The role of high performance and High Performance Varistor

mov varistor what's the use? The most important feature High Performance Varistor is added on top of it when a voltage lower than its threshold "UN" when little current flowing through it, the equivalent of a shut valve when the voltage exceeds the UN, its resistance becomes smaller, so that makes it the current flowing through the surge change on other circuits is unlikely to reduce applied voltage sensitive circuitry on the follow-up. Using this feature, you can suppress the circuit often appear abnormal over-voltage, over-voltage protection circuit from damage.
For example: Our household power circuit TV on the use of zinc oxide varistors efficient, high breakdown Varistor for counter used here is 470V, the maximum surge voltage when the transient (non-RMS) when more than 470V High Performance Varistor is a manifestation of his clamping characteristics, the high voltage is pulled down, so that the subsequent circuit work within a safe

Selection and precautions High Performance Varistor

Selection of High Performance Varistor before, you should know the following relevant technical parameters: Nominal voltage is at a predetermined temperature and direct current flow, voltage across the varistor efficient. Leakage current is at 25 ℃, when the application of the maximum continuous DC voltage, high varistor flowing current. Voltage rating refers Glass Coating varistors ating current pulses through 8/20 presented at both ends voltage peaks. Through traffic is applying a predetermined peak current pulse current (8 / 20μs) waveform when. Surge environmental parameters include a maximum inrush current Ipm (or the maximum surge voltage and surge Vpm source impedance Zo), surge pulse width Tt, two adjacent surge minimum interval Tm and the High Performance Varistor predetermined operating lifetime, the total number of surge pulses N and the like.

Generally, metal oxide varistor function often with the protection device or devices in parallel, under normal circumstances, High Performance Varistors across the DC or AC voltage should be lower than the nominal voltage, even when the power fluctuations at worst should not be selected higher than the rated maximum continuous operating voltage, the maximum continuous operating voltage value corresponding to a nominal voltage value is the choice of values. Overvoltage protection areas for the application, the varistor voltage value should be greater than the voltage value of the actual circuit, the general should be selected using the following formula: VmA = av / bc where:

a circuit for the voltage fluctuation coefficient; v DC operating voltage for the circuit (when ac rms); b for the varistor voltage error; c to component aging coefficients,; VmA actual value thus calculated is 1.5 times the operating voltage of the DC In exchange the state should also consider the peak, and therefore the results should be expanded to 1.414 times.

High Performance Varistor works

Response time and high voltage varistoris ns level, faster than gas discharge tube, slightly slower than the TVS tube, generally used in electronic circuit overvoltage protection to meet the requirements of its response speed. When High Performance Varistor junction capacitance range is generally on the order of hundreds to thousands of Pf, in many cases should not be directly applied in the protection of high-frequency signal line, the application in the protection of the AC circuit, as it greatly increases junction capacitance leakage current protection circuits designed to take full account. High Performance Varistor flow capacity is large, but smaller than the gas discharge tube. High Performance Varistor referred VDR, is a non-linear voltage-sensitive semiconductor element overvoltage protection.
l When applied to the Varistor for counter voltage is below its threshold, the current flowing through it is extremely small, it is equivalent to a resistance infinite resistance. That is, when a voltage is applied on top of it is below its threshold, which is equivalent to an OFF state of the switch.
l When applied to the High Performance Varistor voltage exceeds its threshold, the surge current flowing through it, which is equivalent to the resistance infinitely small resistance. That is, when added on top of it higher than its threshold voltage, which is equivalent to a closed switch.

High Performance Varistor

mov varistor is a non-linear voltage characteristics of the resistance of the device is mainly used in the voltage clamp circuit when subjected to excessive pressure, absorb excess current to protect sensitive devices. English name called "Voltage Dependent Resistor" abbreviated as "VDR", or called "Varistor". High Performance Varistor resistive material is a semiconductor, so it is a variety of semiconductor resistor. Now extensive use of "zinc oxide" (ZnO) varistors efficient, its main material divalent element zinc (Zn) and hexavalent elemental oxygen (O) of the composition. So from the point of view of materials, zinc oxide varistor is an efficient "Ⅱ-Ⅵ Group oxide semiconductor." In China Taiwan, Glass Coating varistors called "surge absorber", sometimes also referred to as "electric shocks (surge) suppressor (absorber)."
High Performance Varistor is a voltage limiting protection devices. Efficient use of

the nonlinear characteristics of the varistor, when an overvoltage occurs between the two poles of the varistor efficient, high varistor voltage can be clamped to a relatively fixed voltage value, in order to achieve protection of the post-stage circuit. The main parameters and High Performance Varistors are: varistor voltage, current capacity, junction capacitance and response time.

The basic characteristics of high performance and High Performance Varistor

(1) protection feature, when the impact of the strong impact of the source (or inrush current Isp = Usp / Zs) does not exceed a predetermined value, High Performance Varistor limit voltage must not exceed the protected object can withstand impact resistance voltage (Urp ). Varistor for counter product
High Performance Varistor product

(2) impact resistance, namely High Performance Varistor itself should be able to withstand the impact of current, the impact energy, and several attacks have appeared when the average power.

(3) Life has two properties, one continuous working voltage of life, namely High Performance Glass Coating varistors (hours) at a predetermined ambient temperature and system voltage conditions should be able to work reliably stipulated time. Second, the impact of life, that can reliably withstand the impact of the number of times specified.

(4) High Performance Varistor after intervention system, in addition to protect a "safety valve", it will also bring some additional impact, which is the so-called "secondary effects", it should not reduce the normal performance of the system. Then there are factors to consider three, one High Performance Varistor itself capacitance (tens to tens of thousands PF), the second is in the system voltage leakage current, three are non-linear current through High Performance Varistor coupled source impedance effects on other circuits.