The one-line diagram of a simple power system is shown in the figure. The neutral of each generator is grounded through a current-limiting reactor of 0.25/3 per unit on a 100- MVA base. The system data expressed in per unit on a common 100-MVA base is tabulated below. The generators are running on no-load at their rated voltage and rated frequency with their emfs in phase. Determine the fault current and voltages for the following faults. a. A double line to ground fault at bus 3 through a fault impedance Z, = j0.125 per unit.

The one-line diagram of a simple power system is shown in the figure. The neutral of each generator is grounded through a current-limiting reactor of 0.25/3 per unit on a 100- MVA base. The system data expressed in per unit on a common 100-MVA base is tabulated below. The generators are running on no-load at their rated voltage and rated frequency with their emfs in phase. Determine the fault current and voltages for the following faults. a. A double line to ground fault at bus 3 through a fault impedance Z, = j0.125 per unit.

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 3.56P: Three single-phase two-winding transformers, each rated 3kVA,220/110volts,60Hz, with a 0.10 per-unit...

See similar textbooks

Similar questions

6. A 3 phase fault occurs at point F as shown in figure. Determine the critical clearing anglefor the system. The generator is delivering 1.0 p.u power under prefault conditio
Q2. The single-line diagram of a simple three-bus power system is shown in Figure-2. Each generator is represented by an emf behind the sub-transient reactance. All impedances are expressed in per unit on a common MVA base. All resistances and shunt capacitances are neglected. The generators are operating on no load at their rated voltage with their emfs in phase. A three-phase fault occurs at bus 3 through a fault impedance of Zf = j0.19 per unit. (i) Using Th'evenin's theorem, obtain the impedance to the point of fault and the fault current in (ii) Determine the bus voltages per unit. ) j0.05 j0.075 j0.75 2 j0.30 j0.45 Figure-2: Single line diagram of the power system network for Q2 3
13.a. Eddy-current loss in the stator core can be reduced by usingA. alloys with low resistivity.B. annealed iron laminations.C. silicon alloys of copper.D. thin laminations of steel.13.b. Which one of the following is damaging to many insulating materials used in alternators?A. Eddy currentsB. SaturationC. CoronaD. Hysteresis
A 3 phase fault occurs at point F as shown in figure. Determine the critical clearing anglefor the system. The generator is delivering 1.0 p.u power under prefault condition.
The bus bars of a power station are in two sections A and Bseparated by a reactor. Connected in section A are two 12MVA generators of 15% reactance each and to B, 8 MVAgenerator of reactance 10%. The reactor is rated 8 MVA and15% reactance. Two feeders are connected to bus bar Athrough transformers, each rated at 4 MVA and 5% reactance.Determine the maximum short circuit MVA with which circuitbreakers on the outgoing side of the transformers have todeal.
What is the maximum volt-ampere rating of transformers supplying Class 2 systems? ___________
Three single-phase two-winding transformers, each rated 3kVA,220/110volts,60Hz, with a 0.10 per-unit leakage reactance, are connected as a three-phase extended autotransformer bank, as shown in Figure 3.36(c). The low-voltage winding has a 110 volt rating. (a) Draw the positive-sequence phasor diagram and show that the high-voltage winding has a 479.5 volt rating. (b) A three-phase load connected to the low-voltage terminals absorbs 6 kW at 110 volts and at 0.8 power factor lagging. Draw the per-unit impedance diagram and calculate the voltage and current at the high-voltage terminals. Assume positive-sequence operation.
What are FACTS (Flexible Alternating Current Transmission Systems) devices, and how do they enhance power system control?
two alternators A and B having 5% speed regulation are working in parallel at a station. Alternator A is rated at 15 MW while B is at 20 MW. When the total load to be shared is 12 MW, then how much of the load will be shared by the alternator B?
synchronous generator threewThe phases are rated at 1000 kVA and operate at a voltage of 6.6 kV. The product resistance per phase is 0.38 ohms and the leakage reactance is 0.5 ohms per phase. The generator works to provide full load at a power factor of 0.85 delayed and at normal voltages. Find the value of the no-load voltage.
A three-phase, wye-connected, 6.25kVA, 220-synchronous generator has a reactance of 8.4 ohms per phase. Using the rated KVA and voltage as base values, determine the per – unit reactance. Then refer this per – unit value to a 230 – V, 7.5 kVA base.
1.a. Separate voltage-regulating units provide voltage-ratio control under load byA. causing different impedance drops in each phase.B. combining voltages from different phases.C. having series transformers in phase with the line-to-neutral voltage.D. exciting transformers having their primaries delta-connected. 1.b. A reactor is sometimes used with an autotransformer toA. limit short-circuit current.B. increase the full-load current.C. provide increased internal impedance.D. decrease the voltage ratio.