What causes the clicking sound when an inverter arc bag welding machine is powered up and turned on and off?

Thread Starter


Joined Aug 6, 2022
I know that when inverter arc welding machines are idle, inside the AC Rectifier Unit card electricity fill the tank capacitors by flowing through the components such as NTC/PTC/Varistor.

When starting welding, the machine draws a lot of current as soon as the electrode hits the metal and the clicking sound comes from the machine and the sound could be coming from the relay because it closes when you draw a lot of current.

Can anyone explain the working principle? I do not know the details.


Joined Apr 2, 2009
Question is, where the relay is used.
Without a diagram I cannot answer.

There is a relay to bypass the current limiting component used to charge the bulk capacitors at power on.


Joined Apr 2, 2020
It is likely either or both...
1) The relay closing or opening
2) the plates in the transformer contracting when the high current generates a magnetic field when the relay closes.