Introduction to Electrical Power and Power Electronics

148 Introduction to Electrical Power and Power Electronics

n : 1

460 V

I

1

I

2

120 V

6 Ω

Load

10. A 2-MVA, 4160/480-V transformer has series impedance of R = 2% and

X= 6%. Determine the (1) full-load voltage regulation of the transformer

at 0.85pf lagging and (2) secondary output voltage on unloading the trans-

former completely.

11. A three-phase, 500-kVA, 4160/480-V transformer bank has R = 1.0% and

X= 5%. Using Equation 2.15 or 2.18 with pu values, determine the % volt-

age rise in the secondary voltage on unloading from the following load

conditions: (1) 80% load at the unity power factor, (2) full load at 0.85 power

factor lagging, and ...