.
.
For delta connection,
l l
L (A)
3
Thus, for (b),
I I
I
P L
P
/ (A)
A
A
3
36 08
1 732
20 83
∴
.
Example 3
Three identical loads each having resistance 30Ω and inductive reactance 40Ω are
connected first star and then delta 400-V three-phase supply. Calculate (a) the line
current and (b) the phase current.Basic Electrical Installation Work
228
Example 2
A kW, 400 balanced delta-connected load has power factor 0.
V
A
P L
Ω
I. .
For each load,
Z X
Z
Z
2
2 2
30 40
2500 50
L )
Ω
∴
Ω
For star connection,
V I
V
V
V
I
V
Z
I
L P
P
L
P
P
P
P
P
and
V
V
V
(A)
3
3
400
1 732
230 9
( )
.
We have that:
Three-phase power cos (W)
L φ
For (a),
I
V
I
I
L
L
L
L
Power
cos
(A)
W
V
(A)
3
20 000
1 732 400 8
36 08
φ
∴
,
. Calculate the phase
currents and line currents for each connection.
.8.
∴
∴
230 9
50
4 62
.
.
