The internal principle of lightning arrester
Working Principle: The zinc oxide arrester (ZnO) is a new type of arrester developed in the 1970s. It is primarily composed of zinc oxide varistors. Each varistor has a specific switching voltage (called the varistor voltage) from the moment it is manufactured. Under normal operating voltage (i.e., less than the varistor voltage), the varistor's resistance is high, equivalent to an insulating state. However, under surge voltage (greater than the varistor voltage), the varistor's resistance is low and breaks down, effectively shorting the circuit. However, after a surge, the varistor can recover its insulating state; when the voltage above the varistor voltage is removed, it returns to a high-resistance state.Therefore, if a zinc oxide lightning arrester is installed on the power line, when lightning strikes, the high voltage of the lightning wave causes the varistor to break down, and the lightning current flows into the earth through the varistor, which can control the voltage on the power line within a safe range, thereby protecting the safety of electrical equipment.
This type of lightning arrester, called a zinc oxide arrester, offers superior protection, is lightweight, resistant to contamination, and offers stable performance. It primarily utilizes zinc oxide's excellent nonlinear volt-ampere characteristics to minimize the current flowing through the arrester (in the microampere or milliampere range) at normal operating voltage. When an overvoltage occurs, the arrester's resistance drops dramatically, dissipating the overvoltage energy and achieving effective protection.
This type of arrester differs from traditional ones in that it lacks a discharge gap. Instead, it utilizes the nonlinear properties of zinc oxide to provide current dissipation and interruption. Previously, it was made of ceramic, which could shatter and fall to the ground, potentially causing injury.
Lightning Arrester Function
The primary function of a zinc oxide surge arrester is to prevent the intrusion of lightning waves or internal overvoltage. Typically, the arrester is connected in parallel with the device being protected. When a lightning strike causes an overvoltage in the line or an internal operating overvoltage, the surge discharge to ground through the arrester prevents the voltage surge and insulation damage to the protected equipment.
Arrester Classification:
Arrester types include metal oxide arresters (MOA), line-type MOA, gapless line-type MOA, fully insulated composite-jacketed MOA, and removable MOA.
The main types of lightning arresters include tubular, valve, and zinc oxide arresters. Each type of arrester operates on different principles, but their fundamental purpose is to protect communications cables and equipment from damage.
Tubular Arrester
A tube-type arrester is actually a protective gap with high arc-extinguishing capability. It consists of two gaps connected in series. One gap, known as the outer gap, is exposed to the atmosphere and isolates the operating voltage, preventing damage to the gas-producing tube from power-frequency leakage current flowing through it. The other gap, known as the inner gap or arc-extinguishing gap, is installed within the gas tube. The arc-extinguishing capability of the tube-type arrester is related to the magnitude of the power-frequency aftercurrent. This is a protective gap-type arrester, mostly used for lightning protection on power supply lines.
Valve-type arrester
A valve-type lightning arrester consists of a spark gap and a valve-plate resistor, made of a special material called silicon carbide. This resistor effectively protects against lightning and high voltages, effectively protecting equipment. When high voltage lightning strikes, the spark gap breaks down, causing the resistance of the valve-plate resistor to drop, diverting the lightning current to the ground, thus protecting cables and electrical equipment from the current's harmful effects. Under normal circumstances, the spark gap does not break down, and the valve-plate resistor maintains a high resistance, preventing disruption to communication lines.
Zinc Oxide Lightning Arrester
A zinc oxide arrester is a lightning protection device with superior protection, lightweight, pollution resistance, and stable performance. It primarily utilizes zinc oxide's excellent nonlinear volt-ampere characteristics to minimize the current flowing through the arrester (microamperes or milliamperes) at normal operating voltage. When an overvoltage occurs, the resistance drops sharply, dissipating the overvoltage energy and achieving the desired protection. This type of arrester differs from traditional arresters in that it lacks a discharge gap and instead utilizes the nonlinear characteristics of zinc oxide to provide current dissipation and interruption.