Lightning strikes are classified into direct strikes and induced strikes. Direct strikes occur when lightning strikes an object directly, causing the most damage. Induced strikes occur when the electromagnetic waves generated by lightning induce high voltage on a conductor, causing overvoltage damage to electrical appliances connected to the conductor. Even with multi-stage surge arresters installed on the power grid, residual voltage from previous lightning strikes or induced voltage from lightning near the frequency converter can still damage it.
Solution: Install an incoming line surge arrester in the inverter control cabinet. The incoming line surge arrester can be a power supply surge protection module, mounted on a sliding track and connected in parallel to ground. This surge arrester module is a gap discharge type, with an impulse discharge current of 15kA (10/350μs) and an operating voltage of 250V. Alternatively, a varistor can be connected in parallel on the power line for surge protection.
