How to measure capacitance for good or bad, an article teaches you how to easily master measurement skills

Capacitors are a common type of electronic component used to store charge and filter current. In practical applications, we need to regularly check the quality of capacitors to ensure the normal operation of equipment. So, how to accurately measure the quality of capacitance? This article will provide you with a detailed introduction to the measurement methods and techniques of capacitance

1、 What is a capacitor

Capacity is a physical quantity used to measure the ability of a capacitor to hold charge. It represents the ratio of the amount of charge stored between the two plates of a capacitor to the voltage. The unit of capacitance is Farad (F, abbreviated as "Farad")

2、 Measurement principle of capacitance

The measurement principle of capacitance is based on Coulomb's law, which states that in a vacuum point charge system, the electric field strength between two points is inversely proportional to their distance and directly proportional to their electrical charge. In practical applications, we can estimate the quality of capacitors by measuring their capacitance and resistance

3、 How to measure the quality of capacitance

1. The use of a multimeter

(1) Firstly, switch the multimeter to the capacitance measurement mode. Usually, this gear is labeled with "C" or "Capacity"

(2) Then, contact the two probes separately at the two ends of the capacitor. To prevent short circuits caused by touch, please make sure to release your fingers immediately after contact

(3) Finally, read the capacitance value displayed on the multimeter. If the reading is 0 or close to 0, it indicates that the capacitor is damaged; If the reading is infinite or close to infinite, it indicates that the capacitor may fail and a short circuit phenomenon needs to be checked

2. Power measurement method

This method is mainly used to test the voltage resistance performance of capacitors. The specific operation is as follows:

(1) Prepare an adjustable DC power supply and a digital multimeter

(2) Connect the positive and negative terminals of the power supply to the two ends of the capacitor. At this point, observe the voltage reading on the multimeter. If the reading is 0 or close to 0, it indicates that the capacitor is damaged; If the reading is a finite value and fluctuates greatly, it indicates that the capacitor may fail

3. AC impedance method

This method is mainly used to detect the AC parameters of capacitors. The specific operation is as follows:

(1) Prepare an oscilloscope and a digital multimeter

(2) Connect the probe of the oscilloscope to the negative and positive terminals of the capacitor, as well as the ground terminal

(3) Start the oscilloscope and observe the waveform on the screen. If the waveform is unclear or disappears, it indicates that the capacitor is damaged; If the waveform shows obvious periodic oscillations, it indicates that the capacitor may fail

4、 Precautions

1. During the measurement process, ensure that the probe of the multimeter is firmly in contact and not affected by vibration interference

2. Do not replace capacitors while they are live to avoid electric shock accidents. Before replacing the capacitor, please discharge it to below the safe voltage