Year 2024

Week # 2 Quiz 1

Q1. A DC shunt generator having \(R_{sh}\: =\:50\Omega\) was generating normally at 1000 rpm. The critical resistance of machine was \(80\Omega\). Due to some reason the speed of the prime mover become such that generator fails to generate. The speed at that time must have been

Q2. A three-phase 400 V, 6-pole, 50 Hz squirrel-cage induction motor is running at a slip of 5%. The speed of rotor with respect to stator magnetic field and speed of the stator magnetic field with respect to rotor magnetic field are

Q3. An 8 pole, 250 V, wave-wound generator has 400 conductors. If the generator is to be lap-wound, the number of conductors required is         

Q4. The mechanical power developed by a d.c. motor is maximum when the back e.m.f is

Q5. A 30 kW, 300 V DC shunt generator has armature and field resistance of 0.05 Ω and 100 Ω respectively. What is generated emf?

Q6. A d.c series motor develops a torque of 30 N-m at 3 A load current. If the current is increased to 6 A, the torque developed will be

Q7. Consider the following statements: A three phase induction motor is connected to the grid. If P is active power and Q is reactive power, the signs of P and Q are respectively 1. positive and positive while operating as motor 2. positive and negative while operating as motor 3. negative and positive while operating as generator 4. positive and positive while operating as generator

Q8. A single phase transformer when supplied from a 220V, 50Hz supply has eddy current loss of 50 W. If the transformer is connected to a voltage of 330 V, 50 Hz, the Eddy current loss will be

Q9. The ratio of rotor input, rotor copper loss and rotor output is

Q10. Corresponding to certain load connected to a 6-pole, 50Hz wound rotor induction motor, frequency of currents in rotor circuit is observed as 90 cycles per minute. Estimate the rotor speed in rpm.