MT 14 - TC 2/MT 14

IEC 60413:2026 concerns graphite-based grades that are used for sliding electrical contacts, such as carbon brushes or pantograph strips. By extension, it is possible to apply the test procedures of this document to all electrical sliding contacts for electrical transmission appliances and to other appliances of graphite-based materials (heat exchangers, bearings, etc.). This document specifies uniformized procedures for determining their following properties:
- density and porosity;
- resistivity;
- flexural strength;
- hardness;
- ash content.
In addition, it provides recommendations on test procedures for other properties:
- Mechanical properties: Charpy impact test, compressive strength, tensile strength (Annex B).
- Thermal properties: coefficient of thermal expansion, specific heat capacity, thermal conductivity (Annex C).
The properties determined by these tests are inherent to the graphite-based materials and it is therefore important to distinguish them from performance characteristics in operation on electrical equipment (carbon brush in an electrical rotating machine, contact strips on a pantograph, etc.). Since these materials are generally brittle, porous materials, it is reasonable that their properties vary much more than the same properties in metals. Some test methods are suitable for use in production quality control (routine tests), others only for more thorough investigations, using precise laboratory techniques (see Annex A).
WARNING — The use of this document can involve hazardous substances, operations and equipment. It does not purport to address all of the safety or environmental problems associated with its use. It is the responsibility of the user of this document to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
This second edition cancels and replaces the first edition published in 1972. This edition constitutes a technical revision. This edition includes the following significant technical changes with respect to the previous edition:
a) Title modified.
b) Addition of definitions in Clause 3.
c) Clause 5 on test specimen: Nomenclature and addition of the different types of test specimen, specification on their dimensions, tolerances and preparation.
d) Improvement of test procedures of the properties already disclosed in the previous edition (Clause 6 to Clause 11).
e) Separation of apparent density and apparent porosity (respectively Clause 6 and Clause 10).
f) Resistivity (Clause 7): Addition of the eddy current method.
g) Rebound hardness (Clause 9): Addition of a new model of scleroscope and addition of Leeb method, as a possible alternative to the traditional scleroscope method.
h) Common elements of the test report in a dedicated Clause 12.
i) Addition of Annex A (normative): introduction of tests categories (serial/type tests), list of properties to be tested for each test category of test according to their purpose.
j) Addition of Annex B: test procedures for other mechanical properties than flexural strength and hardness: tensile, compressive and impact strength.
k) Addition of Annex C: test procedures for thermal properties (coefficient of linear expansion, specific heat capacity and thermal conductivity).
l) Addition of Annex D: supplement to density and porosity.
m) Addition of Annex E: recommendations on methods for elements analysis.
n) Addition of Annex F: supplement of information concerning scleroscope hardness.

IEC 60136:2024 applies primarily to brushes and brush-holders for cylindrical commutators and slip rings for electrical rotating machines. Some clauses of this document may cover other configurations, such as flat commutators or plain disks. It defines the dimensions of brushes and their components, together with their tolerances:
- dimensions of brush block (t, a, r),
- angles α and β,
- chamfer,
- flexibles (shunts),
- standard terminals.
It also covers the conventional designation of principal dimensions, the marking of brushes and the testing methods for the qualification of brushes after their manufacturing (except the brush grade material, covered by IEC 60413). This third edition cancels and replaces the second edition published in 1986 and Amendment 1:1995. This edition constitutes a technical revision.
Please refer to the Foreword of the document for a comprehensive listing of the changes with respect to the previous edition.

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.

IEC 60276:2018 applies to carbon brushes for electrical machinery. This edition applies only to carbon brushes for commutators and slip-rings in rotating machines. Terms and definitions are relative to the brush construction (references 100’s to 500’s and parts of 900’s) and to the markings when operating on a rotating machine (references 600’s to 800’s).
This new edition includes the following significant technical changes with respect to the previous edition:
Some nomenclature has been deleted or added, whereas remaining definitions have been detailed and clarified, to reflect the technical evolution since 1987.
Additional definitions have been included to address the request for reviewing this standard, in particular nomenclature of commutator/slip-rings markings, brush markings and commutation sparks codes.