4.9 Given the system shown in Figure 4.24, calculate the currents in breakers 1, 3 and 5 for a fault at X for the following three conditions: (a) system normal (SIN); (b) line 1-2 open; (c) line 3-4 open. Select and set the appropriate relays from Appendix D for the relays at breakers 1, 3 and 5. Neglect load, and assume breaker 5 needs no coordination. 1 -j1.5- 2 70 v. 3 中 j0.5 5 4 中 j0.8 70 v. Figure 4.24 System diagram for problem 4.9 4.10 You are given that the system shown in Figure 4.25 has a 110/220 kV autotransformer. The positive, and zero-sequence impedances in ohms or percent are as shown in the figure the

4.9 Given the system shown in Figure 4.24, calculate the currents in breakers 1, 3 and 5 for a fault at X for the following three conditions: (a) system normal (SIN); (b) line 1-2 open; (c) line 3-4 open. Select and set the appropriate relays from Appendix D for the relays at breakers 1, 3 and 5. Neglect load, and assume breaker 5 needs no coordination. 1 -j1.5- 2 70 v. 3 中 j0.5 5 4 中 j0.8 70 v. Figure 4.24 System diagram for problem 4.9 4.10 You are given that the system shown in Figure 4.25 has a 110/220 kV autotransformer. The positive, and zero-sequence impedances in ohms or percent are as shown in the figure the

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 3.47P: Consider the oneline diagram shown in Figure 3.40. The three-phase transformer bank is made up of...

See similar textbooks

Similar questions

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.
Does winding geometry in transformers (winding method) have an effect on zero sequence impedance values in transformers?
A single line diagram of a power system is shown in Figure Q2.1. The neutrals for the generators and transformers are solidly grounded. The motor neutral is grounded through reactance ?? = 0.05 per unit on the motor base. i）Calculate the phase currents in kA following a three-phase fault at busbar 2. ii) Calculate the phase currents in kA when a phase-alpha-to-ground fault occurs at busbar 2.
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
b) The single line diagram of a power system is shown in Figure Q2.1 including generator and transformer winding connection and earthing details. The parameters for this system have been calculated on a common 100 MVA base and are given in Table Q2.1. All resistances and shunt susceptances are neglected. This system experiences a single line to ground fault at a point F on line L1. The point F is at a distance d from Bus 4 along the line LI. The total length of the line L1 is 50 km. Note that the location of d is not drawn to scale in Figure Q2.1. The fault current at the fault point F is measured to be 6.106 kA. G1 G1 G2 i) G2 T1 T2 T3 L1 11) 2 Rated voltage (kV) 20 20 20/33 20/33 33/11 11 T1 ΔΕ T2 T3 Figure Q2.1 Table Q2.1 Zero sequence reactance Xo (p.u.) 0.20 0.15 0.12 0.20 0.20 1.20 Positive sequence reactance X₁ (p.u.) 0.30 0.25 0.12 0.20 0.20 0.50 UNIVERSITY OF LIVERPOOL L1 (l-d) 5 Negative sequence reactance X₂ (p.u.) 0.35 0.30 0.12 0.20 0.20 0.50 Determine the zero, positive,…
The single line diagram of a power system is shown in Figure Q2.1 including generator and transformer winding connection and earthing details. The parameters for this system have been calculated on a common 100 MVA base and are given in Table Q2.1. All resistances and shunt susceptances are neglected. This system experiences a single line to ground fault at a point F on line L1. The point F is at a distance d from Bus 4 along the line L1. The total length ?? of the line L1 is 50 km. Note that the location of ?? is not drawn to scale in Figure Q2.1. The fault current at the fault point F is measured to be 6.106 kA. i) Determine the zero, positive, and negative sequence Thevenin equivalent impedances as seen at the fault point F. These should be evaluated in per unit and shown as a function of d.ii) Use the sequence impedances calculated in part (i) to determine the distance d of the fault (in km) from Bus 4.
4. Why adopt open delta test instead of direct loading test to calculate the efficiency of large transformers?
1 Example-1: In a single-loop distribution system shown in the figure consider the generator to be of infinite short-circuitcapacity and with a voltage of 1.0 pu. Determine the fault currents flowing in circuit breakers B1, B2 and Bz for a Three phase to ground fault in the midde of line 4-5 when: a) Both transformers, T, and T2 are in service b) Only T1 is in service 1 T1 2 From То Impedance 0.0 + j0.01(T,) 0.0 + j0.01(T2) 0.0 + j0.08 0.02 + j0.05 0.01 + j0.03 0.0 + j0.06 0.01 + j0.09 0.01 + j0.09 1 B. B2 Вз -머 3 4 4 T2 7 6 5 6. 7 7
The single line diagram of a power system is shown in Figure Q2.1 includinggenerator and transformer winding connection and earthing details. The parametersfor this system have been calculated on a common 100 MVA base and are given inTable Q2.1. All resistances and shunt susceptances are neglected. This systemexperiences a single line to ground fault at a point F on line L1. The point F is at adistance d from Bus 4 along the line L1. The total length l of the line L1 is 50 km.Note that the location of d is not drawn to scale in Figure Q2.1. The fault current atthe fault point F is measured to be 6.106 kA. i) Determine the zero, positive, and negative sequence Thevenin equivalentimpedances as seen at the fault point F. These should be evaluated in per unitand shown as a function of d.ii) Use the sequence impedances calculated in part (i) to determine the distance dof the fault (in km) from Bus 4. It's different from the answer, please don't send it
In a three-phase line, in order to avoid unequal phase inductances due to unbalanced flux linkages, what technique is used?
Equipment ratings for the five-bus power system shown in Figure 7.15 are as follows: Generator G1:Â Â Â Â 50Â MVA,Â 12kV,Â X=0.2 per unit Generator G2: 100Â MVA, 15 kV, X=0.2 per unit Transformer T1: 50 MVA, 10 kV Y/138kVY,X=0.10 per unit Transformer T2: 100 MVA, 15 kV /138kVY,X=0.10 per unit Each 138-kV line: X1=40 A three-phase short circuit occurs at bus 5, where the prefault voltage is 15 kV. Prefault load current is neglected. (a) Draw the positive-sequence reactance diagram in unit on a 100-MVA, 15-kV base in the zone of generator G2. Determine (b) the ThĂ©venin equivalent at the fault, (c) the subtransient fault current in per unit and in kA rms, and (d) contributions to the fault from generator G2 and from transformer T2.
With the same transformer banks as in Problem 3.47, Figure 3.41 shows the oneline diagram of a generator, a step-up transformer bank, a transmission line, a stepown transformer bank, and an impedan load. The generator terminal voltage is 15 kV (line-to-line). (a) Draw the per-phase equivalent circuit, aounting for phase shifts for positive-sequence operation. (b) By choosing the line-to-neutral generator terminal voltage as the reference, determine the magnitudes of the generator current, transmiss ion-line current, load current, and line-to-line load voltage. Also, find the three-phase complex power delivered to the load.