GIS Arresters

If the low-pressure side of the distribution transformer is not installed MOA, when the high-pressure side discharge lightning current polymer arrester to the earth when the grounding device to produce a pressure drop, the pressure drop through the distribution transformer housing while in the neutral point of the low pressure side of the winding. Therefore, low-voltage winding of the lightning arrester current will flow through the high-voltage winding turns ratio induced by a high potential (up to 1000 kV), the potential will thunder and high-voltage side winding voltage is superimposed, causing the high-voltage winding neutral point potential increased insulation breakdown near the neutral point. If the low-pressure side mounted MOA, MOA discharge when the potential of the high-pressure side grounding means is increased to a certain value, the low-pressure side xatge MOV begins to discharge, the low pressure side coil outlet and where the potential difference between the end point and the housing is reduced, so that to eliminate or reduce the impact of "anti-conversion" potential.

Composite arrester

MOA (MOA) during normal operation and distribution transformers in parallel, the terminating line, the lower end of the ground. When the line when an overvoltage occurs, then the distribution transformer will withstand over three parts dropout voltage generated through the arrester, wire and grounding device, called the residual pressure. In this three-part overvoltage, the metal oxide arrester residual voltage on its own performance related to its residual voltage value is constant. Residual voltage on the grounding device can be connected to the grounding deflectors distribution transformer housing, then connected to the grounding device and means to eliminate them. And how to reduce the residual voltage of the leads has become the key to the protection of distribution transformers. Leads through the current frequency impedance, varistors the higher the frequency, the stronger the wire inductance, impedance increases. Seen from U = IR, to reduce the residual pressure on the lead, you have to narrow the lead impedance, and possible ways to reduce the lead impedance is to shorten the distance between Composite arrester from distribution transformer to reduce the lead impedance, lower lead drop, so arresters should be installed in a more appropriate distribution transformer near point distance.

Metal oxide varistors

Mov varistor valve main ingredient is zinc oxide, zinc oxide varistor has a very excellent nonlinear characteristics. Under normal operating voltage of the resistance value is very high, in fact, the equivalent of an insulator, and in the over-voltage is applied, the resistance of the resistive sheet is small, residual pressure is very low. But under normal operating voltage, since the valve sheet to withstand long-term effect of power frequency voltage generated by the degradation caused by changes in resistance characteristics, resulting in increased flow through the valve leakage current. The resistive component of the current sharp increase in temperature will rise valves on thermal crashes, serious, mov metal oxide varistor or even cause explosion arrester. In accordance with the provisions of rules 1, MOA total of six test items, namely (1) Composite arrester Insulation resistance (2) Leakage Current DC U1mA and 0.75U1mA under (3) AC operating voltage under leakage current (4) Power frequency Power frequency reference voltage (5) Base insulation resistance (6) Check discharge counter action case reference current.

High-voltage surge arrester

MOA (MOA) is used to protect the transmission and distribution equipment insulated against overcurrent
Important protection of electrical pressure hazard, overvoltage arrester has fast response, voltage characteristic flat, stable performance,
Flow capacity, residual voltage, long life, simple structure, etc., it is widely used in power generation,
Transmission, substation, distribution and other systems. Composite coat metal oxide surge metal oxide varistor sizing is silicone rubber
Composite materials make coats, and traditional porcelain jacket metal oxide arrester, compared with a small size, light weight, rugged, stain resistance, good explosion-proof performance.

Metal oxide surge arresters

Metal oxide surge arresters are used to protect the transmission and distribution equipment, insulation against over-voltage protection of electrical hazards is important, it has fast response, voltage characteristic flat, stable performance, high flow capacity, low residual voltage, long life, simple structure etc., widely used in power generation, transmission, transformation, distribution and other systems. Composite coat metal oxide surge arresters composite material is made of silicone rubber jacket, and the traditional porcelain jacket arresters, compared with a small size, light weight, rugged, stain resistance, explosion-proof performance.

