3. Two electric furnaces are supplied with 1-phase current at 80 V from 3-phase, 11,000-V supply mains by means of two Scott-connected transformers with similar secondary windings. Calculate the current flowing kW respectively in each of the 3-phase lines at U.P.P. when the loads on the two transformers are 550 kW of 800 kW. [With 550 kW on teaser, line currents are : 57.5 A; 78.2; 78.2 A] (Electrical Machines-I, Madras

3. Two electric furnaces are supplied with 1-phase current at 80 V from 3-phase, 11,000-V supply mains by means of two Scott-connected transformers with similar secondary windings. Calculate the current flowing kW respectively in each of the 3-phase lines at U.P.P. when the loads on the two transformers are 550 kW of 800 kW. [With 550 kW on teaser, line currents are : 57.5 A; 78.2; 78.2 A] (Electrical Machines-I, Madras

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 3.43P: Three single-phase transformers, each rated 10MVA,66.4/12.5kV,60Hz, with an equivalent series...

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Two balanced three-phase loads that are connected in parallel are fed by a three-phase line having a series impedance of (0.4j2.7) per phase. One of the loads absorbs 560 kVA at 0.707 power factor lagging, and the other 132 kW at unity power factor. The line-to-line voltage at the load end of the line is 2203V. Compute (a) the line-to-line voltage at the source end of the line. (b) the total real and reactive power losses in the three-phase line, and (c) the total three-phase real and reactive power supplied at the sending end of the line. Check that the total three-phase complex power delivered by the source equals the total three-phase comp lex power absorbed by the line and loads.
One advantage of balanced three-phase systems over separate singlephase systems is reduced capital and operating costs of transmission and distribution. (a) True (b) False
Figure 3.32 shows the oneline diagram of a three-phase power system. By selecting a common base of 100 MVA and 22 kV on the generator side, draw an impedance diagram showing all impedances including the load impedance in per-unit. The data are given a follows: G:90MVA22kVx=0.18perunitT1:50MVA22/220kVx=0.10perunitT2:40MVA220/11kVx=0.06perunitT3:40MVA22/110kVx=0.064perunitT4:40MVA110/11kVx=0.08perunitM:66.5MVA10.45kVx=0.185perunit Lines I and 2 have series reactances of 48.4 and 65.43, respectively. At bus 4, the three-phase load absorbs 57 MVA at 10.45 kV and 0.6 power factor lagging.
A balanced three-phase load is connected to a 4.16-kV, three-phase, fourwire, grounded-wye dedicated distribution feeder. The load can be mode led by an impedance of ZL=(4.7+j9)/phase, wye-connected. The impedance of the phase conductors is (0.3+j1). Determine the following by using the phase A to neutral voltage as a reference and assume positive phase sequence: (a) Line currents for phases A, B, and C. (b) Line-to-neutral voltages for all three phases at the load. (c) Apparent. active, and reactive power dissipated per phase, and for all three phases in the load. (d) Active power losses per phase and for all three phases in the phase conductors.
Three single-phase transformers, each rated 10MVA,66.4/12.5kV,60Hz, with an equivalent series reactance of 0.1 per unit divided equally between primary and secondary, are connected in a three-phase bank. The high-voltage windings are V-connected and their terminals are directly connected to a 115-kV three-phase bus. The secondary terminals are all shorted together. Find the currents entering the high-voltage terminals and leaving the low-voltage terminals if the low-voltage windings are (a) Y-connected and (b) - connected.
In the above figure, a single line model of a three-phase power system is given. Base power 50MVA, base voltage 13.8kV according to its value, a) Per-unit values of power system circuit elements according to the given base power and base voltage values. calculate. b) The perunit you calculate by drawing the equivalent impedance circuit for one phase of the power system given in the figure. show on the values.
The one-line diagram of a three-phase power system is as shown in the figure attached. Impedances are marked in per unit on a 100-MVA, 400-kv base. The load at bus 2 is S(sub 2) = 15.93 MW - j33.4 Mvar, and bus 3 is S(sub 3) = 77MW + j14 Mvar. I tis required to hold the voltage at bus 3 at 400 angle 0 degrees kV. Working in per unit, determine the voltage at buses 2 and 1.
An 11 KV, 3-phase transmission line has a resistance of 1.5 Ω and reactance of 4 Ω per phase.Calculate the percentage regulation and efficiency of the line when a total load of 5000 KVA at 0.8 lagging power factor is applied at 11KV at the distant end.
A single phase transmission line is delivering 490 kVA load at 14 kV. Its resistance is 6 Ω and inductive reactance is 7 Ω if the load power factor is 0.7 lagging. Determine the: A) Current through the line. B) Sending end voltage. C) Sending end power factor. D) Regulation of transmission line. E) Efficiency of transmission line.
1. A 69-kV, three-phase short transmission line is 16 km long. The line has a per phase series impedance of 0.125+j0.4375 Ω per km. Determine the sending end voltage, voltage regulation, the sending end power, and the transmission efficiency when the line delivers (a) 70 MVA, 0.8 lagging power factor at 64 kV. (b) 120 MW, unity power factor at 64 kV. Use lineperf program to verify your results. 2. A three-phase, 765-kV, 60-Hz transposed line is composed of four ACSR, l,431,000-cmil, 45/7 Bobolink conductors per phase with flat horizontal spacing of 14 m. The conductors have a diameter of 3.625 cm and a GMR of 1.439 cm. The bundle spacing is 45 cm. The line is 400 km long, and for the purpose of this problem, a lossless line is assumed. (a) Determine the transmission line surge impedance Zc, phase constant ß, Wavelength, the surge impedance loading SIL, and the ABCD constant. b) The line delivers 2000 MVA at 0.8 lagging power factor at 735 kV. Determine the sending end quantities and…
470 kVA load at 12 kV. Its resistance is 7 Ω and inductive reactance is 7 Ω if the load power factor is 0.9 lagging. Determine the Current through the line , Sending end voltage , Sending end power factor , Regulation of transmission line , Efficiency of transmission line Note:please do not handwriting
Refer to the 5-bus data given below. Sbase = 400 MVA, the base voltage is 15.0 kV for buses 1 and 3, and 345 kV for buses 2, 4, 5. Note that 1-5 and 3-4 are 15/345 kV transformers.a) Draw a one-line diagram of the power system.b) Find the elements Y23, Y43, Y11 Y33 of the system bus admittance matrix.