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A valve arrester valve arrester The most basic structural components are spark gap (referred to as the gap) and non-linear work resistance (referred to as the valve), which are stacked in series in the sealed porcelain sleeve. When the power system is in danger of over-voltage, the gap is quickly broken down and the inrush current flows through the valve plate to earth. When the overvoltage on the line is eliminated, the spark gap will cut off the power frequency freewheeling immediately (the spark gap will not be punctured by the normal power frequency voltage), so that the line is insulated from the ground and the normal operation resumes. According to the different structural properties and uses, valve arresters are mainly the following types: (1) FS-type arrester. This is a common valve arrester, the structure is simple, general protection, low cost, generally used to protect the distribution equipment 10kV and below. Such as distribution transformers, column circuit breakers, disconnectors, cable head. (2) FZ arrester. This arrester in parallel with spark gap shunt resistance, good protection. Mainly used for 3 ~ 220kV electrical equipment protection. (3) FCD arrester. This is a magnetic blow valve arrester, spark gap not only shunt resistance, as well as shunt capacitance, the protection performance is more ideal, mainly for the protection of rotating electrical machines. (4) FCD arrester. Is also a magnetic blow valve arrester, better electrical performance, dedicated to substation high-voltage electrical equipment protection. 2 valve arrester installation (1) newly installed arrester, should first check whether the voltage level with the equipment to be protected. (2) Before new installation and re-installation (without mine-out period), it is necessary to carry out AC-voltage withstand test and DC leakage test and insulation resistance measurement of power frequency. If it fails to meet the standard requirements, it can not be used. (3) Before installation, should check the arrester is intact. The porcelain pieces should be no cracks, no damage; seal should be intact, each section of the connection should be close; metal contact surface should remove oxide layer, dirt and foreign matter, protection and cleaning. (4) When installing the distance between the lines should meet the requirements: 46kV at 3kV; 69cm at 6kV; 80cm at 10kV. Horizontal distance should be more than 40cm. (5) arrester support to maintain vertical, fixed to be solid, lead connections to be reliable. (6) Arrester's upper and lower leads should be as short and straight as possible, not allowed in the middle of joints. The cross section should not be less than the specified value, aluminum is not less than 25mm2, copper is not less than 16mm2. (7) The distance between the arrester installation location and the equipment to be protected should be as close as possible. The distance to the 3 ~ 10kV electrical equipment should not exceed 15m. Valve arrester before installation, should do a simple field test can be used 2500V and above megger to measure the insulation resistance. FS distribution line commonly used lightning arrester, the insulation resistance should generally be greater than 2000MΩ, each measurement, should make a record card work in order to grasp whether there is any big change in insulation resistance, insulation resistance value compared with the previous decline A large range, indicating that there may be sealed aging caused by moisture or spark gap caused by short circuit. 3 valve arrester inspection (1) porcelain cover is intact, with or without damage, cracks and flashover traces of the surface with or without serious contamination. (2) lead looseness and burn or mechanical damage. (3) the cap at the lead seal is normal, there is no water phenomenon. (4) Ceramics and flange cement joints and paint is intact. (5) Listen to the arrester internal sound.