SSE JE Electrical Engineering 28 Oct 2020 Shift 1 Papers

Question : 157 of 200

Marks: +1, -0

A 75 kW, three-phase star-connected 50 Hz, 440 V cylindrical rotor synchronous motor operates at the rated condition with 0.8 power factor leading. The motor efficiency excluding field and starter losses is 95% and Xs = 2.5 Ω. Calculate the mechanical power developed.

780 W
7 KW
78950 W
79 W

Validate

Solution:

Efficiency

= \P _{ 0 } / \P _{ i }

Given

\η=95 \%

\P _{0}=75 \kW

∴\P _{ i }= \P _{ 0 } / \η

=75000 / 0.95

=78950 \W

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