IEC/IEEE 62271-37-013:2021 is applicable to three-phase AC high-voltage generator circuit-breakers, hereafter called generator circuit-breakers, designed for indoor or outdoor installation and for operation at frequencies of 50 Hz and 60 Hz on systems having voltages above 1 kV and up to 38 kV. This document is published as an IEC/IEEE Dual Logo standard. The IEEE Std C37.013™-1997 (R2008) was revised and converted into the first edition of the IEC/IEEE Dual Logo International Standard IEC/IEEE 62271-37-013 published in 2015. This second edition cancels and replaces the first edition published in 2015. This edition constitutes a technical revision. This edition includes the following significant technical changes with respect to the previous edition: content has been added to address the requirements of the other components of the generator circuit breaker system; requirements for the application of generator circuit-breakers in power plants with multiple generators connected to one step-up transformer have been added; requirements for testing and application of Tee-OFF generator circuit-breakers have been added; requirements for application of generator circuit-breakers in power plants with doubly-fed induction machines, pumped-storage power plants, and wind farms have been added; the clause numbering has been aligned with the numbering in IEC 62271-1:2017; the topic of reference mechanical characteristics has been revised to improve clarity; the modifying effects of capacitors on the prospective TRVs for out-of-phase and load current switching has been addressed in Annex M and in Annex N with use of the tool named "GenCB TRV calculator". This tool provides the values of KE2, RRRV0, KRRRV-U, KRRRV-I, td0, Ktd-U, Ktd-I, as well as the values of the parameters of the prospective TRV modified by the capacitors of the generator circuit-breaker. This document contains attached files in the form of Excel spreadsheets ("GenCB TRV calculator"). These files are intended to be used as a complement and do not form an integral part of the document.