MT 9 - TC 121/SC 121A/MT 9

IEC 60947-2:2016 is available as IEC 60947-2:2016 RLV which contains the International Standard and its Redline version, showing all changes of the technical content compared to the previous edition.
IEC 60947-2:2016 applies to circuit-breakers, the main contacts of which are intended to be connected to circuits, the rated voltage of which does not exceed 1 000 V a.c. or 1 500 V d.c.; it also contains additional requirements for integrally fused circuit-breakers. This fifth edition cancels and replaces the fourth edition published in 2006, Amendment 1:2009 and Amendment 2:2013. This edition constitutes a technical revision. This edition includes the following significant additions with respect to the previous edition:
- tests for verification of selectivity in Annex A (see A.5.3);
- critical load current tests for d.c. circuit-breakers (see 8.3.9);
- new Annex P for circuit-breakers for use in photovoltaic applications;
- new Annex R for residual-current circuit-breakers with automatic reclosing functions. The contents of the corrigendum of November 2016 have been included in this copy.

IEC 61912-2:2009(E), which serves as an application guide for the determination of selectivity between over-current protective devices of low-voltage switchgear and controlgear, summarises the definitions of the terminology and provides examples of application.

This technical report, which serves as an application guide for the short-circuit ratings given in IEC standards for low-voltage switchgear and controlgear and assemblies, summarises the definitions of the ratings and provides examples of their application. This edition cancels and replaces the first edition of IEC 61912, published in 2006, and corrigendum 1 (May 2006). The changes are only editorial.