MT 30 - TC 17/SC 17A/MT 30

IEC 62271-107:2019 applies to three-pole-operated fused circuit-switchers designed with rated voltages above 1 kV up to and including 52 kV for use on three-phase alternating current systems of either 50 Hz or 60 Hz. This third edition cancels and replaces the second edition published in 2012. This edition constitutes a technical revision. This edition includes the following significant technical changes with respect to the previous edition:
a) technical changes introduced by the second edition of IEC 62271-1 are applied, where relevant;
b) rated TRV is removed and TRV is now treated as a test parameter), as in IEC 62271-100;
c) the term "thermal current" is no longer used; the rated continuous current is linked to the installed fuse-links, and values shall be provided by the manufacturer together with the list of the acceptable fuse-links; for tests purpose, the highest rated continuous current listed is referred, where previously the wording was "rated maximum thermal current", for consistency with IEC 62271-105;
d) making and breaking test duties are independent type tests (as some may be omitted if the switching device has been validated as a load-break switch). However, TDIt0 and TDIlow are kept as a sequence as they are linked to the same rated value (It0);
e) differentiation has been introduced between requirements expressed for fulfilling the function expected from a fused circuit-switcher, from requirements only relevant when the function is performed by a stand-alone device. The goal is to avoid duplication or conflicts of requirements with a standard dealing with assemblies, when the function is implemented within such an assembly.

IEC 62271-107:2012 applies to three-pole operated units for distribution systems that are functional assemblies of a circuit-switcher and current-limiting fuses designed so as to be capable of:
- breaking, at the rated recovery voltage, any load or fault current up to and including the rated short-circuit breaking current;
- making, at the rated voltage, circuits to which the rated short-circuit breaking current applies. This second edition cancels and replaces the first edition, published in 2005. It constitutes a technical revision. This edition includes the following significant technical changes with respect to the previous edition.
- the reference to IEC 60694 has been changed to IEC 62271-1;
- the new clauses and subclauses from IEC 62271-1 have been added and where necessary new wording has been provided;
- the normative references have been updated: IEC 60265-1 to IEC 62271-103, IEC 60787 to IEC/TR 60787, IEC 60466 to IEC 62271-201, and IEC/TR 60787 was moved to the bibliography;
- the figures and tables have been placed in the document where they are first cited;
- the numbering of figures and tables has been changed to obtain the correct order;
- the definition of NSDD was deleted. This definition is included in IEC 62271-1;
- the acceptance criteria have been aligned with 6.101.4 of IEC 62271-103:2011;
- the various provisions expressed about "extension of the validity of type tests" have been grouped under 6.103: some of the rules were duplicated in Clauses 6 and 8, and it seems better fitted to deal within each type test sub-clause only with the type test to be performed. Conditions have not been changed, but the wording is clearer;
- new numbering of subclauses in Clauses 8 and 9 to avoid conflict with clauses from IEC 62271-1.
This publication is to be read in conjunction with IEC 62271-1:2007.