TDK Corporation has recently introduced two new series of ThermoFuse® varistors with monitoring outputs and integrated thermal protection elements for overvoltage protection.
Among them, the MT25 series (B72225M*) components currently cover a voltage range of 150 VRMS to 385 VRMS, with a maximum surge current capability of 20 kA (8/20 ?s pulse shape), in compliance with the IEC 61643-11 standard. The protection element is designed to be extremely compact, fully encapsulated, measuring only 25 x 28 x 14 mm, and is available with or without galvanically isolated monitoring outputs.
The MT30 series (B72230M*) components have a Voltage range of 150 VRMS to 750 VRMS, a maximum surge current capability of 25 kA (8/20 ?s pulse shape), are also compliant with IEC 61643-11, and are 34 x 28 x 14 mm, the monitoring output of this varistor is designed with electrical isolation.
The new ThermoFuse varistor is based ON a further development of the varistor with a patented thermal protection element in series. If a sustained overvoltage causes the varistor to heat up, the fuse will blow and reliably disconnect the varistor from the circuit connection, preventing damage to the printed circuit board or components surrounding the varistor. Also, disconnecting the power supply can effectively prevent thermal runaway.
ThermoFuse MT25 and MT30 series varistors achieve flammability ratings up to UL 94 V-0 (details can be found in the fourth edition of the UL 1449 standard) with excellent heat resistance and a housing made of flame retardant materials.
The new series of varistors are used in a wide variety of applications including photovoltaic inverters, high-power industrial power supplies and frequency converters, and power supplies for lighting and telecommunications systems.
● Photovoltaic inverter
● High power industrial power supply
● Power supplies for lighting and telecommunication systems
Main features and advantages
● Wide voltage range: 150 VRMS to 750 VRMS
● High inrush current capability: up to 25 kA (8/20 µs)
● Optional with or without galvanically isolated monitoring output
● Fully encapsulated
● Ultra-compact design