You have completed the syllabus of the SSC JE exam for Electrical Machines. Now BYJU'S Exam Prep brings you the 100 most important questions of the Electrical Machines.
Here you will find the 100 most important questions for the Electrical Machines subject of the Electrical Engineering syllabus. The top 20 questions are attached here rest questions you can find in the below pdf.
1. A universal motor is one which
A. can run on any value of supply voltage
B. has infinitely varying speed
C. can operate on ac as well as dc voltage
D. can work as single-phase or three-phase motor
Sol.: Universal motor can operate both AC and DC supply Voltage.
2. The magnetising current of a transformer is usually small because it has _______
A. Small air gap B. Large leakage flux
C. Laminated silicon steel core D. Fewer rotating parts
Sol.: Air Gap increases the reluctance in the magnetic path of magnetic lines of force. When
there is an air gap in the magnetic circuit the reluctance is high owing to the permeability
of air which is much lower as compared to ferromagnetic materials. The mmf required to
overcome that (maintaining flux density in the air gap) is more.
3. A reluctance motor
A. is self-starting B. is constant speed motor
C. excitation D. all options are correct
Sol.: From the principle of operation of reluctance motor, If is a self starting & maintains constant
speed and it requires DC excitation for it’s operations.
4. Transformer core is laminated,
A. because it is difficult to fabricate solid core.
B. because laminated core provides high flux density.
C. to avoid eddy current and hysteresis losses.
D. to increase the main flux.
Sol.: If the area is large current has got a different direction to flow and this will cause in loss of
power. So, to reduce these eddy currents and hysteresis losses., transformer core is
laminated and current is made to travel in a single direction.
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