Answer / amit khamesra

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.

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

Answer / saka

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

Answer / k.prakashchandra

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

Whis machine is having higher efficiency Transformer or Generator

2 Answers  

---

Can we use 1.1x 2 split air-conditioning at a same time in 2kw power loadar

1 Answers  

---

Write the force balance equation of m ideal mass element.

0 Answers  

---

What is the role of a Production Engg in a Industry?????

1 Answers  

---

in ring main system we use the isolater b/w transfer bus and main bus if we r not use isolatar than wat will be the effect in our sys.

0 Answers  

---

can any one tell me the formula for calculating the power and unit consumpetion

9 Answers   Avalon,

---

How to improve the power factor from 0.8 to 0.98? Also tell me cost vs benefit analysis.

2 Answers  

---

what is harmonics? what are the factors it will depend upon

0 Answers   KSEB,

---

In a synchronous motor. if start is running at high speed.  What will be the starting torque : Higher Lower Zero

0 Answers  

---

which level of transformer oil has got low dielectric strength ?why?

2 Answers  

---

The corona effect is more in a) summer b) winter c) dry weather d) humidity weather

10 Answers   CPCL,

---

Can anyone please give me the parameters , formula needed to calculate the circuit breakers for building services.Thanks

0 Answers   Bhel,

---