Page 354 - Solutions Manual to accompany Electric Machinery Fundamentals

Appendix E: Errata for Electric Machinery Fundamentals 5/e

(Current at 15 April 2011)

Please note that some or all of the following errata will be corrected in future reprints of the
book, so they may not appear in your copy of the text. PDF pages with these corrections are attached to
this appendix; please provide them to your students.

1. Page 145, Problem 2-3, was printed incorrectly in the first printing of this text. By accident a
portion if Problem 2-4 was printed instead of the appropriate text. The correct text is:

2-3. Consider a simple power system consisting of an ideal voltage source, an ideal step-up
transformer, a transmission line, an ideal step-down transformer, and a load. The voltage of


the source is V S  480 0 V . The impedance of the transmission line is
Z line  4 j  , and the impedance of the load is Z load  30  j 40  .
3
(a) Assume that the transformers are not present in the circuit. What is the load voltage
and efficiency of the system?
(b) Assume that transformer 1 is a 1:5 step-up transformer, and transformer 2 is a 5:1
step-down transformer. What is the load voltage and efficiency of the system?
(c) What transformer turns ratio would be required to reduce the transmission line
losses to 1% of the total power produced by the generator?

2. Page 147, Problem 2-13, the transformer is Y- connected.

3. Page 264, Problem 4-6, the generator should be “2-pole, -connected, 60 Hz” instead of “Y-
connected”.

4. Page 269, Problem 4-25, the problem should say “Make a plot of the terminal voltage versus the
load impedance angle” instead of “Make a plot of the terminal voltage versus the load power
factor”.

5. Page 301, Problem 5-4, the synchronous reactance should be 2.5 .

6. Page 304, Problem 5-12, parts (b) and (i) are incorrect. The correct problems is given below, with
the changes in red.

5-12. Figure P5-3 shows a small industrial plant supplied by an external 480 V three-phase power
supply. The plant includes three main loads as shown in the figure. Answer the following
questions about the plant. The synchronous motor is rated at 100 hp, 460 V, and 0.8-PF-
leading. The synchronous reactance is 1.1 pu and armature resistance is 0.01 pu. The OCC
for this motor is shown in Figure P5-4.
(a) If the switch on the synchronous motor is open, how much real, reactive, and
apparent power is being supplied to the plant? What is the current I in the
L
transmission line?

The switch is now closed and the synchronous motor is supplying rated power at rated
power factor.

348