Dingfeng Capacitor - Metallized film capacitor use precautions

Oct 19,2018

The metallized film capacitor is a capacitor made by winding a metal film as a medium and a metallized film as an electrode. The film used for the metallized film capacitor is polyethylene,polypropylene, polycarbonate, or the like. Among them, polyester media and polypropylene film media are the most widely used.

Note on the use of metallized film capacitors:

1. Working voltage.

The choice of film capacitor depends on the highest voltage applied and is affected by factors such as applied voltage waveform, current waveform, frequency, ambient temperature (capacitor surface temperature), capacitance, and the like. Before use, check that the voltage waveform, current waveform and frequency across the capacitor are within the rated value.

2. Working current.

Due to the loss of the capacitor, when used under high frequency or high pulse conditions, the pulse (or alternating current) current through the capacitor causes the capacitor to heat itself and rise in temperature, which may cause thermal breakdown. Therefore, the safe use conditions of the capacitor are not only limited by the rated voltage, but also limited by the rated current.

3. Capacitor charging and discharging.

Since the capacitor charging and discharging current depends on the product of the capacitance and the voltage rising rate, even a low voltage charging and discharging may generate a large instantaneous charging and discharging current, which may cause damage to the performance of the capacitor. When charging and discharging, connect a current limiting resistor of 20 Ω/V to 1000 Ω/V or higher to limit the charge and discharge current to a specified range. If there is a phenomenon of capacitor short-circuit charge and discharge, please include it in the scope of defective products and do not use it.

4. Flame retardancy.

Although a fire-retardant flame-retardant material is used in the outer package of the film capacitor, the external high temperature or flame can deform the capacitor core to cause package cracking,causing the capacitor core to melt or burn.

5. Ambient temperature.

The capacitor is rated for use at a temperature of 85 °C. When the actual operating temperature of the capacitor exceeds the rated operating temperature, the rated voltage of the capacitor will decrease as the temperature increases.


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