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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 line and neutral conductors of a circuit is not equal (the term residual relating to the imbalance), therefore ...
Realistically, the resistance in a fault can be from close to zero to fairly high relative to the load resistance. A large amount of power may be consumed in the fault, compared with the zero-impedance case where the power is zero. Also, arcs are highly non-linear, so a simple resistance is not a good model.
And we should specifically mention "nuisance tripping", and explain that motors have short-term peak surge currents when they start, so circuit breakers are designed to not trip too quickly. -96.233.19.191 16:39, 11 July 2014 (UTC) Lever positions - Article states "Also indicates the status of the circuit breaker (On or Off/tripped)."
Zero-crossing control (or burst-fire control) is an approach for electrical control circuits that starts operation with the AC load voltage at close to 0 volts in the AC cycle. [1] This is in relation to solid-state relays, such as TRIACs and silicon controlled rectifiers . [ 1 ]
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 ...
The hold current is the maximum current at which the device is guaranteed not to trip. The trip current is the current at which the device is guaranteed to trip. [7] When power is removed, the heating due to the leakage current will stop and the PPTC device will cool.
Calculation of the required breaking capacity involves determining the supply impedance and voltage. Supply impedance is calculated from the impedance of the elements making up the supply system. Customers of an electrical supply utility can request the maximum value of prospective short-circuit current available at their point of supply.
A crowbar circuit is an electrical circuit used for preventing an overvoltage or surge condition of a power supply unit from damaging the circuits attached to the power supply. It operates by putting a short circuit or low resistance path across the voltage output (V o ), like dropping a crowbar across the output terminals of the power supply.