A- A 4 poles, 50Hz, Y-connected three phase induction motor has the per phase equivalent circuit parameters of ( R1=R2= 0.12, x1 = x2 = 0.6, Xm=12) 2 and 12=20L0. Draw this equivalent circuit and calculate the following at rated slip of 0.03: stator current, power factor and rated torque? Neglect friction and windage losses. B- Define the following: 1- Induction motor, 2- Duty of motor, 3- motor temperature rise, 4- IP of motor and 5 - Rotor frequency of induction motor?

The resistance and reactance per phase of the rotor of a 3-phase induction motor are 0.6 ohm and 5 ohms respectively. The induction motor has a star-connected rotor and when the stator is connected to a supply of normal voltage, the induced e.m.f. between the slip rings at standstill is 80 V. Calculate the current in each phase and the power factor at starting when (i) the slip-rings are shorted, (ii) slip-rings are connected to a star-connected resistance of 4 ohm per phase.

6- In a stepper motor, how is the speed of rotation determined? a) By the current supplied to the motor. b) By the magnitude of the voltage applied. c) By the load applied to the motor. d) By the frequency of the waveforms used. 7- A transformer core is laminated to a) reduce hysteresis loss b) reduce eddy current losses c) reduce copper losses d) reduce all above losses 8- An induction motor with 580 r.p.m. speed at 60 Hz will have a) 8 poles b) 6 poles c) 4 poles d) 2 poles 9- If any two phases for an induction motor are interchanged a) the motor will run in reverse direction b) the motor will run at reduced speed c) the motor will not run d) the motor will burn 10- No-Load speed of which of the following motor will be highest? a) Shunt motor b) Series motor c) Short-Shunt compound motor d) Long-Shunt compound motor

The starting winding circuit of a capacitor start, induction run motor consists of a 15 Q resistance and a 20 Q2 inductive reactance. These components are in series with a 50 uF capacitor. The circuit is connected to a 120 V, 60 Hz source. Determine: a. the impedance of the series circuit. b. the current. c. the true power. d. the power factor.