1. Gas insulated substation (GIS) use following gas for insulation a) CO2 b) Sulfur hexafluoride c) Nitrogen d) Helium 2. Which of the following Busbar arrangement has the best reliability? a) Single Busbar arrangement b) Single Busbar arrangement with sectionalization c) Double Busbar arrangement d) Not of above 3. The Townsends Criterion for Threshold sparking is given as: a) yead = 2 b) gad

1. Gas insulated substation (GIS) use following gas for insulation a) CO2 b) Sulfur hexafluoride c) Nitrogen d) Helium 2. Which of the following Busbar arrangement has the best reliability? a) Single Busbar arrangement b) Single Busbar arrangement with sectionalization c) Double Busbar arrangement d) Not of above 3. The Townsends Criterion for Threshold sparking is given as: a) yead = 2 b) gad

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

Chapter9: Unsymmetrical Faults

Section: Chapter Questions

Problem 9.19P

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b) A fault occurs at bus 4 of the network shown in Figure Q3. Pre-fault nodal voltages throughout the network are of 1 p.u. and the impedance of the electric arc is neglected. Sequence impedance parameters of the generator, transmission lines, and transformer are given in Figure Q3, where X and Y are the last two digits of your student number. V₁ = 120° p.u. V₂ = 120° p.u. jX(1) j0.1Y p.u. jX2)= j0.1Y p.u. jXko) j0.1X p.u. - 0 jX(1) = j0.2 p.u. 1JX(2) = 0.2 p.u. 2 jX1(0) = j0.25 p.u. jX2(1) j0.2 p.u. V₁=1/0° p.u. jX(2(2) = j0.2Y p.u. jX2(0) = j0.3X p.u. = V₂ = 120° p.u. jXT(1) j0.1X p.u. jXT(2) j0.1X p.u. JX3(1) j0.1Y p.u. JX3(2)=j0.1Y p.u. jXT(0) j0.1X p.u. JX3(0)=j0.15 p.u. 0- = 3 = Figure Q3. Circuit for problem 3b). For example, if your student number is c1700123, then: jXa(n) = j0.13 p. u., jXa(z) = j0.13 p. u., and jXa(o) = j0.12 p. u. 4 (i) Assuming a balanced excitation, draw the positive, negative and zero sequence Thévenin equivalent circuits as seen from bus 4. (ii)…
Fill in the blanks 1. Grounding is connecting …….. of electrical equipment to earth. 2. When a …………………………….… fault occurs on an ungrounded neutral system, the potential of the healthy phases rise to the line voltage. 3. The method of reactance grounding is not used because of ……………………… appearing under fault conditions. 4. The cosine of the angle between the ………………………………………. and the ………………………………...…… is called the sending end power factor. 5. The AC power delivered to a load is equal to ………........
b) A fault occurs at bus 4 of the network shown in Figure Q3. Pre-fault nodal voltages throughout the network are of 1 p.u. and the impedance of the electric arc is neglected. Sequence impedance parameters of the generator, transmission lines, and transformer are given in Figure Q3, where X and Y are the last two digits of your student number. jX(1) j0.1Y p.u. jX2)= j0.1Y p.u. jXko) = j0.1X p.u. V₁ = 120° p.u. V₂ = 120° p.u. (i) (ii) 0 jX(1) = j0.2 p.u. 1 jx(2) j0.2 p.u. 2 jX1(0) = j0.25 p.u. jXT(1) jXT(2) 종 3 j0.1X p.u. JX3(1) j0.1Y p.u. j0.1X p.u. JX3(2) j0.1Y p.u. jXT(0) j0.1X p.u. JX3(0)=j0.15 p.u. 0 = x = 1, jX2(1) j0.2Y p.u. V₁=1/0° p.u. jX(2(2) = j0.2Y p.u. jX2(0) = j0.3X p.u. = V3 = 120° p.u. Figure Q3. Circuit for problem 3b). For example, if your student number is c1700123, then: y = 7 = = jXa(r) = j0.13 p.u., jXa(z) = j0.13 p. u., and jXa(o) = j0.12 p. u. Assuming a balanced excitation, draw the positive, negative and zero sequence Thévenin equivalent circuits as seen from…
Maximum Voltage harmonics Order Vhmax 5 7 11 13 17 19 23 25 6% 5% 3.5% 3% 2% 1.5% 1.5% 1.5% 3) Draw the schematics of a HVDC and of a HVDC light, compare the systems evidencing advantages and disadvantages, describe their inclusion in a Load Flow. 4) Compare the critical distance method and the fault position method, evidencing the equations needed for each of the methods in case of sag due to three phase short circuit.
