Thermal fuse, also called "thermal fuse, thermal fuse", is a kind of disposable element connected to the circuit and used to protect the circuit. When the current on the circuit is too high, the metal wire or sheet in it will fuse at high temperature, which will cause the current to be interrupted when the circuit is open, so as to protect the circuit from damage. The thermal fuse is a current protector that melts the melt with the heat generated by itself and cuts off the circuit after the current exceeds the specified value for a period of time. Thermal fuse is widely used in high and low voltage distribution system, control system and electrical equipment. As a protector of short circuit and overcurrent, it is one of the most widely used protective devices.
Working principle of thermal fuse.
A thermal fuse is an electrical device that uses a metal conductor as a melt and is connected in series with a circuit. When an overload or short-circuit current passes through the melt, it is fused due to its own heat, and it is an electrical device that cuts off the circuit. Fuses are simple in structure and convenient to use, and are widely used as protective equipment in power systems, various electrical equipment and household appliances.
Characteristics of thermal fuse.
The rated current of the fuse is not equal to the rated current of the fuse, but should be greater than the rated current of the fuse and determined in cooperation with the main electrical appliance.
Fuse is mainly composed of melt, shell and support, in which melt is the key element to control the fusing characteristics. The material, size and shape of the melt determine the fusing characteristics. Melt materials are divided into two types: low melting point and high melting point. Materials with low melting point, such as lead and lead alloy, are easy to fuse because of their low melting point. Because of their high resistivity, the cross-section size of the melt is large, and more metal vapors are produced when fusing, so they are only suitable for fuses with low breaking capacity. Materials with high melting point, such as copper and silver, have high melting point and are not easy to fuse. However, due to their low resistivity, they can be made into smaller cross-section size than melts with low melting point, and produce less metal vapor when fusing, so they are suitable for fuses with high breaking capacity. Melt shapes are divided into filiform and ribbon shapes. Changing the shape of variable cross-section can significantly change the fusing characteristics of fuses.
Fuses have anti-delay characteristics, that is, when the overload current is small, the fusing time is long; When the overload current is large, the fusing time is short. Therefore, within a certain overload current range, when the current returns to normal, the fuse will not blow out and can be used continuously. Fuses have different fusing characteristic curves, which can meet the needs of different types of protected objects.
Thermal fuse action
Electrical components installed in the circuit to ensure the safe operation of the circuit. When a circuit fails or is abnormal, the current rises continuously, and the rising current may damage some important or valuable devices in the circuit, and may also burn the circuit or even cause a fire. If the fuse is correctly installed in the circuit, the fuse will fuse itself to cut off the current when the current abnormally rises to a certain height and at a certain time, thus playing a role in protecting the safe operation of the circuit. Cut off the current, so as to protect the safe operation of the circuit.
