I have a problem to solve that involves a poly phase (3 phases) transformer...
The given info about is is:
Wiring setup - Dy
Sn = 50kVa
50Hz
30000V/400V -- 75
I_0 = 1%
cos(φ) = 0.2
r1 = 810Ω
x1 = 1080Ω
r2 = 48mΩ
x2 = 64mΩ
I'm calculating the approximate equivalent circuit parameters and I already found a couple of parameters:
\(
m = \frac{1}{sqrt{3}}\cdot \frac{N_1}{N_2} = 129.9
\)
r12 = r1 / m² = 48mΩ
x12 = x1 / m² = 64mΩ
R2 = r12 + r2 = 96mΩ
X2 = x12 + x2 = 128mΩ
Now, I was trying to find the current that I called I_0 which is 1% of In
\(
S_n = I_{2n}\cdot \sqrt{3}\cdot U_c
\)
\(
I_{2n} = \frac{50000 V}{\sqrt{3}\cdot 400 V} = 72.17A
\)
Then I_0 = 0.01 * 72.17 A = 0.7217 A
But I tried to do it using the high voltage side just to check if I would get the same result but I can't get the same result.
The Sn is the same on both sides of the transformer, knowing that one wiring is delta setup (high side) and the other is a star setup (low side).
How should I do the math to get the same result, but using the 30000 V side of the transformer?
The given info about is is:
Wiring setup - Dy
Sn = 50kVa
50Hz
30000V/400V -- 75
I_0 = 1%
cos(φ) = 0.2
r1 = 810Ω
x1 = 1080Ω
r2 = 48mΩ
x2 = 64mΩ
I'm calculating the approximate equivalent circuit parameters and I already found a couple of parameters:
\(
m = \frac{1}{sqrt{3}}\cdot \frac{N_1}{N_2} = 129.9
\)
r12 = r1 / m² = 48mΩ
x12 = x1 / m² = 64mΩ
R2 = r12 + r2 = 96mΩ
X2 = x12 + x2 = 128mΩ
Now, I was trying to find the current that I called I_0 which is 1% of In
\(
S_n = I_{2n}\cdot \sqrt{3}\cdot U_c
\)
\(
I_{2n} = \frac{50000 V}{\sqrt{3}\cdot 400 V} = 72.17A
\)
Then I_0 = 0.01 * 72.17 A = 0.7217 A
But I tried to do it using the high voltage side just to check if I would get the same result but I can't get the same result.
The Sn is the same on both sides of the transformer, knowing that one wiring is delta setup (high side) and the other is a star setup (low side).
How should I do the math to get the same result, but using the 30000 V side of the transformer?
