Residual Current Protection Circuit for Lightning Over-Energy Absorption

The patent applies preliminary action by introducing over-energy absorption circuits (first and second over-energy absorption circuits) that activate before the residual current determining circuit makes a judgment. These circuits absorb excessive energy from lightning strikes in advance, preventing the over-energy current from reaching the detection threshold and causing misjudgment. This preliminary energy absorption ensures reliable operation while maintaining relatively simple circuit structure.

The patent applies segmentation by dividing the over-energy absorption function into two separate circuits: a first over-energy absorption circuit connected to the secondary side of the current transformer, and a second over-energy absorption circuit connected in series with the residual current determining circuit. This segmented approach allows each circuit to handle different levels of over-energy conditions, with the first circuit handling initial energy absorption and the second circuit providing additional protection, thereby achieving high reliability without excessive complexity.

The patent applies feedback by using the residual current determining circuit to continuously monitor the current after over-energy absorption. The circuit only triggers disconnection when the residual current meets predetermined conditions indicating actual leakage or fault. This feedback mechanism ensures that normal over-energy events (like lightning strikes) do not cause unnecessary disconnections, maintaining system availability while ensuring reliable protection against actual faults.