This part of IEC 61881 applies to capacitors for power electronics intended to be used on rolling stock. The rated voltage of capacitors covered by this part is limited to 10 000 V. The operating frequency of the systems in which these capacitors are used is usually up to 15 kHz, while the pulse frequencies may be up to 5 to 10 times the operating frequency. It distinguishes between AC and DC capacitors. They are considered as components mounted in enclosures. NOTE This standard covers an extremely wide range of capacitor technologies for numerous applications: overvoltage protection, DC and AC filtering, switching circuits, DC energy storage, auxiliary inverters, etc. Examples are given in Clause 9. The following are excluded from this standard: – capacitors for induction heat-generating plants operating at frequencies between 40 Hz and 24 000 Hz (see IEC 60110-1 and 60110-2); – capacitors for motor applications and the like (see IEC 60252-1 and IEC 60252-2); – capacitors to be used in circuits for blocking one or more harmonics in power supply networks; – small AC capacitors as used for fluorescent and discharge lamps (see IEC 61048 and IEC 61049); – capacitors for suppression of radio interference (see IEC 60384-14); – shunt capacitors for AC power systems having a rated voltage above 1 000 V (see IEC 60871-1 and IEC 60871-2); – shunt power capacitors of the self-healing type for AC systems having a rated voltage up to and including 1 000 V (see IEC 60831-1 and IEC 60831-2); – shunt power capacitor of the non self-healing type for AC systems having a rated voltage up to and including 1 000 V (see IEC 60931-1 and IEC 60931-2); – series capacitors for power systems (see IEC 60143-1, IEC 60143-2 and IEC 60143-3); – coupling capacitors and capacitors dividers (see IEC 60358); – capacitors for applications requiring energy storage/high current discharge such as photocopiers and lasers; – capacitors for microwave ovens; – capacitors for power electronics (see IEC 61071).