What is the test method for capacitors?

In the absence of special instrumentation, the quality and quality of the capacitor can be detected and judged by the resistance level of the multimeter. For fixed capacitors with a large capacity (more than 1 f), the resistance stage (R 1000) of the multimeter can be used to measure the two electrodes of the capacitor, and the gauge hand should swing in the direction of the low resistance value, and then slowly swing back to the vicinity. Then exchange the test rod and try again to see the swing of the watch hand, the larger the swing, the greater the capacitance of the capacitor.

If the test rod has been touching the capacitor lead, the gauge needle should be pointed nearby, otherwise, it indicates that the capacitor has leakage, the smaller its resistance value, the greater the leakage, the poor quality of the capacitor; If the gauge hand does not move at all during the measurement, it means that the capacitor has failed or is broken; If the watch hand oscillates, but cannot return to the starting point, it indicates that the capacitor has a large leakage and its quality is not good. For capacitors with small capacities, the needle swing can not be seen when measured with a multimeter, at this time, you can use an external DC voltage and a multimeter DC voltage file to measure, adjust the multimeter to the corresponding DC voltage level, the negative (black) test rod is connected to the negative pole of the DC power supply, the positive (red) test rod is connected to one end of the capacitor being tested, and the other end is connected to the positive pole of the power supply. When a capacitor with good performance is connected to the power supply, the hand of the multimeter should have a large swing; The larger the capacitance of a capacitor, the greater the swing of the watch hand, which gradually returns to the zero position after swinging.

If the pointer of the multimeter does not swing at the moment when the capacitor is turned on, it means that the capacitor is invalid or open-circuited; If the watch hand keeps indicating the power supply voltage without oscillating, it means that the capacitor has been broken down and short-circuited; If the watch hand swings normally, but does not return to the zero position, it means that the capacitor has leakage, and the higher the indicated voltage value, the greater the leakage. It should be pointed out that the auxiliary DC voltage used in the capacitor with small measurement capacity should not exceed the withstand voltage of the capacitor under test, so as to avoid the breakdown damage of the capacitor due to measurement.

To accurately measure the capacitance of a capacitor, a capacitor bridge or Q-meter is required. The above simple detection method can only roughly judge the quality of the capacitor.

Multimeter detection method, for the above fixed capacitors. The capacitor can be directly tested with the R 1k stop of the multimeter for the charging process and whether there is an internal short circuit or leakage, and the capacitance of the capacitor can be estimated based on the amplitude of the pointer swinging to the right. When testing the operation, first touch the two pins of the capacitor with two meter pens, and then change the meter pen to touch it again, if the capacitance is good, the multimeter pointer will swing to the right, and then quickly return to the infinity position to the left.

The greater the capacitance, the greater the swing of the pointer. If the multimeter needle does not swing to the right after repeatedly changing the meter pen and touching the two pins of the capacitor, the capacitance of the capacitor has been reduced or has disappeared. During the measurement, if the pointer swings to the right and cannot return to the infinity position to the left, it means that the capacitor has leaked or has broken down.

The simple detection method of fuse is used to use the fuse (the rated current of the fuse in is determined by the following formula: in=, where c is the capacitance of the capacitor) and the capacitor to be detected are connected in series on the AC power supply of 220V, if the fuse of the fuse bursts, it means that the capacitor has been short-circuited inside. If the fuse of the fuse does not burst, after a few seconds of charging, cut off the power supply, and use a screwdriver with an insulating handle to short-circuit the two poles of the capacitor to discharge, and if there is a spark, the capacitor is good.

Conversely, it means that the capacitance of the capacitor has become smaller or has been opened. Judging the quality of capacitors with this method should be repeated several times to get the correct conclusion. Incandescent bulb and capacitor series detection method, the incandescent bulb and capacitor are connected in series on the 220V AC power supply, if the brightness of the incandescent bulb is darker than directly connected to the 220V AC power supply, the capacitor is good; If the incandescent bulb does not light up, it means that the inside of the capacitor to be tested has been disconnected; If the brightness of an incandescent bulb is the same as the brightness of the bulb that is connected directly to the 220V AC power supply, the inside of the capacitor has been shorted.

The megohmmeter detection method can also be detected with a megohmmeter (250V class). Shake the handle, such as the pointer pointing at infinity, indicating that the capacitor is internally open; If the pointer is at zero, it means that the capacitor is short-circuited. It can also be used to test the capacitor through the ground by:

Connect the binding posts of the megohmmeter to the terminal block and housing of the capacitor respectively. Shake the handle, such as the pointer pointing at zero, to indicate that the capacitor is grounded inside. 5. Measurement of capacitor capacitance, in the absence of a special instrument, the capacitance of the power capacitor can be measured with a multimeter.

