Zinc oxide varistors Features

TGE AC and DC High Performance MOV are widely used in electronic circuits, transient voltage surge protection because of the power supply system may harm the circuit. Varistor is generally used in parallel with the circuit when the voltage across the resistor changes rapidly, resistance short circuit current fuse blows, play a protective role. varistor metal oxide in the circuit, commonly used in the power supply voltage protection and regulation. Decrease the resistance of the TGE metal oxide varistor identification will be shunt currents, to protect against excessive transient voltage damage or interference.

Parallel applications of zinc oxide varistor

TGE metal oxide varistors application is a voltage limiting protection devices. Nonlinear characteristics of the use of zinc oxide varistors, when an overvoltage occurs between the two poles of the varistor, the varistor voltage can be clamped to a relatively fixed voltage value, in order to achieve protection of the post-stage circuit. Varistor TVS diode can be used instead tvs tube, a combination Zener diode and a capacitor.
Varistor circuit IC can be protected and other equipment, to prevent electrostatic discharge, surges and other transient current (such as lightning, etc.) and cause damage to them. Simply use varistors and connected to the protected IC or device circuit, when the transient voltage is higher than a certain value, the varistor resistance rapidly drops, turned a large current, thereby protecting the IC or appliances equipment; when the voltage drops below the operating voltage varistor, varistors high resistance, almost open, and thus will not affect the normal operation of the device or electrical equipment.
Zinc oxide varistor connected in parallel circuit generally used when the voltage across the resistor changes rapidly, resistance short circuit current fuse blows, play a protective role. Metal oxide varistors in the circuit, commonly used in the power supply voltage protection and regulation. Set the multimeter measurement 10k file, table pen connected to both ends of the resistor, the varistor should exhibit marked resistance multimeter, if you exceed this value is large, then the varistor has been damaged. Zinc oxide varistors and protected electrical equipment or components used in parallel. When the lightning over-voltage or transient operating voltage VS circuit occurs, varistors and protected equipment and components withstand VS, due to the fast response of the varistor, it exhibits excellent nanosecond time quickly non-linear electrical properties, then the voltage drop across the TGE Glass Coating varistors rapidly, far less than the VS, on such equipment and components to be protected actual withstand voltage is much lower than the over-voltage VS, so that the equipment and components for Free It was over-voltage shocks.

Zinc oxide varistors to protect the inverter application

 Lightning or lightning impulse voltage induced formation sometimes cause damage to the inverter. When the primary-side power supply system with vacuum circuit breakers, shunt opening and closing can also generate a higher voltage shocks. The drive side of the vacuum breaker opens once, formed by coupling the secondary side of high voltage surge spikes. To prevent over-voltage impulse voltage caused damage, usually at the input side of the inverter plus TGE metal oxide varistor application absorbing devices to ensure that the input voltage is not higher than the allowed maximum voltage during the inverter main circuit. When using the vacuum circuit breakers, the impact should be formed using an additional RC surge absorber. If the transformer primary vacuum circuit breakers, because to ensure the control timing before the first drive is disconnected vacuum circuit breakers.
Most factories are powered generator, or use the generator for a rainy day, when the generator has a fault, the output of the high-voltage inverter and electronic equipment often burned. This condition is often seen in our Shenzhen have had a wire drawing plant once it broke two dozen sets of 30KW inverter, discontinued ten days, causing heavy losses in the generator plant equipment to engage a lot of protection methods the effect is not obvious. Then join metal oxide varistor identification on the input of the inverter or instrument air switch, depending on the voltage 380V with a 821K, 220V with a 471K, so that when a high voltage varistor will be short-circuited, air switch trip, the protection of the inverter, Inverter failure rate is greatly reduced.
Note zinc oxide varistor must be connected to the output end of the air switch, parallel (three-phase triangular connection) wattage varistor size is not critical, a little input current is large is selected relatively large varistor or several varistors in parallel. When the TGE metal oxide varistor theory play a role in it will immediately complete a short circuit. Then switch also requires good air quality equipment, quick response and protect current is not too big.

