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3. A 200 MVA, 20 kV, 60 Hz Y-connected solidly grounded three phase synchronous generator connect...
1. A three-phase synchronous generator connected to a 345-KV transmission line through a transformer as shown...
1. A three-phase synchronous generator connected to a 345-KV transmission line through a transformer as shown in Figure P1. Parameters of both generator and transformer are given in the figure. Transformer losses and exciting current are neglected. A three-phase short-circuit occurs on the line side of the circuit breaker when the generator is operated at rated terminal voltage and at no-load. The breaker interrupts the fault three cycles after fault inception. Neglect the effect of the transformer on the time...
4. A generator having a solidly grounded neutral and rated 50-MVA, 30-kV has positive, negative-, and...
4. A generator having a solidly grounded neutral and rated 50-MVA, 30-kV has positive, negative-, and zero-sequence reactances of 35, 25, and 5 percent, respectively (a) What reactance must be placed in the generator neutral to limit the fault current for a bolted line-to-ground fault to that for a bolted three-phase fault? (b) What reactance must be placed in the generator neutral to limit the fault current for a bolted double line-to-ground fault to that for a bolted three-phase fault?
The positive, negative and zero-sequence reactances of a 20-MVA, 13.2 kV synchronous generator are 0.3 pu,...
The positive, negative and zero-sequence reactances of a 20-MVA, 13.2 kV synchronous generator are 0.3 pu, 0.2 pu, and 0.1 pu respectively. The generator is solidly grounded and is not loaded. If a double line-to-ground fault occurs at the generator terminals, calculate: (i) The fault current (ii) The line voltages (iii) Explain the steps that was carried out in the sequence voltage changes at all buses of the system. (Do include explanations and analysis of your solutions such as use...
A 300-MVA, 13.8-KV, three-phase, 60-Hz, Y-connected synchronous generator is adjusted to produce rated voltage on open...
A 300-MVA, 13.8-KV, three-phase, 60-Hz, Y-connected synchronous generator is adjusted to produce rated voltage on open circuit. A bal- anced three-phase fault is applied to the terminals at t = 0. After analyz- ing the raw data, the symmetrical transient current is obtained as 1 S.S. trans. iae(t) = 10(i + e 1/200 + 6e-1/15). sin ( 1 (a) Sketch inc(t) as a function of time for 0 st s 500 ms. (b) Determine X]" and X, in per unit...
Transformer TI : 50 MVA, 10 kV Y/138 kV Y, X=0.10 per unit; Transformer T2: 100 MVA, 15 kV D/138 kV Y, X-0.10 per unit; Each 138-kV line: X1-400 A three-phase short circuit occurs at bus 5,...
Transformer TI : 50 MVA, 10 kV Y/138 kV Y, X=0.10 per unit; Transformer T2: 100 MVA, 15 kV D/138 kV Y, X-0.10 per unit; Each 138-kV line: X1-400 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 per-unit on a 100-MVA, 15-kV base in the zone of generator G2. Determine: (b) the The'venin equivalent at the fault, (c) the subtransient fault current...
A single line diagram of a power system is shown in Fig. 2. The system data with equipment ratings and assumed sequence reactances are given the following table. The neutrals of the generator and A-Y...
A single line diagram of a power system is shown in Fig. 2. The system data with equipment ratings and assumed sequence reactances are given the following table. The neutrals of the generator and A-Y transformers are solidly grounded. The motor neutral is grounded through a reactance Xn 0.05 per unit on the motor base. Assume that Pre-fault voltage is takin as VF-1.0 ,0° per unit and Pre- fault load current and Δ-Y transformer phase shift are neglected In the...
The following are the answers: Autumn 2013 T1 G1 5 kV 50 MVA 5/20 kV 50...
The following are the answers:
Autumn 2013 T1 G1 5 kV 50 MVA 5/20 kV 50 MVA 20 kV 50 MVA X 0.1 p.u Figure A13 In the system shown, per-unit series equivalent impedances are shown for each element. Before a balanced 3-phase fault occurs in the location shown, the pre-fault current is at its rated value at 90 % lagging power factor flowing from generator G1 The generator is operating at full voltage. How much current in kA is...
The ratings of a three-phase, three-winding transformer are Y connected, 66 kV, 20 MVA Primary (1):...
The ratings of a three-phase, three-winding transformer are Y connected, 66 kV, 20 MVA Primary (1): Secondary (2):Y connected, 13.2 kV, 15 MVA Tertiary (3): A connected, 2.3 kV, 5 MVA Neglecting winding resistances and exciting current, the per-unit leakage reactances are: X12 0.08 on a 20-MVA, 66-kV base X13 0.10 on a 20-MVA, 66-kV base X23 0.09 on a 15-MVA, 13.2-kV base (a) Determine the per-unit reactances Xi, X2, X3 of the equivalent circuit on a 20- MVA, 66-kV...
QUESTION 3. (a) The positive-, negative- and zero-sequence reactances of a 20-MVA, 13.2-LV synchronous generator are...
