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特性-A |
| CHARCATERISTICS REFERENCE |
| GENERAL APPLICATION REFERENCE |
Plastic film capacitors are now widely used by the electronic industry, and their selection is based upon the following factors:
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- FREQUENCY :
Polyester (PE) capacitors have higher dielectric losses and as are generally suitable at frequencies of 10KHz or less. They have a wider temperature range than the other common use dielectric materials and due to a higher dielectric constant can produce high C values in smaller package dimensions.
Polypropylene (PP) capacitors have relatively low dissipation factors and dielectric losses, as such they are suitable for high voltages, high frequencies and high pulse current. They are larger in size, have a narrow temperature range and negative temperature coefficient.
Polycarbonate (PC) capacitors have moderate features of both PE & PP styles, but are more expensive. They do and more stable capacitance versus temperature characteristics and good long term stability.
Polystyrene (PS) capacitors have excellent high frequency performance due to their low dissipation factor and very low dielectric absorption characteristics.
- PEAK VOLTAGE :
The peak voltage against a zero potential reference shall always be less than nominal DC voltage rating of the capacitor.
The rate of voltage change (div/DT) of individual specification are valid for pulse voltage equal to or less than the rated DC voltage. If the pulse voltage is less, then a factor of "VDU/applied" may be used.
Vp< = VDC rated
and the Vrms voltage dervied from the peak voltage shall always be less than the nominal AC voltage rating of the capacitor.
- PERMISSIBLE CURRENT :
Under AC operation, the permissible current to capacitor must be less than Ap-p. As the following details and graphs indicate, operation at higher than permissible currents may deteriorate performance and damage the capacitor due to internal temperature rise.
- INHERENT TEMPERATURE RISE :
When capacitor is operated in AC circuit, especially at high frequency, temperature of capacitor rises inherently In case temperature rises too high, performance of capacitor may be deteriorated or damaged. The inherent temperature rise at no air circulation (Ambient. at 40 o C) shall be within a value specified below. (The allowable value depends on dielectric. For details, consult our office or sales representative.)
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