Advances in Solid-State Circuit Breakers

Abstract

Underwriters Laboratories (UL) listed solid-state circuit breakers (SSCBs) are now being deployed for the first time ever. SSCBs eliminate the magnetic forces between phase conductors during short circuit events and do not require 1-2 cycles before clearing a short circuit. New silicon-carbide (SiC) semiconductors and current sensing methodologies mean SSCB’s interrupt short circuits faster than mechanical breakers. A SSCB can withstand millions more operations than traditional circuit breakers and achieves interrupting ratings of up to 200,000-amps. When a short circuit condition is sensed, nanosecond-speed SiC semiconductors first clear the fault and then open an internal air-gap mechanism, but yet, the air gap is never required to break the flow of current through air (i.e. no arc). The SSCB is software defined which means that their time current curves (TCC’s) are also software defined requiring fewer hardware stock keeping units (SKU’s). Other features include; remote control, revenue power metering, soft starting, virtual relaying, inherent arc flash mitigation, 60% size reduction, and far less maintenance than mechanical breakers.