i am a student. i have a question about three phase power.
question: a three phase delta connected motor draws a line current of 18A∠-85 degree from the 400v supply.
1) how much power does the load dissipate?
my anwer is:
P=√3 VIcosφ=√3*400*18*cos85=1087w
2) calculate the motor output when connected in star?
my anwer is:
first calculated impedence in three winding
IN delta connection:
Ip=18/√3= 10.4∠-55A (line current lag phase current 30 degree in delta)
Z=400/(10.4∠-55)=38.46∠-55 ohm
IN star connection:
I=V/Z=230/38.46∠-55 =6∠-55
P=√3 VIcosφ=√3 *400*6*cos55
= 2384w
problem is power in delta shoud be 3 time more
in star . my anwer is wrong. but i donot known where
is wrong?
question: a three phase delta connected motor draws a line current of 18A∠-85 degree from the 400v supply.
1) how much power does the load dissipate?
my anwer is:
P=√3 VIcosφ=√3*400*18*cos85=1087w
2) calculate the motor output when connected in star?
my anwer is:
first calculated impedence in three winding
IN delta connection:
Ip=18/√3= 10.4∠-55A (line current lag phase current 30 degree in delta)
Z=400/(10.4∠-55)=38.46∠-55 ohm
IN star connection:
I=V/Z=230/38.46∠-55 =6∠-55
P=√3 VIcosφ=√3 *400*6*cos55
= 2384w
problem is power in delta shoud be 3 time more
in star . my anwer is wrong. but i donot known where
is wrong?