FIGURE 3.38

One-line diagram for

AND

3.47 Consider the one-line diagram shown in Figure 3.38. The three-phase transformer

bank is made up of three identical single-phase transformers, each specified by X₁ =

0.24 2 (on the low-voltage side), negligible resistance and magnetizing current, and

turns ratio = N₂/N₁ = 10. The transformer bank is delivering 100 MW at 0.8 PF

lagging to a substation bus whose voltage is 230 kV.

(a) Determine the primary current magnitude, primary voltage (line-to-line) magni-

tude, and the three-phase complex power supplied by the generator. Choose the line-

to-neutral voltage at the bus, Van, as the reference. Account for the phase shift, and

assume positive-sequence operation.

(b) Find the phase shift between the primary and secondary voltages.

ZE

AY

Step-up

transformer bank

Problem 3.47 Generator

v p

To rest of the system

230-kV substation

bus