Classification of Lightning Arresters

Surge arresters are classified into numerous types, including metal-oxide surge arresters, line-type metal-oxide surge arresters, gapless line-type metal-oxide surge arresters, fully insulated composite-housed metal-oxide surge arresters, and disconnectable surge arresters.

The primary types of surge arresters include tubular surge arresters, valve-type surge arresters, and zinc-oxide surge arresters. While the specific operating principles of each type differ, their fundamental function remains the same: to protect communication cables and equipment from damage.

Tubular Surge Arresters
A tubular surge arrester is essentially a protective spark gap characterized by a high arc-extinguishing capability. It consists of two spark gaps connected in series: one gap is situated in the open air-known as the "external gap"-and serves to isolate the operating voltage, thereby preventing the gas-generating tube from being damaged by power-frequency leakage currents flowing through it; the other gap is housed inside the tube-known as the "internal gap" or "arc-extinguishing gap." The arc-extinguishing capacity of a tubular surge arrester is directly related to the magnitude of the subsequent power-frequency current. This type of protective spark-gap arrester is predominantly utilized on power supply lines to provide lightning protection.

Valve-Type Surge Arresters
A valve-type surge arrester comprises a spark gap and a valve resistor; the valve resistor is fabricated using a specialized silicon carbide material. By utilizing silicon carbide, the valve resistor effectively mitigates the effects of lightning strikes and high-voltage surges, thereby safeguarding the equipment. When a high-voltage lightning surge occurs, the spark gap breaks down, causing the resistance value of the valve resistor to drop significantly; this diverts the lightning current into the earth, thereby protecting the cables or electrical equipment from the destructive effects of the lightning current. Under normal operating conditions, the spark gap does not break down, and the valve resistor maintains a high resistance value, ensuring that the normal operation of the communication line remains unaffected.

Zinc-Oxide Surge Arresters
A zinc-oxide surge arrester is a lightning protection device characterized by superior protective performance, lightweight construction, resistance to environmental contamination, and stable operational characteristics. It primarily leverages the excellent nonlinear voltage-current (V-I) characteristics of zinc oxide to ensure that, under normal operating voltages, the current flowing through the arrester remains extremely low (typically in the microampere or milliampere range). However, when an overvoltage surge occurs, the resistance drops abruptly, effectively discharging the energy associated with the overvoltage and thereby achieving the desired protective effect. The distinction between this type of surge arrester and traditional arresters lies in the absence of a discharge gap; instead, it utilizes the nonlinear characteristics of zinc oxide to perform both current-diverting and current-interrupting functions.

The foregoing has introduced several types of surge arresters. Each type possesses its own unique advantages and characteristics; therefore, to achieve effective lightning protection, it is essential to select and deploy the appropriate arrester based on the specific environmental conditions.