Power system fundamentals - Wind Power Integration: Connection and System Operational Aspects - page 38

I L

I PH

V L V PH

Figure 2.19 Star-connected load

I A ( I L )

I CA

A

I AB

I BC

B

C

Figure 2.20 Delta-connected load

2.4.5 Balanced delta-connected load
The connections for a delta-connected load are shown in Figure 2.20.
The current in line A, for example, is related to the currents in adjacent phases by

I A ¼ I AB I CA

This is shown in phasor form in Figure 2.21.
From Figure 2.21 it is clear that the magnitude of the current in line A is related
to an adjacent phase current magnitude by

p I AB

I A ¼

In general, for a balanced, delta-connected load:

V L ¼ V PH
I L ¼

p I PH
P ¼ 3 V PH I PH cos f ¼

ð 2 : 16 Þ

p V L I L cos f

Note that the expression for power in (2.16) is the same regardless of the load
connection.