MCQOPTIONS
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MCQOPTIONS
This section includes 131 Mcqs, each offering curated multiple-choice questions to sharpen your Electrical Engineering Questions knowledge and support exam preparation. Choose a topic below to get started.
| 101. |
Torque developed by a D.C. motor depends upon_____________? |
| A. | magnetic field |
| B. | active length of the conductor |
| C. | current flow through the conductors |
| D. | number of conductors |
| E. | all above factors |
| Answer» F. | |
| 102. |
In a manual shunt motor starter? |
| A. | over load relay is connected in series and no volt relay in parallel with the load |
| B. | over load relay is connected in parallel and no volt relay in series with the load |
| C. | over load relay and no volt relay are both connected in series with the load |
| D. | over load relay and no volt relay are both connected in parallel with the load |
| Answer» B. over load relay is connected in parallel and no volt relay in series with the load | |
| 103. |
Which of the following losses are significantly reduced by laminating the core of a D.C. generator ? |
| A. | Hysteresis losses |
| B. | Eddy current losses |
| C. | Copper losses |
| D. | Windage losses |
| Answer» C. Copper losses | |
| 104. |
D.C. shunt motors are used for driving____________? |
| A. | trains |
| B. | cranes |
| C. | hoists |
| D. | machine tools |
| Answer» E. | |
| 105. |
Which of the following loss in a D.C. generator is dissipated in the form of heat? |
| A. | Mechanical loss |
| B. | Core loss |
| C. | Copper loss |
| D. | All of the above |
| Answer» E. | |
| 106. |
The total losses in a well designed D.C. generator of 10 kW will be nearly______________? |
| A. | 100 W |
| B. | 500 W |
| C. | 1000 W |
| D. | 1500 W |
| Answer» C. 1000 W | |
| 107. |
Where D.C. motor of H.P. 12 or more requires frequent starting, stopping, reversing and speed control______________? |
| A. | drum type controller is used |
| B. | three point starter is used |
| C. | four point starter is used |
| D. | all above can be used |
| Answer» B. three point starter is used | |
| 108. |
D.C. generators are installed near the load centres to reduce_____________? |
| A. | iron losses |
| B. | line losses |
| C. | sparking |
| D. | corona losses |
| Answer» C. sparking | |
| 109. |
In a D.C. generator, the iron losses mainly take place in___________ |
| A. | yoke |
| B. | commutator |
| C. | armature conductors |
| D. | armature rotor |
| Answer» E. | |
| 110. |
Hopkinson’s test on D.C. machines is conducted at_______________? |
| A. | no-load |
| B. | part load |
| C. | full-load |
| D. | overload |
| Answer» D. overload | |
| 111. |
The condition for maximum efficiency for a D.C. generator is______________? |
| A. | eddy current losses = stray losses |
| B. | hysteresis losses = eddy current losses |
| C. | copper losses = 0 |
| D. | variable losses = constant losses |
| Answer» E. | |
| 112. |
D.C. generators are normally designed for maximum efficiency around_____________? |
| A. | full-load |
| B. | rated r.p.m |
| C. | rated voltage |
| D. | all of the above |
| Answer» B. rated r.p.m | |
| 113. |
During rheostat braking of D.C. series motors_____________? |
| A. | motor is run as a generator |
| B. | motor is reversed in direction |
| C. | motor is run at reduced speed |
| Answer» B. motor is reversed in direction | |
| 114. |
The purpose of retardation test on D.C. shunt machines is to find out____________? |
| A. | stray losses |
| B. | eddy current losses |
| C. | field copper losses |
| D. | windage losses |
| Answer» B. eddy current losses | |
| 115. |
Which D.C. motor has got maximum self relieving property ? |
| A. | Series motor |
| B. | Shunt motor |
| C. | Cumulatively compounded motor |
| D. | Differentially compounded motor |
| Answer» B. Shunt motor | |
| 116. |
Which of the following tests will be suitable for testing two similar D.C. series motors of large capacity ? |
| A. | Swinburne’s test |
| B. | Hopkinson’s test |
| C. | Field test |
| D. | Brake test |
| Answer» D. Brake test | |
