IEC 62631-3-4:2019 covers procedures for the determination of insulation resistance and volume resistivity of insulating materials by applying DC-voltage and temperatures up to 800 °C. The typical application materials include high temperature mica plate and alumina ceramics.
This edition of IEC 62631-3-4 cancels and replaces IEC 60345 “Method of test for electrical resistance and resistivity of insulating materials at elevated temperatures”, published in 1971. This edition constitutes a technical revision.
This edition includes the following significant technical changes with respect to IEC 60345:

* The revised standard becomes part of the series IEC 62631-3-x. Title of the standard is changed and adapted to the series as Part 3-4.
* Clauses 2 "Normative references", 3 "Terms and definitions", and 4 "Significance" are added.
* Subclauses 5.2 "Power supply, Voltage", 5.3.1.2 "Number of test specimens" and 5.3.1.3 "Conditioning and pre-treatment of test specimens" are added.
* In 5.3.5 "Special precautions during measurements", errors analysis in the measurement of current are modified, and aligned with IEC 62631-3-1.
* In 6.2 "Increasing the temperature by steps (method B)", the method for more than one specimen is removed.
* The standard atmospheric conditions for testing and conditioning, especially the temperature, are replaced according to IEC 60212.
* The circuit diagram of test apparatus is modified, and the structure diagram and pictures of test apparatus are added in Annex A.
* The orders of part clauses are adjusted.