Design of Electrical Machines Practice Test 6

1. How many types of bearings are made use of in the PMDC motors?

2. What type of gear is made use of in the high inertia motors?

worm gears

spur gears

spur and helical gears

helical gears

3. What is the range of length of the magnet in the PMDC motors?

1.5-4 cm

2.5-4 cm

2.5-3 cm

2-3 cm

4. How is the specific electric loading related to the synchronous reactance of the machines?

specific electric loading is low, leakage reactance is high, giving high synchronous reactance

specific electric loading is high, leakage reactance is high, giving low synchronous reactance

specific electric loading is high, leakage reactance is low, giving low synchronous reactance

specific electric loading is high, leakage reactance is high, giving high synchronous reactance

5. What is the formula for the height of length of mean turn of armature?

length of mean turn = 2*length + 2.5*pole pitch + 0.06 kV + 0.2

length of mean turn = 2*length + 2.5*pole pitch - 0.06 kV - 0.2

length of mean turn = 2*length + 2*pole pitch + 0.06 kV + 0.2

length of mean turn = 2*length - 2.5*pole pitch - 0.06 kV - 0.2

6. How many number of poles should be used for large motors of relatively low speed?

should be lesser than 2

should be greater than 2

should be equal to 2

should be more than 4

7. What is the relation of the force and the air gap length in the flat faced plunger type?

force is directly proportional to the air gap length

force is indirectly proportional to the air gap length

force is indirectly proportional to the square of the air gap length

force is directly proportional to the square of the air gap length

8. Among the following what are the applications of the tractive electromagents?

buzzers

track switches

electric bells

track switches, bells, buzzers

9. By how much should the depth of slot not exceed the width?

three times

six times

four times

two times

10. What factor does the permeance coefficient depend upon?

associated non-portions of the magnetic circuit

geometry of the magnet

airgap

geometry of the magnet, airgap, associated non-portions of the magnetic circuit