A metal-oxide arrestor conducts less than what percentage of follow-current after a lightning strike?

A metal-oxide arrestor is a crucial device used in electrical systems to protect equipment from voltage spikes caused by lightning or switching surges. After a lightning strike, the functioning of the arrestor is essential in ensuring that it does not allow excessive follow-current to pass through, as this could damage equipment or lead to safety hazards.

The correct answer indicates that a metal-oxide arrestor conducts less than 1% of follow-current after a lightning strike. This low level of follow-current is vital because it demonstrates the arrestor's effectiveness in clamping down the excessive voltage and minimizing the residual effects that could potentially harm the electrical infrastructure. The design and material properties of metal-oxide varistors, commonly used in these arrestors, allow them to provide excellent voltage clamping characteristics while reducing follow-current substantially after the initial high current event caused by lightning.

This capability to conduct less than 1% not only helps in protecting against immediate voltage spikes but also ensures that the system stabilizes quickly, allowing for ongoing reliable operation post-event. Understanding the specifics of how metal-oxide arrestors function reinforces the importance of their role in safeguarding electronic systems from transient overvoltages.