ThermoFuse® Varistors are used for overvoltage protection with an additional thermal element as safety feature.
Over the last years the fail safe functions got more popular and as a result the variety of thermally protect varistors increased on the market which resulted in many designs for different sizes and surge capabilities.
This article will show the benefits and features of TDK ThermoFuse® Varistor vs Standard Varistors.

TDK Corporation (TSE: 6762) presents two new series of ThermoFuse® varistors, which are equipped with monitor outputs and integrated thermal protective components for overvoltage protection.
The MT25 series (B72225M*) currently covers a voltage range from 150 VRMS to 385 VRMS, and its maximum surge current capability is 20 kA at a pulse form of 8/20 µs, according to IEC 61643-11. With dimensions of 25 x 28 x 14 mm, the completely encapsulated protective components feature a particularly compact design. Their monitor outputs are optionally available with or without electrical isolation.

TDK Corporation (TSE:6762) has extended its EPCOS ThermoFuse™ family of fuse protected varistors with the new compact NT14 and NT20 series. The new ThermoFuse components feature a footprint that fits into existing circuit board layouts.