Introduct of Surge Arrester
Surge arrester is a key protective device in the power system, whose core function is to prevent lightning intrusion or system overvoltage from posing a threat to equipment safety. The essence of its technology lies in utilizing nonlinear resistance characteristics to limit tens of thousands of volts of impulse voltage to a safe level within nanoseconds.
Working principle:
Normal high resistance standby: Under normal system voltage, the surge arrester exhibits a high resistance state, with only a small leakage current passing through.
Overvoltage transient response: When struck by lightning or overvoltage, the Surge arrester quickly switches to a low resistance state, providing a low
impedance discharge channel for overcurrent, thereby clamping the voltage on the equipment terminals to a safe value.
Self recovery feature: After the overvoltage disappears, the surge arrester automatically returns to the high resistance state without generating continuous power frequency current, ensuring that the system can continue to operate normally.
Main types:
Surge arresters are mainly divided into the following categories:
Tube type surge arrester: mainly used for 10kV distribution network.
Silicon carbide valve type surge arrester: mainly used for the renovation of old power stations below 35kV.
Metal Oxide Surge Arrester (MOA): Using zinc oxide resistors, it is currently the mainstream surge arrester used in power stations.
Epoxy resin surge arrester: also using zinc oxide resistor sheets, sealed by epoxy resin casting or rubber jacket, mainly used in switchgear (switch equipment) and high pollution areas, its application is rapidly increasing.
Advantage:
Surge arresters, especially modern metal oxide surge arresters (MOAs), have significant advantages:
Quick response without gaps: No spark gap required, fast action speed.
Large current capacity: capable of effectively discharging powerful surge currents or operating overvoltage energy.
Non continuous current self recovery: After overvoltage, the power frequency continuous current is automatically blocked, eliminating the need for arc extinguishing devices and simplifying the structure.
High explosion-proof safety: Designed with excellent explosion-proof performance.
Long life maintenance free: reliable operation, long service life, and basically no maintenance required.
Strong environmental adaptability: The silicone rubber jacket has good UV resistance, weather resistance, and anti fouling properties.