Method for testing capacitors (2)

3. Incandescent bulb and capacitor series detection method

Connect the incandescent bulb and capacitor in series to a 220V AC power supply. If the brightness of the incandescent bulb is darker than if it is directly connected to the 220V AC power supply, the capacitor is good; if the incandescent bulb is not bright, it indicates the inside of the capacitor under test It has been disconnected; if the brightness of the incandescent bulb is the same as that of the directly connected to 220V AC power source, it means that the capacitor has a short circuit inside.

4.Megohmmeter test method

It can also be tested with a megohmmeter (250V class). Shake the handle. If the pointer is at infinity, it means that the capacitor is open. If the pointer is at zero, it means that the capacitor is short-circuited. The grounding test of the capacitor can also be done by connecting the terminal of the megohmmeter to the terminal and the shell of the capacitor respectively. Shake the handle, if the pointer is at zero, it means that the capacitor is grounded.

5.Measurement of capacitor capacitance

In the absence of a special instrument, a multimeter can be used to measure the capacitance of a power capacitor. The specific method is: use a fuse (its specification depends on the capacitance of the capacitor) and the capacitor to be tested in series connected to a 220V AC power supply. Measure the voltage U (V) across the capacitor using the AC voltage range of the multimeter.

Use the AC current range of the multimeter to measure the current I (mA) through the capacitor. Because I = U / XC and XC = 1 / (2πfC), where f is the frequency of the alternating current. So the capacitance of the capacitor is CC = 3.18 & TImes; (I / U) (micro method).