Temperature fuses can induce overheating in the abnormal operation of electrical and electronic products, thereby cutting off the circuit to avoid the occurrence of fire. Used in: hair dryer, electric irons, electric cooker, electric stove, transformer, motor, water dispenser, coffee pot and so on temperature fuse after the operation can not be used, only in a temperature fuse action.

Temperature fuse has a variety of forms, the following introduction of the three common:
First kind:
Organic type temperature fuse
By movable contact (sliding contact), spring (spring), can melt (electrically nonconductive thermalpellet) constitute. The current flows from the left lead to the movable contact (sliding contact) prior to the start of the temperature fuse and flows through the metal casing to the right. When the external temperature reaches a predetermined temperature, the organic matter melts and the compression spring becomes loose. Spring expansion, movable contact (slidingcontact) and left lead separation. The circuit is opened, the current between the movable contact (sliding contact) and the left lead is cut off. Second species:
Porcelain tube type temperature fuse
Lead by axial symmetry (LEED), the fusible alloy at a specified temperature can be melted (fusible alloy) and to prevent the oxidation of molten special mixture (special compound) and an insulation porcelain pipe (ceramic insulator) a. Ambient temperature rise specific resin mixture at the start of liquefaction, when reaching the melting point in the resin mixture with the help of (surface tension increases of molten alloy, molten alloy) under the effect of surface tension on both ends of the lead as the center quickly shrink into a ball, thereby cutting off the circuit permanent.

Third species:
Square shell type temperature fuse
Temperature fuse pin two connected between a fusible alloy wire, special resin coated with fusible alloy wire, electric current can flow from a pin flow to another pin, when the temperature fuse ambient temperature rises to its operating temperature, the fusible alloy melts and under surface tension and special resin help, attached to the two pin shrink into spherical end. In this way, the circuit is permanently cut off.
The following items are necessary to ensure the normal operation of fuses:
I) each temperature fuse has rated current and voltage, fusing temperature (Tf), use temperature (Th), maximum temperature (Tm), to use under the specified parameters.
II select the installation position of the fuse should pay attention to the vibration and other parts of the product can not be modified, so that stress transferred to the fuse.
III to be installed in the temperature fuse fuse temperature will not rise to the maximum temperature above the place.
IV) not used in liquid or humidity maintaining machines above 95%.
V) temperature fuse to be installed in the temperature fuse can only heat the place. When the structure is inevitable to set thermal insulation, such as when installed in the heater should pay attention to not directly connected, so as not to hot wire heating fuse
VI) for the amount of current to improve the temperature fuse and connected in parallel or sustained by overcurrent and overvoltage, internal contact temperature fuse is damaged, will affect the normal operation, and therefore can not be used in these conditions.

Although the temperature fuse is highly reliable in design, the exceptional conditions that a single temperature fuse can handle are, after all, limited. Coupled with man-made or unforeseen force majeure function ordered the temperature fuse damage can not play a normal role, the machine will not be able to cut off the abnormal circuit. Therefore, when the action error in the machine overheating directly to the human body, in addition to no effect when the fuse circuit cut-off equipment, high safety requirements in the case, to use more than 2 temperature fuse with different temperature fuse.

Thin temperature fuse is specially developed for over temperature protection of lithium ion battery, its working principle is the same as the above second kinds of temperature fuse, connection circuit with low melting point alloy, low melting point alloy wrapped around the fluxing resin, low melting point alloy and metal conductive connection, and plastic material sealing. When a short circuit or other causes the internal temperature of the battery is increased to a certain level of internal or external battery, fast temperature fuse fuse will be close to the electric core, so as to cut off the external circuit of the battery and prevent the battery from exploding, life injury event. Because handheld electronic devices need to be more portable, so the size of the temperature fuse needs smaller, the better, the thinner the better. Currently the thinnest temperature fuse can do 0.65mm thick, width can be 7mm. The resistance temperature fuse is also very small, only 8m ohm, standby power consumption is very small, can greatly increase the lithium ion battery standby time.

It also has some shortcomings, first of all it is not recoverable, as PTC, even if the occasional fault leading to PTC action, once the troubleshooting, the battery can continue to work. Once the temperature fuse moves, the whole battery will no longer work. Of course, with the lithium ion battery quality is getting better and better, the accident probability failure occurred more and more small, once abnormal will not let the battery can continue to use, but has become the advantages of the temperature fuse. After all, the cost of a battery is negligible compared with physical injury. The so-called rather kill wrong, also can not let go. As long as the cell phone battery had a high temperature failure, who would dare to put this potential bomb on the side? Second, it can not be welded by ordinary methods and processing, such as PPTC, can withstand high temperature and short time, so after reflow welding, direct injection into the battery, but the temperature fuse can only use spot welding, laser welding and other local welding way to prevent temperature fuse.

Is currently using more thin temperature fuse 98 degrees and 92 degrees, the heating rate of 1 DEG C / min, melting temperature of 98 DEG C thin temperature fuse is 94 + 3, fuse the temperature of 92 DEG C thin temperature fuse is 89+3/-4, which is 85 DEG ~92 deg. At present, the manufacturers in the development of thin temperature fuse high temperature fuse.