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Lightning Arrestor use to
Protection against Lightning Surge
Maintain Constant voltage
Make power DC
Any of above
Protection against Lightning Surge
A lightning arrestor is a protective device used in power systems to protect equipment from high-voltage surges caused by lightning strikes or switching operations. It provides a low-impedance path to the ground for the surge current, thereby limiting the overvoltage across the equipment insulation.
A lightning arrestor is a protective device used in power systems to protect equipment from high-voltage surges caused by lightning strikes or switching operations. It provides a low-impedance path to the ground for the surge current, thereby limiting the overvoltage across the equipment insulation.
VresтАЛ=IsurgeтАЛтЛЕZarrestorтАЛ тАФ Residual voltage across the arrestor during discharge
IdischargeтАЛ=ZsourceтАЛVsurgeтАЛтИТVresтАЛтАЛ тАФ Discharge current flow during a surge
During a lightning surge, the voltage at the terminal of the equipment rises rapidly. The lightning arrestor acts as an insulator at normal operating voltage but becomes a conductor when the voltage exceeds a threshold (breakdown voltage). This diverts the surge current to the earth while preventing the system's power frequency current from flowing to the ground after the surge has passed.
Installed in parallel with the equipment to be protected.
Must have a high breakdown voltage compared to the operating voltage.
Must have a very low impedance path to ground during surge conditions.
Commonly uses non-linear resistors like Zinc Oxide (ZnO) blocks.
Prevents insulation failure in transformers and switchgear.
High-speed operation during overvoltage transients.
Low maintenance and reliable self-restoring capability.
Subject to thermal degradation over many discharges.
Requires proper earthing resistance to be effective.
Power Transformers
Transmission Lines
Electrical Substations
Electric Traction Overhead Equipment
Option B is incorrect because constant voltage is maintained by Voltage Regulators or Transformers.
Option C is incorrect because power conversion (AC to DC) is handled by Rectifiers.
The lightning arrestor does not operate at normal line voltage; it only activates when a surge threshold is reached.
A is correct тАФ A lightning arrestor acts as an overvoltage protection device that diverts lightning surge energy to the ground.
Always remember that protective devices like fuses or circuit breakers protect against overcurrent, while lightning arrestors specifically protect against overvoltage.