What is the basic difference between 90% stator earth fault and 100% stator ear

What is the basic difference between 90% stator earth fault
and 100% stator earth fault, and its phenmenona?

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What is the basic difference between 90% stator earth fault and 100% stator earth fault, and its ph..

As neutral of the generator is approched, the driving
voltage available between the fault point and the neutral
is very low & hence not detectable. So last 5% of the
generator winding remains nprotected with the conventional
schemes of E/F protection. that is why it is called 95%
stator earthfault protection. For covering the rest of 5%
winding other techniques like 3rd harmonic principle ets
are available.

Is This Answer Correct ?

10 Yes

1 No

What is the basic difference between 90% stator earth fault and 100% stator earth fault, and its ph..

Answer / a.p.nanjappa

This is an application with power plant genrator protection.
In early 1950-75,only 90% stator earth fault protection
used for Generator Stator winding.
GE,westinghouse,hitahachi,GEC,BBC,KWU.ON 1975 ONWARDS,
THEN 100% STATOR EARTH FAULT DEVELOPED USING OPEN DELTA
VOLTAGE OFGENERATOR AND USING FIRST AND THIRD HARMONIC
BRIDGE.
WEST AND EUROPE,INDIA USED GENERATOR NETRAL GROUNDING
TRANSFORMER AND ON SECONDARY OF THIS TRANSFORMER90%STATOR
EARTH FAULT PROTECTION IS USED.
FOR 100% STATOR EARTF FAULT USE OPEN DELTA VOLTAGE.
Russian practice is use voltage transformer for generator
neutral gounding.
when I was DISCUSSING this with european manufacturer, they
want to delete 100% protection.In a generator it is meaning
less.fault is fault.It is time consuming for repair.
As a new challenge-generator manufacture claim 100%
availabilty of Generator with VIP.
/MICADOUR ELASTIC INSULATION. In gas turbine a single
generator rating is selected for single shaft gas turbine
and steam turbine. upto 275MW. AND 400MW

Is This Answer Correct ?

2 Yes

2 No

What is the basic difference between 90% stator earth fault and 100% stator earth fault, and its ph..

Answer / saka

90% Stator earth fault protection achieved through NGR and
100% Stator earth fault achieved through REF ( NGTR )

Is This Answer Correct ?

1 Yes

6 No

What is the basic difference between 90% stator earth fault and 100% stator earth fault, and its ph..

Answer / k.prakashchandra

90% means providing protection for 90% of stator winding and
100% means for entire winding

Is This Answer Correct ?

4 Yes

10 No

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