The selection and application of varistor - Knowledge of electrical resistance

by:Thermistor-Mov     2020-06-21
Varistor the selection and application of this article mainly discusses the varistor how to selection and application scope of the analysis of the series, this article word count 1290 words, read to 13 minutes. 1) Pressure-sensitive voltage choice, want to consider the power supply voltage fluctuation, MOV voltage precision, MOV aging coefficient of factors such as; 2) MOV clamping voltage should be less than the biggest affordable level after protection circuit transient voltage security; 3) Or low power circuits in the communication circuit, to pay special attention to MOV junction capacitance and leakage current, and doesn't affect the normal operation; 4) MOV is aging model components in applications, consider using the environment, impact test standard and method, the specific reference varistor derating curve; 5) Packaging format, varistor, all for the plug-in components, size is proportional to the flux flow, large size, large flow, the greater the resistance to impact current, the protection of circuit more reliable; The vice. Pressure sensitive resistance of four kinds of common application type in the surge and transient protection circuit, for the application of pressure sensitive resistance in a circuit connection, can be divided into four types: 1) Between the power cord or the power cord and the earth connection: the most representative type of applications, is widely used in lightning surge prevention system; 2) Load of connections: mainly used for inductive load caused by sudden disconnect induction pulse to absorb, thus protecting circuit components from damage; 3) Contact between connections: prevent induced charge switch contact is arc burning, general and contact parallel connected to the pressure sensitive resistance; 4) For the protection of the semiconductor device connections: mainly used for thyristor, power transistor for effective protection of semiconductor devices, etc. Along with the development of science and technology fields, also drive the application fields of capacitor. Varistor is applied in voltage protection, lightning protection, inhibiting surge current and absorption peak pulse, clipping, high voltage arcing, de-noising, protection of semiconductor components, etc. What are the applications in the pressure sensitive resistance in a circuit, 1) Circuit input overvoltage protection atmosphere overvoltage caused by lightning, most belong to the induced overvoltage, lightning overvoltage discharge on transmission line, the overvoltage of the voltage value is very high, up to 100 ~ 10000 v, the harm is great. So for electrical equipment must be take measures to prevent the atmospheric overvoltage. Pressure sensitive resistor can be used. Generally USES parallel with the device. If electrical equipment requires the residual pressure is very low, can use multilevel protection. 2) To prevent operating overvoltage protection circuit operating overvoltage is circuit working condition suddenly changes, electromagnetic energy conversion sharply, quick release as a kind of overvoltage, prevent the overvoltage pressure-sensitive resistor can be used to protect a variety of power equipment, electrical, etc. 3) Semiconductor overvoltage protection device to prevent the semiconductor devices work for some reason cause overvoltage when burned, varistor is commonly used to protect it, in a transistor between the emitter and the collector, or in a transformer connection varistor, can effectively protect overvoltage damage of the transistor. Under normal condition, the pressure sensitive resistance is high resistance state, only wanted to leakage current, and when to withstand overvoltage, varistor quickly into a state of low resistance, overvoltage energy absorbed by the pressure sensitive resistance in the form of discharge current and surge voltage disappeared later, when a circuit or element under normal voltage, pressure sensitive resistance to high resistance body. For diode and brake pipe, the pressure sensitive resistance and the semiconductor elements in parallel or in the power supply in parallel, and should satisfy the two requirements: one is the direction of the repetitive voltage is larger and the residual pressure of varistor, two are repetitive reverse voltage is greater than the residual pressure of varistor. 4) Contactor, relay protector when cut off the contactor, relay and other perceptual load circuit, the overvoltage can be several times more than supply voltage, overvoltage caused by contact between the electric arc and spark discharge, burning contactor, shorten the life of equipment. Due to the effect of shunt of the varistor in high potential, thus protecting the contact. Varistor and coil in parallel, the contact between the overvoltage is equal to the power supply voltage and the pressure sensitive resistance is the sum of residual pressure, pressure sensitive resistance to absorb energy for coil storage energy, pressure sensitive resistance and contact in series, the contact of the overvoltage is equal to the pressure sensitive resistance of residual pressure, pressure sensitive resistance absorption energy for coil storage energy of 1. 2 times. 文章/ ymdzdxxyyy。 HTML this paper label: resistance varistor varistor - the selection and application Resistance of knowledge - New chenyang electron on a: inductive magnetic ring materials and characteristics of the next article: a integrated inductance in magnetic field
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