TEST 1
EEE2115 ELECTRICAL POWER AND MACHINES
ANSWER ALL QUESTIONS
AUGUST 2020
60 MINUTES ONLY
This test covers CLO1: Solve problems using Electrical Power and Machines principles. [C3, PLO1]
Question 1
Figure Q1 below shows a coil of resistance 8 Ω and inductance 150 mH, is connected in series
with a 100 μ F capacitor, across a 240 V, 50 Hz a.c. supply. Compute
Figure Q1
(a)
(b)
(c)
(d)
(e)
the circuit current,
the circuit phase angle,
the p.d. across the coil,
the p.d. across the capacitor, and
the power dissipated.
(20 marks)
(8 marks)
(10 marks)
(6 marks)
(6 marks)
Question 2
A RC circuit consisting of a 4.7 μ F capacitor in series with a 250 Ω resistor is connected to a
250 V, 50 Hz supply. Compute
(a)
(b)
(c)
the current,
the power factor, and
the values for true, apparent and reactive powers.
(12 marks)
(8 marks)
(10 marks)
Question 3
(a)
(b)
Explain the differences between AC and DC power supply.
Illustrate the scenario of power factor leading and power factor lagging.
(10 marks)
(10 marks)