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Varistor Values

Western

Member
Hi, I have a question about varistors.

I fix stuff for a living, I don’t design it ... and I’ve never really understood how the values are chosen because the datasheets show so many different values for each device.

I have a basic 240V – 24V switched mode power supply that got hooked up to 440V apparently.

Seems to have blown a fuse, NTC resistor and a varistor.

What I am surprised about is that the varistor is a 470V varistor ... TVR14471-D.

Does that sound right for a supply operating on 240V?

Thanks.
 

kubeek

Well-Known Member
Most Helpful Member
With the numbers on the right it seems correct, you don´t want it to activate for minor overvoltage. You can have 264Vac in the 240V system all the time, so rating it for 300Vac (thats 424V peak) sounds reasonable.
 

Western

Member
Thanks kubeek, I don't look at varistor datasheets that often ... and I got myself confused in the way some of the parameters are listed ... between the original ... and the ones I keep in stock.
 

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