Overview
IEC TR 63434:2023 - Low voltage switchgear and controlgear - provides awareness and guidance on partial discharge (PD) phenomena in low-voltage switchgear and controlgear connected to networks up to 1 000 V AC (internal operational voltages may be higher). It explains how electrical field stress, insulation type, construction geometry and environmental conditions (voltage, frequency, temperature, humidity, clearances and voids) influence PD inception, PD-level and the risk of insulation failure. This Technical Report focuses on design guidance and interpretation, not on prescriptive test procedures.
Key topics
- Partial discharge physics: homogeneous vs. inhomogeneous electric fields, PD inception/extinction behavior and the influence of electrode geometry.
- Field stress and insulation: how field distribution through air gaps, voids and solid insulation affects PD risk and insulation dimensioning.
- Design and dimensioning examples: practical examples and models for clearances, series combinations of air gaps and solid insulation for AC (and discussion for DC).
- Material and environmental effects: temperature and humidity impacts on dielectric strength, and how these change PD inception voltages and operational margin.
- Application rules and mitigation: recommended measures to reduce PD probability through design decisions (conductor layout, distances, insulation thickness) and construction practices.
- Informative annexes: summaries of research on PD in low-voltage devices and voltage factors relevant to PD coordination.
Practical applications
Who uses IEC TR 63434:2023 and how it helps:
- Switchgear and controlgear designers: optimize conductor layouts, clearances and insulation thickness to reduce PD risk and extend service life.
- Insulation/material engineers: understand temperature/humidity influences on dielectric strength for realistic dimensioning.
- Test and certification engineers: interpret PD test results and understand limitations of PD testing at low field strengths (document notes PD testing is unreliable below about 4 kV/mm and references IEC 60270 for PD test procedures).
- Manufacturers and asset managers: apply guidance to reduce premature insulation ageing, improve reliability and set internal PD acceptance practices.
- Standards developers and researchers: reference consolidated background, examples and research summaries in Annex A/B.
How it is used:
- Design reviews, failure-mode assessments, risk mitigation for PD-related insulation aging, and harmonizing PD coordination for products rated up to 1 000 V AC.
Related standards
- IEC 60664-1 (insulation coordination - notes on PD testing thresholds and field strength guidance)
- IEC 60270 (partial discharge measurement techniques - test procedures)
- IEC Electropedia / IEC vocabularies for terms and definitions
Keywords: IEC TR 63434:2023, partial discharge, PD-level, low voltage switchgear, controlgear, insulation dimensioning, electrical field stress, PD inception, PD testing.