Thermistor Relays
Thermistor relays are relays that monitor the resistance of PTC thermistors placed in the motor windings and, when the winding temperature reaches the sensor's response temperature, disconnect the motor through the output contact. They are used against overheating that current measurement cannot detect in motors that start and stop frequently, run at low speed with a frequency inverter or have weakened cooling. The category includes the Entes PT-01 with a 220-230 V AC supply. Choose the supply voltage, the PTC sensor circuit to be connected, the output contact type and the reset method after a fault according to the sensor in your motor. This protection can be applied only to motors that have a PTC sensor in their windings. A thermistor relay should not be confused with a thermal overload relay; the thermal overload relay monitors the motor current, while the thermistor relay monitors the resistance of the sensor embedded in the winding.
Products
- Entes PT-01 Thermistor Relay, 220-230VAC, with PTC Protection — Entes · SKU: M1907 · TRY 949.20 · In stock
How to choose Thermistor Relays
Thermistor relays are relays that monitor the resistance of PTC thermistors placed in the motor windings and, when the winding temperature reaches the sensor's response temperature, disconnect the motor through the output contact. They are used against overheating that current measurement cannot detect in motors that start and stop frequently, run at low speed with a frequency inverter or have weakened cooling.
- Separate overcurrent/leakage protection, motor starting and local isolation requirements.
- Select rated current, pole count and breaking capacity (kA) from the installation calculation.
- Match coil voltage, auxiliary contacts and tripping curve to the control circuit and load type.
Frequently asked questions
What is Thermistor Relays and where is it used?
Thermistor relays are relays that monitor the resistance of PTC thermistors placed in the motor windings and, when the winding temperature reaches the sensor's response temperature, disconnect the motor through the output contact. They are used against overheating that current measurement cannot detect in motors that start and stop frequently, run at low speed with a frequency inverter or have weakened cooling.
What should I compare when choosing Thermistor Relays?
Choose the supply voltage, the PTC sensor circuit to be connected, the output contact type and the reset method after a fault according to the sensor in your motor.
Where can I find technical details for Thermistor Relays products?
They are used against overheating that current measurement cannot detect in motors that start and stop frequently, run at low speed with a frequency inverter or have weakened cooling.