Protection Engineering Basics and Schemes Protection Engineering | Page 40
But in name plate ALF is not mention , we can calculate ALF with help of Dimensioning Factor ( K ) and Short circuit symmetrical current ( K ssc )
Dimensioning Factor is the multiple of secondary current during fault conditions at transient stage and short circuit symmetrical current is the multiple of secondary current during fault condition at steady state current
So ALF = K ∗ K SSC = 18.74 ∗ 21 = 393.54A
R ct = 4.7Ω as mention on nameplate R B = 9.4Ω as mention on nameplate I s = I n = 1A as mention on nameplate V k = ALF ∗ I s ∗ ( R ct + R B )
V k = 393.54 ∗ 1 ∗ ( 4.7 + 9.4 ) = 5548.914v The V k mention on name plate is bit more than that , which is ok .