QUESTION 3. (a) The positive-, negative- and zero-sequence reactances of a 20-MVA, 13.2-LV synchronous generator are 0.3 pu, 0.2 pu and 0.1 pu, respectively. The generator is solidly grounded and is not loaded. A line-to-ground fault occurs on phase a. Neglecting all the resistances, determine the fault current. Assume V, = 120° pu. (b) Explain why a bolted single-line-to-ground fault at the sending end of a transmission line might be higher than the bolted three-phase short circuit on the same...
QUESTION 4. A single-line diagram of a power system is shown in Figure Q3 below, where...
QUESTION 4. A single-line diagram of a power system is shown in Figure Q3 below, where negative and zero-sequence reactances are also given. The neutrals of the generator and A-Y transformers are solidly grounded. The motor neutral is grounded through a reactance X.=0.05 per unit on the motor base. Prefault voltage is VF1.05<Oº per unit whereas prefault load current is zero. Take A-Y transformer phase shifts into consideration. M Line tool X, - X2 - 200 100 MVA X =...
1. A three-phase synchronous generator connected to a 345-KV transmission line through a transformer as shown in Figure P1. Parameters of both generator and transformer are given in the figure. Transformer losses and exciting current are neglected. A three-phase short-circuit occurs on the line side of the circuit breaker when the generator is operated at rated terminal voltage and at no-load. The breaker interrupts the fault three cycles after fault inception. Neglect the effect of the transformer on the time...
4. A generator having a solidly grounded neutral and rated 50-MVA, 30-kV has positive, negative-, and zero-sequence reactances of 35, 25, and 5 percent, respectively (a) What reactance must be placed in the generator neutral to limit the fault current for a bolted line-to-ground fault to that for a bolted three-phase fault? (b) What reactance must be placed in the generator neutral to limit the fault current for a bolted double line-to-ground fault to that for a bolted three-phase fault?
A 300-MVA, 13.8-KV, three-phase, 60-Hz, Y-connected synchronous generator is adjusted to produce rated voltage on open circuit. A bal- anced three-phase fault is applied to the terminals at t = 0. After analyz- ing the raw data, the symmetrical transient current is obtained as 1 S.S. trans. iae(t) = 10(i + e 1/200 + 6e-1/15). sin ( 1 (a) Sketch inc(t) as a function of time for 0 st s 500 ms. (b) Determine X]" and X, in per unit...
Transformer TI : 50 MVA, 10 kV Y/138 kV Y, X=0.10 per unit; Transformer T2: 100 MVA, 15 kV D/138 kV Y, X-0.10 per unit; Each 138-kV line: X1-400 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 per-unit on a 100-MVA, 15-kV base in the zone of generator G2. Determine: (b) the The'venin equivalent at the fault, (c) the subtransient fault current...
A single line diagram of a power system is shown in Fig. 2. The system data with equipment ratings and assumed sequence reactances are given the following table. The neutrals of the generator and A-Y transformers are solidly grounded. The motor neutral is grounded through a reactance Xn 0.05 per unit on the motor base. Assume that Pre-fault voltage is takin as VF-1.0 ,0° per unit and Pre- fault load current and Δ-Y transformer phase shift are neglected In the...
The following are the answers:
Autumn 2013 T1 G1 5 kV 50 MVA 5/20 kV 50 MVA 20 kV 50 MVA X 0.1 p.u Figure A13 In the system shown, per-unit series equivalent impedances are shown for each element. Before a balanced 3-phase fault occurs in the location shown, the pre-fault current is at its rated value at 90 % lagging power factor flowing from generator G1 The generator is operating at full voltage. How much current in kA is...
The ratings of a three-phase, three-winding transformer are Y connected, 66 kV, 20 MVA Primary (1): Secondary (2):Y connected, 13.2 kV, 15 MVA Tertiary (3): A connected, 2.3 kV, 5 MVA Neglecting winding resistances and exciting current, the per-unit leakage reactances are: X12 0.08 on a 20-MVA, 66-kV base X13 0.10 on a 20-MVA, 66-kV base X23 0.09 on a 15-MVA, 13.2-kV base (a) Determine the per-unit reactances Xi, X2, X3 of the equivalent circuit on a 20- MVA, 66-kV...
QUESTION 3. (a) The positive-, negative- and zero-sequence reactances of a 20-MVA, 13.2-LV synchronous generator are 0.3 pu, 0.2 pu and 0.1 pu, respectively. The generator is solidly grounded and is not loaded. A line-to-ground fault occurs on phase a. Neglecting all the resistances, determine the fault current. Assume V, = 120° pu. (b) Explain why a bolted single-line-to-ground fault at the sending end of a transmission line might be higher than the bolted three-phase short circuit on the same...
QUESTION 4. A single-line diagram of a power system is shown in Figure Q3 below, where negative and zero-sequence reactances are also given. The neutrals of the generator and A-Y transformers are solidly grounded. The motor neutral is grounded through a reactance X.=0.05 per unit on the motor base. Prefault voltage is VF1.05<Oº per unit whereas prefault load current is zero. Take A-Y transformer phase shifts into consideration. M Line tool X, - X2 - 200 100 MVA X =...
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