The working principle and function of thermal relays

The working principle and function of thermal relays are as follows:

How it works. The working principle of the thermal relay is that the current flowing into the thermal element generates heat, so that the bimetal sheet with different expansion coefficients is deformed, and when the deformation reaches a certain distance, the connecting rod is pushed to action, so that the control circuit is disconnected, so that the contactor loses power, the main circuit is disconnected, and the overload protection of the motor is realized.

Function. As an overload protection component of electric motors, thermal relays have been widely used in production due to their small size, simple structure and low cost.

Common types of thermal relays

1. Electrically heated thermal relay

Electrically heated thermal relays are mainly used in the power industry to achieve instantaneous power-off protection.

It uses the heat generated by the electric current through the heating element to measure the temperature, and when the temperature reaches a certain value, the contact will automatically disconnect, cutting off the power supply and protecting the safety of equipment and circuits.

2. Steam thermal relay

Steam thermal relays are widely used in oil refining, chemical, metallurgy, pharmaceutical and other industries. It controls the on/off of circuits by sensing temperature changes in the steam pipes, thus protecting the safety of equipment and pipelines.

As an important electrical protection component, thermal relays play an important role in safe production and daily life.

The working principle of thermal relay: Thermal relay is an electrical appliance composed of thermal elements (such as thermistors) and contactors, and its function is to make the contactor act when a given temperature reaches the trigger point, so as to provide control signals or control power supply to other electrical appliances or circuits. The role of thermal relays:

Thermal relays are mainly used for temperature control, temperature protection and energy saving, etc. It can be used to control the temperature of electric heating equipment, such as electric water heaters, electric blankets, electric pots, etc.; It can also be used to protect the safety of electrical appliances, such as electric ovens, electric irons, etc. In addition, it can also be used for energy saving, such as electric heaters, electric stoves, etc.

The principle and function of the thermal relay are as follows:

The current of the circuit generates heat through the thermal relay, and the heat will deform the two metal sheets with different expansion coefficients, and when the deformation reaches a certain extent, the connecting rod action will be triggered, so that the thermal relay can disconnect the upper and lower end circuits, so as to disconnect the overcurrent circuit and protect the safety of the circuit. Thermal relay is a protective appliance that uses the thermal effect principle of current to cut off the motor circuit when there is an overload that the motor cannot bear, and provides overload protection for the motor.

The role of thermal relays:

The thermal relay is mainly used for overload protection of the load motor, when the current of the circuit exceeds the set current of the thermal relay, the thermal relay will be disconnected from the circuit, which will protect the safety of the circuit and prevent the load motor and related components from being burned out. Accompaniment to the cleft.

Precautions for the use of thermal relays

1. The use conditions should be clear, and the frequent start-stop and reverse braking circuits should not be heated relays.

2. The setting value of the current should be set accurately, the setting value is too large and does not work, and the setting value is too small for the motor to run, generally the rated current of the motor is doubled. Small is selected when light load is selected and large is selected when heavy load, and the setting current value is equal to the rated current of the motor in the case of closed rock.

3. Even the contact points should be tight to prevent malfunction caused by heating caused by poor contact.

4. Check after the overload fault to ensure that the thermal relay is intact before it can be used again, the reset method should be reasonable, and the manual reset should be played when there is no one on the scene to prevent the automatic reset after the failure, and the motor will start again.