MOA on the proper use of distribution transformers

Distribution transformers shall be installed near side of the metal oxide surge arresters (MOA) during normal operation and distribution transformers in parallel, the terminating line, the bottom ground. When the line when an overvoltage occurs, this time with a change would put too three parts dropout voltage generated through the arrester, leads and grounding device, called a residual pressure. In this three-part overvoltage, the arrester residual voltage on its own performance related to its residual voltage value is constant. Residual voltage on the grounding device can be connected to the grounding deflectors distribution transformer housing, then connected to the grounding device and how to eliminate them.
Distribution transformer low-voltage side of distribution transformer should be installed if the low-pressure side is not installed AC and DC High Performance MOV, when the high-pressure side discharge lightning current arrester to the earth when the grounding device to produce a pressure drop, the pressure drop through the distribution transformer housing while in the low-pressure side coil The neutral point. Therefore, the low-pressure side of the lightning current flowing through the windings allow high voltage winding turns ratio induced by a high potential (up to 1000 kV), the potential will thunder and high-voltage side winding voltage is superimposed, resulting in high voltage winding neutral point potential increased insulation breakdown near the neutral point. If the low-pressure side mounted MOA, MOA discharge when the potential of the high-pressure side grounding means is increased to a certain value, the low-pressure side Glass Coating MOV begins to discharge, the low pressure side coil outlet and where the potential difference between the end point and the housing is reduced, so that eliminate or reduce the impact of "anti-conversion" potential.
MOA grounding wire should be connected to the distribution transformer housing MOA grounding wire should be connected directly to the power distribution transformer shell, then shell and then connected to ground. That the arrester ground wire directly connected to the earth, and then another from the ground stake lead a ground wire to the transformer housing approach is wrong
In strict accordance with the regulations require regular maintenance test regularly MOA insulation resistance measurement and leakage current test, if it is found MOA insulation resistance was significantly reduced or breakdown should be replaced immediately to ensure the safety and health of distribution transformer operation.

Advantages Surge arrester

Flow capacity. Arrester easy to absorb energy, no series gap constraints, only the strength of the valve itself relevant. Comparison with silicon carbide valves, through-flow capacity of the oxide valve unit area of ​​4 to 4.5 times larger. Therefore, the use of such valves made of lightning, not only can limit atmospheric over-voltage, and can be used to limit the operating voltage, they can even withstand certain short duration (frequency) overvoltage.
Simple structure, small size, easy to mass production, low cost
For a variety of special needs. Metal oxide surge AC High Gradient MOV good stain resistance, not due to changes in the surface potential distribution is filthy coat or charged cleaning affect the performance of the arrester. Meanwhile, the air valve from the environment, can adapt to a variety of insulation media, it also applies to a variety of special needs high altitudes and 6 SF - enclosed appliances.
Surge arrester has a number of advantages, great potential for development, is the main direction of development of the world arrester, will gradually replace the traditional band gap metal oxide arresters, it will also be key to the future of UHV system overvoltage protection device.
Flow capacity. Arrester easy to absorb energy, no series gap constraints, only the strength of the valve itself relevant. Comparison with silicon carbide valves, through-flow capacity of the oxide valve unit area of ​​4 to 4.5 times larger. Therefore, the use of such valves made of lightning, not only can limit atmospheric over-voltage, and can be used to limit the operating voltage, they can even withstand certain short duration (frequency) overvoltage.

Simple structure, small size, easy to mass production, low cost.

For a variety of special needs. Metal oxide surge arresters good stain resistance, not due to changes in the surface potential distribution is filthy coat or charged cleaning affect the performance of the arrester. Meanwhile, the air valve from the environment, can adapt to a variety of insulation media, it also applies to a variety of special needs high altitudes and 6 SF - enclosed appliances.

Surge arrester has a number of advantages, great potential for development, is the main direction of development of the world arrester, will gradually replace the traditional band gap arrester, it will also be key to the future of UHV system overvoltage protection device.