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Accidental energizing Protection (27/50)

Cause:

Operating error,breaker head flash over ,control ckt al f!nction or cobination of

these ca!se accidentl" energizing generator off line#

$hree phase energizing of generator at stand still ca!se accelerate siilarl" toind!ction otor

%enerator at this point represented b" s!b&transient reactance to s"ste and it 'illdra'n #0 to #0 p#! c!rrent(00&00*) depend on s"ste ipedance#

+igh c!rrent prod!ced in rotor d!e to behavior of generator as ind!ction otora" therall" daage otor in fe' sec#

Protection:

$his condition for generator onitors a# phase c!rrent and a#ph&ph voltage ofgenerator#

-voltage s!pervised over c!rrent protection. base

Protect generator fro this is to operate over c!rrent f!nction s!pervised b"13 4O$A% f!nction#

Over c!rrent f!nction disabled 'hen achine achine is online and if an" overc!rrent is detected 'hen achine is O66 line for specific d!ration, than it 'illiss!e a trip

etting g!ide line8

9:argest c!rrent prod!ced d!ring accidental energizing

9:$o be less than 0#; 9energisation

9energisation < (4n/=> ) / ?d@@?tB net'ork

Chere 4n8 rated generator voltage

?d.8s!b transient reactance of generator

?t8 step !p transforer reactance(oh)

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50 I>

27 V