Thermal protection pressure sensitive adhesive resistor

Varistor is widely used for overvoltage protection. For conventional varistors, when the voltage at both ends is near the critical on-off voltage value for a long time or to the surge impact with large energy, the current through the varistor significantly increases, and the temperature of the ceramic substrate in the varistor significantly increases. In the abnormal inert condition, the varistor base will be heated to more than 300℃, thus constituting fire and other safety hazards.

Chinese utility model patent Application No. 00237913.9 discloses a safe varistor, which is characterized by temperature insurance that can conduct heat conduction with the varistor. The varistor and the temperature insurance are insulated in the same shell with the heat conduction medium.

In the working process of the product, if the temperature of the varistor is too high due to abnormal factors, the temperature insurance placed next to the varistor will be heated and melted due to heat conduction, to prevent fire and other accidents caused by the high rise of the varistor. Therefore, the above existing products have certain advantages. However, in practical application, it is found that the response speed of the temperature insurance is slow, which is not conducive to the safe implementation of protection. At the same time, the ability of temperature insurance to withstand the impact of a large current is weak, and easy to fail after the impact. Therefore, the above existing products have defects.

The aim now is to improve the overheating protection structure of the above existing products and provide a thermal protection varistor with fast response speed and strong resistance to large current impact. The thermal protection varistor of the utility model has a shell and a varistor covered by a shell, on which a first leading electrode and a second leading electrode are arranged.

One end of the first leading electrode and the second leading electrode are respectively electrically connected with two internal electrodes on the pressure-sensitive ceramic substrate, and the other end of the first leading electrode and the second leading electrode extend to the shell. It is characterized by a metal spring and a third electrode, the metal spring is arranged in the shell, in the varistor with a pressure-sensitive ceramic substrate of an internal electrode conductive metal, one end of the metal spring through the low melting point metal, and the metal conductor phase welding, the other end of the metal elastic yellow fixed on the shell and the third electrode conductive connection, The third electrode has an outlet end extending out of the shell.