75 kVA, 2400/4800 V, 50 Hz one-phase two-winding transformer will be connected as auto transformer with an input voltage of 4800 V and an output voltage of 7200 V. a)auto transformer rated power b)Auto transformer input, output and winding (common and series) currents c)Power values transmitted by induction and conduction

75 kVA, 2400/4800 V, 50 Hz one-phase two-winding transformer will be connected as auto transformer with an input voltage of 4800 V and an output voltage of 7200 V. a)auto transformer rated power b)Auto transformer input, output and winding (common and series) currents c)Power values transmitted by induction and conduction

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 3.58P: A single-phase two-winding transformer rated 90MVA,80/120kV is to be connected as an autotransformer...

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A single-phase l0-kVA,2300/230-volt,60-Hz two-winding distribution transformer is connected as an autotransformer to step up the voltage from 2300 to 2530 volts (a) Draw a schematic diagram of this arrangement, showing all voltages and currents when delivering full load at rated voltage. (b) Find the permissible kVA rating of the autotransformer if the winding currents and voltages are not to exceed the rated values as a two-winding transformer. How much of this kVA rating is transformed by magnetic induction? (C) The following data are obtained from tests carried out on the transformer when it is connected as a two-winding transformer: Open-circuit test with the low-voltage terminals excited: Applied voltage =230V, input current =0.45A, input power =70W. Short-circuit test with the high-voltage terminals excited: Applied voltage =120, input current =4.5A, input power =240W. Based on the data, compute the efficiency of the autotransformer corresponding to full load, rated voltage, and 0.8 power factor lagging. Comment on why the efficiency is higher as an autotransformer than as a two-winding transformer.
For developing per-unit equivalent circuits of single-phase three-winding transformer, a common Sbase is selected for all three windings and voltage bases are selected in proportion to the rated voltage of the windings (a) True (b) False
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For a short-circuit test on a 2-winding transformer, with one winding shorted, can you apply the rated voltage on the other winding? (a) Yes (b) No
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Consider Figure 3.4. For an ideal phase-shifting transformer, the imda nce is unchanged when it is referred from one side to the other. (a) True (b) False
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The label values of the single-phase transformer whose electrical equivalent circuit is given below are 20 kVA, 15400V / 240V, 50 Hz. This transformer Calculate what is required below. a. What is the value of the active power measured in the short circuit test? b. What is the value of the active power measured in the idle test? c. Voltage regulation was found to be 0.1% at 0.8 back power factor. Accordingly, using any method you want Find out how many kVA the transformer draws from the network (primary apparent power).