Temperature switches are generally used in industry for limiting temperature. They monitor the temperature of machinery and equipment and, for example, switch off machinery if it overheats or switch on a fan to cool the equipment.

Function
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.

Contact version
The model 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.

For extended temperature control the TFS135 is available with a second normally closed contact or with an additional Pt1000/Pt100 measuring element.