Thermal relays and fuses are common electrical components that play a protective role in circuits. Although they can both interrupt the circuit, there are some differences between them. In this article, we will provide a detailed introduction to the differences between thermal relays and fuses.

Definition and function of thermal relays

A thermal relay is an electrical component that can play a protective role in a circuit. Its main function is to detect changes in current or temperature in the circuit and disconnect the circuit when necessary to prevent electrical overload or overheating. A thermal relay usually consists of a thermistor and an electromagnetic relay. When the current or temperature in the circuit exceeds the rated value of the thermal relay, the thermal element will change, causing the electromagnetic relay to operate and thus disconnect the circuit.

Definition and Function of Fuses

A fuse is an electrical component that can also play a protective role in a circuit. Its main function is to detect changes in current in the circuit and disconnect the circuit when necessary to prevent electrical overload or short circuit. A fuse usually consists of a fuse and a fuse holder. When the current in the circuit exceeds the rated value of the fuse, the fuse will melt, thus disconnecting the circuit.

Thermal relays and fuses are both devices used for electrical protection, but their working principles and protection objects are different.

1. Working principle: Thermal relays are achieved by utilizing the thermal expansion principle of resistive materials to convert the relationship between current and temperature into mechanical motion. Fuses, on the other hand, use the principle of conductors melting when heated to add a fuse or core to the circuit. When the current in the circuit exceeds the rated current of the fuse, the fuse or core will melt and cut off the circuit.

2. Protection object: The protection object of thermal relays is electrical equipment and circuits, which can detect whether the current in the circuit exceeds the rated value and cut off the circuit in case of overload or short circuit, thereby protecting electrical equipment from the impact of electrical faults such as overload and short circuit. The protection object of fuses is also electrical equipment and circuits, but they are mainly used to protect conductors such as wires and cables in the circuit. When the current exceeds the rated value, the fuse or core will melt and cut off the circuit, avoiding damage to conductors such as wires and cables due to overload.

3. Reusability: Thermal relays can be used repeatedly, as long as the current in the circuit does not exceed the rated value, it can continue to operate. Once a fuse blows, it needs to be replaced with a fuse or core in order to continue using it.

Overall, thermal relays and fuses are electrical protection devices, but their working principles and protection objects are different. Users can choose suitable equipment according to their actual needs. Thermal relays are mainly used to protect electrical appliances, while fuses are mainly used to protect circuits. When choosing which protection component to use, it needs to be determined based on the specific situation.

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