保定电气厂家价格-交流无间隙金属氧化物避雷器

金属氧化物避雷器在配电变压器上的正确使用

Correct use of metal oxide arrester in distribution transformer

应安装在靠近配电变压器侧

It should be installed near the side of the distribution transformer

金属氧化物避雷器(MOA)在正常工作时与配变并联，上端接线路，下端接地。当线路出现过电压时，此时的配变将承受过电压通过避雷器、引线和接地装置时产生的三部分压降，称作残压。在这三部分过电压中，避雷器上的残压与其自身性能有关，其残压值是一定的。接地装置上的残压可以通过使接地引下线接至配变外壳，然后再和接地装置相连的方式加以消除。对与如何减小引线上的残压就成为保护配变的关键所在。引线的阻抗与通过的电流频率有关，频率越高，导线的电感越强，阻抗越大。从U=IR可知，要减小引线上的残压，就得缩小引线阻抗，而减小引线阻抗的可行方法是缩短MOA距配变的距离，以减小引线阻抗，降低引线压降，所以避雷器应安装在距离配电变压器近点更合适。

The metal oxide arrester (MOA) is parallel to the transformer in normal operation, the upper end connection and the lower end grounding. When the line has overvoltage, the change will bear the three part pressure drop produced by the overvoltage through the lightning arrester, the lead line and the grounding device, called the residual pressure. In these three parts overvoltage, the residual pressure on the arrester is related to its own performance, and its residual pressure is certain. The residual pressure on the grounding device can be eliminated by connecting the grounding wire to the variable shell and then connecting to the grounding device. How to reduce the residual pressure on the lead is the key to the protection and change. The impedance of the lead is related to the current frequency, the higher the frequency, the stronger the inductance of the wire, and the greater the impedance. From the U=IR to the residual pressure decreases lead, will reduce the lead resistance, and feasible method to reduce the lead resistance is shortened from MOA with variable distance to reduce the lead resistance, reduce lead drop, so the arrester should be installed in the near distance distribution transformer is more appropriate.

配变低压侧也应安装

The low pressure side of the transformer should also be installed

如果配变低压侧没有安装MOA， 当高压侧避雷器向大地泄放雷电流时，在接地装置上就产生压降，该压降通过配变外壳同时作用在低压侧绕组的中性点处。因此低压侧绕组中流过的雷电流将使高压侧绕组按变比感应出很高的电势（可达1000 kV），该电势将与高压侧绕组的雷电压叠加，造成高压侧绕组中性点电位升高，击穿中性点附近的绝缘。如果低压侧安装了MOA，当高压侧MOA放电使接地装置的电位升高到一定值时，低压侧MOA开始放电，使低压侧绕组出线端与其中性点及外壳的电位差减小，这样就能消除或减小“反变换”电势的影响。

If there is no MOA installed on the low voltage side of the distribution transformer, when the lightning current is released to the earth on the high voltage side arrester, a voltage drop will occur on the grounding device. The voltage drop will act on the neutral point of the low voltage side winding through the distributing transformer housing. Therefore, the lightning current flowing through the low voltage side winding will cause the high voltage side winding to induce a high potential (up to 1000 kV) according to the ratio of change, which will superimpose with the lightning voltage of the high voltage side winding, causing the neutral point potential of the high voltage side winding to rise, and breakdown the insulation near the neutral point. If the low pressure side of the installation of MOA, when the high side MOA the discharge potential of grounding device is increased to a certain value, MOA low voltage side to discharge the low voltage side winding terminal and the potential of reducing point and shell, so you can eliminate or reduce the potential impact of "transform".