The main characteristics of zinc oxide varistors and precautions

TGE mov metal oxide varistor is a zinc oxide as the main body, add a variety of metal oxides, various metal oxides classic electronic ceramics made classic electronic ceramics made of polycrystalline semiconductor ceramic element ʱ?? Because of its unique non-linear conductivity of polycrystalline semiconductor ceramic element.
 Because of its unique non-linear electrical conductivity and flow capacity, low voltage limit, fast response, Sobig and flow capacity, limiting low voltage, fast response, polarity, voltage and low temperature coefficient characteristics, widely used power, resistance, low voltage temperature coefficient, widely used in electric power, telecommunications, railways, telecommunications, chemical, petroleum and other areas set up communications facilities, railways, telecommunications, chemical, oil and other fields of facilities and equipment from momentary voltage surge damage. Prepare against momentary voltage surge damage.
 metal oxide varistor testing and protected electrical or components in parallel. When the circuit voltage surge does not appear, varistor surge work when the circuit voltage does not appear, varistors in pre-breakdown, the equivalent circuit for the grain boundary resistance is about the pre-breakdown region, etc. Validity circuit grain boundary resistance of about 10 1012 12 ~ 10 1013 13Ω / cm / cm, the varistor is high impedance, high impedance does not affect the varistor does not affect the normal operation of equipment to be protected; electric sound occurs when the circuit the normal operation of equipment to be protected; when the surge voltage circuit occurs, since the response speed is very varistor surge voltage, since the TGE varistor metal oxide fast response, it quickly turned nanosecond time.

Zinc oxide varistor of use

TGE metal oxide varistor basics is a non-polar overvoltage protection element, whether it is AC or DC circuits, simply TGE metal oxide varistor sizing and is to protect electrical equipment or components parallel protection device purpose

Protection of zinc oxide varistors

(1) distinguish between power supply protection, or signal lines, data lines with TGE Varistor for counter protection, they are to meet different technical standards.
(2) Depending on the varistor applied continuous operating voltage can be across the line with a varistor can be divided into AC or DC with the use of two types, varistors in both voltage stress different aging characteristics performance.
(3) According to the varistor withstand abnormal over-voltage characteristics of different, can be divided into varistor for surge suppression, high-power and high-energy type of these three types.
Surge suppression: is used to suppress lightning over-voltage and over-voltage and other transient over-voltage varistor, this transient overvoltage occurs it is random, and current-voltage non-peak periods may be Big. The vast majority mov metal oxide varistor fall into this category.
High power type: refers to the absorption cycle for continuous bursts appear varistor, for example, and connected to the switching power converter varistor voltage cycle where impact occurs, and the cycle shows that the energy value may be calculated in general out, the peak voltage is not large, but the high frequency of occurrence, the average power is considerably large.
Energy Type: generator means for absorbing the excitation coil, and other large lifting electromagnet coil inductance coil magnetic energy varistor voltage is, for such applications, the main technical indicators are energy absorption capability.
Varistor protection, the vast majority of applications, it can repeatedly effect, but sometimes also to make it into the current fuse as a "one-off" protection device. For example, and then on some of the short-circuit current transformer load contacts TGE metal oxide varistor identification.

High voltage gradient zinc oxide varistor formulation and preparation methods

Reasonable formula of TGE metal oxide varistor sizing is preferably the component with the content of the zinc oxide varistor, prepared using the formulation of zinc oxide varistor with up to 350 ~ 600V / mm high voltage gradient, while at the high voltage gradient, oxidation zinc varistor capable of maintaining good nonlinear properties, electrical properties and anti-aging properties, in order to meet the practical application of electronic components, such as arrester miniaturization requirements. The preparation method of zinc oxide varistor resistance of the zinc oxide film sub-component and trace ingredients and mix evenly matched tiny size, reduce the amount of contamination, while the addition of the low-temperature thermal processes during the sintering process leaving the metal oxide varistor basics to form a stable grain boundary structure, help to improve the stability of the zinc oxide varistor and a secondary heat treatment during the phase transition of bismuth oxide, thereby improving the electrical properties of TGE Glass Coating varistors.
Zinc oxide can be inserted to corrosion or food supplement zinc, but the product demanding, especially to control the content of harmful heavy metals.
Zinc oxide itself is not toxic, but can be inhaled zinc oxide particles are harmful.
Zinc smelting industry, preparation of brass, galvanized work are likely to produce zinc oxide smoke.
To prevent smoke, galvanized iron can not be welded directly, you must first remove the surface film of zinc.

