What are surge arresters designed to do?

Surge arresters are specifically designed to protect electrical equipment and systems, particularly in substations, from voltage spikes or surges caused by lightning strikes or switching operations. When a voltage spike occurs, the surge arrester acts as a protective device by diverting excessive voltage away from sensitive equipment, thereby preventing damage. This function is crucial for ensuring the reliability and longevity of electrical infrastructure, as it helps maintain the integrity of the system by keeping voltage levels within safe operational limits.

The other options focus on functions that are not within the purpose of surge arresters. Preventing equipment overheating relates more to thermal management rather than voltage protection. Regulating current levels typically involves various types of regulatory devices and controllers, while converting AC to DC pertains to rectification processes, which are distinctly different from the protective role of surge arresters.