A three-phase, eight-pole, 60-Hz, 4160-V, 1000-kW squirrel-cage induction motor has the following equivalent-circuit parameters in ohms per phase Y referred to the stator: R₁ = 0.220 R₂ = 0.207 X₁ = 1.95 X2 = 2.42 X_m = 45.7. Determine the changes in these constants which will result from the following proposed design modifications. Consider each modification separately.

a. Replace the stator winding with an otherwise identical winding with a wire size whose cross-sectional area is increased by 4 percent.

b. Decrease the inner diameter of the stator laminations such that the air gap is decreased by 15 percent.

c. Replace the aluminum rotor bars (conductivity 3.5 ? 10⁷ mhos/m) with copper bars (conductivity 5.8 ? 10⁷ mhos/m).

d. Reconnect the stator winding, originally connected in Y for 4160-V operation, in ? for 2.4 kV operation.

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3-phase Source Slip rings Induction Synchronous Shaft motor motor Rotor terminals