What is the role of thermal relay what is it?
According to the thermal effect of the relay made, and the function of electromagnetic relays almost. Conductive switch
Mainly used to overload the motor overload protection, his working principle is the overload current through the thermal components, the bimetal heating to bend the action to promote the action mechanism to drive the contact action, so the motor control circuit disconnect the motor to achieve power off , Play the role of overload protection. In view of the bimetallic heating process, the heat transfer takes a long time, so the thermal relay can not be used for short circuit protection, but can only be used as overload protection
Thermal relay is controlled by the temperature of the switch off the relay, the role is to use low-voltage circuit on the off to control the high-voltage circuit off
The thermal relay is generated by the current flowing into the heat element; so that the bimetal with different expansion coefficient is deformed. When the deformation reaches a certain distance, the connecting rod is pushed and the control circuit is disconnected, The main circuit is disconnected to achieve overload protection of the motor.
effect:
When using the thermal relay to overload the motor, connect the thermal element in series with the stator winding of the motor, connect the normally closed contact of the thermal relay in the control circuit of the electromagnetic contact of the AC contactor, and adjust the setting current adjustment knob, The dial lever is spaced from the push rod by a suitable distance. When the motor is working properly, the current through the thermal component is the rated current of the motor, the heat element heats up, the bimetallic sheet is heated and bent, so that the push rod is in contact with the chevron lever and can not push the chevron. Normally closed contact in a closed state, AC contactor to keep the pull, the motor normal operation.
