A 30 hp, three-phase, wye connected, 60 Hz, 360 VLL, synchronous motor is operating at 50% full load, rated voltage and 0.8 pf leading (over-excited). The motor has negligible armature resistance and a synchronous reactance of 2.5 02/phase. Stator core loss is 1kW and friction and windage loss is 1.5 kW. a. Calculate the new value of line-to-neutral excitation voltage and load angle when the field current is adjusted for 0.85 pf lagging with the same 15 hp load. Determine the load angle, current (with angle), and the reactive power exported (positive) or imported (negative), when the motor load is 30 hp and the line-to-neutral excitation voltage is 255V. b.

A 30 hp, three-phase, wye connected, 60 Hz, 360 VLL, synchronous motor is operating at 50% full load, rated voltage and 0.8 pf leading (over-excited). The motor has negligible armature resistance and a synchronous reactance of 2.5 02/phase. Stator core loss is 1kW and friction and windage loss is 1.5 kW. a. Calculate the new value of line-to-neutral excitation voltage and load angle when the field current is adjusted for 0.85 pf lagging with the same 15 hp load. Determine the load angle, current (with angle), and the reactive power exported (positive) or imported (negative), when the motor load is 30 hp and the line-to-neutral excitation voltage is 255V. b.

Delmar's Standard Textbook Of Electricity

7th Edition

ISBN:9781337900348

Author:Stephen L. Herman

Publisher:Stephen L. Herman

Chapter32: Three-phase Motors

Section: Chapter Questions

Problem 6RQ: Name three factors that determine the torque produced by an induction motor.

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