Monitoring heating of motor winding in range given by resistance of in-built PTC thermistor (1.8…3.3kΩ).
The Elko TER-7 thermostat controls motor winding temperatures with PTC thermistor, which is generally placed in the motor winding or very close to it. Resistance of PTC thermistor run to max 1.5kΩ in cold stage.
By temperature increase the resistance goes strongly up and by overrun the limit of 3.3kΩ the contact of output relay switch off - mostly contactor controlling a motor. By temperature decrease and thereby decrease of thermistor resistance under 1.8kΩ the output contact of relay again switches on. The relay has a "Control of sensor fault" function. This controls the interruption or disconnection of the sensor.
When the switch is in position “TK” the monitoring of faulty sensor is not functional - it is possible to connect a bimetal sensor with only 2 states: ON or OFF. The device can work with a bi-metal sensor in this position.
Other safety unit is function “Memory”. By temperature overrun (and output switches off ) the output is hold in faulty stage until service hit.
This brings the relay to normal state (with RESET button) on the front panel or by external contact (remote).