The specific method is to connect the fuse (the specification of which is determined by the capacitance of the capacitor) and the capacitor to be tested in series to the 220V AC power supply. Use the AC voltage level of the multimeter to measure the voltage U(V) at both ends of the capacitor

Detection A of fixed capacitors detects small capacitances of 10 pF or less. Because the capacitance of fixed capacitors below 10pf is too small, it can only be qualitatively checked for leakage, internal short circuit or breakdown by measuring with a multimeter. When measuring, you can choose to use the multimeter R 10K block, and use the two meter pens to connect the two pins of the capacitor at will, and the resistance value should be infinity.

If the measured resistance (right swing of the pointer) is zero, it means that the capacitor is damaged by leakage or internal breakdown. b. Detect whether the 10pf 0 01 f fixed capacitor has the charging phenomenon, and then judge its quality or bad. The multimeter uses R 1K gear.

Both transistors have a value of 100 or more, and the penetration current should be small. 3DG6 and other types of silicon transistors can be selected to form composite tubes. The red and black pencils of the multimeter are connected to the emitter E and collector C of the composite tube, respectively.

Due to the amplification effect of the composite transistor, the charging and discharging process of the measured capacitor is amplified, so that the swing amplitude of the multimeter pointer is increased, so as to facilitate observation. It should be noted that during the test operation, especially when measuring the capacitance of a smaller capacitance, it is necessary to repeatedly switch the pins of the capacitor under test to contact the two points A and B, so that the swing of the multimeter pointer can be clearly seen.

c For fixed capacitors above 0 01 F, the R 10K stop of the multimeter can be used to directly test whether the capacitor has a charging process and whether there is an internal short circuit or leakage, and the capacitance of the capacitor can be estimated according to the amplitude of the pointer swinging to the right.

What is Capacitor? Capacitor structure, capacitor working principle, capacitor measurement method.

There are several ways to detect the quality of capacitors:

Multimeter: Using a multimeter for capacitance measurement is one of the most common methods. Select the capacitance measurement level, connect the test pen to the two poles of the capacitor, and read the value of the multimeter.

If the value is not much different from the nominal value, the capacitor is good; If the value is close to zero or minimum, the capacitor is damaged or failed.

Oscilloscope: The oscilloscope can detect the charging and discharging process of the capacitor, if the oscilloscope shows that the voltage of the capacitor shows an exponential decrease or exponential rise curve with time, it means that the capacitor is good; If the curve shown is irregular, the capacitor is damaged or failed.

Simple circuit test: You can connect a capacitor to a simple circuit, such as an LED circuit, and see if the LED can work properly. If the LED lights up normally, it means that the capacitor is normal; If the LED does not light up, the capacitor may have been damaged.

ESR test: ESR is an abbreviation for the equivalent series resistance of a capacitor, which can reflect the loss and wear inside the capacitor. The ESR value of the capacitor can be measured using an ESR tester, and if the ESR value is too high, the capacitor has failed.

DC voltage test: Connect the capacitor to the DC power supply and observe the voltage change of the capacitor. If the capacitor is able to reach the nominal voltage value in a short period of time, and the voltage change is stable, the capacitor is normal; If the capacitor does not reach the nominal voltage or the voltage changes unevenly, it may have failed.

In short, the above methods can be used to detect the quality of capacitors. The choice of different methods depends on the needs of the tester and the tools available.

1. Use a multimeter to judge the quality of the capacitor, depending on the capacity of the electrolytic capacitor, you can choose to use the multimeter R times 10, R times 100, R times 1K block for test judgment;

2. The red and black pencils are connected to the negative pole of the capacitor respectively, and the quality of the capacitor is judged by the deflection of the watch hand;

3. When the withstand voltage value of the capacitor is greater than the battery voltage value in the multimeter, you can use R times 10K gear to reverse charge the capacitor, and observe whether the watch needle stays stable or not, so as to judge the quality of the capacitor with high accuracy.

What is Capacitor? Capacitor structure, capacitor working principle, capacitor measurement method.

To detect capacitance in amateur conditions, a digital multimeter with capacitance testing can be used as a tool, such as the DT9205A, which can detect capacitance at 1P 200 F.

To detect capacitors professionally, you need to purchase instruments such as "digital bridge" to detect capacitance capacity, "electrolytic capacitance leakage current tester" to detect the leakage current of capacitors, and "electrolytic capacitor withstand voltage tester".

The traditional method is to use the multimeter to measure the resistor, first use the red tester pen to connect the positive pole of the capacitor, the black tester pen to connect the negative pole of the capacitor, and the battery in the multimeter to charge the capacitor, the pointer (or reading) of the multimeter will change from less to large (because the capacitor charge amount is from large to less), and then the red and black tester of the multimeter are exchanged for the negative positive pole of the capacitance, and the pointer of the multimeter should be turned to the extreme left (due to capacitance discharge) and then return to infinity (capacitance discharge is completed).

In this way, you can roughly try the capacitor charge and discharge. Use a low resistance level for measuring large capacitance (with a multimeter battery), and a high resistance level for measuring a small capacitance (use a 9V battery in a multimeter).