Which type of arrester is often referred to as a double-gap arrester?

The term "double-gap arrester" commonly refers to a primitive arrester. This type of arrester generally employs two gaps (or electrodes) to control and mitigate overvoltages. When an excessive voltage occurs, the electrical breakdown can happen between these gaps, effectively diverting the surge energy and protecting electrical equipment downstream. Primitive arresters are some of the earliest forms of lightning protection, developed primarily to protect telephone lines and early electrical systems.

Understanding the nature of primitive arresters helps appreciate the evolution of surge protection technologies, where more advanced designs have improved insulation and response times but still retain the fundamental principle of voltage diversion that the double-gap design exemplifies. This historical context enhances the familiarity with various types of surge protection devices available today.