Probe current voltage pin 420*4450 head diameter 5.0 over current current and voltage pin

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The thermal relay generates heat from the current flowing into the heat element, and deforms the bimetal having different expansion coefficients. When the deformation reaches a certain distance, the link is pushed to break the control circuit, thereby causing the contactor to lose power. The main circuit is disconnected to achieve overload protection of the motor. As the overload protection component of the motor, the relay has been widely used in production due to its small size, simple structure and low cost.

When testing the setting current of the thermal relay, the phase heat elements can be connected in series. For the heat elements with phase failure protection, the heat elements can be connected in series. A steady current power supply or a regulated power supply should be used in the test to ensure stable test current. The test shall be carried out at an ambient temperature of (20 ± 5) °C.

During the test, first input the rated current of 1.05 times to the thermal relay. After the heat is stable, the current is raised to 1.2 times the rated current. After 2~3 minutes, the current regulating cam of the thermal relay is rotated to activate the thermal relay. The current is the rated current of the thermal relay to be tested.

The function of the thermal relay is: mainly used for overload protection of the asynchronous motor. His working principle is that after the overload current passes through the heat element, the bimetal is heated and bent to push the action mechanism to drive the contact action, thereby breaking the motor control circuit. Turn on the motor to stop the power, and play the role of overload protection. In view of the fact that the transfer of heat takes a long time during the bending of the bimetal, the thermal relay cannot be used as a short circuit protection, but can only be used as an overload protection.