- Whether the shell of the power capacitor is intact, there is no obvious expansion, deformation, cracks and other phenomena. If the above situation occurs, it means that the capacitor is in serious trouble, i.e., it can not continue to be used.
- whether the terminals of the capacitor are firmly connected, whether there is any looseness, corrosion and other problems. If there are problems with the terminals, it may lead to poor contact and affect the normal operation of the capacitor.
Second, capacity test
Measure the capacity of the power capacitor to see whether the actual capacity of the capacitor should match the nominal capacity. If the actual capacity is too much lower than the nominal capacity, it means that the capacitor has aged and failed.
Insulation resistance test
Measure the insulation resistance of the capacitor with relevant instruments. Under normal circumstances, the insulation resistance should be greater than 10 megohms. If the insulation resistance is lower than this value, it means that the insulation performance of the capacitor may have been damaged, and further inspection is required.
IV. Voltage and current test
- Measure the voltage value of the power capacitor during operation. If the voltage value fluctuates greatly, it means that the power capacitor may have problems.
- Measure the current value of the capacitor under the rated voltage. If the actual current value exceeds the current value, the guidelines indicate that the capacitor may be overloaded.
TEMPERATURE TEST
Detect whether the operating temperature of the power capacitor is within the specified range, under normal circumstances the capacitor should be operated under suitable temperature conditions. If the temperature is too high, it proves that the capacitor may have some kind of failure, need to stop using immediately.
Above is to determine whether the power capacitor failure method. In actual operation, power capacitors should be regularly inspected, if abnormalities are found in a timely manner out of operation, to avoid triggering safety hazards.
The specific methods to test the capacitor are as follows
Method 1: Multimeter Test
We can use a digital multimeter to perform the test. In resistance mode, follow these steps: make sure the capacitor is fully discharged, set the meter to ohm range (at least 1000 ohms), connect the multimeter probe to the capacitor terminals and observe the value displayed by the digital multimeter. The value will then immediately return to the OL (open line) or infinity state. If each attempt shows the same result, the capacitor is good; otherwise, it may be faulty.
Method 2: Analog Multimeter Test
An analog multimeter can also be used to check the capacitance. In ohms mode, do the following: make sure the capacitor is discharged, select resistance mode and connect the multimeter leads to the capacitor terminals. Note the value read and compare it to the standard result. A shorted capacitor will show a low resistance and an open capacitor will not deflect on the ohmmeter. A good capacitor, on the other hand, will show a low resistance at the beginning and then gradually increase to infinity, indicating that the capacitor is in good condition.
Method 3: Checking Capacitance with a Multimeter in Capacitance Mode
Testing in capacitance mode is only possible if the analog or digital multimeter has a capacitance “C” function. In addition, the multimeter’s capacitance mode function is also suitable for testing small capacitance. Observe the reading displayed by the multimeter. If the reading is close to the actual value of the capacitor (i.e., the value printed on the capacitor case), the capacitor is in good condition. Note that the reading may be slightly less than the actual rating of the capacitor, which is usually within the range of ±10 or ±20. If the multimeter shows a reading significantly lower than expected or zero, this may mean that the capacitor is damaged and replacement is recommended to ensure proper operation of the circuit.
Method 4: Testing with a Voltmeter
Test with a voltmeter. This method is equally applicable to both polarized and non-polarized capacitors, but only if we know the nominal voltage value of the capacitor. This voltage level is usually clearly marked on the nameplate of the electrolytic capacitor. Observe the initial voltage reading in the voltmeter. If the reading is close to the supply voltage, the capacitor is in good condition; if the reading is significantly lower, the capacitor may have failed.
Method 5: Testing Capacitance by Measuring Time Constant
If the capacitance value of a capacitor (printed on it in microfarads) is known and the capacitor does not show any abnormalities such as fusing or burning, we can further verify the capacitance value by measuring the time constant. The time constant, usually denoted as τ or Tau, is the time it takes for a capacitor to charge to approximately 2% of the supply voltage, starting from a voltage of 0 during the charging process. This time constant can be calculated by the following formula: τ = R x C, where R is the known resistance value and C is the capacitance value to be measured. Calculate the capacitance value by using the time constant formula. Compare the calculated capacitance value with the value printed on the capacitor. If they are similar or equal, the capacitor is in good condition; if there is a significant difference, it may be necessary to consider replacing the capacitor as it may be operating abnormally. .