disconnector

A disconnector, or disconnect switch, is an electrical switching device used to isolate all or part of an electric circuit to allow safe maintenance or to segment a power network for reliability. It provides a visible break in the conductor, which helps operators confirm that a section is de-energized. Disconnectors are typically installed in substations and on high-voltage overhead lines as part of switchgear assemblies. They are designed to withstand the arcing and mechanical stresses that occur when a circuit is opened or closed.

Disconnectors are distinguished from circuit breakers by their primary purpose. A disconnector is intended to create a visible isolation and is not primarily used to interrupt current during normal operation or fault conditions. Most disconnectors should be opened only when the circuit is de-energized; some designs called load-break disconnectors can interrupt small, limited currents, but they are not substitutes for protective circuit breakers in fault scenarios. In practice, disconnectors are often interlocked with circuit breakers and grounding devices to ensure safety and to prevent reconnection until the section is verified de-energized.

Types and construction vary, but disconnectors are commonly multipole (two, three, or four poles) and can be configured for vertical or horizontal layouts. They use insulating materials such as porcelain or polymeric insulators and employ moving contact arms connected to a fixed contact. Common variants include air-break disconnectors and load-break disconnectors. In modern substations, they may be integrated into gas- or solid-insulated switchgear, and they may employ mechanical, electric motor, spring, or hydraulic/pneumatic operating mechanisms.

Applications include transmission and distribution networks, where they perform isolation and sectionalizing duties to enable maintenance, protection coordination, and system reliability.