Safety capacitance detection and substitution(I)

A capacitor is a kind of energy storage element and it is one of the basic components that make up an electronic circuit. When a voltage is applied across the capacitor, the capacitor absorbs energy from the power supply and stores it in the electric field established between the two plates. When the voltage across the capacitor drops, it releases the energy of the previously stored electric field. . In electronics manufacturing, the amount of capacitors is second only to resistance, and it is widely used in coupling, filtering, DC blocking, regulation circuits, and inductive components to form an oscillation circuit.

The quality of the capacitor is mainly reflected in the capacity of the capacitor and the leakage resistance. The capacitance of the safety capacitor can be measured using a capacitance tester or a digital multimeter; the leakage resistance can be measured simply using an analog multimeter. In the following, we mainly introduce qualitative and semi-quantitative quality inspection methods for safety capacitors using a multimeter.

Abnormal performance of the capacitor is mainly as follows: failure, short circuit, open circuit, leakage, etc. The following briefly introduces the method of using an analog multimeter to detect.

1. Detection of fixed capacitance (non-electrolytic capacitance).

According to the charge-discharge principle of the capacitor, it can be measured using a multimeter R×1K or R×10K depending on the size of the capacitor. During the measurement, the two table pens are respectively contacted with two pins of capacitance (capacity greater than 0.01 microfarad). At this time, the meter pointer will be rapidly deflected in the clockwise direction, and then gradually return to the “∞” position in counterclockwise direction. If the pointer is returned Less than “∞” indicates that the capacitance of the safety capacitor is leaking, and the reading referred to after the pointer is stable is the leakage resistance value of the capacitor. In general, the leakage resistance of a capacitor is large, about several hundred megaohms to several gigaohms. The greater the leakage resistance, the better the insulation performance of the capacitor. If the leakage resistance value is much smaller than the above data, it indicates that the capacitor is seriously leaking and cannot be used. If the meter pointer is stable at “0Ω”, it indicates that the capacitor is short-circuited and cannot be used; if the meter pointer is not reflected, If you stay at “∞” all the time, it means that the capacitor is open inside and cannot be used.