EN IEC 61643-361:2026

Low-voltage surge protective devices - Part 361: Surge isolation transformers (SITs) connected to low-voltage distribution system - Requirements and test methods

Publication date:   Aug 13, 2026

Scope

IEC 61643-361:2026 applies to surge isolation transformers (SITs) dedicated to surge mitigation and for connection to 50/60 Hz power circuits and equipment rated up to 1 000 V RMS. This document covers the surge and mitigation performance of SITs with an impulse withstand voltage performance of at least 30 kV, and provides standard methods for testing and rating.

This document covers surge-related parameters but does not address typical transformer tests and parameters covered by the IEC 61558 series [13]<a href="#_ftn1">[1]</a>. This document also does not cover SIT operation under differential mode lightning surge conditions.

<a href="#_ftnref1">[1]</a> Numbers in square brackets refer to the Bibliography.