3 Types of Lightning Arresters and Their Functionality
When lightning strikes, aircraft electrical devices and electrical equipment in general must be protected. This protection is achieved through the use of lightning arresters, or surge protectors as they are called for smaller versions . These devices divert lightning surges either to the ground or away from electrical components by providing a path of which high-voltage lightning currents can bypass connected equipment. This is achieved by spark gaps or blocks made of semiconducting material -- such as silicon carbide or zinc oxide -- connected to lines entering volt-sensitive electrical devices and equipment.
Selecting the right type of lightning arrester depends on voltage thresholds, current capacity, discharge rate, maintenance frequency and reliability. In this article, we will discuss three of the twelve classifications of lightning arresters, including the sphere gap arrester, auto valve arrester and oxide film arrester. Other types include the road gap, horn gap, multi-gap, impulse protective, electrolytic, expulsion, valve, thyrite and metal oxide.
A sphere gap arrester is essentially two spheres on a line with an air gap between them. One sphere is connected to the line, then a gap, and the other sphere is connected to the ground. These types of arresters are commonly used in the calibration of meters in high voltage measurements. A diversion or discharge will only occur when temperatures exceed the normal operating conditions of a line. Auto valve arresters consist of a stack of flat discs separated by thin insulated mica washers. When a higher than normal voltage is detected on a line, the space between these ceramic discs is closed, allowing for the voltage to divert from its normal trajectory and discharge out through the discs and down to the ground.
A new type of lightning arrester is the oxide film arrester. This arrester is made up of a film of insulation in contact with a conducting powder. When overvoltage occurs on a line the film is pierced, but the powder quickly turns into insulation and plugs any caused laceration. These arresters absorb and seperate energy produced by high frequency disturbances.
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