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Location of lightning arrester is near to
Generator
Transformer
Bus bar
Circuit breaker
Transformer
A lightning arrester (surge arrester) is placed as close as possible to the terminal equipment, typically a power transformer, to protect its insulation from high-voltage surges. By minimizing the physical distance, the arrester ensures that the voltage at the transformer terminal does not exceed the arrester's residual voltage, thereby preventing damage from travelling waves.
A lightning arrester (surge arrester) is placed as close as possible to the terminal equipment, typically a power transformer, to protect its insulation from high-voltage surges. By minimizing the physical distance, the arrester ensures that the voltage at the transformer terminal does not exceed the arrester's residual voltage, thereby preventing damage from travelling waves.
VmaxтАЛ=2├ЧVincidentтАЛ тАФ The reflection phenomenon at the open-circuited end of a line
ZsurgeтАЛ=CLтАЛтАЛ тАФ Characteristic impedance of the transmission line
When an incoming surge voltage wave reaches the substation, it reflects off the impedance mismatch at the transformer terminal, potentially doubling its amplitude. A lightning arrester provides a low-impedance path to ground during overvoltage conditions. Placing it near the transformer minimizes the 'lead length' impedance, ensuring the clamping voltage is effective before the wave reaches the sensitive transformer windings.
The lightning arrester must be installed in parallel with the equipment to be protected.
The connection lead length must be kept minimum to avoid inductive voltage drops during high-speed surges.
Transformers are the most expensive and critical components in a substation, requiring priority protection.
The discharge voltage of the arrester should be lower than the Basic Insulation Level (BIL) of the transformer.
Prevents catastrophic breakdown of transformer insulation
Reduces maintenance costs by limiting surge damage
Improves overall substation reliability
Requires proper grounding resistance for effective operation
May degrade over time depending on the number of surge operations
Power Transformers
Switchgear Busbars
High voltage circuit breakers
The distance between the arrester and the transformer should ideally be zero; in practice, it is kept under 5-10 meters.
Option A (Generator) also requires protection, but generators are typically protected by surge capacitors and arresters at the generator terminals.
The circuit breaker (Option D) is a switching device, not the primary focus of insulation protection.
B is correct тАФ The lightning arrester is placed nearest to the transformer to minimize the impact of voltage surges on its sensitive insulation.
Always remember that the protective device must be placed as close as possible to the insulation that is most vulnerable to steep-fronted voltage surges.