In circuits, overloading is a common problem, which may cause damage to circuit components or malfunction of the circuit. To prevent this from happening, a thermal relay can be used for overload protection. This article explains why thermal relays are used for overload protection.

1. What is a thermal relay?

The thermal relay is an electrical component that senses current or power changes in the circuit through a thermal sensor to control the switch of the circuit. When the current or power in the circuit exceeds the rating of the thermal relay, the thermal sensitive element will generate heat, causing the thermal relay contacts to open, thereby realizing the overload protection function.

2. Why use thermal relay for overload protection?

1. Avoid damage to circuit components

In a circuit, if the current or power exceeds the rated value of the component, it will cause damage or burning of the component. Using thermal relays for overload protection can cut off the circuit in time to prevent excessive current or power, thereby avoiding damage to components.

1. Protect the safety of the circuit

Overloading will reduce the safety of the circuit and may cause fire and other dangers. Using thermal relays for overload protection can cut off the circuit in time and protect the safety of the circuit.

1. Improving the reliability of the circuit

Using thermal relays for overload protection can improve the reliability of the circuit and avoid circuit failures due to overload. fault to ensure the normal operation of the circuit.

3. Overload protection principle of thermal relay

The overload protection principle of thermal relay is based on the thermal effect of the thermal element. When the current or power in the circuit exceeds the rating of the thermal relay , the thermal element will generate heat, causing the thermal relay contacts to disconnect, thus realizing the overload protection function.

Specifically, the heat-sensitive element in a thermal relay is usually a bimetal structure. When the current or power in the circuit exceeds the rating of the thermal relay, the heat-sensitive element will be heated and bent, causing the Thermal relay contacts are open. When the thermal element cools down, the contacts automatically close, restoring normal operation of the circuit.

IV. Application occasions of overload protection of thermal relays

The overload protection of thermal relays is suitable for various circuits, especially for occasions where circuit components need to be protected, such as motors, transformers, etc. .

The above is an introduction to why thermal relays are used for overload protection. Using thermal relays for overload protection can avoid damage to circuit components, protect the safety of the circuit, and improve the reliability of the circuit. When applying thermal relays for overload protection, it is necessary to select the appropriate model and specifications according to the actual conditions of the circuit to ensure that the circuit operates normally.