Design of Electrical Machines Practice Test 3

1. What is the loss dissipated by tubes by convection, given area of the tubes = 3.5?

12.3 W per °c

30.8 W per °c

2.51 W per °c

5.3 W per °c

2. What is the formula for the diameter of the circumscribing circle of the transformer?

diameter of the circumscribing circle = 3*square root of ratio of cross sectional area of the core to the space factor

diameter of the circumscribing circle = square root of ratio of cross sectional area of the core to the space factor

diameter of the circumscribing circle = 4*square root of ratio of cross sectional area of the core to the space factor

diameter of the circumscribing circle = 2*square root of ratio of cross sectional area of the core to the space factor

3. Given the bars per pole is 6 and the current per bar is 20 A, what is the value of the maximum current in the end rings?

60 A

70 A

90 A

80 A

4. The temperature difference between the incoming and outgoing water is greater than 10°C.

false

true

5. What is the formula for the calculation of rotor resistance?

rotor resistance = resistance of the bars - resistance of end rings

rotor resistance = resistance of the bars + resistance of end rings

rotor resistance = resistance of the bars / resistance of end rings

rotor resistance = resistance of the bars * resistance of end rings

6. The range of the ratio of the height of the window to the width of the window is 2-4.

false

true

7. What is the formula for the area of the ring?

area of the ring = depth of the end ring + thickness of the end ring

area of the ring = depth of the end ring - thickness of the end ring

area of the ring = depth of the end ring * thickness of the end ring

area of the ring = depth of the end ring / thickness of the end ring

8. What is the formula for height of the single phase core type transformer?

height = height of the window – height of the yoke

height = height of the window – (2*height of the yoke)

height = height of the window + (2*height of the yoke)

height = height of the window + height of the yoke

9. What is the range of the permissible peripheral speeds in the 3 phase induction machine?

60-70 m per s

40-70 m per s

50-70 m per s

60-75 m per s

10. What is the formula to calculate the number of turns/phase?

number of turns = secondary voltage * voltage per turn

number of turns = secondary voltage - voltage per turn

number of turns = secondary voltage / voltage per turn

number of turns = secondary voltage + voltage per turn