Ali K. Abdul Abbas Q1] Select the correct answer: (9 Marks) 1- Which of the following statements is false for a series-wound d.c. motor? (a) The speed decreases with increase of resistance in the armature circuit (b) The speed increases as the flux decreases (c) The speed can be controlled by a diverter (d) The speed can be controlled by a shunt field regulator. 2- With a d.c. motor, the starter resistor: (a) limits the armature current to a safe starting value (b) controls the speed of the machine (c) prevents the field current flowing through and damaging the armature (d) limits the field current to a safe starting value. 3- The effect of inserting a resistance in series with the field winding of a shunt motor is to: (a) increase the magnetic field (b) increase the speed of the motor (c) decrease the armature current (d) reduce the speed of the motor. 4- If residual magnetism of a shunt generator is destroyed accidentally, it may be restored by connecting its shunt field (a) to earth (b) to an A.C. source (c) in reverse (d) to a D.C. source. 5- The efficiency of a transformer will be maximum when (a) copper losses = hysteresis losses (b) hysteresis losses (c) eddy current losses = copper losses (d) copper losses = iron losses. 6-No-load current of a transformer has Attempt All Questions Date: 4/6/2018 Time: 3 Hours 3-1 eddy current losses (a) high magnitude and low power factor (b) high magnitude and high power factor (c) small magnitude and high power factor (d) small magnitude and low power factor. 7- The transformer ratings are usually expressed in terms of (a) volts (b) amperes (c) kW (d) kVA. 8- A 3-phase 440 V, 50 Hz induction motor has 4% slip. The frequency of rotor current will be (a) 2 Hz (b) 50 Hz (c) 5 Hz (d) 25 Hz.