Fall_2012_HW#7 Solution

# 32 the power factor of motor is d 15 the magnitude and

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Unformatted text preview: angle of the armature current in the machine, ∴ c) | | 3 ∵ in this machine, 440 377.32 √3 1.5 3 | 191.705 The magnitude of the armature current and the new power factor is, | | | 0.9| 1.2 377.32 339.59 ∵ | ∴ 440 ∠0 √3 . | | ∴ ∴ | 31.44 339.59∠ 31.44 cos 11.39 120.47∠11.39 1.5 0.98 5 ECE3602012FLHW#7 Problem#4 a) The rated input power of this motor, 6600 Since it is Y connected, 6600 3811 √3 1404 √3 b) The . √3 6600 1404 16050 at rated conditions is (assume per unit bases are rated values), 1∠0 . . 1∠0 . . 1∠0 0.02 0.9 1∠0 0.98 0.9 1.33∠ 42.56 . . ∴ 1.33∠ 42.56 3811 5070.8∠ 42.56 c) At full-load 21000 100% 21000 746 / 16050 100 97.6% d) 21000 1200 746 / 1 60 2 124.67 . 1 6 ECE3602012FLHW#7 Problem #5 a) The input power to the motor at rated condition is, 100 746 0.86 86.74 b) The line current and the phase current at rated condition, 86.74 √3 √3 440 142.28 √3 142.28 0.8 82.14 √3 c) The reactive pow...
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