5. Repeat the previous problem for a single-line-to-ground arcing fault with are impedance

Problem-2 A junior engineer for Evergy has been given the assignment to design a new 4.16 kV. three-phase feeder that will have the following characteristics: The total length of feeder = 5000 ft Load: Ten 500 kVA (three-phase), 0.9 lagging power spaced every 500 ft with the first load 500 ft from the substation Voltage drop: Not to exceed 5% from the sub to the last load Figure. 2 illustrates the new feeder. The engineer has decided to use 336,400 26/7 ACSR (Linnet) conductors constructed on 45 ft poles with 8 ft crossarms. The spacings of the conductors on the crossarms are 2.5, 4.5, and 7.0 ft. a. Determine the percent voltage drop to the last load point and the total three- phase power loss for the feeder as shown in Figure. 2 b. Lump the total feeder load at the midpoint of the feeder and compute the percent voltage drop to the end of the feeder. c. Use the "exact lumped load model and compute the percent voltage drop to the end of the line and the total three-phase power loss down the line.

Part a) In no more than 200 words explain why a phase shift occurs between the current and voltage in an inductor and describe the characteristics of that phase shift in an ideal and a real inductor.

Part b) An electrical load of unknown characteristics, is connected to an AC power supply. The voltage and (lagging) current supplied to it are recorded and are shown in Figure 1. (i) Which basic circuit components, connected in series, could you use to represent this load in an equivalent circuit? Explain your choices and using the data from the graph, calculate their values. (25%) (ii) The frequency of the supply is slowly increased up to double the value shown in the graph, but the measured voltage amplitude remains the same. Create a graph, showing how - the magnitude of the phasor current drawn by the load, and 101 - the phase angle between the current and voltage, vary with the increasing frequency.

Part c) (i) The supply frequency is returned to its previous value and the load from part b) is replaced with another and the measured voltage and current characteristics are shown in Figure 2. Explain what kind of load this is and calculate its impedance. (ii) The frequency of supply is again slowly increased to double the value of that shown in Figure 2, with the voltage magnitude is held constant. Produce a graph showing how |I| and |Z| vary as the frequency increases.

1. The single line diagram, shown below, has the following ratings and reactances: G1: 100 MVA, 25 kV, X1-X2-0.20, X0-0.05 per unit, Zng-j0.03 G2: 100 MVA, 13.8 kV, X1-X2-0.20, X0=0.05 per unit, Zng-j0.03 T1: 100 MVA, 25 kV Y/230 kV Y, X-0.05 per unit T2: 100 MVA, 13.8 kV A/230 kV Y, X-0.05 per unit Line 1-2: 100 MVA, 230 kV, X1=X2-0.1, X0-0.3 Line 1-3: 100 MVA, 230 kV, X1-X2-0.1, X0-0.3 Line 2-3: 100 MVA, 230 kV, X1=X2-0.1, X0-0.3 Using a 100 MVA, 230 kV base for the transmission lines, draw the per-unit sequence networks and reduce them to their Thevenin equivalents, "looking in" at bus 3. Neglect transformer phase shifts. Compute the fault currents for a bolted three-phase fault at bus 3.

3. During a phase "a" single line-to-ground fault, the phase angle on phase "a" voltages is always zero. Explain why we would expect this behavior for a bolted SLG fault.

2. In a distribution feeder shown in the following figure, the loads are $1 = 600 kVA, S2=300 kVA, and S3 = 500 kVA (a) If the Kdrop factor of the feeder is 0.000147 % drop/kVA-km, calculate the total percent drop from N1 to N3. (b) If the total percentage drop from N2 to N4 is 2.1%, calculate the Kdrop factor of the feeder. (c) A capacitor of 300 kVAr is connected at the node N4. If the voltage drop is improved from 2.8% to 1.5% due to the capacitor for the given loading, calculate the Krise factor (%rise / kVAr-km) of the feeder.

Problem 5: A 60Hz 30 EHV TL has four ACSR Finch conductors per bundle with an operating temperature of 25°C, and is arranged as shown below. Find its per phase resistance, inductance, and reactance per km. Also, determine the current carrying capacity per phase. Assume the TL is fully transposed.

1. A single-phase lateral serves four transformers as shown in Figure. 1. Assume that each customer's maximum demand is 15.5 kW + j7.5 kvar. The impedance of the single-phase lateral is z = 0.4421 + j0.3213 2/1000 ft. The four transformers are rated as T1 and T2: 37.5 kVA, 2400-240 V, Z = 0.01 + j0.03 per unit T3 and T4: 50 kVA, 2400-240 V, Z = 0.015 + j0.035 per unit Use the DF's in Table 1 and determine the following: (a) Determine the total 15 min maximum diversified kW and kvar demands on each transformer. (b) The 15 min maximum diversified kW and kvar demands for each line section. (c) If the voltage at node 1 is 2600/0 V, determine the voltage at nodes 2 through 9. In calculating the voltages, take into account diversity using the answers from (a) and (b). (d) Take the maximum diversified demand from node 1 to node 2 and "allocate" that to each of the four transformers based on their kVA ratings. To do this, take the maximum diversified demand and divide it by 175 (total kVA of the four transformers). Now multiply each transformer's kVA rating by that number to give how much of the total diversified demand is being served by each transformer. Again, calculate all the voltages. (e) Compute the percent differences in the voltages for parts (c) and (d) at each of the nodes using part (c) answer as the base.