What is the Clamping voltage of Metal oxide varistor

[nareshgtr]

varistor clamping voltage

hi every body,
Please explain about what is the clamping voltage, what is the selection criteria of Metal oxide varistor.
thans advance
V. Naresh Kumar

 

[GrandAlf]

clamping voltage

Its the voltage that conduction starts. So a 14v Dc rated device would be around 14v DC or 10v AC. They effectively absorb spikes above these thresholds, by shorting them out. I suggest checking out data sheets to work out power ratings etc. Pulse width, repetition rate and voltage etc, all affect dissapation calculations.

 

[nareshgtr]

metal oxide varistor selection

thanks GrandAlf for your reply.....
while reading the MOVs datasheets i got the term "Varistor Voltage"....... Please explain about Varistor voltage, what is the difference between clamping voltage and varistor voltage.
V. Naresh Kumar

 

[GrandAlf]

varistor voltage

I should have explained better. Unlike a zener for instance, a varistor, as its name suggests, lowers its resistance with increasing voltage. I think the rated voltage is when this starts to occur, but not absolutely certain on this. This is much better for absorbing energy than a sudden resistive transition. This takes place around the rated voltage, with an effective open circuit at lower voltages. It does in fact do nothing until an over voltage spike occurs. Hope this helps a little.

Added after 5 minutes:

Try this!

https://en.wikipedia.org/wiki/Varistor

 

[Freddybaby]

clamp varistor

There are sometimes 2 ratings on Varistor clamps. One would be the nominal clamp, where the device starts to conduct, and often a max clamp, as the current through the device goes up so does the voltage across. There is also the working voltage rating, a safe operating area usually several volts below the nominal clamp.

 

[nareshgtr]

clamping voltage of varistor

thanks GrandAlf & Freddybaby