Design of Electrical Machines Practice Test 3

1. What is the formula for the height of the window?

height of window = area of window * width of the window

height of window = area of window / width of the window

height of window = area of window + width of the window

height of window = area of window - width of the window

2. What is the formula for the rms value of the end ring current?

rms value of end ring current = (bars per pole * current per bar) / (3.14*no of poles)

rms value of end ring current = (bars per pole * current per bar) / (3.14+no of poles)

rms value of end ring current = (bars per pole * current per bar) / (no of poles)

rms value of end ring current = (bars per pole * current per bar) * (3.14*no of poles)

3. What type of cooling is being made use of in transformers having a capacity of less than 11MVA?

air blast cooling

natural cooling

forced cooling and air blast cooling

forced cooling

4. What is the formula for the width of the window of the transformer?

width of the window = distance between core centers / diameter of the circumscribing circle

width of the window = distance between core centers - diameter of the circumscribing circle

width of the window = distance between core centers + diameter of the circumscribing circle

width of the window = distance between core centers * diameter of the circumscribing circle

5. What are the parameters which come under the term “Main Dimensions”?

diameter

diameter and length

area

length

6. What is the rating of the transformer for the voltage of about 11 kV?

100-500 kVA

100-3000 kVA

1000-2000 kVA

1000-5000 kVA

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

2.51 W per °c

12.3 W per °c

5.3 W per °c

30.8 W per °c

8. What is the range of the ratio of the core length to pole pitch for minimum cost?

1-2

1.0-1.25

2-2.5

1.5-2

9. What factors does the current in the bars depend on?

instantaneous emf

emf

emfs, position of bars in magnetic field

instantaneous emfs, position of bars in magnetic field

10. What is the formula for the width over one limb?

width over one limb = 2*Diameter + outer diameter of hv winding

width over one limb = outer diameter of hv winding

width over one limb = Diameter + outer diameter of hv winding

width over one limb = 2*Diameter – outer diameter of hv winding