D14 Metal Oxide Varistors

The nominal disc diameter of the ceramic body, about fourteen millimetres. It is a mechanical classification for filtering by size and footprint. Actual dimensions, lead spacing and mounting requirements come from the datasheet for the specific part number, not from the size code.

A larger disc has more ceramic volume, so it absorbs more surge energy and degrades more slowly under repeated events. Clamping voltage is set mainly by the voltage class, so two parts of the same class clamp similarly. The trade is board area and lead spacing.

Not automatically. A larger part still has to sit within the available space and lead pitch, and the clamping voltage must still protect what is downstream. Oversizing on energy does not help if the clamping figure at your surge level already exceeds what the circuit survives.

Yes. Disc size changes how many events the part survives, not the end-of-life behaviour. A degraded varistor can fail short and keep dissipating power. On mains lines, pair it with a fuse or thermal cut-out, or specify a thermally protected part.

With a complete part number, send the part number, quantity, delivery region and the date you need it. If you are still selecting, send the line voltage and type, the surge standard and level you must meet, and whether thermal protection is required.

VOOHU supplies them, with the gas discharge tubes and TVS diodes used in staged surge protection. Send your line voltage and surge level, and our FAE team will confirm options.

Often, if the bus never exceeds 65 V, float charge included. A MOV near its rating leaks more and ages faster, and the converter must tolerate the 135 V clamp.

A MOV absorbs more energy for its size but wears with each large surge; a TVS diode clamps faster and lower. DC inputs often use both: the MOV first, then a bidirectional TVS diode.