The effective resistance of a 2200 V, 50 Hz, 440 KVA, 1 -phase alternator is 0.5 ohm. On short-circuit, a field current of 40 A gives the full load current of 200 AS. The electromotive force on open-circuits with same field excitation is 1160 V. Then the synchronous impedance and reactance is _______ ohm and _______ ohm respectively.

The effective resistance of a 2200 V, 50 Hz, 440 KVA, 1 -phase alternator is 0.5 ohm. On short-circuit, a field current of 40 A gives the full load current of 200 AS. The electromotive force on open-circuits with same field excitation is 1160 V. Then the synchronous impedance and reactance is _ ohm and _ ohm respectively.

Power System Analysis and Design (MindTap Course List)

6th Edition

ISBN:9781305632134

Author:J. Duncan Glover, Thomas Overbye, Mulukutla S. Sarma

Publisher:J. Duncan Glover, Thomas Overbye, Mulukutla S. Sarma

Chapter3: Power Transformers

Section: Chapter Questions

Problem 3.25P: Consider a single-phase electric system shown in Figure 3.33. Transformers are rated as follows:...

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Consider a three-phase generator rated 300MVA,23kV, supplying a system load of 240 MA and 0.9 power factor lagging at 230 kV through a 330MVA,23/230Y-kV step-up transformer with a leakage reactance of 0.11 per unit. (a) Neglecting the exciting current and choosing base values at the load of 100 MVL and 230 kV. Find the phasor currents IA,IB, and IC supplied to the load in per unit. (b) By choosing the load terminal voltage IA as reference, specify the proper base for the generator circuit and determine the generator voltage V as well as the phasor currents IA,IB, and IC, from the generator. (Note: Take into account the phase shift of the transformer.) (C) Find the generator terminal voltage in kV and the real power supplied by the generator in MW. (d) By omitting the transformer phase shift altogether, check to see whether you get the same magnitude of generator terminal voltage and real power delivered by the generator.
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Consider the oneline diagram shown in Figure 3.40. The three-phase transformer bank is made up of three identical single-phase transformers, each specified by X1=0.24 (on the low-voltage side), negligible resistance and magnetizing current, and turns ratio =N2/N1=10. The transformer bank is delivering 100 MW at 0.8 p.f. lagging to a substation bus whose voltage is 230 kV. (a) Determine the primary current magnitude, primary voltage (line-to-line) magnitude, and the three-phase complex power supplied by the generator. Choose the line-to-neutral voltage at the bus, Va as the reference Account for the phase shift, and assume positive-sequence operation. (b) Find the phase shift between the primary and secondary voltages.
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2- Why it's imporctical carry out actual load test on large rating transformers ?3- What will be the current in the primary windings?i) When secondaries are not loaded ?ii) When secondaries are loaded ?
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