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What is the reason for the arc generated by the inductor?
Mar 28, 2017


      What is the reason for the arc generated by the inductor?


An arc is a discharge phenomenon that occurs in the air when an instantaneous high voltage is generated in the circuit. Generally, when the circuit is turned off, an arc is generated in the switching power supply circuit using the inductor. What is the reason for this?

 

Inductor is a kind of energy storage device used in LC oscillation circuit, low-frequency filter circuit, DC-DC energy conversion and so on. Its application frequency range rarely exceeds 50MHz.

 

At the moment of disconnection of the inductive circuit, the inductor generates a high voltage that resists the disconnected voltage. This is known in physics as the induced electromotive force, the back-EMF. So there will be an arc on the switch.

 

When the switch is off, there is no current loop, then there is no energy stored in the inductor?

 

Of course, no, because at the instant when the switch is turned off, a large back electromotive force is generated due to the inductance holding current characteristics, and an instantaneous high voltage (arc) is generated at the switch.

 

From the energy point of view, when the switch is turned off, the magnetic field disappears and it is converted into an electric field. It looks like the current in the inductor will become smaller, and the voltage across the switch will increase.

 

Therefore, the arc is created by the instantaneous high voltage generated by the inductor.

                    smd inductor.jpg

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