Three Phase Induction Motor Test - 2

1. What is the formula for the maximum current in end ring, if the current in all bars are maximum at the same time?

maximum current in the end ring= bars per pole * 2 / current per bar

maximum current in the end ring= bars per pole / 2 / current per bar

maximum current in the end ring= (bars per pole / 2) * current per bar

maximum current in the end ring= bars per pole * 2 * current per bar

2. The end resistance, if not negligible, will tend to distort the bar current distribution from being sinusoidal.

true

false

3. What is the formula for the maximum value of current through end ring, when the current is not maximum in all the bars under one pole at the same time?

maximum current in end ring= (2*3.14) / (bars per pole/2*no of poles) * current per bar

maximum current in end ring= (2/3.14) * (bars per pole/2*no of poles) / current per bar

maximum current in end ring= (2*3.14) * (bars per pole/2*no of poles) * current per bar

maximum current in end ring= (2*3.14) / (bars per pole/2*no of poles) / current per bar

4. The value of the current density is chosen for the end rings such that the desired value of rotor resistance is obtained.

true

false

5. What happens if the resistance of the end rings is negligible?

resistance coming in each current path is resistance of two bars

resistance coming in each current path is resistance of four bars

resistance coming in each current path is resistance of five bars

resistance coming in each current path is resistance of three bars

6. How does the revolving field produce emf in the bars?

revolving field produces emf of third frequency in the bars

revolving field produces emf of fundamental frequency in the bars

revolving field produces emf of no frequency in the bars

revolving field produces emf of sinusoidal frequency in the bars

7. What is the formula for the maximum current through each bar?

maximum value of the current through each bar = (2 * current through each bar)^1/2

maximum value of the current through each bar = (2 * current through each bar)²

maximum value of the current through each bar = (2 * current through each bar)^1/3

maximum value of the current through each bar = 2 * current through each bar

8. How is the current density of the rotor bars chosen with respect to the end rings?

current density of rotor bars > current density of end rings

current density of rotor bars = current density of end rings

current density of rotor bars < current density of end rings

current density of rotor bars <= current density of end rings

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

instantaneous emf

emfs, position of bars in magnetic field

instantaneous emfs, position of bars in magnetic field

emf

10. 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?

70 A

80 A

60 A

90 A

11. 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

12. 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) * (3.14*no of poles)

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