Lightning arresters are devices that help prevent damage to apparatus due to high voltages. The arrester provides a low-impedance path to the ground for the current from a lightning strike or transient voltage and then restores to a normal operating condition. A lightning arrester may be compared to a relief valve on a boiler or hot water heater. It will release high pressure until a normal operating condition is reached. When the pressure is returned to normal, the safety valve is ready for the next operation.
When a high voltage (greater than the normal line voltage) exists on the line, the arrester immediately furnishes a path to the ground and thus limits and drains off the excess voltage. The arrester must provide this relief and then prevent any further flow of current to the ground.
The arrester has the following functions-
- It must provide a point in the circuit at which an over-voltage pulse can pass to the ground.
- To prevent any follow-up current from flowing to the ground.
- It limits the voltage produced by lightning.
- It protects the equipment connected in parallel with it.
- Transformer is the heart of the modern power system. so it is mandatory to protect the transformer from any kind of disturbances.
High voltage occurs due to lightning creating insulation failure in transformers. This is the reason why lightning arresters are placed close to the transformer.
After Lightning strikes, lightning current pass-through the transformer and causes insulation failure, and equipment in the home may also damage.
When a lightning arrester is available in the system, lightning current flow through the Lightning arrester. The transformer is now safe and performs efficiently.