Just a quick question about Real 3 phase power

Thread Starter

Amanda_Riley

Joined May 12, 2010
22
The equations to find real power is:

P = 3 x Vphase x Iphase x cos(v - i)

or √3 x Vline x Iline x cos(v - i)

My question is if you have a delta connected 3 phase system and have

Vphase = Vline = 120 angle 0
Iphase = 41.6 angle -36.87
Iline = 72.05 angle -66.87

Would you use the angle of 36.87 for both the real power equations?
 

t_n_k

Joined Mar 6, 2009
5,448
How did you arrive at ...

Vphase = Vline = 120 angle 0 ?

The phase(line)-to-neutral and phase(line)-to-phase(line) voltages can't be the same.
 

Thread Starter

Amanda_Riley

Joined May 12, 2010
22
its delta connected - delta source and a delta load so no line to neutral line

Phase voltage (Vab) = Line voltage(VAB)
Line current = √3 x phase current
 

subtech

Joined Nov 21, 2006
123
In short, the answer is yes.

The phase measurement (some call this the winding current) is the current magnitude and angle to use in your calculation.
 
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