Ministry of Higher Education
First Term
& Scientific Research
Examination
Erbil Polytechnic University
2013 – 2014
Erbil Technical Engineering College
Ref. & Air Cond. Eng. Techniques Department
Subject: Elec. & Electronic Eng.
Class: 3rd Class
Date: 11.01.2014
Time: 90 min.
Q1: (25 Marks)
A. What are the types of DC generators? Just list and draw (10 Marks)
B. What do you mean by a DC motor? (5 Marks)
C. Induction motor can run at synchronous speed? True or false? Explain. (10 Marks)
Q2: (25 Marks)
A 4 pole, 220V shunt motor has 540 lap-wound conductors. It takes 32A from the supply
mains and develops output power of 5.595kW. The field winding takes 1A. The armature
resistance is 0.09 and the flux per pole is 30mWb. Calculate: (i) The speed and (ii) The
shaft torque developed in newton-meter.
Q3: (25 Marks)
A 4 pole d.c. generator is delivering 20A to a load of 10. If the armature resistance is 0.5
and the shunt field resistance is 50, calculate the induced e.m.f. (Eg) and the efficiency of
the machine. Allow a drop of 1V per brush.
Q4: (25 Marks)
A 3 phase induction motor is wound for 4 poles and is supplied from 50Hz system.
Calculate (i) the synchronous speed (ii) the rotor speed, when slip is (4%) and (iii) rotor
frequency when rotor runs at 600 rpm.
GOOD LUCK!
Lecturer
Zana Ozairi
Head of Department
Dr. Banipal N. Yaqob