TO FIND %R & %X VALUE
TO FIND %R & %X VALUE
(OP)
Dear all,
I am doing the design of 220kV/66kV 100MVA substation.
short circuit MVA = 20000MVA
X/R Ratio = 34.1
short circuit current = 52.486kA
From the above i want to know how to calculate %Resistance(R) & %Reactance(X)
Kindly help me
Thanks & Regards,
LSK
I am doing the design of 220kV/66kV 100MVA substation.
short circuit MVA = 20000MVA
X/R Ratio = 34.1
short circuit current = 52.486kA
From the above i want to know how to calculate %Resistance(R) & %Reactance(X)
Kindly help me
Thanks & Regards,
LSK






RE: TO FIND %R & %X VALUE
David Castor
www.cvoes.com
RE: TO FIND %R & %X VALUE
I have some more doubt about the calculation, please find the below calculation:
System Voltage = 220kV
Short circuit Amps = 52.486kA
Z= (220*10^3)/(52.486*10^3)
= 4.19 ohms
Z base = (V base)^2/ MVA = 484 ohms
MVA base = 100 MVA
V base = 220 kV
Z pu = Z/(Z base) = 4.19/484 = 0.008660318
R pu = 0.008196852
by using ETAP Software I got an ans. of %R = 0.01466 for positive sequence.
From the above, please note the value of "R". i don't know why there is change in value of "R".
Kindly help me
Thanks & Regards,
LSK
RE: TO FIND %R & %X VALUE
RE: TO FIND %R & %X VALUE
Your Z should be 2.42ohm and Zpu=0.005, thus R%=0.01466
RE: TO FIND %R & %X VALUE
Dear sir
R pu = Z pu / (1+(X/R)^1/2
= 0.008660318 / (1+ .341)^1/2
where X/R = 34.1%
Also I am unable to know how did you calculate that z= 2.42 ohms
can u please forward the formula to calculate the value of "Z"
Thanks & Regards
LSK
RE: TO FIND %R & %X VALUE
RE: TO FIND %R & %X VALUE