Email：sales@arlin.com.cn
Thermal Fuses – Working Principle and Key Parameters Explained
Published on:
Jul 24,2026
A thermal fuse, also known as a thermal cutoff, is a component that protects circuits and electronic devices by utilizing a melting principle triggered at a specific temperature. When the current in a circuit becomes overloaded or the temperature rises excessively, the thermal fuse instantly senses the condition and melts rapidly, cutting off the circuit to prevent equipment overheating or fire hazards.
A thermal fuse typically consists of thermally sensitive materials, insulating materials, and metal wires. The selection of the thermally sensitive material determines the rated triggering temperature of the fuse. Its working principle is based on the characteristics of thermally sensitive materials: when the current flowing through the circuit exceeds the rated design value, the resulting temperature rise is sensed by the thermal element inside the fuse. Once the temperature reaches a preset threshold, the thermal element rapidly undergoes a phase change, causing the fuse to quickly disconnect the circuit, thereby cutting off the current supply and providing overload protection.
Under normal operating conditions, the resistance of the fuse is very low, allowing current to pass through smoothly. However, when the circuit becomes overloaded, the temperature rise characteristic of the thermally sensitive material causes the fuse to disconnect rapidly, providing effective protection. This simple yet effective design enables thermal fuses to play a critical role in a wide range of electronic devices and circuits, ensuring safe and reliable operation of equipment.
Address: Building F, Longxin Industrial Park, Fenghuang Third Industrial Zone, Fuyong Street, Baoan District, Shenzhen, Guangdong, China
Follow us
Copyright © 2023 A.R.Electrical Co.,Ltd.