Q5. With reference to three phase induction motors:
a) Explain the phenomenon of crawling and cogging in these motors. (6)
b) The output of an induction motor running at 4% slip is 36.775 kW and the friction and windage losses are 1500W. find the rotor copper loss and motor efficiency if stator losses are 3kW. (10)
Q1. a) Write a short note on the principle of operation of induction motors (8)
b) What is slip for an induction motor? (4)
c) If a 6-pole motor is supplied at 60Hz and runs with a slip of 5%. What is the actual rotor speed? (4)
Q2. Describe how the starting torque of electric induction motors may be improved by using EACH of the following:
(a) Wound rotor; (5)
(b) Double cage. (5)
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