Testing An Electric Capacitor

A capacitor can be tested to know its current status. For example, the condition, strength and the remaining capacity of a capacitor could be determined. Capacitor provides initial electric charges to the electrical appliances. Capacitor can be tested with the help of a basic analogue ohm meter. The analogue ohm meter has a needle to indicate the readings. The task could be a bit difficult for an amateur. This is due to the fact that capacitor may give an electric shock even if it not connected to an active electrical source. Hence, a risk of shock is always there.

First of all, you have to discharge the capacitor. In order to discharge it completely, you would need a screw driver with an insulated handle. Grip the screw driver from the insulated end and touch the metal end of the screwdriver to the capacitor. The screwdriver would discharge the capacitor with an electric spark.

Now, switch on the ohm meter and change the setting to \’ohm\’. Some ohm meters don\’t have \’ohm\’ indicator. In such a case, switch the indicator to RX1. RX1 indicates that all the readings are measured with a one-to-one ratio.

Touch the metal ends of the instrument to each other. On touching the probes to each other, the needle on the scale steers towards the extreme right (zero ohms). Now, separate the leads and the needle would come back to the far left side which is infinite position or a wide open circuit.

Touch the red lead to one of the terminals of the capacitor and the black one to the other terminal. The needle deflects gradually toward right (zero ohms) and then gradually comes back to infinity. This movement signifies that the capacitor is in good condition. Moreover, the capacitor is properly charging and discharging.

Next, reverse the position of the leads on the capacitor terminals. If no difference occurs then it is ok. If however the needle deflects towards the right (zero ohm) and does not come back to left (infinity) then it refers to a shorted capacitor.

In case the needle of the meter never deflects then a wide open circuit or an internal break is detected in the capacitor. In both the cases, the capacitor needs to be replaced.

Make sure that the capacitors replaced once they have exceeded their expiry period.

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