MOV's in Surge protectors and Modified Sine wave Inverters

Discussion in 'General Electronics Chat' started by RodneyB, Nov 7, 2014.

  1. RodneyB

    Thread Starter Well-Known Member

    Apr 28, 2012
    I made a simple surge arrestor using 220 Volt MOV's . This is for a desktop computer. As I live in a country with power cuts of up to 15 hours a day I have a modified sine wave inverter to run the computer when the power goes.

    The system in the Inverter has an automatic transfer switch so we have uninterrupted power. Since I put the surge arrestor into the circuit the computer switches off as soon as the power goes.

    Is there a conflict between modified sine wave inverters and 275 Volt 10mm MOV's
  2. alfacliff

    Well-Known Member

    Dec 13, 2013
    the peak voltage of the line is higher than the mov's. the peak voltage of 220 volts is 310 volts.use a higher voltage mov.
    RodneyB likes this.
  3. ian field

    AAC Fanatic!

    Oct 27, 2012
    You need MOVs rated at least 275VAC, some manufacturers are very confident of their designs and install MOVs rated as high as 1100V!

    Every time an MOV catches a surge event - it takes a hit. Some times they chimble away round the edges, sometimes they shatter completely.

    AFAIK; Sidac diodes are like super power diacs - they switch to fully conducting at their rated breakover voltage. So adding sidacs as well as MOVs but at a higher breakover voltage than the MOV - a good MOV should clamp any spikes before they trip the sidac, as the MOV gets weaker - a spike will trip the sidac which blows the fuse, then you know its time to fit new MOVs.