Page 355 - Solutions Manual to accompany Electric Machinery Fundamentals

(b) What is the field current in the motor?

(c) What is the torque angle of the motor?
(c) What is the power factor of the motor?

(d) How much real, reactive, and apparent power is being supplied to the plant now?
What is the current I in the transmission line?
L
Now suppose that the field current is increased to 3.0 A.
(e) What is the real and reactive power supplied to the motor?

(f) What is the torque angle of the motor?
(g) What is the power factor of the motor?
(h) How much real, reactive, and apparent power is being supplied to the plant now?
What is the current I in the transmission line?
L
(i) How does the line current in part (d) compare to the line current in part (h)?
Why?

7. Page 305, Problem 5-17, the power supplied by the generator is 80 kW.

8. Page 358, Figure 6-34, one of the numbers in the table of NEMA starting code letters are incorrect.
The correct table is given below, with the corrected error in red.

Nominal code letter Locked rotor kVA/hp Nominal code letter Locked rotor kVA/hp
A 0-3.15 L 9.00-10.00
B 3.15-3.55 M 10.00-11.20
C 3.55-4.00 N 11.20-12.50
D 4.00-4.50 P 12.50-14.00
E 4.50-5.00 R 14.00-16.00
F 5.00-5.60 S 16.00-18.00
G 5.60-6.30 T 18.00-20.00
H 6.30-7.10 U 20.00-22.40
J 7.10-8.00 V 22.40-up
K 8.00-9.00

9. Page 400, Problem 6-23, the motor develops its full-load induced torque at 3.5 percent slip.

10. Page 402, Problem 6-31, this problem refers to the motor of Problem 6-21, not the motor of problem
6-23.

11. Page 402, Problem 6-32, the parameters of the outer bar are
R = 4.80  X = 3.75 
2o
2o
and the parameters of the inner bar are
R = 0.573  X = 4.65 
2i
2i
12. Page 553, Problem 8-4, the armature reaction is 1000 A turns at full load.

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