PRODUCTION OF ELECTRICAL ENERGY (EEEP3106)
Electrical and Electronic Engineering - EEE
Semester: First Semester
Level: 300
Year: 2018
UNIVERSITY OF BAMENDA
COLLEGE OF TECHNOLOGY
FIRST SEMESTER EXAMINATION
COURSE INSTRUCTOR: Pr NFAII / Mr. FOTSO
MONTH: July COURSE CODE & NUMBER: EEEP3106
YEAR: 2U18 COURSE TITLE: Production of Electrical Energy
DATE: 07/2018 TIME:
TIME ALLOWED: 2 HOURS CREDIT VALUE: 3
INSTRUCTION: Answer ALL questions. Mark allocation for each question is given
QUESTION I (30 pts)
A 30, 2000 kVA, 11 kV, 1800 rpm synchronous generator has a resistance of 1.5 D. and synchronous reactance
of 15 D. per phase.
1. The field current is adjusted to obtain the rated terminal voltage at open circuit.
a. Determine the excitation voltage E
f
. (5 Marks)
b. If a short circuit is applied across the machine terminals, find the stator current. (6 Marks)
2. The synchronous machine is next connected to an infinite bus. The generator is made to deliver the rated
current at 0.8 power factor lagging.
a. Determine the excitation voltage
Ef.
(10 Marks)
b. Determine the percentage increase in the field current relative to the field current of part 1. (4 Marks)
c. Determine the maximum power the synchronous machine can deliver for the excitation current of part 2.
Neglect R
a
. (5 Marks)
QUESTION II (20 pts)
A three-phase, 100 hp, 60Hz, 480 V, four-pole, wye-connected, cylindrical-rotor synchronousmotor has an
armature resistance of 0.15 Q. and a synchronous reactance of 2 Q per phase, respectively. At the rated load
and a leading power factor of 0.8, the motor efficiency is 0.95. Determine the following:
1. The internal generated voltage(11 Marks)
2. The torque angle (2 Marks)
3. The maximum torque (7 Marks)
QUESTION III (10 pts)
A 25 hp synchronous motor has a full-load efficiency of 92% and operates at a leading power factor of 0.8.
Determine the following:
1) The power input to the motor (5 Marks)
2) The kVA input to the motor (5 Marks)
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