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This set of Electrical and Electronics Engineering Multiple Choice Questions & Answers (MCQs) focuses on Electrical And Electronics Engineering Set 4
Q1 | ____ motor has the best speed regulation
- series
- cumulatively compounded
- shunt
- differentially compounded
Q2 | The deciding factor in the selection of a dc motor for a particular application is its ____ characteristics
- speed-torque
- speed-armature current
- torque-armature current
- none of the above
Q3 | A series motor will over speed when ____.
- the load is increased
- the field is opened
- the armature circuit is opened
- laod is removed
Q4 | A cumulatively compounded motor does not run at dangerous speed at light loads because of the presence of ______.
- shunt winding
- series winding
- interpoles
- compensating windings
Q5 | DC shunt motor are used in those applications where____ is required.
- high statring torque
- practically constant speed
- high no load speed
- variable speed
Q6 | DC series motor are used in those applications where ____ is required.
- high statring torque
- constant speed
- low no load speed
- none of the above
Q7 | Cumulatively compounded motors are used where we require _____.
- variable speed
- poor speed regulation
- sudden heavy loads for short duration
- none of the above
Q8 | ____ motors never use belt- connected loads.
- series
- shunt
- cumulatively compounded
- differential compound
Q9 | For 20% increase in current, the motor that will give the greastest increase in torque is ___ motor
- shunt
- series
- cumulatively compounded
- differnetially compounded
Q10 | Each commutator segment is connected to armature conductor by means of ___
- insulator
- dielectric
- copper lug
- resistance wire
Q11 | In a 4 pole machine___
- alternate poles are north and south
- two north poles follow two south poles
- in all there are north poles
- in all there are south poles
Q12 | If the applied voltage of dc motor is reduced to half with load torque doubled the armature current will be____
- unaltered
- zero
- doubled
- half
Q13 | Back EMF of DC motor depends on
- field flux
- shape of conductor
- type of sliprings
- brush material
Q14 | A DC motor develops torque of the 100Nm at 400 rpm, at 300 rpm a motor will develop torque of___.
- 133nm
- 100nm
- 67nm
- 180nm
Q15 | A DC series motor is most suitable for _____.
- cranes
- pump
- lathes
- punch presses
Q16 | ____ motor is most suitable for punch presses
- shunt
- series
- differential compound
- cumulative compound
Q17 | In a vaccum cleaner, we generally use ____ motor
- shunt
- cumulative - compound
- series motor
- differetial compounded
Q18 | The most suitable motor for elevators is the ___ motor.
- series
- shunt
- differential compound
- cumulative compound
Q19 | The friction and windage losses in a DC motor depends upon ____.
- speed
- flux
- armature current
- field and armature resistance
Q20 | A motor takes a large starting currents because _____.
- the armature resistance is high
- back emf is low
- shunt field is produce weak field
- none of the above
Q21 | Excessive sparking at the brushes may be caused due to _____.
- dirt on the commutator
- loose coupling
- misalignment of machine
- worn bearing
Q22 | A 440V shunt motor has an armature resistance of 0.8Ω field reistnace of 200Ω . Find the back emf when giving an output of 7.46kW at 85 % efficiency?
- 222.4v
- 425.8v
- 312.6v
- 392.7v
Q23 | A 250V DC shunt motor takes a total current of 20A. Resistance of shunt field winding is 200Ω and that of armature is 0.3Ω . What is the current in the armature?
- 9.65a
- 11.25a
- 18.75a
- 16.62a
Q24 | A 220V DC shunt motor takes a total current of 80A and runs at 800 rpm. Resistnace of a shunt field is 50Ω and that of armature 0.1Ω. The iron and friction losses amount to 1600W. What is the armture torque?
- 212nm
- 176nm
- 192nm
- 242nm
Q25 | A 220V DC shunt motor takes a total current of 80A and runs at 800 rpm. Resistnace of a shunt field is 50Ω and that of armature 0.1Ω. The iron and friction losses amount to 1600W. What is the lost torque?
- 11nm
- 19nm
- 22nm
- 34nm