| 117. |
In the D.C. motor the iron losses occur in____________? |
| A. | the field |
| B. | the armature |
| C. | the brushes |
| D. | the commutator |
| Answer» C. the brushes | |
| 118. |
Which method of braking is generally used in elevators ? |
| A. | Plugging |
| B. | Regenerative braking |
| C. | Rheostatic braking |
| D. | None of the above |
| Answer» B. Regenerative braking | |
| 119. |
In variable speed motor___________? |
| A. | a stronger commutating field is needed at low speed than at high speed |
| B. | a weaker commutating field is needed at low speed than at high speed |
| C. | same commutating field is needed at low speed than at high speed |
| D. | none of the above is correct |
| Answer» C. same commutating field is needed at low speed than at high speed | |
| 120. |
When the armature of a D.C. motor rotates, e.m.f. induced is___________? |
| A. | self-induced e.m.f. |
| B. | mutually induced e.m.f. |
| C. | back e.m.f |
| D. | none of the above |
| Answer» D. none of the above | |
| 121. |
D.C. motor is to a drive a load which is almost nil for certain part of the load cycle and peak value for short duration. We will select this______________? |
| A. | series motor |
| B. | shunt motor |
| C. | compound motor |
| D. | any of the above |
| Answer» D. any of the above | |
| 122. |
If a D.C. shunt motor is working at full load and if shunt field circuit suddenly opens____________? |
| A. | this will make armature to take heavy current, possibly burning it |
| B. | this will result in excessive speed, possibly destroying armature due to excessive centrifugal stresses |
| C. | nothing will happen to motor |
| D. | motor will come to stop |
| Answer» B. this will result in excessive speed, possibly destroying armature due to excessive centrifugal stresses | |
| 123. |
The speed of a D.C. shunt motor is required to be more than full load speed. This is possible by______________? |
| A. | reducing the field current |
| B. | decreasing the armature current |
| C. | increasing the armature current |
| D. | increasing the excitation current |
| E. | none of the above methods |
| Answer» B. decreasing the armature current | |
| 124. |
A dc series motor should not be started on no load because it would___________? |
| A. | not develop starting torque |
| B. | fail to start without load |
| C. | run at dangerously high speed |
| D. | draw more current without producing sufficient torque |
| Answer» D. draw more current without producing sufficient torque | |
| 125. |
Which of the following method is used for the speed control of DC shunt motor? |
| A. | voltage control method |
| B. | flux control method |
| C. | rheostat control method |
| D. | all of the above |
| Answer» E. | |
| 126. |
Armature reaction in dc motor results___________? |
| A. | decrease in speed |
| B. | increase in speed |
| C. | short circuit |
| D. | open circuit |
| Answer» C. short circuit | |
| 127. |
Ward Leonard method of speed control is basically a______________? |
| A. | field control method |
| B. | armature controlled method |
| C. | field diverter |
| D. | frequency control method |
| Answer» C. field diverter | |
| 128. |
Which of the following test can be performed on DC series motor? |
| A. | Swinburne test |
| B. | Hopkinson test |
| C. | Brake test |
| D. | Field test |
| Answer» E. | |
| 129. |
In a DC motor the inter-pole winding is connected in________________? |
| A. | series with field winding |
| B. | series speed armature winding |
| C. | parallel big field winding |
| D. | parallel with armature winding |
| Answer» C. parallel big field winding | |
| 130. |
One D.C. motor drives another D.C. motor. The second D.C. motor when excited and driven_______________? |
| A. | runs as a generator |
| B. | does not run as a generator |
| C. | also runs as a motor comes to stop after sometime |
| Answer» B. does not run as a generator | |
| 131. |
For which types of D.C. motor, dynamic braking is generally used ? |
| A. | Shunt motors |
| B. | Series motors |
| C. | Compound motors |
| D. | All of the above |
| Answer» E. | |