Jumo Surface-mounting double thermostat series ATH 603026
Thermostats are used to control and monitor thermal processes. Surface-mounting double thermostats of the ATH type series consist of two separate measuring and switching systems.
The devices are available as temperature controllers TR, temperature monitors TW, safety temperature monitors STW (STB) and safety temperature limiters STB. In the event of a malfunction, the STB switches the monitored machine line to an operationally safe status.
Surface-mounting double thermostats operate according to the fluid expansion principle, a microswitch serves as an electrical switching element.
Switching function
Temperature controller TR and temperature monitor TW If the temperature exceeds the set point value set on the temperature probe, the microswitch will be tripped by the transmission mechanics and the current circuit opened or closed. The microswitch is reset to its original status once the set point value set is gone below (by the hysteresis).
Restart lock for the safety temperature limiter STB
If the temperature exceeds the limit value set on the temperature probe, the current circuit is opened and the microswitch mechanically locked. The microswitch can be manually unlocked, once the dangerous temperature drops by approx. 10 % of the scale range (approx. 15% with a limit value setting > + 350 °C).
Use of the safety temperature monitor STW(STB) as a safety temperature limiter STB
Ensure that the switching circuit downstream of the thermostat complies to DIN EN 14597 and VDE 0116.
Self-monitoring for the safety temperature limiter STB and safety temperature monitor STW(STB)
If the measuring system is destroyed, i.e. if the expansion fluid escapes, the pressure in the diaphragm of the STB and STW (STB) drops and permanently opens the current circuit. Unlocking is no longer possible. The electrical circuit opens when cooling the probe of STW (STB) and STB down to the negative temperature range, but it then closes again if the temperature rises. The STB must be unlocked manually if the minimum probe temperature is exceeded. The STW (STB) unlocks itself automatically.