Varistor mainly used in maintaining the transient overvoltage, but the similarity in the conductor and insulator zener diode volt-ampere characteristic, also make it have a variety of electronic components, performance such as available in: 1, high voltage dc voltage components, low current intensity varistor voltage stable cocoa for kv, this is the common diode can't do it. 2. Voltage fluctuation test components. 3. Dc battery shift components. 4. All pressure components. 5. Fluorescent device.
The protection function of Varistor
(1) to protect nature, when attack source of impact strength, or when the impact current is not beyond the limit, limit of varistor voltage can not be beyond acceptable by maintenance target impulse withstand voltage test.
(2) the impact resistance characteristics of the pressure sensitive resistor itself should be able to withstand the limited impact current, impact capacity, and the average force of repeated shocks.
(3) there are two kinds of life characteristics, one is the life of the continuous task voltage, which is the time when the pressure sensitive resistor can work rules in the time limit of the temperature and system voltage. The second is the life of transient motion, which is the number of times that the required impact is possible.
(4) when the varistor participates in the preparation, in addition to the protection efficiency of the normally closed state, it will also enter some side effects, which is the secondary effect of the content, which should not reduce the normal working function of the system. At this time to think about the elements of the three, one is the varistor own electric capacity can reach dozens to hundreds of thousands of pf, the second is to reduce interference under the system voltage, three is a varistor nonlinear modulation current through the power of internal coupling effect on other circuits.