Film capacitor power(III)

The film capacitor has many excellent characteristics, non-polarity, high insulation resistance, excellent frequency characteristics (wide frequency response), and small dielectric loss. Therefore, a thin film capacitor is used in a large amount in an analog circuit.

What the editor wants to tell you today is about the energization of the film capacitor. The current operation of the film capacitor is very regular. When using a film capacitor, we will find that the current is not normal. How do we handle this? The problem is.

Film capacitors are manufactured and polarized similarly to the methods used to make aluminum electrolytic capacitors, however, their storage time is not limited and they can operate for long periods of time without DC polarity. Instantaneous reverse voltage does not generally damage capacitors, but aluminum electrolytic capacitors are different.

In practice, there is not always a DC bias voltage. Non-polar tantalum capacitors can also be manufactured, but they are more expensive and may not be used after storage. If two identical tantalum capacitors are connected back to back in series, a nonpolar capacitor can be obtained. The total capacitance is half of each series capacitor, which is C/2.

A good performance film capacitor at the moment of power supply, the multimeter's hands should have a larger swing; the greater the capacity of the film capacitor, the larger the swing of the hands, after the swing, the watch can gradually return to zero. If the capacitor is turned on at the moment when the power is turned on, the indicator of the multimeter will not swing, which means that the capacitor is in failure or open circuit; if the hands constantly indicate the supply voltage without swinging, it indicates that the capacitor has been punctured and short-circuited; if the hands move normally, they will not return to zero This shows that the capacitor has a leakage current.