmed by testing and service experience where required.

Typical use and users

Primary users are transmission and distribution utilities, overhead-line and substation designers, insulator manufacturers and R&D teams, testing laboratories, and consultants. The specification is used to: specify insulator creepage/geometry for polluted sites, justify reduced creepage when HTM behaviour is proven, and support procurement and testing programs.

Related standards

Companion and related documents include IEC TS 60815-1:2025 (general principles and definitions), IEC TS 60815-2:2025 (dimensioning for conventional insulators in AC systems), IEC 60383 (creepage/insulator tests), IEC 60050-471 (IEV insulator vocabulary), and relevant CIGRE technical brochures such as TB 158 and TB 361 which provide complementary background on pollution performance.

Keywords

polymer insulators, polymeric/composite insulators, pollution, creepage distance, RUSCD, USCD, hydrophobicity transfer (HTM), correction factors, shed profile, outdoor high-voltage insulators.

FAQ

Q: What is this standard?

A: IEC TS 60815-3:2025 is a Technical Specification that provides guidance for selection and dimensioning of polymer (composite) insulators for AC high-voltage outdoor systems in polluted conditions, including methods to determine and adjust creepage distance requirements.

Q: What does it cover?

A: It covers determination of the Reference Unified Specific Creepage Distance (RUSCD) from site pollution severity, conversion to a candidate Unified Specific Creepage Distance (USCD) using correction factors (altitude, diameter, profile, parallel insulators, mounting), recommendations on shed profiles and materials (including HTM), and verification measures; it does not treat snow or ice effects.

Q: Who typically uses it?

A: Transmission and distribution utilities, overhead-line and substation designers, insulator manufacturers and product engineers, test laboratories, and consultants involved in specifying, testing or procuring polymer insulators for polluted outdoor environments.

Q: Is it current or superseded?

A: This is the second edition published on 3 December 2025; it constitutes a technical revision and cancels and replaces IEC TS 60815-3:2008. The IEC record shows a stability date through 2028.

Q: Is it part of a series?

A: Yes — it is Part 3 of the IEC TS 60815 series on selection and dimensioning of high-voltage insulators for polluted conditions (Parts 1–3 published in the 2025 revision cycle for AC applications), with Part 4 addressing DC applications planned in the technical work program.

Q: What are the key keywords?

A: RUSCD, USCD, creepage distance, polymer/composite insulators, hydrophobicity transfer (HTM), pollution, shed profile, correction factors, outdoor high-voltage systems.