Fuse Protection Types
Based on the protection type, fuses can be divided into overcurrent protection and overtemperature protection. Fuses used for overcurrent protection are commonly known as fuses (also called current-limiting fuses). Fuses used for overtemperature protection are generally called thermal fuses.

The operating principle of a resettable fuse is a dynamic balance of energy. The current flowing through the RF/WH series components generates heat due to the RF/WH series. This heat is dissipated in whole or in part to the environment. The heat that is not dissipated increases the temperature of the RF/WH series components.

Reasons for Fuse Non-Conductivity
A fuse is absolutely conductive when it is not damaged.

Possible causes of non-conductivity include the following:
1. When testing for continuity between the two ends of the fuse with a multimeter, the wrong points were taken, resulting in an incorrect conclusion.

2. When testing on the circuit board, other circuits may be connected in parallel near the fuse, resulting in an incorrect conclusion.

It is recommended to remove the fuse with a soldering iron and then test it with a multimeter. If the fuse is not damaged, check the copper foil on the circuit board for breaks. There are five factors that can cause a fuse to blow:
1. A sudden surge in high voltage from the power grid, such as a lightning strike or the self-induced high voltage from a nearby large motor shutting down, can cause the fuse to blow and protect the internal circuitry.

2. When a large appliance in the internal circuit starts up, it draws a large current. If there are already large appliances in use at the time, the total current overloads, causing the fuse to blow.

3. The fuse is small and easily blows.

4. The fuse holder is old or loose, increasing contact resistance and making it prone to overheating and accidentally blowing.

5. A short circuit in the appliance or wiring can cause the fuse to blow.