- #1
robcowlam
- 9
- 0
Hi guys,
Im having some trouble with a question about 3 phase power system. I have a balanced delta connected load of 30+18.86j ohms. The voltage is given as 400v @Hz and I am asked to calculate the phase voltage and current using the voltage Vr as the reference.
Now from my knowledge of 3 phase I understand that with this type of load the line and phase voltage are the same (400v) with each phase 120deg lagging from the previous.
Z= 30+18.86j = 35.43 @ 32.14degrees
This leads me to do the calculation:
I = V/Z = (400 @ 0 degrees)/35.43 @ 32.14degrees = 11.29 @ -32.14 degrees.
Repeating this for the other 2 phases gives answers with +/- 120degrees
The magnitude is correct however the angle is 30 degrees out and I cannot see why, the only thing I can think of is that the line voltage is 30degrees out of phase with the phase voltage which I am using as the reference.
Does anyone have any idea if this might be a correct assumption?
Thanks in advance,
Rob
Im having some trouble with a question about 3 phase power system. I have a balanced delta connected load of 30+18.86j ohms. The voltage is given as 400v @Hz and I am asked to calculate the phase voltage and current using the voltage Vr as the reference.
Now from my knowledge of 3 phase I understand that with this type of load the line and phase voltage are the same (400v) with each phase 120deg lagging from the previous.
Z= 30+18.86j = 35.43 @ 32.14degrees
This leads me to do the calculation:
I = V/Z = (400 @ 0 degrees)/35.43 @ 32.14degrees = 11.29 @ -32.14 degrees.
Repeating this for the other 2 phases gives answers with +/- 120degrees
The magnitude is correct however the angle is 30 degrees out and I cannot see why, the only thing I can think of is that the line voltage is 30degrees out of phase with the phase voltage which I am using as the reference.
Does anyone have any idea if this might be a correct assumption?
Thanks in advance,
Rob
