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Lightning arrester provides
Low impedance path
High impedance path
Low resistance path
High resistance path between line and earth during operation
Low impedance path
A lightning arrester is a protective device designed to protect power system equipment from high-voltage transients caused by lightning or switching surges. It acts as a diversionary path that directs the surge current to the ground instead of allowing it to pass through the protected equipment.
A lightning arrester is a protective device designed to protect power system equipment from high-voltage transients caused by lightning or switching surges. It acts as a diversionary path that directs the surge current to the ground instead of allowing it to pass through the protected equipment.
ZsurgeтАЛ=CLтАЛтАЛ тАФ characteristic impedance of the transmission line
VdischargeтАЛ=IsurgeтАЛ├ЧZarresterтАЛ тАФ voltage appearing across the arrester during discharge
During normal operating conditions, the arrester acts as an open circuit (high impedance). When a surge voltage exceeding the breakdown voltage of the arrester occurs, it undergoes an instantaneous transition to a highly conductive state, providing a low impedance path to the earth. Once the surge has dissipated and the system voltage returns to normal, the arrester reverts to its high impedance state to prevent power frequency follow current.
Lightning arresters must have a low breakdown voltage to operate before the equipment insulation fails.
They should effectively dissipate the energy of the surge.
After the transient event, the arrester must be able to limit the power frequency follow current.
Common materials used are Non-linear Resistors like Silicon Carbide (SiC) or Metal Oxide (Zinc Oxide).
Prevents catastrophic failure of expensive insulation (transformers, insulators).
Rapid response time to transient surges.
Self-restoring nature after the surge is diverted.
May require regular maintenance to ensure sealing against moisture.
Can fail if subjected to sustained overvoltages beyond rated capacity.
High-voltage transmission substations
Distribution transformers
Power plant switchyards
The lightning arrester is connected in parallel with the equipment to be protected.
Option B (High impedance path) describes the state of the arrester during normal operation, not during the transient operation. Options C and D refer to resistance; while low resistance is a factor, low impedance is the more comprehensive term in transient analysis as it considers both resistance and reactance.
A is correct тАФ A lightning arrester provides a low impedance path to earth during transient surge events to protect equipment.
Remember that while a lightning arrester has a low impedance path during a surge, it must maintain a very high resistance to the power frequency voltage to prevent a line-to-ground fault.