Electrical Electronic

Understanding voltage rating of a capacitor

In all kinds of capacitors, there is a maximum voltage rating. This is why the maximum amount of voltage that can be applied to the capacitor without damaging must be considered when selecting. In this article, you’ll get to know the voltage rating of a capacitor and its major role in its operation.


capacitor voltage rating

Read more: Understanding capacitor

Capacitors have the maximum amount of voltage that when obtained it won’t cause damage to their dielectric material. It can be given in the data sheets as WV, (working voltage) or as WV DC, (DC working voltage). Also, the voltage rating is one of the things to consider when choosing a type of capacitor, it gives the electrician the amount of voltage to be applied across the capacitor.

The dielectric of a capacitor breaks down if the voltage is applied across it, this is known as electrical breakdown. Also arcing will occur between the capacitor plates resulting in a short-circuit. The working voltage of a capacitor depends on the type and thickness of the dielectric material employed. The DC working voltage is the maximum DC voltage and NOT the maximum AC voltage. A capacitor with a DC voltage rating of 100 volts DC cannot be safely used to an AC voltage of 100 volts. This is because an alternating voltage that has an RMS value of 100 volts will have a peak value over 141 volts (√2 x 100).

So, a capacitor that is required to work at 100 volts AC should have a working voltage of about 200 volts. This is because a capacitor should be selected so that its working voltage either DC or AC should be at least 50 percent greater than the highest effective voltage to be applied to it.

Read more: Understanding capacitance in AC circuits

Dielectric leakage is another factor that affects the voltage rating of a capacitor.  This occurs due to the result of unwanted leakage current that flows through the dielectric material. It is generally assumed that the resistance of a dielectric is extremely high and is capable of blocking the flow of DC current through the capacitor from one plate to the other. However, dielectric leakage is still common.

Watch the video below to learn more about the voltage rating of a capacitor:

Read more: Understanding the types of capacitors

Furthermore, if the dielectric material is damaged by too high voltage or over temperature, the leakage current through the dielectric becomes extremely high. This results in rapid loss of charge on the plates and an overheating of the capacitor will result in premature failure of the capacitor. This is why it’s not advisable to use a capacitor in a circuit with higher voltages than the capacitor that is rated for less. It may become hot and result in an explosion.

Read more: Understanding Capacitor Voltage Divider

That is all for this section where the voltage rating of a capacitor is being explained. I hope you get a lot from the reading, if so, kindly share with other students. Thanks for reading, see you next time!

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