Lightning Arresters

Lightning arresters, also known as surge arresters or lightning protection devices, are essential components in power systems. They are designed to protect electrical equipment and systems from the damaging effects of lightning strikes. These lightning strikes can cause direct and indirect strokes, leading to overvoltage and overcurrent conditions. However, the primary purpose of lightning arresters is to protect against direct strokes of lightning.

Direct Strokes of Lightning

- Direct strokes of lightning occur when a lightning bolt directly strikes a power line or any other electrical equipment.
- The high energy of the lightning bolt can cause an extremely high voltage surge that can damage or destroy electrical equipment.
- Lightning arresters are designed to provide a low-impedance path for this high-energy surge to ground.
- By diverting the lightning surge to ground, the lightning arrester prevents the excessive voltage from reaching and damaging the protected equipment.

Overvoltage due to Indirect Lightning Stroke

- Indirect lightning strokes occur when a lightning bolt strikes near the power line or any other object that is in close proximity to the electrical equipment.
- The electromagnetic field generated by the lightning stroke induces a high voltage surge in nearby conductors, including power lines.
- This induced voltage surge can cause overvoltage conditions in the power system, which can damage or disrupt the operation of electrical equipment.
- While lightning arresters can provide some level of protection against indirect lightning strokes, their primary function is to handle direct lightning strikes.

Power Frequency Overvoltage

- Power frequency overvoltage is a condition where the voltage in the power system exceeds its normal operating range.
- This can occur due to various reasons, such as a sudden loss of load, switching operations, or faults in the system.
- While lightning arresters can help mitigate power frequency overvoltage to some extent, their primary purpose is to protect against lightning-induced overvoltage.

Overcurrent due to Lightning Stroke

- Lightning strokes can cause overcurrent conditions in power systems.
- When a lightning bolt strikes a power line or any other conductive path, it can generate a high current surge.
- If this surge is not properly controlled, it can damage or destroy electrical equipment.
- Lightning arresters are designed to handle these overcurrent conditions and provide a low-impedance path for the surge current to ground.

Conclusion

In summary, while lightning arresters can provide some level of protection against overvoltage, power frequency overvoltage, and overcurrent due to lightning strokes, their primary purpose is to protect against direct strokes of lightning. By providing a low-impedance path to ground, lightning arresters divert the high-energy lightning surge away from electrical equipment, preventing damage and ensuring the reliable operation of power systems.