Surge Protection Design(Without Varistor)

[owais19m]

I have Ac welding machine about 30KVA rating , when I check the output voltage on open load on the welding machine there's a high surge voltage >1000v, high frequency of about 3Mhz thats messing with the controller , now is there a way I can build a protection Circuit without a Large Varistor that can reject high frequency noise on the output ?

 

[KlausST]

Hi,

I´d rather try to find out where it comes from, and avoid it, than suppress it.
A welding maching sounds like a lot of ampreres.

How is it related to a microcontroller? Maybe it needs some improvements, too.

Klaus

 

[owais19m]

Hi,

I´d rather try to find out where it comes from, and avoid it, than suppress it.
A welding maching sounds like a lot of ampreres.

How is it related to a microcontroller? Maybe it needs some improvements, too.

Klaus

Hi @KlausST ,

Thankyou for replying , The problem is when the 60Hz transformer is turned on , I dont actually weld something on it (I use a acrylic sheet in between the welding tip),the transformer is basically open load . I did this and not directly weld because of calibration on the welding tip .When transformers outputs open there's this sudden surge voltage, I dont think you can mitigate that effect except design a protection Circuit .If now I use a tungsten sheet to weld two pieces of metal , then thats a different situation , it works fine because when welding machine is short circuited for a few uS I can allow those voltage to pass through a switch(IGBT) to rotate and dampen. Just Curious ,Can I use an RLC filter on my output ?

 

[KlausST]

HI,

RLC will have influence on the welding current.

Are you sure this is not a signal needed for welding? maybe gas ionisation to ignite the arc?
(I´m not that experienced with welding machines)

So maybe you don´t need to weld, but what information from the signal do you need/expect?

Klaus

 

[FvM]

I agree, sounds like normal operation of a HF ignitor circuit. A welding machine controller should be designed so that it tolerates welding arc and ignitor circuit noise.

It's however not completely clear what you are trying to achieve. If the ignitor circuit starts at the wrong time, you should find a way to inhibit it.