how to measure the maximum clamping voltage of a varistor?

Hi, i am gonna make a varistor modeling to simulate by using ANSYS tools.

I have the datasheet only. I think If I know how to measure a the maximum clamping voltage of varistors, it would be helpful to make it for me.

Hi,

The datasheet should tell you.

Usually there are specifications about claming voltage. And with this specification there are the "test conditions".
For a varistor I expect there is a "current".
If so, then use a (pulsed) current source ... and measure the voltage across the varistor.

Klaus

To measure you need a pulse circuit, e.g. a current limited variable volt DC source, 0 - 500V say

then a variable inductor - large iron cored, say 500uH or larger, 10A pk capable - and mains rated caps, say 1uF or larger, 1kVrated, and a suitable switch or SCR with triggering.

The DC source goes thru the switch and L to the C to complete the ckt, the MOV goes across the C.

Using a scope to look across the MOV, raise the VDC source by 50V or so each time and close the switch, noting the peak volts that the MOV breaks down at, you need to discharge the C every time to reset its volts to zero - with a 10W 100R resistor say on a stick, the volts can ring up to 2x the input volts - so be careful.

This is a very effective MOV tester, you can put a 1 ohm resistor in the return path (0v) of the MOV and see its clamping current - on the scope.

thus you will see a 320Vac rated MOV clamping at ~ 600-700V ...

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for a low power DC source you can use it to charge up 100uF say of 600V mains rated caps, and then feed this thru the switch to the test ckt...

Ideally have a series pass diode on the output of the source 10A 1kV

- - - Updated - - -

for a low power DC source you can use it to charge up 100uF say of 600V mains rated caps, and then feed this thru the switch to the test ckt...

Ideally have a series pass diode on the output of the source 10A 1kV

When you perform such a test, be careful to note the Varistor's maximum energy rating.

Exceeding that will result in Varistor failure, and depending on the applied energy level, it could fail violently.