Modelling an MOV voltage versus current characteristic

The previous “There’s an R in varistor” post showed how the varistor is really a current controlled component. In modelling the varistor resistance or voltage, it is logical that current should be the controlling parameter used in the data set curve fitting equations. The IEC 61051-1 ED3 includes a 2-term power law equation, V = BxICĀ , in its varistor definition. However, this is a misdirection as it will be shown this equation is only valid over a small range of currents.

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