What are the common testing methods for electrolytic capacitors? Component testing organization

Date：2022-11-08 14:40:22Views：517

Electrolytic capacitor is a kind of capacitor. The metal foil is the positive pole (aluminum or tantalum). The oxide film (aluminum oxide or tantalum pentoxide) that is close to the metal with the positive pole is the dielectric. The cathode consists of conductive materials, electrolyte (electrolyte can be liquid or solid) and other materials. Since the electrolyte is the main part of the cathode, the electrolytic capacitor gets its name. At the same time, the positive and negative of the electrolytic capacitor must not be connected incorrectly. Aluminum electrolytic capacitors can be divided into four categories: lead type aluminum electrolytic capacitors; Horn type aluminum electrolytic capacitor; Bolt type aluminum electrolytic capacitor; Solid aluminum electrolytic capacitor. This paper collects and sorts out some electronic components and expects to be of great reference value to all readers.

Detection method of electrolytic capacitor

1. Detection when leaving the line

Use multimeter R × For gear 1K, before testing, first touch the two pins of the electrolytic capacitor to discharge the residual charge in the capacitor. When the probe is just switched on, the pointer deflects to the right by an angle, then slowly rotates to the left, and finally the pointer stops. The resistance indicated by the meter needle when it stops is the leakage resistance of the capacitor. The greater the resistance, the better. It is better to approach infinity. If the leakage resistance is only tens of kiloohms, it means that the electrolytic capacitor has serious leakage. The greater the angle of the needle swinging to the right (the needle should also swing back to the left), the greater the capacitance of this electrolytic capacitor, on the contrary, the smaller the capacity.

2. Direct detection on the line

It is mainly to detect whether it has opened or broken down, which are two obvious faults, while the leakage fault is generally uncertain due to the influence of external circuits. Use multimeter R × First gear, discharge the residual charge in the capacitor after disconnecting the power supply. If the meter needle does not deflect to the right during measurement, it indicates that the electrolytic capacitor is open circuit internally. If the indicated resistance value is very small (close to short circuit) after the meter needle deflects to the right, it indicates that the capacitor has serious leakage or has been broken down. If there is no rotation after the meter needle deflects to the right, but the indicated resistance is not very small, it indicates that the capacitor may have a large open circuit, and it should be further detected after disconnecting the circuit.

3. Detection when the line is powered on

If it is suspected that the breakdown fault exists only when the electrolytic capacitor is powered on, the circuit can be powered on, and then the DC voltage at both ends of the capacitor can be measured with the DC gear of the multimeter. If the voltage is very low or 0 V, the capacitor has been broken down.

If the positive and negative signs of electrolytic capacitors are not clear, the positive and negative signs must be identified first. Change the multimeter probe to measure twice, whichever is greater (less resistance). One pin connected to the black probe is the negative pole and the other is the positive pole.

Select appropriate electrolytic capacitor

1. The prototype electrolytic capacitor shall be selected as far as possible.

2. Generally, the capacitance deviation of the electrolytic capacitor is larger, which will not seriously affect the normal operation of the circuit, so the capacitor with slightly larger or smaller capacitance can be used instead. However, it cannot be used in frequency division circuit, S correction circuit, oscillation circuit and delay circuit, and the capacitance shall be consistent with the calculation requirements as much as possible. In some filter networks, the capacity of electrolytic capacitor is also required to be very accurate, and its error should be less than ± 0.3% - 0.5%.

3. The withstand voltage requirements must be met, and the selected withstand voltage value should be equal to or greater than the original value.

4. The non-polar electrolytic capacitor is generally replaced by the non-polar electrolytic capacitor. If there is no way to do so, two polar capacitors with twice the capacity can be used for replacement after being connected in reverse series. The method is to connect the positive poles of the two polar electrolytic capacitors (or their two negative poles).

5. When selecting electrolytic capacitor, it is better to use high-temperature resistant electrolytic capacitor. The maximum working temperature of high-temperature resistant capacitor is 105 ℃. When it works at the maximum working temperature, it can guarantee about 2000 hours of normal working time. When the 80 ℃ capacitor is used at 50 ℃, its service life can reach 22000 hours. If the high-temperature electrolytic capacitor is used at this time, its service life can reach 90000 hours.

The above is the relevant content of the "electrolytic capacitance test method" brought about by the core creation test. I hope it can be helpful to everyone. We will bring more wonderful content later. The company's testing services cover: testing and verification of electronic components, IC authenticity identification, product design material selection, failure analysis, functional testing, factory incoming material inspection, tape weaving and other test items. Welcome to call Chuangxin Testing, we will serve you wholeheartedly.