PSG Unit3 Motor Protection

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Protection & Switchgear

UNIT III - APPARATUS PROTECTION


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IFETCE/EEE/IV year/VIISem/EE2402/PSG/unit-


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Generator Capability CurveSynchronous generators are rate in terms o! the ma"imum #V$ out%ut at a

s%eci!ie &o'tage an %o(er !actor )usua''y 0.*+ or 0., 'agging (hich they can

carry continuous'y (ithout o&erheating

There are t(o %o(ers

1. ea' %o(er

2. eacti&e %o(er

Real power is limited b prime mo!er capabilit"

Reacti!e power is limited b three parameters"

$rmature current 'imit

Fie' current 'imit

En region heat 'imit


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1. $#$TE CET I#IT

Com%'e" %o(er3 S P567

S

S

Gra%h is ra(n 8et(een rea' an rea' %o(er.

9here3 P rea' %o(er3 7 reacti&e %o(er3

%hasor ang'e3

r raius o! the %o(er ang'e

]sin[cos|||| iVtIt +

VtIt*

In the P-7 %'ane the armature current'imit3 as sho(n in Fig3 a%%ears as a

circ'e (ith centre at the origin an

raius e:ua' to the #V$ rating


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2.) FIELD CURRENT LIMIT:

It is limited b !ollo"in# t"o e$%&tions !o' 'e&l &nd 'e&cti(e o"e'.

Xs

ItjIt

Xas

XadQ

VtItQ

jItXas

XadP

VtItP

2*cos

sin||||

sin

cos||||

=

=

=

=

&bo(e e$%&tions 'e'esents t+e !ield

c%''ent limit %sin# It.

T+%s t+e !ield c%''ent c&n &lso be limited b 'ed%cin# R!d

I!d*2 in 'e&cti(e o"e'.


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,.) END RE-IN /E0T LIMIT:

End 'e#ion +e&t c&n be limited onl d%'in# t+e %nde' e1cited condition.


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#otor %rotection


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Protection circ#it

$or ind#ction

motor


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Protection circ#it

$or single phasingo$ ind#ction motor


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;us8ar %rotection


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Transmission 'ine %rotection

or

Feeer %rotection

orPi'ot %rotection

orCarrier current %rotection


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CT


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PSG Unit3 Motor Protection

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