Posted on 18 June 2019

Power Capacitors - Technology and Basics








Power capacitors are used in power systems engineering, power electronics, and in high voltage engineering. Such capacitors belong to the family of metallized paper and polypropylene film capacitors. Power capacitors also include ceramic power capacitors, vacuum capacitors, and standard SF6 gas insulated capacitors, which are used mainly in the high frequency technology sector.

Power capacitors are designed to cope with high levels of electrical power and most can withstand high electrical potentials as well. However, their voltage range and stability are not precisely defined. In the German speaking community, their classification is derived historically from their applications in power systems engineering, high voltage, and high frequency technologies.

As high-frequency AC surges of up to 1,000A can occur during the operations of high-performance transmitters, they must be controlled either by interconnecting several capacitors in large square casings or by using an alternative capacitor technology. The structural design of such capacitors is largely defined by their application.

Power capacitors are also used in lower frequency AC and DC operations and in pulsed DC operations in low voltage facilities. This type of application often utilizes metallized paper and polypropylene film capacitors with wound electrolytes which are implemented in large round cans. Several of these capacitors can be accommodated in box-shaped cases. However, various designs are found in the extended industrial power electronics sector.

Ceramic power capacitors, mainly in specific designs, as well as vacuum capacitors and standard SF6 gas insulated capacitors, are widely used for high frequency operations. They operate in LC oscillator circuits to generate high frequencies for power transmission, radar technology, synthetic materials welding, and in HF heating plants. Standard SF6 gas insulated capacitors also act as high-voltage capacitors in voltage dividers to precisely measure high voltages or as bridge capacitors to measure the capacitance and the dissipation factor in high-voltage plants.

The design driving parameters of power caps are:

  • Capacitance
  • AC and DC ripple current at nominal voltages
  • RMS current
  • Transient current loads
  • Temperature profile
  • Frequency range
  • Dimensions and fixing parameters
  • Terminals


For further information, please read:

Aluminium Electrolytic Capacitors and General Features

Aluminum Electrolytic Capacitors - Overview and Key Applications

Equivalent Series Resistance (ESR) for Capacitors

Temperature Influence on Series Capacitance

Heat Dissipation and Cooling for Aluminum Capacitors

Mounting Positions of Aluminum Electrolytic Capacitors with Screw Terminals


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