The vital electrical systems aboard Bloodhound SSC are protected by around forty circuit breakers and battery isolators provided by E-T-A. The circuit breakers are installed to isolate key parts of the system in the event of short circuits or overloads. Rather than using fuses whose characteristics change with age and lead to nuisance blowing, E-T-A circuit breaker performance is stable over time.
Circuit breakers for equipment (CBEs) are specifically designed for the protection of equipment, capable of making, carrying and breaking currents under normal circuit conditions and also making, carrying for a specified time and automatically breaking currents under specified abnormal conditions. Circuit breakers also offer designers considerably more options than fuses. Auxiliary contacts may communicate an alarm condition to an indicator or software. In addition, combined switch/circuit breakers save space, installation time and cost. Remote tripping is another function possible with circuit breakers but not with fuses.
The E-T-A CBEs used on Bloodhound protect, for example, the on-board computers, air brakes, parachute deployment, winglets that can adjust air flow, communications systems, lighting, pumps for the many hydraulic systems, as well as fire control systems and rocket and hydraulic kill switches. Most of the circuits are protected by E-T-A 4120 high-performance, thermal magnetic circuit breakers with a push/pull manual actuation. With a thread-neck for panel mounting, they are temperature-compensated and fully approved for commercial aircraft.
A CBE is a special type of circuit breaker designed to provide carefully matched protection for any individual piece of equipment including electronic, electrical, communications and industrial systems. Using CBEs for circuit protection allows designers to quite considerably reduce ratings on wiring, connectors and other components to achieve significant cost, space and weight savings.
CBEs provide precisely tuned protection, allowing tripping characteristics to be specified to deliver the required protection for any particular equipment. The high sensitivity of CBEs safeguards equipment against low but potentially harmful overloads, such as slowly increasing currents caused by gradual circuit or component failure, or equipment malfunction or abuse, while allowing normal current surges such as switch-on transients. CBEs can also be reset easily and reused once the fault is cleared.