Jumo Hot Air Thermostats 604514

Thermostats are used to control and monitor thermal processes.
The thermostats of the WTHc series are suitable for the use in hot air systems acc. to DIN 4794 and consist of 3 separate measuring and switching systems with the following functions: temperature controller TR, temperature monitor TW, and safety temperature limiter STB.
In the event of a malfunction, the STB switches the monitored machine line to an operational safe status.
Hot air thermostats operate according to the fluid expansion principle. The electrical switching elements are microswitches.

Switching function
Temperature controller TR and temperature monitor TW
If the temperature on the temperature probe exceeds the setpoint value, the microswitch is activated by the transmission mechanics and the electrical circuit is opened or closed. If the temperature falls below the selected setpoint value (by the amount of the switching differential), the microswitch is reset to its initial position.
Temperature monitor TW and safety temperature limiter STB
The microswitch can be manually unlocked once the dangerous temperature drops by approx. 10 K. The microswitch can be manually unlocked once the dangerous temperature drops by approx. 10 K.
Self-monitoring for the safety temperature limiter STB
If the measuring system is destroyed (i.e. if the expansion fluid escapes) the pressure in the membrane of the STB drops and permanently opens the electrical circuit. Unlocking is then no longer possible. The electrical circuit opens when cooling the probe of STB down to the negative temperature range, but it then closes again if the temperature unlocks itself automatically.