b) A fault occurs at bus 2 of the network shown in Figure Q3. Pre-fault nodal voltages throughout the network are of 1 p.u. and the impedance of the electric arc is neglected. Sequence impedance parameters of the generator, transmission lines, and transformer are given in Figure Q3, where X and Y are the last two digits of your student number. JX20 /0.1X p.u. jXa2) 0.1X p.u. JX20 j0.2Y p.u. V,= 120° p.u. V, 120° p.u. V, 120° p.u. jX4-70.2X p.u. jX2 j0.2X p.u. jX o 0.2Y p.u. jXncay J0.25 p.u. jXna J0.25 p.u. 3 jXno0.3 p.u. jXTu) /0.2Y p.u. jXra j0.2Y p.u. - j0.2Y p.u. Xp-10.1X p.u. jXa j0.1X p.u. jXp0)- j0.05 p.u. 0 Figure Q3. Circuit for problem 3b). For example, if your student number is c1700123, then: jXac1) = j0.22 p.u., jXac2) = j0.22 p.u., and jXaco) = j0.23 p. u. X-2 Y=8 (iv) Determine the short-circuit fault current for the case when a phase-to- phase fault occurs at bus 2.
b) A fault occurs at bus 4 of the network shown in Figure Q3. Pre-fault nodal voltages throughout the network are of 1 + j0 p.u, and the impedance of the electric arc is neglected (Zf = 0 + j0 p.u.). The positive, negative and zero sequence impedance parameters of the generator, transmission lines and transformer are given in Figure Q3. (i) Determine the positive sequence fault current for the case when a three-phase-to-ground fault occurs at bus 4 of the network (ii) Determine the short-circuit fault current for the case when a one-phase- to-ground fault occurs at bus 4. Recall that phasors can be expressed in terms of their symmetrical components as shown in the picture attached. where F stands for any three-phase quantity (e.g., current, voltage) (iii) Determine the short-circuit fault current for the case when a phase-to-phase fault occurs at bus 4 ReplyForward
In an outdoor substation the three bus-bar conductors are supported by units of post type insulators. Each unit consists of a stack of 3 pin type insulators fixed one on the top of the other. The voltage across the lowest insulator is 13kV and that across the next unit is 12KV. Estimate: 17. i. ratio of mutual to self-capacitance ii. the bus-bar voltage of the substation. iii. Efficiency across the string of insulators
Q2 Figure Q2 shows a single line diagram of a power system and the associated data of this system are given in Table Q2. The pre-fault load current and A-Y transformer phase shift are neglected. (a) (b) If a Single Line-to-Ground (S-L-G) fault occurs at Bus 5 and the pre-fault voltage is 1.0 pu, calculate the subtransient fault current in Ampere. (c) (d) (e) Using base of 100 MVA and 11 kV at generator G₁, construct the positive sequence, negative sequence and zero sequence networks with their corresponding component values indicated. G₁ Recalculate (b) if the neutral on HV side of T3 is solidly grounded. Repeat part (b) with Line-to-line (L-L) fault. What will happen to L-L fault current in (d) if the neutral on the HV side of T3 is solidly grounded? Bus 1 T₁ Bus 4 Line 1 Line 2 Figure Q2 Bus 5 T2 T3 Bus 2 Bus 3 G₂ G3
The system values are given below. The bus 1 voltage after fault = 1.5 p.u The bus 2 voltage after fault = 1.2 p.u The line admittance between bus 1 and bus 2 (Y12 ) is = 0.8 p.u The post fault current current flow between bus 1 and 2 is ..............
400Ω A k=0.9 600Ω B k=0.8 66Ω 600Ω
8.In a line-by-line failure we can expect Immersive reader A) Currents exist in the ground connections. B) The current values at the ground connections are zero. C) Short-circuit currents exist in all three phases. D) The voltages at the fault point with respect to ground are zero in the faulted phases. E) N. A.
9. Which grounding method is typically required of higher-voltage systems? A. Grounding through inductorsB. Grounding through a low amount of resistanceC. Grounding through a high-impedance device D. Grounding through surge arresters 10. Which term relates to the conductors connected to the output side of a separately derived system? A. Neutral conductorB. Transformer secondary conductorC. System conductor D. Derived phased conductor 11. If there's no service disconnect at a remotely supplied building, then the grounding electrode conductor and the equipment grounding conductor can be bonded together at a A. junction box.B. structural steel location. C. grounding electrode rod. D. water line. 12. In a DC system, the bonding jumper between the negative of the supply and ground is normally made at the source or at the A. first disconnecting means. B. first device on the supply. C. end of the DC line.D. entrance to the building. 13. Which of the following is a common raceway…