Thermal relay does not operate fault processing method - Database & Sql Blog Articles

Photocoupler

If the motor has burned out and the thermal relay has not been activated, there may be several reasons for this. After the identification, it can be handled accordingly.

(1) The rated current value of the thermal relay does not match the rated current value of the motor. At this time, the thermal relay should be selected according to the capacity of the motor (the thermal relay cannot be selected according to the capacity of the contactor).

(2) The action mechanism is stuck or the guide plate is released. When handling, open the lid of the thermal relay, check the action mechanism, re-place the guide, and press the reset button. Check if the action of the action mechanism is flexible.

(3) The thermal element passes through the short-circuit current, and the bimetal produces permanent deformation, so that the thermal relay cannot operate when the motor is overloaded, causing the motor to burn. At this point, the bimetal should be replaced and re-adjusted.

(4) When repairing the thermal relay, due to negligence, the bimetal is reversed, or the wrong bimetal and heating element are used. In this case, when an overcurrent passes through the heating element, the bimetal cannot push the guide, the motor is burnt due to overload operation, and the thermal relay does not operate. When handling, check and adjust the mounting direction of the bimetal, or replace it with a suitable bimetal and heating element.

(5) The rated value of the thermal relay is too large, and the contact of the contact is poor. The rating can now be adjusted to eliminate dirt or oxide on the contact surface.

(6) The motor itself has failed. If the cooling fan is damaged or the air duct is blocked, and the ambient temperature is too high, the motor will burn out and the thermal relay will not operate. This is not a problem with thermal relays and should be addressed to troubleshoot the motor.