ALLInterview.com :: Home Page            
 Advertise your Business Here     
Browse  |   Placement Papers  |   Company  |   Code Snippets  |   Certifications  |   Visa Questions
Post Question  |   Post Answer  |   My Panel  |   Search  |   Articles  |   Topics  |   ERRORS new
   Refer this Site  Refer This Site to Your Friends  Site Map  Bookmark this Site  Set it as your HomePage  Contact Us     Login  |  Sign Up                      
Google
   
 
Categories >> Engineering >> Electrical Engineering
 
 


 

 
 Civil Engineering interview questions  Civil Engineering Interview Questions (3014)
 Mechanical Engineering interview questions  Mechanical Engineering Interview Questions (3272)
 Electrical Engineering interview questions  Electrical Engineering Interview Questions (13225)
 Electronics Communications interview questions  Electronics Communications Interview Questions (2348)
 Chemical Engineering interview questions  Chemical Engineering Interview Questions (407)
 Aeronautical Engineering interview questions  Aeronautical Engineering Interview Questions (77)
 Bio Engineering interview questions  Bio Engineering Interview Questions (16)
 Metallurgy interview questions  Metallurgy Interview Questions (79)
 Industrial Engineering interview questions  Industrial Engineering Interview Questions (162)
 Instrumentation interview questions  Instrumentation Interview Questions (2319)
 Automobile Engineering interview questions  Automobile Engineering Interview Questions (104)
 Mechatronics Engineering interview questions  Mechatronics Engineering Interview Questions (38)
 Marine Engineering interview questions  Marine Engineering Interview Questions (43)
 Power Plant Engineering interview questions  Power Plant Engineering Interview Questions (73)
 Engineering AllOther interview questions  Engineering AllOther Interview Questions (1190)
Question
HOW CAN WE CALICULATE NGR RESISTANCE FOR A GENERATOR AND
TRANSFORMER ?
WHAT TYPE OF TRANSFORMER REQUIRES NGR ?
 Question Submitted By :: Tcrajarupesh
I also faced this Question!!     Rank Answer Posted By  
 
  Re: HOW CAN WE CALICULATE NGR RESISTANCE FOR A GENERATOR AND TRANSFORMER ? WHAT TYPE OF TRANSFORMER REQUIRES NGR ?
Answer
# 1
NGR-Neutral Grounding Resistor.It is used to limit the
fault current in the neutral line.calculation based on fault
current in stator in generator and star side in trfr
 
Is This Answer Correct ?    12 Yes 2 No
Ramesh
 
  Re: HOW CAN WE CALICULATE NGR RESISTANCE FOR A GENERATOR AND TRANSFORMER ? WHAT TYPE OF TRANSFORMER REQUIRES NGR ?
Answer
# 2
The value of the NGR to be inserted in the cicuit can be
calculated by the simple formula

R = V / (√3 * I)

Where V is the System Line voltage in Volts
I is the value of the fault current to be limited

In general practice the fault current is limited to the
full load rating of the largest equipment available in the
system.
 
Is This Answer Correct ?    6 Yes 4 No
Pavan
 
 
 
  Re: HOW CAN WE CALICULATE NGR RESISTANCE FOR A GENERATOR AND TRANSFORMER ? WHAT TYPE OF TRANSFORMER REQUIRES NGR ?
Answer
# 3
DESIGN AND SELECTION CRITERIA OF
NGR

Neutral Grounding Resistor:

The power transformer secondary 6.6kV neutral shall be
medium resistance earthed in order to limit the 6.6kV
system earth faults to low values such as to limit
excessive damage to 6.6kV equipments.
Also that the earth faults are not too low value to cause
earth fault relay non-operation.

System voltage = 6.6kV
System voltage per phase = 6.6/√3
Vph = 3810.6Volts
Earth fault current (I) =50A for 5 sec

NGR calculation is done on the basis of following formula,

Vph= I X R

R= Vph / I

R= 3810.6/50

Resistance= 76.21 Ohms

NGR Selected is 6.6kV , 50A, 76.2Ohms, 5sec.

Normally 50 A
 
Is This Answer Correct ?    6 Yes 1 No
Ravi Kumar Purohit
 
  Re: HOW CAN WE CALICULATE NGR RESISTANCE FOR A GENERATOR AND TRANSFORMER ? WHAT TYPE OF TRANSFORMER REQUIRES NGR ?
Answer
# 4
Ohmic value of neutral grounding resister for a transformer is calculated as follows:

R = Vph/ I where I - value of fault current to be limited to flow through the neutral path, normally it is 50A for 5 sec.

Based on above, for 6.6 kv star side of a transformer
resister value shall be 76.21ohm.
 
Is This Answer Correct ?    0 Yes 1 No
A S Bhandari
 

 
 
 
Other Electrical Engineering Interview Questions
 
  Question Asked @ Answers
 
what r the types of transmission line? RRB 26
why voltage is low at reciving end in summer?? JSW 4
what is vector diagram in three phase transformer   1
What is the difference between induction motor and the Synchronized one? Sabic 3
is the power of a single phase induction motor(Fans) is constant under varying speeds?   3
HARMONICS ARE ALWAYS IN INTEGER LIKE 2ND OR 3RD HARMONICS,NOT IN FRACTION LIKE 0.5 HARMONICS.....????????   2
what is power ratio between star & delta connection of 3 phase induction motor   1
DIFFERENCE BETWEEN POWER AND CONTROL CABLES   9
Can anyone tell me what will happen if AC & DC supply get mixed???   9
what is static electricity and how it generates?   2
what is the difference between analog and digital signal?   3
mention the earthing system as per BIS?   1
 
For more Electrical Engineering Interview Questions Click Here 
 
 
 
 
 


   
Copyright Policy  |  Terms of Service  |  Articles  |  Site Map  |  RSS Site Map  |  Contact Us
   
Copyright 2013  ALLInterview.com.  All Rights Reserved.

ALLInterview.com   ::  KalAajKal.com