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WorksheetsDCM Drives_1
Total questions: 17
Worksheet time: 11mins
Direction of rotation of motor is determined by ________
Faraday’s law
Lenz’s law
Coulomb’s law
Fleming’s left-hand rule
In which of the following application DC series motor is used?
Centrifugal Pump
Motor Operation in DC and AC
Water pump drive
Starter for car
In DC motor, which of the following part can sustain the maximum temperature rise?
Field winding
Commutator
Slip rings
Armature winding
These days D.C. motors are widely used in
pumping sets
air compressors
electric traction
machine shops
Which power is mentioned on a name plate of a motor?
Gross power
Power drawn in kVA
Power drawn in kW
Output power available at the shaft
Which of the following quantity will decrease if supply voltage is increased?
Starting torque
Operating speed
Full-load current
Cannot be determined
The speed of a D.C. shunt motor more than its full-load speed can be obtained by
Decreasing the field current
Increasing the field current
Decreasing the armature current
Increasing the armature current
Which D.C. motor has got maximum self loading property?
Series motor
Shunt motor
Cumulatively compounded ‘motor
Differentially compounded motor
Identify the speed torque characteristics of a dc series motor.
Which of the following is the best braking method?
Friction
Electromechanical action
Eddy-currents
Electric braking
DC motor is still widely used in tractions due to its excellent braking properties.
True
False
Which of the following is not the method of electrical braking?
Plugging or counter-current
Dynamic or rheostatic
Regenerative
Eddy current
Electrical braking of any variety becomes less effective as ________________
Speed increases
Speed decreases
Independent of speed
Depends on supply voltage
Plugging is applied in a motor, if we don’t make the switch OFF what will happen?
Motor will come to rest as a result of plugging
Motor will come to rest and will start rotating in another direction
Motor will burn
Which of the following is dynamic braking?
Reversal of field connections
Reversal of armature connections
Addition of equal and opposite field
Removal of armature circuit from current machine circuit
In dynamic braking, when braking is applied system acts as ___________
Freely running machine
Motor with slow speed
Generator
Motor with same speed in opposite direction
In which of the following electrical braking method, energy is supplied back to the supply?
Plugging
Dynamic braking
Regenerative braking
