Power capacitors are particularly voltage-resistant capacitors used in high- frequency technology, power electronics, energy technology and HVDC technology. In addition to their higher dielectric strength, power capacitors are generally also characterized by high capacitance values.
The term power capacitor is not specified in relation to the characteristic values mentioned, it is rather characterized by the areas of application in low and high voltage technology and is used for capacitors whose reactive power is above 200 VAR (Voltage-Ampere Reactive ) and may well reach several kilo- Var.
Whereas earlier power capacitors were metal-paper capacitors because of their self-healing properties, thermoplastic films made ofpolyethylene terephthalate( PET), polycarbonate ( PC), polyethylene naphthalate (PEN) and polypropylene( PP) are used today. They have a high dielectric strength of about 600 V/µm, a high contact resistance of `10^17` and higher, and can be used in a wide temperature range between -50 °C and about 100 °C.
Power capacitors are housed in cup-shaped sheet metal cases and can be grounded. They are available with plug-in or screw terminals.