University of Bahrain
College of Engineering
Electrical Engineering
Homework # 1
Single-phase induction machine
EENG 342
Dr. Mohamed Fnaiech
Problem 1:
Problem 2:
A 1-kW, 120-V, 60-Hz capacitor-start motor has the following parameters for the main and
auxiliary windings (at starting):
Zmain = 4.82 + j7.25 Ω
main winding
Zaux = 7.95 + j9.21Ω
auxiliary winding
a) Find the magnitude and the phase angles of the currents in the two windings when rated
voltage is applied to the motor under starting conditions.
b) Find the value of starting capacitance that will place the main- and auxiliary-winding
currents in time quadrature at starting.
c) Repeat part (a) when the capacitance of part (b) is inserted in series with the auxiliary
winding.
Problem 3:
500-W, four-pole, 115-V, 60-Hz single-phase induction motor has the following parameters
(resistances and reactances in Ω/phase):
R l,main = 1.68, R 2,main = 2.96
X l,main =1.87 , X m,main = 60.6, X 2,main = 1.72
Core loss = 38 W Friction and windage = 11.8 W
Find the speed, stator current, torque, power output, and efficiency when the motor is operating at
rated voltage and a slip of 4.2 percent.