Please explain Metal Oxide Varistors (MOV) datasheet

Discussion in 'General Electronics Chat' started by Mad Professor, Dec 6, 2009.

  1. Mad Professor

    Thread Starter Active Member

    Apr 15, 2009
    Good Day All.

    I have been reading on Wiki about Metal Oxide Varistors, and I now understand the basics of what they do and how they work.

    But as I have not worked with MOV's before I don't fully understand how to read the datasheets for these units.

    I have some VCR07D470K MOV's, that I am trying to understand the datasheet values.

    The maximum allowable voltage for this MOV is 30vac or 38vdc.

    So does this mean that the MOV starts clamping the voltage past this point?

    Thanks for your time.

    Best Regards.
  2. Duane P Wetick

    Active Member

    Apr 23, 2009
    Data sheets specifications need some interpretation as they look suspiciously like reprints from other MOV manufacturers. To answer your voltage threshold question, it appears the MOV conducts above these thresholds, however, the curves show a lot of data that is somewhat confusing. I've had most success by selecting units and then using them across coils with other devices; zeners and resistors and observing the clamping characteristics on a scope.

    Regards, DPW [ Spent years making heaters out of op-amps.]