Disassembling the principle of film capacitors

Why are power capacitors different from film capacitors?

Although the materials and the construction of power capacitors are mostly similar to the smaller film capacitors, they are specified and marketed differently for historical reasons. The "film capacitors" were developed together with the growing market of broadcast and electronic equipment technology in the mid-20th century.

What are film capacitors?

The "film capacitors" were developed together with the growing market of broadcast and electronic equipment technology in the mid-20th century. These capacitors are standardized under the rules of IEC/EN 60384-1 "Capacitors for use in electronic equipment" and different "film materials" have their own sub standards, the IEC/EN 60384- n series.

How does film shrinkage affect a capacitor?

Additional changes in the capacitor dimensions will follow as a consequence of film shrinkage. The absorption of moisture increases the number of permanent dipoles inside the capacitor, pro-ducing reversible effects on capacitance, dissipation factor and insulation resistance, which are treated in the respective sections.

How can film capacitors be optimized?

Film capacitors can be optimized through diferent materials and manufacturing methods. Capacitors are all unique; their fundamentals, the manufacturing processes, advantages and even technology trends are worth highlighting. There are diferent grades and applications critical to considering before choosing the best option.

How do metalized film capacitors work?

The electrodes of metalized film capacitors consist of an extremely thin metal layer (0.02 μm to 0.1 μm) that is vacuum deposited either onto the dielectric film or onto a carrier film. The opposing and extended metalized film layers of the wound capacitor element are connected to one another by flame spraying different metals to the end-faces.

What are standardized conditions for film capacitors?

Standardized conditions for film capacitors are a measuring frequency of 1 kHz and a temperature of 20 °C. The percentage of allowed deviation of the capacitance from the rated value is called capacitance tolerance. The actual capacitance value of a capacitor should be within the tolerance limits, or the capacitor is out of specification.