Kenmore thermal fuse is also called over-temperature fuse, thermal fuse and so on. The text symbol in the circuit diagram is Ft; the graphic symbol is shown in Figure 1.

Kenmore thermal fuse is a non-resettable one-time protection element, which is connected in series with various electrical power input terminals, and its function is to protect against overheating. When the household appliance in use has abnormal temperature, or the temperature control fails to cause the temperature rise to be too high, the Kenmore thermal fuse quickly breaks the circuit.

In order to ensure the normal use of household appliances, especially electric heating appliances, and improve their safety performance, the new national standard clearly stipulates that household appliances must be equipped with thermal fuses. To prevent the overheating of electrical appliances from causing fires and endangering personal safety.

1. Types and characteristics of thermal fuse

There are many types of thermal fuse products, which are classified according to temperature-sensitive materials. Commonly used thermal fuse mainly includes: composite thermal fuse, low melting point alloy fuse and compound thermal fuse.

1. Composite thermal fuse
The structure of the composite thermal fuse is shown in Figure 2. The temperature-sensitive material adopts a low melting point alloy, and a layer of organic matter is covered on the alloy, and the melting point of the alloy can be ensured to match the melting point of the organic matter. That is, the melting points of both are the same. In this way, the organic matter not only prevents the surface of the alloy from oxidizing, but also enables the alloy to fuse reliably when it reaches the rated operating temperature, thereby breaking the circuit.

Features of composite thermal fuse:

(1) The action temperature has high accuracy, the fusing action is reliable, and the fusing will not be prematurely or delayed;
(2) The thermal stability is good, and it will not get out of control after long-term high temperature;
(3) The load current of the temperature sensing body can be as high as 20A, which can be adapted to the use of household appliances with large load current;
(4) The shell is not live, safe to use and easy to install;
(5) Low price, suitable for mass production.