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Which of the following is the protective device against lightning over voltage?
Road gap
Surge absorber
Horn gap
All of above
All of above
Lightning protection devices are designed to divert transient high-voltage surges away from sensitive electrical equipment to the ground. Rod gaps, surge absorbers, and horn gaps all serve as protective measures to limit overvoltage spikes caused by lightning strikes or switching operations.
Lightning protection devices are designed to divert transient high-voltage surges away from sensitive electrical equipment to the ground. Rod gaps, surge absorbers, and horn gaps all serve as protective measures to limit overvoltage spikes caused by lightning strikes or switching operations.
VsurgeтАЛ=IsurgeтАЛ├ЧZsurgeтАЛ тАФ Fundamental relation for surge voltage based on surge current and line surge impedance
dtdvтАЛ тАФ The rate of change of voltage, which surge absorbers aim to reduce
These devices operate on the principle of breakdown or impedance matching. A rod gap or horn gap ionizes the air during an overvoltage surge, creating a low-impedance path to ground (sparkover). A surge absorber, typically an inductor-capacitor (LC) circuit, reduces the steepness of the surge wavefront (dv/dt) to protect transformer windings.
Rod gaps provide simple, low-cost protection but have poor time-lag characteristics.
Horn gaps are an improvement over rod gaps as they utilize the arc-quenching effect of the diverging gap geometry.
Surge absorbers are specifically used to protect the internal insulation of power transformers.
Lightning overvoltages are external surges that can reach values of several million volts.
Protects expensive power system equipment from insulation failure
Prevents fire hazards and permanent damage to transformers and insulators
Rod gaps can cause power frequency follow-through currents
Surge absorbers can introduce minor phase shifts in high-speed signaling
Transmission lines
Power transformers
Switchgear assemblies
A rod gap consists of two rods bent at right angles with a specified gap, set to spark over at a voltage lower than the equipment's withstand voltage.
Option B (Surge Absorber) specifically reduces the steepness of the wave, whereas gaps (A and C) primarily limit the peak voltage magnitude.
D is correct тАФ All listed devices serve to limit or divert lightning-induced overvoltages to protect the electrical power system.
Always remember that surge arresters (like ZnO or SiC) are the modern standard, while rod/horn gaps are considered legacy protective schemes with lower precision.