When measuring the insulation resistance of a capacitor using an insulation resistance meter, first disconnect the power supply and load connected to the capacitor, and then discharge.
(1) Check that the voltage and measurement range of the insulation resistance meter meet the requirements of the capacitor and inspect the insulation resistance meter.
(2) When measuring electrolytic capacitors, pay attention to the positive and negative polarity of the insulation resistance meter. The positive pole is connected to the positive (L) terminal, and the negative terminal is connected to the negative (E) terminal. It cannot be reversed. Otherwise, the capacitor will be broken down.
When measuring a non-polar capacitor, the corresponding connection of positive and negative polarity can be ignored.
(3) When measuring the insulation between the capacitor lead and its outer casing, the "L" end of the insulation resistance meter shall be connected to the lead pin of the capacitor, and the "E" end shall be connected to the outer casing of the capacitor.
(4) Shake the insulation resistance meter. Do not flicker and slow. When the pointer is stable after shaking for about 1min at 120r/min, the data read is the correct value. After the measurement is over, the capacitor should be discharged.