What type of resistance does the arrestor offer to the flow of surge current?

The arrestor is designed to provide low resistance to the flow of surge current. When a surge occurs, either from lightning strikes or switching transients in the power system, the arrestor allows the surge current to pass through easily, thus minimizing the voltage that appears across the system equipment. This low resistance ensures that the circuit is effectively protected by shunting excess energy away from sensitive components, thereby preventing damage.

The nature of surge protection is such that, during normal operating conditions, the resistance remains high to avoid energy loss, but when a surge is detected, the resistance drops to a low value, allowing the surge to be diverted. This characteristic is crucial for the protective operation of the arrestor, making it highly effective in safeguarding electrical systems from unexpected high-voltage events.