Quality of induction motor capacitors
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Pict 1. Capacitor layout
- Metallized film
- Enforced edge
- Filler
- Core
- Case
Pict 2. Self-healing
- Breakdown
- Film
- Metallization
- Place of metal vaporization
Pict 3. Enforced edge
- Metallized film
- Enforced edge
In the last 25 years the capacitor production technology for network 50 Hz / 1000 V has survived serious changes.
Constant tendency to decreasing dimensions, finished product weight, as well as to reducing production process costs has forced manufacturers to pass from dielectric paper to metallized polypropylene film. Metallized polypropylene film is used for production of section, which represents a capacitor base, i.e. defines its operating parameters and safe functioning.
Therefore we have chosen the best option existing currently at the world market of capacitor films – this is a special thin-walled, AL+Zn-metallized polypropylene film with zinc heavy edge, from leading European companies, in compliance with standard IEC60674.
Most important technical characteristics of such a film are the following: No capacity reduction even in case of capacitor long-term utilization.
Zinc heavy edge is one of the most up-to-date inventions, the purpose of which consists in a more tight contact between metallized layers of the section and capacitor terminals. Heavy edge application of reduces dielectric loss-angle tangent of capacitor to the minimum.
When carrying out periodic tests of capacitors on AL+Zn metallization no capacity reduction occurs, as it usually happens with Al-metallized film, widely used by Russian capacitor manufacturers for the purpose of money saving. Under the same operating conditions service life of capacitors, made of AL+Zn-metallized film, exceeds service life of those made of Al-metallized film, by 30% - 40%. The film that we use in our production withstands a breakdown voltage of about 670V/mm, which allows manufacturing of capacitors with smaller overall dimensions and ensures their safe and steady operation.
All motor capacitors manufactured by our company are being filled with a compound, compliant with fire-safety class VI of European standard UL94.
This way complete sealing of all the components is achieved, as well as their protection against environmental impact, humidity and other negative factors. Capacitor becomes heat-resistant and resistant to different mechanical loads (shock, vibration and so on)
Capacitor section is being wound on a specially balanced, chemically resistant and thermally normalized plastic core, the properties of which define stability of capacity and capacitor safe operation.
Capacitor case does not sustain combustion and is fully fire-safe. It is made of self-extinguishing plastic, acquired from the leading European manufacturers, and corresponds to fire-safety class according to European standards.