The thermal relay is installed on the three-phase motor, and sometimes it can still burn out the motor. Therefore, if there is a protective circuit, it should not burn out the electricity? Sometimes, it is not uncommon for not only single-phase operation to burn out, but also overload to burn out. There is no elixir of immortality in the world, nor are there advanced facilities to “prevent” electrical equipment from being burned out. The maximum limit can only be prevented and may be prevented. For example, a new equipment, starter, and motor were tested to meet all the standards before use. However, after running for a period of time, the motor suddenly burned out, and the leader held the electrician responsible, but the electrical engineer felt very aggrieved. After disassembling the motor, it was discovered that the C core of the motor had a short circuit to the ground of the motor winding.
Thermal relay
This indicates that the distance between the motor core and the motor winding was originally very close, with only one layer of insulation between them. During operation, the vibration insulation layer was damaged, resulting in a short circuit to ground. At this time, the thermal relay is not very sensitive to short-circuit current. Is the setting value of the thermal relay reasonable and correct. Secondly, check the installation position of the round-trip thermal relay to see if the selection and setting values of the thermal relay are correct. In order to save costs, some contactors are installed at the lower or upper end of the star triangle, and the current passing through the thermal relay is only half of the branch. If the selection is still based on the motor current, the thermal relay setting value is too large to provide protecti