Zinc oxide varistors major role in the electrical industry

Many TGE mov varistor for counter used in the product must use explosion-proof zinc oxide varistors, which is specified in the Design Manual: The controller does not allow the choice of non-explosion type varistor varistors, air-conditioning control panel functions as designed distinction, lightning varistor generally refers to the use of varistors between power line and the earth, sometimes leaving the voltage rise due to poor ground between line and ground, so the ratio between the line and usually use the occasion higher nominal line varistor voltage. Varistor in the circuit must be considered able to withstand the lightning over-voltage, over-voltage and over-voltage transient frequency effects. Lightning varistor and fuse or general discharge with the use of the power portion of the first stage ZNR varistor in parallel with the power transformer primary coil ends, with fuse tubes series circuit, surge voltage suppression.
Under normal circumstances, voltage, resistance zinc oxide varistors great can be achieved by Meg level (the current flowing through it only microampere level, can be ignored), in the open state, no effect on the circuit. But when you experience a power voltage exceeds the breakdown voltage, its resistance suddenly reduce design to a few tenths of Europe even in Europe, up to the current moment by thousands of amperes, ZnO varistor immediately turned on by the deadline, because it and power supplies in parallel, so soon the power fuse blows, the main circuit board to prevent burn out. In addition, when faced with a slight momentary power surge fluctuation (220 ± 10%), varistor buffer will absorb this flow Chung clutter, there are encountered lightning, transformers and other inductive circuit switching operation, instantaneous overpressure effect produced on varistor, its resistance suddenly decreases, the current through the large drainage role to play to protect the entire circuit, this effect is called over-voltage protection. Varistors ZNR common in the schematic representation.
Zinc oxide varistors can also be used as over-voltage protection. Over-voltage atmospheric over-voltage and over-voltage points. Atmospheric over-voltage caused by lightning: Operating overvoltage is due to mutations in the electrical system status, sharp electromagnetic energy caused by the conversion. TGE metal oxide varistor theory is mainly used for lightning induced over-voltage protection, over-voltage electronic devices (surge) absorption, relay contacts spark arrestor, transistors, thyristors, integrated over-voltage protection switch current.

Zinc oxide varistors used in automotive circuits

Automotive products of TGE metal oxide varistor symbol have become increasingly demanding, more and more attention because of the zinc oxide varistor has a good protective effect, good or bad quality can directly affect the use of the car, zinc oxide varistors and at the circuit input is broken, there is no impact on the normal circuit operation, when for some reason caused by the input voltage is increased to a certain value. varistor will burn to protect further damage to the circuit. (Varistor protection element one-off, so after the breakdown want to change with the type of new elements)
1. zinc oxide varistor structure like two characteristics consistent back-coupled regulator, which is basically the same nature. The main characteristics of the varistor, when the ends of the applied voltage is within the nominal rating, its resistance value is almost infinite, in a high impedance condition, the leakage current of <50 microamps, when the voltage across it slightly exceeded rated voltage, its resistance drops sharply immediately in the conduction status, the operating current increases several orders of magnitude, and the reaction time is only in nanoseconds. metal oxide varistor application in foreign commonly known as "chopper" and "limiter", which is from its practical effect and its name.
2. zinc oxide varistor in the circuit can absorb such counter electromotive force, thereby effectively protect the switching circuit from damage. In the car the most used appliances or car computer board in power protection circuit, TGE metal oxide varistor testing Toyota cars computer board with a sheet of black circle, while American cars and Daewoo cars in the pressure-sensitive computer board Most resistance is red, if the car alternator voltage regulator failure, resulting in long lines and battery voltage is too high or the battery pile loose, disengage and start using the power of the power to start the engine, often cause the computer board pressure sensitive resistor damaged.

Zinc oxide varistor selection

Selection of TGE Glass Coating varistors before, you should first understand the following related technical parameters: Nominal voltage is at a predetermined temperature and DC flow, voltage across the varistor. Leakage current is at 25 ℃, when the application of the maximum continuous DC voltage, varistor flowing current value. Level refers mov metal oxide varistor voltage by 8/20 rating current pulses at both ends exhibit 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, the minimum time interval of two adjacent surge Tm and scheduled TGE high voltage varistor working life period, the total number of surge pulses N and the like.

Works zinc oxide varistor

TGE varistor metal oxide is a resistor made of zinc oxide in Taiwan is called the surge absorber, zinc oxide TGE metal oxide varistor application voltage because of the change in resistance has nonlinear way (positive and negative) also symmetry, and Can abnormal voltage response line, absorbed most of the surge / surge energy while suppressing the abnormal voltage to a safe range so that safety and stability to improve lines, and thus subject to many areas of favor.

Zinc oxide use

Another major use of zinc oxide is used as a coating, 1834, for the first time became the watercolor, but insoluble in oil. But soon the problem will be solved by a new zinc oxide production process. In 1845, Leclair began mass production of zinc white oil paint in Paris, 1850, zinc oxide became popular throughout Europe. High purity zinc oxide, so that in the 19th century, some artists painted zinc white as a background in painting, but these paintings have appeared through the crack years later.