This International Standard applies to capacitors for power electronics applications. The operating frequency of the systems in which these capacitors are used is usually up to 15kHz, while the pulse frequencies may be up to 5 to 10 times the operating frequency. The standard distinguishes between a.c. and d.c. capacitors which are considered as components when mounted in enclosures. This standard covers an extremely wide range of capacitor technologies for numerous applications, e.g. overvoltage protection, d.c. and a.c. filtering, switching circuits, d.c. energy storage, auxiliary inverters, etc.