What can sustained overvoltage and damping effect cause during switching transients?

Sustained overvoltage and damping effects during switching transients can lead to a variety of issues in electrical systems. In the context of this question, the correct choice relates to the failure of lightning arrestors. Lightning arrestors are designed to protect electrical equipment from voltage spikes caused by lightning strikes and other transient events. When sustained overvoltage conditions occur, the stress on these devices can become excessive, potentially leading to their failure.

The overvoltage can degrade the insulation in the arrestors, making them less effective or completely nonfunctional when a voltage spike occurs. This can put downstream equipment and the entire system at risk because the arrestor cannot perform its protective function.

While other equipment, such as generators or transformers, can also experience issues during overvoltage scenarios, the direct and immediate function of lightning arrestors is specifically to mitigate such transients. Hence, they are particularly vulnerable to sustained overvoltage conditions, making it crucial to monitor and control these levels within the electrical system.