Single Phase Induction Motor -- 2 Questions

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  • Thread starter jaus tail
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  • #1
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Homework Statement


upload_2018-1-13_11-54-5.png


Question 2
upload_2018-1-13_11-54-55.png


Homework Equations


Flux time lag depends on L/R ratio. More resistance, less time lag.
Single Phase IM---Double Revolving field theory

The Attempt at a Solution


For 1st question, I think answer should be A. BB circuit has more resistance so BB Flux will have less time lag than AA flux. So flux will sweep from right horizontal to down vertical like along third quadrant towards the negative Y axis.

But book answer is D

For second question. I think answer is A as per double revolving field theory but book answer is C.
Are book answer wrong or am I wrong somewhere?
 

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Answers and Replies

  • #3
jim hardy
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The Attempt at a Solution


For 1st question, I think answer should be A. BB circuit has more resistance so BB Flux will have less time lag than AA flux. So flux will sweep from right horizontal to down vertical like along third quadrant towards the negative Y axis.

Rather than try to solve it by intuition
How about if you calculate
what is the current in each winding (flux will be in proportion)

what is their phase difference ?
Has author mentioned any minimum phase difference necessary to start the motor?
If not, i agree motor should rotate one direction or the other..
http://www.learnengineering.org/201...eld-synchronous-speed-motor-single-phase.html

For second question. I think answer is A as per double revolving field theory ....

Unless he's allowing current to flow in the other winding, i'd say you're right. Has he hinted that winding B1 B2 is short circuited outside the motor ?
 
  • #4
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These are questions at back of book. No other information is given only these questions with answers at end.
 
  • #5
jim hardy
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See my reply to your other thread. I'm losing confidence in that textbook. old jim
 

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