The Safety Temperature Limiter type STR 100 is an electronic thermostat monitoring the temperature of heating equipment and machinery. When the permitted temperature-limit is exceeded or in case of a malfunction, the STR 100 switches off without delay. An active reset must be made for a restart. The temperature limit is adjustable with a scaled potentiometer. An unintended or unauthorized adjusting of the limit is prevented through a lead-sealed transparent cover.

With supply voltage switched on, the STR 100 operates in a changeable lockout mode and the relay must be started by a reset (manually with built-in reset button or external reset) to make contact (no) close. Applicable for plants with supervised operation. The mode of operation corresponds to type 2BJK according EN 60730/VDE 0631.

The temperature is measured with a Pt 100 resistance temperature detector (RTD) according to EN 60751 / IEC 751. The process qualification in combination with the sensor must be proved. To fulfil affords for higher safety functionality the function has to be routine-tested periodically. The thermostat series STR 100 meets safety category 3 (Safety of machines EN 954-1, TÜV Rheinland documents T 24/00 + T103 2007 Z1 + T103 2007 E2). If safety approval is recommended only use listed RTD.

Temperature Limiter
A temperature-limiter is an equipment that switches of permanently (locked) after the limit has been exceeded. A reset (manually or with a tool) is possible after the temperature has fallen below switch-back point (limit minus hysteresis).

Safety Temperature Limiter
A safety temperature limiter is a limiter that fulfils in addition the requirements of extended safety according to DIN 3440.