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.

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.