3)
Substituting Equation (11.3) into Equation (11.2) into Equation (11. Calculate (a) the phase voltage, (b) the line current and (c)
the total power consumed.2)
Substituting Equation (11.
For star connection,
V I
L P
and
3
For (a),
V
V
V
P
L
P
(V)
V
V
3
400
1 732
230 9
.
.
For (b),
I I
V
R
I I
L P
P
P
L P
(A)
V
A
230 9
10
23 09
.1), have:
Total three-phase power cos (W)
L φ
Now consider delta connection:
V I
I
P P
L
and
(11.Polyphase three-phase electrical systems
227
Now for star connection,
V
V
I I
P
L
L P
and
(11.1) have, for any balanced
three-phase load,
Total three-phase power cos (W)
L φ
so, general Equation for three-phase power is:
Power cos
L L
3 φ
Example 1
A balanced star-connected three-phase load 10Ω per phase supplied from 400V, 50Hz
mains supply unity power factor.
Ω
For (c),
Power cos (W)
Power kW
L L
3
1 732 400 16
V φ
∴.
