"This part of IEC 60143 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: ?C to formulate requirements regarding performance and testing; ?C to provide a guide for coordination of fuse and bank protection. NOTE External fuses for series capacitors are treated in IEC 60143-1:2004@ Annex A: ""Test requirements and application guide for external fuses and units to be externally fused""."