IEC 61558-1:1997/ISH1:2003

IS 01 Interpretation of subclause 19.8

IEC 61558-1:1997, First edition

Safety of power transformers, power supply units and similar– Part 1: General

requirements and tests
INTERPRETATION SHEET
Introduction:
WG1 of TC96 has been requested to provide urgently a clarification of the bridge allowed by

resistors or capacitors between different conductive parts.

A clarification of subclause 19.8 of IEC 61558-1 Ed.1 has been agreed by WG1 of TC96 as
follows:
“19.8 Conductive parts separated by double or reinforced insulation, e.g. live parts and
the body or primary and secondary circuits, may be bridged (conductive bridge) by
resistors or Y2 capacitors provided that they consist of at least two separate components
whose impedance is unlikely to change significantly during the lifetime of the transformer.
If the resistors are used they shall comply with the requirements of test (a) in 14.1 of
IEC 60065. If capacitors are used they shall comply with the relevant requirements of
IEC 60384-14.
Where two capacitors are used in series, they shall each be rated for the total working voltage
ac
...