powersys
Advanced Member level 1
apparent power calculation
The attached example was scanned from a textbook. I tried to calculate S1 but the answer I got was different from the one shown in text. Could someone please help me to verify whether the solution provided in the text is CORRECT or WRONG?
My calculation:
I
= (V1 - V2) / Z
= (240 - 208 - j120) / j10
= -12-j3.2
S1
= V1 x (-I*)
= 240 x (12-j3.2)
= 2880-j768
Question: Why a negative '-' sign in front of I* is required for the calculation of S1? Pls advise.
S2
= V2 x (I*)
= (208+j120) X (-12+j3.2)
= -2880-j774.4
The attached example was scanned from a textbook. I tried to calculate S1 but the answer I got was different from the one shown in text. Could someone please help me to verify whether the solution provided in the text is CORRECT or WRONG?
My calculation:
I
= (V1 - V2) / Z
= (240 - 208 - j120) / j10
= -12-j3.2
S1
= V1 x (-I*)
= 240 x (12-j3.2)
= 2880-j768
Question: Why a negative '-' sign in front of I* is required for the calculation of S1? Pls advise.
S2
= V2 x (I*)
= (208+j120) X (-12+j3.2)
= -2880-j774.4