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A residual-current device (RCD), residual-current circuit breaker (RCCB) or ground fault circuit interrupter (GFCI) [a] is an electrical safety device, more specifically a form of Earth-leakage protection device, that interrupts an electrical circuit when the current passing through a conductor is not equal and opposite in both directions, therefore indicating leakage current to ground or ...
At two multiples of the rated current, the recloser's rapid trip curve can cause a trip (off circuit) in as little as 1.5 cycles (or 30 milliseconds). During those 1.5 cycles, other separate circuits can see voltage dips or blinks until the affected circuit opens to stop the fault current.
A shunt-trip unit appears similar to a normal breaker and the moving actuators are ganged to a normal breaker mechanism to operate together in a similar way, but the shunt trip is a solenoid intended to be operated by an external constant-voltage signal, rather than a current, commonly the local mains voltage or DC. These are often used to cut ...
Sulfur hexafluoride circuit breakers protect electrical power stations and distribution systems by interrupting electric currents, when tripped by a protective relay. Instead of oil, air, or a vacuum, a sulfur hexafluoride circuit breaker uses sulfur hexafluoride (SF 6) gas to cool and quench the arc on opening a circuit. Advantages over other ...
In electrical engineering, a protective relay is a relay device designed to trip a circuit breaker when a fault is detected. [ 1 ] : 4 The first protective relays were electromagnetic devices, relying on coils operating on moving parts to provide detection of abnormal operating conditions such as over-current, overvoltage , reverse power flow ...
In an electric power system, a fault or fault current is any abnormal electric current. For example, a short circuit is a fault in which a live wire touches a neutral or ground wire. An open-circuit fault occurs if a circuit is interrupted by a failure of a current-carrying wire (phase or neutral) or a blown fuse or circuit breaker.
Another cause of nuisance tripping is due to accumulated or burden currents caused by items with lowered insulation resistance. This may occur due to older equipment, or equipment with heating elements, or even wiring in buildings in the tropics where prolonged damp and rain conditions can cause the insulation resistance to lower due to ...
An automatic trip is an action performed by some system, usually a safety instrumented system, programmable logic controller, or distributed control system, to put an industrial process into a safe state. It is triggered by some parameter going into a pre-determined unsafe state.