huaju

　　The varistor is a voltage-limiting protection device. Utilizing the nonlinear characteristics of the varistor, when overvoltage occurs between the two poles of the varistor, the varistor can clamp the voltage to a relatively fixed voltage value, thereby protecting the subsequent circuit. The main parameters of the varistor are: varistor voltage, current capacity, junction capacitance, response time, etc.

　　The response time of the varistor is ns level, which is faster than the air discharge tube and slightly slower than the TVS tube. Generally, its response speed can meet the requirements for over-voltage protection of electronic circuits. The junction capacitance of a varistor is generally in the order of hundreds to thousands of Pf. In many cases, it is not suitable to be directly used in the protection of high-frequency signal lines. When used in the protection of AC circuits, its large junction capacitance will increase leakage. Current needs to be fully considered when designing protective circuits. The flow capacity of the varistor is larger, but smaller than that of the gas discharge tube.

　　The biggest feature of the varistor is that when the voltage applied to it is lower than its threshold "UN", the current flowing through it is extremely small, equivalent to a closed valve. When the voltage exceeds UN, its The resistance becomes smaller, which causes the current flowing through it to surge without much change in the impact on other circuits, thereby reducing the impact of overvoltage on subsequent sensitive circuits. Using this function, abnormal overvoltage that often occurs in the circuit can be suppressed and the circuit can be protected from overvoltage damage.

　　Product type description:

　　The thermal protection varistor series represents a new development in integrated circuit protection. Both versions consist of multiple radial-lead metal oxide varistors and contain an integrated thermally activated element designed for disconnection due to abnormal overvoltage, limited current and overheating caused by various conditions outlined in UL 1449 . TMOV over-temperature protection varistor is a varistor series with over-temperature disengagement (disconnection) function. It is a temperature-sensitive device attached to an ordinary MOV chip. Because the integrated thermal element is very close to the MOV tube body, TMOV can provide fast thermal response. When the power frequency current continues to increase or the MOV fails, due to the increase in power frequency current or leakage current of the MOV, the temperature of the MOV body rises to the set operating temperature of the TMOV, and the temperature sensitive device will be disconnected. This cuts off the current supplied to the MOV, so that the temperature of the MOV no longer rises, thereby preventing the new zinc oxide varistor from catching fire due to the failure of the MOV. It uses standard leads as terminals and is very suitable for installation on PCB circuit boards. TMOV pressure-sensitive actuators can be widely used in computers. Switching power supply, plug strip, UPS, telecommunications, network, railway and other fields. The integrated configuration has lower inductance than most discrete solutions, thus improving clamping performance against fast overvoltage transients. In addition, TMOV varistors are of the wave-soldering type, which reduces the expense and duplication of effort associated with manual soldering operations, thereby simplifying the assembly of the final product. The integrated thermal element of the TMOV varistor, combined with the corresponding packaging design, helps the transient voltage surge suppressor module comply with the requirements of UL 1449 for cord-connected and permanently connected equipment.

　　Structural features and packaging methods:

　　- Resistor structure: round, with leads, with over-temperature release mechanism, epoxy resin encapsulation;

　　- Encapsulating material: flame-retardant epoxy resin, compliant with UL94-0;

　　- Electrode lead: tinned copper wire;

　　- Packing method: bulk

　　3. Model name, appearance structure and dimensions:

TM0V14-20mm

TM0V25F

TM0V32F

TM0V34S

The company can also produce varistors with higher voltages according to customer requirements. Currently, the highest varistor voltage the company can produce is 2700V.