TFS135 Bimetal temperature switch

Temperature switches are used in industry for limiting temperature. They monitor the temperature of machinery and equipment and, for example, switch off machinery if it overheats or switches on a fan to cool the equipment. Bimetals form the basis of the WIKA TFS135 temperature switches. Temperature sensing is carried out by a bimetal disc, which snaps over when the Nominal Switching Temperature (NST) is reached.

After cooling back down to the Reset Switching Temperature (RST), the switch returns to its original state. The reset switching temperature is typically 15 ... 30 K below the switching temperature.

The WIKA TFS135 bimetal temperature switch is built with a normally closed contact. A Normally Closed contact (NC = closed in the normal state) opens a circuit and shuts down the machinery. After cooling down below the reset switching temperature, the contact returns to the original state, so that the monitored equipment can again work normally.


  • Fixed switching temperature
  • Current-independent switching
  • Automatic reset
  • No additional voltage supply
  • Switching voltages up to AC 250 V / 2.5 A