20-150C CAPILLARY THERMOSTAT ENCLOSED

Intended use

The thermostat monitors and controls the overshooting or undershooting of limit values in process plants. The device can be used in the following areas:

- Heating engineering and Air conditioning

- Heating cabinets

- Plastics industry

- General mechanical engineering

Design

The enclosed thermostat is available with capillary. A snap-action switch serves as the electrical switching element.

Function

The thermostat operates on the principle of liquid expansion. The device is available as temperature monitor TW, temperature controller TR, safety temperature monitor STW, or safety temperature limiter STB. The panel-mounted thermostat is RoHS-compliant and cadmium-free.

Temperature controller TR and Temperature monitor TW

If the temperature on the temperature probe exceeds the setpoint value, the electrical circuit is opened or closed by a microswitch. If the temperature falls below the selected setpoint value (by the switching differential), the microswitch is reset to its initial position.

Restart lock at safety temperature limiter STB

If the temperature at the temperature sensor exceeds the set limit value, the electrical circuit is opened and the microswitch is mechanically locked. After falling below the limit value by approx. 10 % of the temperature range (approx. 15% of the limit value setting > +350 °C), the switch can be unlocked manually.

Self-monitoring for 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 membrane of the STB and STW (STB) drops and permanently opens the electrical circuit. Unlocking is then no longer possible. When the STW (STB) and STB sensors cools down to the negative temperature range, the circuit opens, but must be unlocked manually by the restart knob when the temperature rises. The STW (STB) restarts automatically.