Electrical Machines (EE4003) In-class questions 4

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Electrical Machines (EE4003) In-class questions

Q.1      A 50 Hz, four-pole, three-phase induction motor has 4 slots per pole per phase on the stator. The number of turns per phase of the stator winding is 400 and the effective length of core is 100 cm. The machine has a single-layer winding. All conductors in the same phase are connected in series. The leakage flux above the slot and toothis ignored. Fig. Q1 shows the slot shape of the stator, where

b1 = 2.0 cm b2 = 8 cm b3 = 10 cm

d1 = 2.0 cm d2 = 1.0 cm d3 = 1.0 cm d4 = 12 cm d5 = 1 cm.

Calculate the stator slot leakage reactance per phase. Explain how the slot leakage reactance will be changed

i)                     if b2 is increased but smaller than b3;

ii)                    if d5 is reduced;

iii)                   if the frequency is changed to 60 Hz.

Discuss each situation separately.