Design of Electrical Machines Practice Test 6

1. What is the formula for the total eddy current loss in conductors?

total copper loss = 3 / average value of the eddy current constant * current per phase² * dc resistance

total copper loss = 3 * average value of the eddy current constant / current per phase² * dc resistance

total copper loss = 3 * average value of the eddy current constant * current per phase² * dc resistance

total copper loss = 3 * average value of the eddy current constant * current per phase² / dc resistance

2. What type of gears are used in the small loads and low inertia motors?

worm gears

worm gears and helical gears

helical gears

spur gears

3. What is the formula for the length of the stator slots?

length of the stator slots = 2 * perimeter of one magnet

length of the stator slots = 1/3 * perimeter of one magnet

length of the stator slots = 1/2 * perimeter of one magnet

length of the stator slots = 3 * perimeter of one magnet

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

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

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

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

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

5. What material is the flat faced armature type made of?

cast iron

hard steel

cast steel

soft steel

6. How many primary reasons are present for the thermal failure?

7. What factor/s does the cooling coefficient depend upon?

speed of the machine and configuration of the surface

configuration of the surface

speed of the cooling medium

speed of the machine or configuration of the surface

8. What is the relation between number of poles and flux reversal in the armature?

number of poles is directly proportional to the flux reversal in the armature

number of poles is directly proportional to the square of the flux reversal in the armature

number of poles is indirectly proportional to the flux reversal in the armature

number of poles is indirectly proportional to the square of the flux reversal in the armature

9. Coils are being made use of in electromagnets as an exciting source for production of magnetic field.

true

false

10. What is the relation between axial dimension and the area of the magnet?

area of the magnet is indirectly proportional to the axial dimension

area of the magnet is directly proportional to the axial dimension

area of the magnet is indirectly proportional to the square of the axial dimension

area of the magnet is directly proportional to the square of the axial dimension