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Lighting arrester are mounted in pole mounted substation at
Top of the structure
Bottom of the structure
Near transformer
LT side
Top of the structure
Lightning arresters in a pole-mounted substation are installed at the top of the structure to provide the shortest, most direct, and low-impedance path to the ground for transient surges. Positioning them above the transformer ensures they intercept atmospheric discharges or switching surges before they reach sensitive substation equipment.
Lightning arresters in a pole-mounted substation are installed at the top of the structure to provide the shortest, most direct, and low-impedance path to the ground for transient surges. Positioning them above the transformer ensures they intercept atmospheric discharges or switching surges before they reach sensitive substation equipment.
VsтАЛ=VnтАЛ+LdtdiтАЛ тАФ relationship between surge voltage and inductive drop
ZcтАЛ=CLтАЛтАЛ тАФ characteristic impedance of the transmission line
The lightning arrester acts as a non-linear voltage-dependent resistor. Under normal operating conditions, it acts as an insulator; however, when a surge voltage exceeds the breakdown voltage (sparkover voltage), it instantly transitions to a low-resistance state, providing a path to divert the surge current to the earth while maintaining the system voltage at a safe level.
Arresters must be placed as close to the transformer as possible to minimize inductive voltage drop.
The ground lead must be kept as short and straight as possible to minimize the lead impedance.
Installed at the top of the pole to maintain physical clearance from other equipment and personnel.
Protects equipment from both direct lightning strikes and incoming surges from transmission lines.
Prevents catastrophic failure of expensive transformer insulation.
Reduces the magnitude of incoming voltage transients.
Provides a safe dissipation path for high energy surges.
High cost of replacement after severe discharge events.
Requires periodic inspection and insulation resistance testing.
Distribution transformers
Outdoor circuit breakers
Switchgear structures
Standard practice follows the principle that the lead length between the transformer and the arrester, and the arrester to the earth, should be kept at the absolute minimum.
Option C is partially correct in functionality but incorrect in the context of installation geometry; 'Top of the structure' specifies the mounting location precisely.
A is correct тАФ Lightning arresters are mounted at the top of the structure to ensure the shortest, most direct path to the ground for discharge currents and to provide optimal protection for the transformer.
In competitive exams, always prioritize the 'shortest path to ground' rule for protection devices; the fewer the bends and shorter the length of the conductor, the lower the inductive voltage drop (LdtdiтАЛ), which is critical during high-frequency surges.