Arc-Resistant Metal-Enclosed Switchgear

Circuit Configurations

Arc-Resistant Metal-Enclosed Switchgear is readily configured in circuit arrangements that make power system planning and design easy. The basic arrangements shown here are often combined to handle even the most complex distribution system needs. Other circuit designs are possible to fit specific needs.

Radial System

A radial system is the simplest system and is economical, permitting extensive use of dedicated radial circuits. The direct circuitry facilitates quick location and repair of faulted circuits. Segmentation of a distribution system with multiple radial circuits limits the extent of service interruption due to faults. In this example, the service-entrance bay of the S&C Metal-Enclosed Switchgear is provided with electronic power fuses to achieve full coordination with the upstream protective device.

Common-Bus Primary-Selective

S&C Metal-Enclosed Switchgear assures a higher level of service continuity. Two utility sources — one source preferred, the other alternate — supply power to the metal-enclosed switchgear. A power-operated interrupter switch for each source plus a source-transfer control effect automatic two-way transfer in primary-selective switchgear. Interrupter switches with power fuses switch and protect the load circuits; in this example, two are manually operated while the third is power operated, with an electronic overcurrent relay and switch operator providing automatic three-phase isolation when a fuse operates.

Split-Bus Primary-Selective

S&C Metal-Enclosed Switchgear allows large in-plant systems to be supplied power through one switching center since both utility sources are fully utilized under normal operation, with the two source interrupter switches closed and the bus-tie switch open. Each source, in effect, is the preferred source for its bus section and the alternate source for the other bus section.