MINIMUM BRANCH- LOAD COUNT VA/UNIT NEC LOAD CONNECTED LOAD CALCULATED LOAD NEUTRAL LOAD CIRCUIT Classrooms NEC 220.12 Luminaires Subtotal Corridor NEC 220.12 Luminaires Subtotal Exterior Luminaires Subtotal Receptacles NEC 220.14(1) Subtotal Motors NEC 220.14(C) Subtotal Totals 10. The calculated load is VA. 11. The connected load is V.

MINIMUM BRANCH- LOAD COUNT VA/UNIT NEC LOAD CONNECTED LOAD CALCULATED LOAD NEUTRAL LOAD CIRCUIT Classrooms NEC 220.12 Luminaires Subtotal Corridor NEC 220.12 Luminaires Subtotal Exterior Luminaires Subtotal Receptacles NEC 220.14(1) Subtotal Motors NEC 220.14(C) Subtotal Totals 10. The calculated load is VA. 11. The connected load is V.

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 9.18P

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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.
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
What is the per unit impedance of a 50 MVA, 2% impedancetransformer if the base is changed to 100 MVA?
Question 3. A three-phase impedance load balanced D a connected load in parallel with a balanced ? connected load made of bonding. D each arm for the load ?D = 6 + 6? and ? each arm for the connected load It is given as ?? = 2 + 2?. ? the connected load ?? = 1? is earthed through the neutral impedance. To this impedance load, the symmetrical component voltages ?0 = 10∠60°, ?1 = 100∠0° and ?2 = Unbalanced phase-to-earth voltages ??, ?? and ?? of 15∠200° volts were applied. a) Draw the zero, positive and negative sequence circuits. b) Find the complex powers imparted to each component circuit.
What is the Ybus ? voltages and impedances are given per-unit.
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.
The one line diagram of a simple three bus power system is shown in figure Each generator is represented by an emf behind the subtraction 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. Athree phase fault occurs at bus 3 through a fault impedance of Zf=j0.19 per unit. a-using thevenin’s theorem obtain the impedance to the point of fault and the fault current in per unit. b-determine the bus voltage and line currents during fault
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
Calculate the initial symmetrical short circuit current that will occur when a 3 phase short circuit error occurs at the F point in the Figure below İ k3 phase-max ?
determine the ransfer function of this system using block diagram transformations like moving pickoff points and/or moving summing points.
In short circuit studies, the positive sequence bus impedance matrix [Z1bus] and negative sequencebus impedance matrix [Z2bus] are assumed to be _______________
A single-line diagram of a four-bus system is shown in fiugre. Equipment ratings and per-unit reactances are given as follows.Machines 1 and 2: 100 MVA 20 kV; X1= X2 = 0.2; X0= 0.04 Xn= 0.05 Transformers T1 and T2: 100 MVA 20Y/345Y kV; X1 = X2 = X0 = 0.08. On a base of 100 MVA and 345 kV in the zone of the transmission line, the series reactances of the transmission line are X1 = X2 = 0.15 and X0=0.5 per unit. (a) Determine the bus impedance matrix for each of the three sequence networks. (b) Assume the system to be operating at nominal system voltage without prefault currents when a bolted single-line-toground fault occurs on phase A at bus 3. Compute the fault current, the current out of phase C of machine 2 during the fault, and the line-toground voltages at the terminals of machine 2 during the fault. Total detailed answer is needed. The figure is attached.