Transformer help...

[elec123]

Hi,

Yes, this is my college work, but i have attempted it and need a just need a few things clarified for me....

Using a 48kVA, 4800/240 V step down transformer:

open circuit test: V = 240V, I =2A, P = 120W
short circuit test: V= 150V, I=10A, P =600W

O.k in o/c i get:

Rc = (V^2) / W = (240^2) / 120 = 480 ohm
Xm = 124 ohm

and in s/c i get:

R= W / (I^2) = 600 / (10 ^2) = 6 ohm
Xl = 13.7 ohm

Do these values seem correct?

I have to determine the equivalent circuit viewed from the high voltage side, is my attempt (see attached) correct?

To find the rated current in the primary is this just 48kVA / 4800 = 10A?


I appreciate this site is not for students to get their homework done for them, but if someone could look over what i have done that would be most appreciated....

Thanks in advance

elec123

 

[Russlk]

Here is the problem: in the open circuit case, the current in the secondary is zero, therefore the 2 amps is in the primary. Using the secondary voltage is incorrect. In the short circuit case, I don't know if the 10 amps is the short circuit current in the secondary or primary current. It would make sense that the current is measured in the primary because the 150 volts has to be primary voltage, the secondary voltage is zero.