A capacitor is an electrical component that stores electrical charge. This electronic component is generally used to stabilize a power supply, process signals, store energy or separate AC from DC.
Present in many electrical devices, the capacitor must be tested to ensure its smooth operation. A capacitor consists of two conductive plates constituting the armature, and these plates are separated by an insulating material (paper, aluminum, plastic, etc.). When the capacitor is subjected to an electric current it accumulates and stores the power up to its storage capacity, and then dissipates this energy when required.
how to check a capacitor
Typical failures of a capacitor might be due to the following reasons:
-- Dielectric breakdown of the electrolytic capacitor;
-- Aging of the capacitor;
-- Mechanical deformation of the electrolytic capacitor;
-- Excess heat;
-- High voltage;
-- Reversed polarity in the case of electrolytic capacitors, and many others...
In this article titled "How to check a Capacitor", we will go over the various tests that we can use to tell if a capacitor is good or not while using the functions of a multimeter.
The tools required
- A Multimeter - Using a multimeter, you can test the load or the capacity of your capacitor.
- A resistor or a screwdriver
Testing the Capacitor by using the Multimeter in the Capacitance Mode
This method is suitable for tiny capacitors and your multimeter must have a Capacitance meter housed in it.
how to check a capacitor
Steps to be followed:
-- Initially, make sure the capacitor is discharged to its full capacity.
-- Then you need to remove the capacitors from the circuit or board.
-- Set your multimeter to the Capacitance meter option.
-- Now connect the multimeter leads to the capacitor terminal.
-- If the reading displayed on the multimeter is near to the actual value of the capacitor, which you can find printed on the Capacitor container box, then the capacitor is in a proper working condition.
Note that the resultant value displayed by the multimeter might be less than the actually printed value of the capacitor. If you read a considerably lower capacitance, then the capacitor is dead. Verification the capacitance of a capacitor is an excellent test for determining whether a capacitor is good or not.
Testing the Capacitor using the Multimeter in the Ohmmeter Mode
Step 1: Disconnect the capacitor
It is initially necessary to disconnect the electrical circuit. After disconnecting it, you have to drain the capacitor of all the remaining charges, using a resistor, or a screwdriver.
Step 2: Set the Multimeter
The next step is to set your multimeter. Make it sound like a traditional circuit test by setting the capacitor into an ohm meter. According to the capacity of your capacitor, you have to adjust the calibration of the ohmmeter, so that it best matches your capacitor’s storage capacity. If you have a digital multimeter, set the meter on Ohm range by setting it to at least 1000 Ohm = 1k.
Step 3: Read the result
In the case of a needle based model, you have to observe the movement of the needle of the ohm meter, and interpret the results of your test by following these directions:
- If the ohmmeter's needle goes up and then down completely: your capacitor is working properly;
- If the ohmmeter's needle does not fall at all: your capacitor is not working;
- If the ohmmeter's needle does not go completely down (i.e. it rises and then falls partially): your capacitor leaks;
- If the ohmmeter's needle does not rise at all: your capacitor is not supplied.
HOW TO TEST A CAPACITOR WITH A VOLTMETER
Step 1: First of all, you have to connect a power supply and the capacitor with cables. Connect a wire from a terminal of the power supply to a terminal of the capacitor. Do the same with the other wire and the remaining terminals of the power supply and capacitor.
Step 2: In the second step, connect the voltmeter in parallel with the capacitor. That is, one terminal of the voltmeter must be connected on one side of the capacitor, and the other terminal must be connected to the other side.
Step 3: Finally, check the screen for the reading. The voltage reading must be different from zero. If the reading is zero, it implies that there is no potential difference across the capacitor, indicating a malfunction thereof.