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Valve Protected Equipment Protection
Aug 08, 2017

In the past, commonly used valve type arrester for the ordinary valve arrester, is now not produced. At present only the production of metal oxide valve type arrester.

At present, the metal oxide arrester is the only allowed to produce and sell in the power system used in the valve type arrester.

Metal oxide arrester commonly known as zinc oxide arrester. Its main working element is a metal oxide non-linear resistance film, which has a nonlinear volt-ampere characteristic, low resistance in the over-voltage, thus limiting the residual voltage on the arrester, the protection of protective equipment. And in the normal power frequency voltage was high resistance, flow does not exceed 1mA of ground leakage current, in fact, so that the live bus to the ground in an insulated state, without the need for series gap to isolate the operating voltage. As the zinc oxide arrester resistance chip resistance with the external voltage over-voltage and suddenly become smaller, so also known as the varistor. The zinc oxide valve has a very good volt-ampere characteristic, and its linearity α is 0.015-0.05, which is much smaller than the nonlinear coefficient of the silicon carbide valve.

Normal operation, the zinc oxide arrester work in the normal power frequency voltage, the arrester zinc oxide resistance film has a very high resistance, was insulated; when lightning over-voltage or internal over-voltage, the voltage exceeds the start value, the valve Showing low resistance state, discharge current, both ends of the arrester to maintain a lower residual voltage to protect the electrical equipment from over-voltage damage. After the overvoltage is over, the arrester immediately returns to the extremely high resistance and continues to maintain the insulation state, and the leakage current of the current is not more than 1mA to ensure the normal operation of the power system. Therefore, zinc oxide arrester can not need to set the spark gap, do not need to arc. Zinc oxide arrester action quickly, through flow, residual pressure is low, no freewheeling, the atmospheric over-voltage and some internal over-voltage can play a protective role.