A MOV is normally open circuit.

If the voltage across it exceeds its nominal rated voltage it will very quickly clamp it by becoming very low impedance, shunting an overload through it for instance.

When shunting a MOV is dissipating all of the energy across itself and therefore it’s often used in combination with a PTC placed in series with the input. The PTC is slow to act but will heat up and increase in resistance in the event of a MOV and provide the longer term protection.

Using MOV’s in series

  • You can dissipate more power / have the MOV’s last longer in an overvoltage event
  • You create more creepage distance

We benefit hugely from resources on the web so we decided we should try and give back some of our knowledge and resources to the community by opening up many of our company’s internal notes and libraries through mini sites like this. We hope you find the site helpful.
Please feel free to comment if you can add help to this page or point out issues and solutions you have found, but please note that we do not provide support on this site. If you need help with a problem please use one of the many online forums.


Your email address will not be published.