Why use a surge protector

Lightning is extremely destructive, and it is not enough to rely on external lightning protection (lightning rods, etc.). Lightning waves will directly or indirectly (through electromagnetic induction) invade various electrical paths and metal channels (such as power lines, signal lines, antenna feeders and Metal pipes, etc.). The resulting lightning overvoltage and surge voltage will cause great harm to electronic, electrical equipment, and information network systems, ranging from damage to the line, to damage to the equipment, and paralysis of the system, causing inestimable losses.

Rapidly changing lightning currents can induce high voltages on electrical loops and double-stranded wires, which can damage the insulation of the system. Various operations of the power system can produce operating overvoltages on the power lines; some electrical equipment switching operations, short circuit trips, etc. can produce overvoltages (surge voltages) higher than the normal operating voltage in the power supply lines and thus harm the electrical equipment .

The role of surge protector

The surge protector uses a varistor with excellent nonlinear characteristics. Under normal circumstances, the surge protector is outside the extremely high resistance state, and the leakage current is almost zero, ensuring the normal power supply of the power system. When the power system has the overvoltage in the above situation, the surge protector immediately turns on within nanoseconds, and the amplitude of the overvoltage is limited to the safe working range of the device. At the same time, the energy of the overvoltage is released. Subsequently, the protector quickly changes to a high-impedance state, which does not affect the normal power supply of the power system.

Main structure and working principle

In the three-phase four-wire system, protectors are connected between the three phase wires and a neutral wire to the ground wire. Under normal circumstances, the protector is in a high-resistance state. When the surge overvoltage occurs in the power grid due to lightning strikes or other reasons, the protector will quickly turn on within nanoseconds and introduce the surge overvoltage into the ground, thereby protecting Electrical equipment on the electricity network. When the surge voltage passes through the protector and disappears, the protector changes to a high-resistance state again, thereby not affecting the normal operation of the power grid.

The window color indicates the working status: green (normal), red (fault)

Scope of application: B-level surge protection level (SPD) protection, used for equipotential over-connection during lightning strike, installed at the junction of LPZOA zone or LPZOB zone and LPZ1. Usually installed in the floor distribution box, computer center, telecommunications room, elevator control room, cable TV room, building automatic control room, security monitoring center, fire center, industrial automatic control room, frequency conversion equipment control room, hospital operating room, monitoring room and equipment In the distribution box of the place with electronic medical equipment. It can also be installed in the main distribution box of residential lighting below six floors. For decentralized villas, SPD should be installed in the household distribution box.