IEC 60143-3:2015 applies to internal fuses designed to isolate faulty capacitor elements, 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 60143 is: - to formulate requirements regarding performance and testing; - to provide a guide for coordination of fuse and bank protection. This second edition cancels and replaces the first edition published in 1998. This edition constitutes a technical revision. This edition includes the following significant technical changes with respect to the previous edition: The test procedure has been largely simplified. Keywords: faulty capacitor elements, fuse and bank protection