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Selective coordination generally describes the design of an electrical system in which the upstream protective device (fuse or circuit breaker) nearest to the system fault clears the fault without affecting the protective devices that are upstream from itFigure (click here to see Fig) illustrates this concept, where a fault is seen on a

An overcurrent protective device usually will have protection from ground fault, short circuit as well as over currentHere is the definitionA device capableof providing protection for service, feeder, and branchcircuits and equipment over the full range of overcurrents.

Overcurrent protective devices, such as fuses and circuit breakers, have time current characteristics (TCC) that determine how long it takes to clear the fault for a given value of fault currentIf the circuit were not opened, the excessive current would overheat the wire insulation, burn the wires and possibly start an electrical fire.

Electrical discrimination occurs when a protective device near a fault or short comes on and keeps the other circuits working properlyDiscrimination can either partially block a fault from disrupting other systems or completely block it, depending on the type of protection device that is installed.

of a protective device that is for fault or short circuit current and ionstantaneous tripping were talking about I Overcurrent not fault current Ia this current is mch smaller then ia like a fusing factor what the gentelmen wants to know is where is the official I table for Protective devices Thanks

Essentially, if a protective device nearest to an electrical fault is operated without disturbing any upstream connected devices, this will improve reliability of the electrical distribution and maximise a facilitys uptimeAchieving discrimination

Electrical Protective Device A device used to protect equipment,machinery,components and devices,in electrical and electronic circuit,against short circuit,over current and earth fault,is called as protective devicesNecessity of Protective Devices Protective devices are necessary to protect electrical appliance or equipment against a)Short Circuit b)Abnormal variations in the supply voltage

Discrimination (or selectivity) is the selection of protective devices so that the device nearest to a fault will operate rather than any upstream deviceThe purpose is to ensure that the fault is isolated and supply is maintained to other parts of the installation without disruptionFor example, in a domestic installation, a fault in a ring

Available fault current at the service overcurrent protective devicesThe clearing time of service overcurrent protective devices based on the available fault current at the service equipmentThe date the label was appliedItem above is no big dealIt is expected that the installing electrician will know the nominal system voltage for the