Please give the complete solution.... A 50-hp, six-pole, three-phase, 450-V, 60-

Question

Please give the complete solution....

A 50-hp, six-pole, three-phase, 450-V, 60-Hz, 1120 r/min induction motor, operating at rated conditions, has an efficiency of 91 percent and a power factor of 89 percent. When starting at rated voltage, the motor develops 170 percent rated torque and draws five times rated current. Determine (a) slip at rated conditions; (b) rated torque; (c) blocked-rotor torque; (d) rated line current, (e) Design a V-V transformer bank of the correct turns ratio that will limit the stator line current to 200 percent rated current. (f) Determine the primary line current for the conditions in (e); (g) motor line current when starting at the reduced voltage.

Explanation / Answer

given,

Is = 5I(rated)=5I

Ts=1.7T(rated)

so I(line) =5(5I) = 25I

so we know

Ts/T = (Is/I)^2 *s

s=1.7/25 =0.068

B)

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