Question

A three-phase wye-connected (Y) synchronous generator is operating at Ea = 8.OLO° kV (lineneutral) and has synchronous reactance of X~ = 1.0 fl . The generator is connected to a threephase delta-wye connected step-down transformer that is constructed from three individual single-phase transformers. Each the single-phase transformers has rated power of 200 kVA has a turns ratio of 4:1 where the rated primary voltage of 8.0 kV and a rated secondary of 2.0 kV and a per-unit series reactance of 5% (neglect series resistances, core loss resistance and magnetizing reactance). The three-phase transformer supplies power to a three-phase 4-pole induction motor. The induction motor has the following parameters (all values referred to the stator circuit).

R1= 0.500 0 ohms, R2= 0.5000 ohms X1= 1.00 ohms, X2= 1.00 ohm and Xm =10.00 ohm

A)Determine the magnitude of the generator line current when the motor is started from a zero-speed condition

B) What is the line-line (magnitude) of the motor’s stator voltage under the conditions in part ‘a’?

Answer 1