How to Test a Capacitor easily by using 6 Methods | Electronics Engineering Technology
Capacitors get malfunctioned occasionally and it’s always necessary to make sure whether your electronic components are working or not. This article will highlight 6 ways through which you can check if your capacitor is still functioning properly.
1) Checking A Capacitor Using A Voltmeter:
This is one of the easiest methods to check if your capacitor is functioning properly or not. All you need to do is apply voltages to your capacitor and check if it has retained that amount of charge across its plates. The main function of a capacitor is to store charge, its anode plate will have positive voltages and the cathode plate will have negative voltages. Remember to check the polarity of the capacitor terminals, the positive voltages are to be applied to the anode side which is the longer leg of the capacitor and the negative voltages are to be applied on the cathode side which is the shorter leg.
“Charge the capacitor with voltages less than the voltage rating of the capacitor, then check the voltages across the capacitor using a multimeter”
If the multimeter does not read the voltages which you had applied then there is some issue with the capacitor.
2) Checking A Capacitor Using The Capacitance Mode Of A Multimeter | Best for Electronics Engineering Technology students:
Most multimeters have a capacitance mode on them as well, they generally have the capacitor symbol made on them along with the other symbols including (Ohm, volts, Ampere .. )
First, you will have to fully charge your capacitor, after removing it from the charging source connect the capacitor terminals to the multimeter leads. You must have your multimeter on “Capacitance” mode if the reading on the multimeter is close to the actual value than your capacitor is in good condition. If the reading is low or zero then the capacitor has gone bad.
3) Checking A Capacitor Using The Ohmmeter Mode Of A Multimeter:
This method is also a very useful method for testing your capacitor, by measuring the resistance of your capacitor using a digital multimeter. For this, you have to make sure that your capacitor is discharged. Set the multimeter to the resistance mode (to a high valu3) and connect the multimeter leads to the terminals of the capacitor.
Initially, you will see a reading that will move towards infinite and then retreat back to the original value, if this is the case then your capacitor is in good condition. If the reading just shows an infinite or zero value then it means that the capacitor is dead.
4) Checking A Capacitor Using An Analog Multimeter:
If you have an AVO meter (Ampere, Voltage, Ohm meter) you can also test the functionality of your capacitor. Make sure that you fully discharge your capacitor and the multimeter is on its resistance mode. Then connect the multimeter leads to the terminals of the capacitor (positive lead to the longer leg and the negative to the shorter leg). Take an assessment of the reading accordingly:
* A Shorted capacitor will not show any resistance so it must be replaced.
* An open capacitor will not show any deflection
* If at first the reading is on zero resistance and gradually starts moving towards infinite resistance then the capacitor is not damaged.
5) Traditional Sparking Method (shorting the capacitor terminals):
This method is not as safe for Electronics Engineering Technology students as the above-mentioned methods so only use it if you’re a professional or if you’re in dire need.
If you’re using a DC supply then you can use both polarized and non-polarized capacitors (for the former case keep in mind to check the polarity).
Use a 24V DC supply and charge the capacitor for a few seconds and remove it from the charging source. After removing the capacitor, short both of its terminals using a metal contact (have some type of insulation for yourself). If the capacitor is in good condition then strong sparks will be originated, otherwise, the capacitor has gotten bad.
6) Testing A Capacitor By Measuring Its Time Constant:
If you know the value of the capacitor you are using, you can use the time constant method to test the capacitor. The time constant of a capacitor is the time which it takes to charge up to 63.2% of the applied voltage. You also need a resistor of known value.
Time constant T = R X C
Connect the resistor in series with the capacitor and connect that circuit to a power supply on a fixed voltage. Start measuring the time it takes for the capacitor to charge up to 63.2% of the applied voltage.
Now from that time and the value of the resistor you can find out the value of the capacitor.
“If the value of the capacitor which you have found is close to the known value then the capacitor is in good condition.”