QV A: For the power system shown, calculate fault current and when a 3-phase fault occurs at point F. The data are given below. Equipment XI X2 Rating 20% 20% 6% 2.50 50 MVA-II KV TI 10% 10% 10% 1/132 KV30 MVA LINE 1000 1000 3000 72 10% 10% 132/11 KV.30 MVA 10% MI 25% 25% 6% 40 MVA,1IKV M2 25% 25% 40 MVA,1IKV Line MI G TI MI Fault

QV A: For the power system shown, calculate fault current and when a 3-phase fault occurs at point F. The data are given below. Equipment XI X2 Rating 20% 20% 6% 2.50 50 MVA-II KV TI 10% 10% 10% 1/132 KV30 MVA LINE 1000 1000 3000 72 10% 10% 132/11 KV.30 MVA 10% MI 25% 25% 6% 40 MVA,1IKV M2 25% 25% 40 MVA,1IKV Line MI G TI MI Fault

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

Chapter7: Symmetrical Faults

Section: Chapter Questions

Problem 7.17P

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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.
Equipment ratings for the four-bus power system shown in Figure 7.14 are as follows: Generator G1: 500 MVA, 13.8 kV, X=0.20 per unit Generator G2: 750 MVA, 18 kV, X=0.18 per unit Generator G3: 1000 MVA, 20 kV, X=0.17 per unit Transformer T1: 500 MVA, 13.8/500YkV,X=0.12 per unit Transformer T2: 750 MVA, 18/500YkV,X=0.10 per unit Transformer T3: 1000Â MVA, 20/500YkV,X=0.10 per unit A three-phase short circuit occurs at bus 1, where the prefault voltage is 525 kV. Prefault load current is neglected. Draw the positive-sequence reactance diagram in per unit on a 1000-MVA, 20-kV base in the zone of generator G3. Determine (a) the ThĂ©venin reactance in per unit at the fault, (b) the subtransient fault current in per unit and in kA rms, and (c) contributions to the fault current from generator G1 and from line 1-2.
Consider the oneline diagram of a simple power system shown in Figure 9.20. System data in per-unit on a 100-MVA base are given as follows: The neutral of each generator is grounded through a current-limiting reactor of 0.08333 per unit on a 100-MVA base. All transformer neutrals are solidly grounded. The generators are operating no-load at their rated voltages and rated frequency with their ENIFs in phase. Determine the fault current for a balanced three-phase fault at bus 3 through a fault impedance ZF=0.1 per unit on a 100-MVA base. Neglect -Y phase shifts.
Figure 3.39 shows a oneline diagram of a system in which the three-phase generator is rated 300 MVA, 20 kV with a subtransient reactance of 0.2 per unit and with its neutral grounded through a 0.4- reactor. The transmission line is 64km long with a cries reactance of 0.5-/km. The three-phase transformer T1 is rated 350MVA.230/20kV with a leakage reactance of 0.1 per unit. Transformer T2 is composed of three single-phase transformers, each rated 100 MVA, 127/13.2kV with a leakage reactance of 0.1 per unit. Two 13.2kV motors M1 and M2 with a subtransient reactance of 0.2 per unit for each motor represent the load. M1 has a rated input of 200 MVA with its neutral grounded through a 0.4- current-limiting reactor, M2 has a rated input of 100 MVA with its neutral not connected to ground. Neglect phase shifts associated with the transformers. Choose the generator rating as base in the generator circuit and draw the positive-sequence reactance diagram showing all reactances in per unit.
At a 220 kV substation of a power system, it is given that the three-phase fault level is 4000 MVA and single-line to ground fault level is 5000 MVA. Neglecting the resistance and the shunt susceptances of the system, (B) And the zero sequence driving point reactance at the bus is: (@)2.2Q (b) 4.84Q (€)18.18 Q (d)22.72Q
In the shown below power system, both generators G1 and G2 emf’s are equal.All the system data are shown on the system diagram.a) Draw the system diagram in per unit using (MVA)base = 75 and (KV)base =20 KV in the generators side.b) Calculate the three-phase balanced short circuit current (If) at busbar 3 inAmpere and the fault level (MVA)sc in MVA.c) If the fault at busbar 3 is a line-to-line fault, calculate the fault current inAmpere and the fault level (MVA)sc in MVA.
Figure 2 shows the circuit of a simple power system. The ratings of the generators, transformers and the motors are as shown in the figure. The reactance of lines 1 and 2 are 40 ohms and 50 ohms respectively. Assume that system is unloaded, and the generators are generating their rated voltage. Select the generator G₁ ratings as base values. Choose the fault location in bus 1 And give the below answers For a symmetrical three phase fault on the bus (a).Determine the Thevenin's equivalent circuit which can be used to calculate the fault current. (b) Calculate the fault current contribution from the generator connected to the bus on which you have selected for fault calculation
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For the circuit shown, if a symmetrical three-phase fault occurs in node 2, determinea. The short-circuit current in all three phases. b. The voltage at node 1 during the fault.c. The current in generator 1 during the fault. Neglect the prefault currents and consider the reference voltage of the system at 10√3 ??.
For the following network, calculate the fault currents (IF1, IF2, IF3 and IF4) in pu and in kA, and circuit breaker ratings (i.e. fault MVA ) at the indicated locations. Internal reactance of generators are j0.9 pu. Base quantities: 11 kV, 400 MVA on the generator side.
A generator rated 100 MVA, 20 kV has X1=X2=20% and X0 =5% Its neutral is grounded through reactor of 0.32 ohms. The generator is operating at rated voltage with load and is disconnected from the system when a single line to ground fault occurs at its terminals. Find the subtransient current in the faulted phase and line to line voltage.
The 60 mile, 115 kV line GH (Figure P12.8) is operating with the voltages ateach end 30° out of phase when a three-phase fault occurs at 80% of the distance from bus G. This fault has 12 Ω arc resistance. The currents flowing tothe fault are as shown and are in per unit at 100 MVA, 115 kV.a. Determine the apparent impedance seen by the distance relays at G forthis fault.b. Determine if the zone 1 mho unit at G set for 90% of the line GH canoperate on this fault. Assume that the angle of the mho characteristic(Figure 6.12b) is 75°.c. Determine the apparent impedance seen by the distance relays at H for thisfault.