IEC 60773:2021 applies to test methods for the measurement of the operational characteristics of brushes designed to operate on commutating and slip ring machines under specified test conditions. By extension some tests may be relevant for other kinds of sliding electrical contacts for electrical appliances.

This second edition cancels and replaces the first edition published in 1983. This edition includes the following significant technical changes with respect to the previous edition:

- the clause structure has been modified on the view point of a laboratory testing procedure. The new sequence is as follows: test rig specification, general testing procedure, and specific procedure for each operational characteristic

- a new clause has been added to introduce the black-band test for the characterisation of the brush grades for DC machines.