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An earth-leakage protection device is a safety device used in electrical installations to prevent shock. It consists of either a current sensing mechanism, or a voltage sensing mechanism. Such devices may be found in the form of either a circuit breaker , known as an earth-leakage circuit breaker ( ELCB ), or built into a socket (aka receptacle ) .
The grounding system must also have a minimum of two or more earth pits (electrodes) to better ensure proper grounding. According to rule 42, an installation with a connected load above 5 kW exceeding 250 V shall have a suitable earth leakage protective device to isolate the load in case of earth fault or leakage. [21]
The use of the term ground (or earth) is so common in electrical and electronics applications that circuits in portable electronic devices, such as cell phones and media players, as well as circuits in vehicles, may be spoken of as having a "ground" or chassis ground connection without any actual connection to the Earth, despite "common" being ...
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 ...
Normal circuit currents flow only in the neutral, and the protective earth conductor bonds all equipment cases to earth to intercept any leakage current due to insulation failure. The neutral conductor is connected to earth at the building point of supply, but no common path to ground exists for circuit current and the protective conductor.
Today, microprocessor-based relays can perform many protective functions in one device. [1] When one device performs several protective functions, it is typically denoted "11" by the standard as a "Multifunction Device", but ANSI Device Numbers are still used in documentation like single-line diagrams or schematics to indicate which specific ...
Current and voltage transformers to step down the high voltages and currents of the electrical power system to convenient levels for the relays to deal with; Protective relays to sense the fault and initiate a trip, or disconnection, order; Circuit breakers or RCDs to open/close the system based on relay and autorecloser commands
In a digital/numeric relay, many functions are implemented by the microprocessor programming. Any one numeric relay may implement one or all of these functions. A listing of device numbers is found at ANSI Device Numbers. A summary of some common device numbers seen in digital relays is: 11 – Multi-function Device; 21 – Distance; 24 ...