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Chapter 1 of 12 • Page 1 of 248🔒 Protected PDF • Watermarked
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Which is not a type of lightning arrester?
Rod gap
Horn gap
Multi gap
Air gap
Air gap
Quick Summary: Lightning arresters are protective devices used in power systems to divert high-voltage surges caused by lightning or switching operations to the ground. 'Air gap' is a basic insulation parameter or a component found within other arresters, but it is not a distinct classification of a lightning arrester device.
Lightning arresters are protective devices used in power systems to divert high-voltage surges caused by lightning or switching operations to the ground. 'Air gap' is a basic insulation parameter or a component found within other arresters, but it is not a distinct classification of a lightning arrester device.
Vres=I×Rnon−linear — Voltage across arrester during discharge
Idischarge=ZsurgeVsurge−Vresidual — Surge current magnitude
A lightning arrester typically consists of a series combination of a spark gap and a non-linear resistor (such as Silicon Carbide or Metal Oxide). When an overvoltage occurs, the spark gap breaks down, allowing the surge current to flow through the non-linear element to the ground, which offers low impedance to high voltage but high impedance to normal operating voltage.
Lightning arresters provide a low-impedance path to the ground during surge conditions.
The primary requirement of an arrester is to not allow power-follow current to persist.
Metal Oxide Varistor (MOV) arresters are the most advanced type used in modern power systems.
Protects expensive power equipment like transformers and circuit breakers.
Limits transient overvoltages to safe levels below the Basic Insulation Level (BIL).
Can undergo degradation over multiple high-energy discharge operations.
Requires periodic maintenance and testing of the leakage current.
Substation protection
Transmission and distribution line insulation protection
Consumer-end surge protection devices
Rod gap arresters are the simplest form but lack self-clearing capacity.
Horn gap arresters utilize the magnetic blow-out principle to extinguish the arc.
Air gap is merely a feature (the physical distance) used in gap-type arresters, not a category of the device itself.
D is correct — 'Air gap' describes the insulation distance used within various arresters but is not a specific type of protective device.
Always distinguish between a component feature (like an air gap) and the protective device itself (like a valve-type arrester) to avoid confusion in protection systems questions.