How to detect the fixed capacitor?

1.Detection of non-polar capacitance

1) Small capacitance below 100.

Because the capacity of the fixed capacitor below 10 is too small, the pointer type multimeter is used for measuring, which can only qualitatively check whether there is leakage, internal short circuit or breakdown. When measuring, you can use the pointer type multimeter RX10k.2 block, with two stylus are arbitrarily connected to the two pins of the capacitor, the resistance should be infinite. If the resistance is measured ( the pointer swings to the right ) or the positive value is zero, the leakage damage or internal breakdown of the capacitor is explained.

 2)Detect the fixed capacitor above 0.01 pF. For the fixed capacitor of 0.01 pF, the RX10K2 of the pointer type multimeter can be used to directly test whether the capacitor has the charging process and whether there is an internal short circuit or leakage the capacity of the capacitor can be estimated according to the magnitude of the swing to the right of the pointer. When testing the operation, first use two stylus to touch the two pins of the capacitor, and then change the stylus to touch again. If the capacitor is good, the multimeter pointer swings to the right and immediately returns to the infinity immediately to the left. The greater the capacitance, the greater the amplitude of the pointer swing. If the stylus is repeatedly changed to touch the two pins of the capacitor, the pointer of the multimeter will not swing to the right all the time, indicating that the capacity of the capacitor is less than 0.01 F or has disappeared . In the measurement, if the pointer swings to the right and can not go back to the infinity position left to the left, indicating that the capacitor is leaking or has breakdown short circuit.

2. Detecting the selection of electrolytic capacitor.

The capacity of the electrolytic capacitor is much larger than that of the general fixed capacitor, so the measuring range should be suitable for different capacity.

In general, the capacitor between 1 ~ 100F can be measured by the pointer type multimeter RX100 ~ RX1k2, and the capacitor of greater than 100F can be used the pointer type multimeter RX100 ~ RX1 block measurement leakage resistance.

The pointer type multimeter red pen is connected to the negative pole, and the black pen is connected with the positive pole, and the pointer is deflected to the right for a large amplitude ( for the same electric barrier ) at the instant of contact, the bigger the capacity, the bigger the swing, and then gradually turn to the left until it stops at a certain position. The resistance at this time is the positive leakage resistance of the electrolytic capacitor. The larger the value, the smaller the leakage current is, the better the capacitance performance is. Adjust the red and black stylus, and the pointer will repeat the phenomenon. At this time, the measured resistance is the reverse leakage resistance of the electrolytic capacitor, which is less than the positive direction.

When using the above method for testing, we should pay attention to the correct operation. Do not touch the two pins of the measured capacitance with your fingers, otherwise the human body resistance will affect the test accuracy it is easy to cause misjudgment. In particular, when measuring the high barrier ( RX10k2 ) of the pointer type multimeter, if the finger touches the metal part of the capacitor two pins or two pen pens at the same time, will cause the pointer back to infinity position to the tester caused by illusion, mistakenly believe that the measured capacitance leakage. When measuring with a digital multimeter or a bridge, the capacitor can be directly inserted into a capacitor socket, and the capacity can be read out by placing the instrument in the corresponding gear position.

Estimating the capacity of electrolytic capacitor.

Using the pointer type multimeter electric barrier, the method of forward and reverse charging and discharging for electrolytic capacitor is adopted, according to the magnitude of swing of the pointer to the right, the capacity of the electrolytic capacitor can be estimated. When measuring, first charge the capacitor with two stylus, then reverse the discharge, and then reverse charge, record the situation of the three times of the watch needle swing. Then find the capacitor with a known capacity to measure the swing of the stylus. It is the capacity of the capacitor when it is close to it. The capacity of the capacitor can be directly measured with a digital multimeter, a bridge, or a capacitance meter. That is, select the appropriate gear, and the capacity of the capacitor is displayed by the meter.

This article is from Allicdata Electronics　Limited.