STW II Capillary Tube Thermostat 16 A Fail-Safe

Ex Proof Heat Tracing Equipment - STW II Capillary Tube Thermostat 16 A Fail-Safe

The STW II is a compact ON/OFF type capillary tube thermostat, housed in an Ex e certified polyester enclosure.

STW II Capillary Tube Thermostat 16 A Fail-Safe

The STW II is a compact ON/OFF type capillary tube thermostat, housed in an Ex e certified polyester enclosure. Heaters, fans, motors and other equipment are energised and de-energised by means of this thermostat when specific temperature ranges are exceeded. This device can also be used to control the temperature in air or on various surfaces.

FUNCTION

Any change in temperature at the sensor bulb causes a change in the volume of fluid in the measuring system, which in turn results in a movement of the diaphragm membrane. This membrane is connected to a mechanical device that activates a microswitch. If the temperature at the sensor bulb exceeds the pre-set value, terminals 1 and 4 are opened. If there is a rupture or break in the sensor tube (leakage), then the switch remains permanently open (fail-safe). If the temperature falls below the minimum setting, the autocontrol opens the circuit but closes again on temperature rise.

APPLICATION EXAMPLE

The STW II thermostat can directly switch temperature-dependent equipment loads (heaters etc.) of up to 16 A. Higher rated currents can be switched by means of a contactor; the STW II switches the contactor coil. If an interlock is installed by means of an additional relay (according to DIN VDE 0116), the STW II can also be used as a limiter.

FEATURES

• Small construction
• Varying temperature ranges can be combined in one enclosure
• Can be mounted directly in Zone 1
• Temperature can be set in Zone 1
• Many variants available