IEC 60871-4:2014 applies to internal fuses which are designed to isolate faulty capacitor elements, in order to allow operation of the remaining parts of that capacitor unit and the bank in which the capacitor unit is connected. Such fuses are not a substitute for a switching device such as a circuit-breaker, or for external protection of the capacitor bank or any part thereof. The object of this part of IEC 60871 is to formulate requirements regarding performance and testing and to provide a guide for coordination of fuse protection. This second edition cancels and replaces the first edition published in 1996. This edition constitutes a technical revision. This edition includes the following significant technical changes with respect to the previous edition: The disconnecting requirements have been modified. Keywords: internal fuses, faulty capacitor elements, fuse protection