determine the per-unit impedances and the per-unit source voltage. Then cal- culate the load current both in per-unit and in amperes. Transformer winding resistances and shunt admittance branches are neglected. V₂ Zone 1 = 220/0° volts Three zones of a single-phase circuit are identified in Figure 3.10(a). The zones are connected by transformers T₁ and T₂, whose ratings are also shown. Using base values of 30 kVA and 240 volts in zone 1, draw the per-unit circuit and مع و T₁ 30 kVA 240/480 volts = 0.10 p.u. Xa Zone 2 Xune 202 उह T₂ 20 KVA 460/115 volts = 0.10 p.u. Xea Zone 3 کند Zload = 0.9 +10.20 ทะ

determine the per-unit impedances and the per-unit source voltage. Then cal- culate the load current both in per-unit and in amperes. Transformer winding resistances and shunt admittance branches are neglected. V₂ Zone 1 = 220/0° volts Three zones of a single-phase circuit are identified in Figure 3.10(a). The zones are connected by transformers T₁ and T₂, whose ratings are also shown. Using base values of 30 kVA and 240 volts in zone 1, draw the per-unit circuit and مع و T₁ 30 kVA 240/480 volts = 0.10 p.u. Xa Zone 2 Xune 202 उह T₂ 20 KVA 460/115 volts = 0.10 p.u. Xea Zone 3 کند Zload = 0.9 +10.20 ทะ

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

Chapter3: Power Transformers

Section: Chapter Questions

Problem 3.53P: The ratings of a three-phase, three-winding transformer are Primary: Y connected, 66kV,15MVA...

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Similar questions

Consider three ideal single-phase transformers (with a voltage gain of ) put together as three-phase bank as shown in Figure 3.35. Assuming positive-sequence voltages for Va,Vb, and Vc find Va,Vb, and VC. in terms of Va,Vb, and Vc, respectively. (a) Would such relationships hold for the line voltages as well? (b) Looking into the current relationships, express IaIb and Ic in terms of IaIb and Ic respectively. (C) Let S and S be the per-phase complex power output and input. respectively. Find S in terms of S.
The per-unit equivalent circuit of two transformers Ta and Tb connected in parallel, with the same nominal voltage ratio and the same reactan of 0.1 per unit on the same base, is shown in Figure 3.43. Transformer Tb has a voltage-magnitude step-up toward the load of 1.05 times that of Ta (that is, the tap on the secondary winding of Tb is set to 1.05). The load is represented by 0.8+j0.6 per unit at a voltage V2=1.0/0 per unit. Determine the complex power in per unit transmitted to the load through each transformer, comment on how the transformers share the real and reactive powers.
With the same transformer banks as in Problem 3.47, Figure 3.41 shows the oneline diagram of a generator, a step-up transformer bank, a transmission line, a stepown transformer bank, and an impedan load. The generator terminal voltage is 15 kV (line-to-line). (a) Draw the per-phase equivalent circuit, aounting for phase shifts for positive-sequence operation. (b) By choosing the line-to-neutral generator terminal voltage as the reference, determine the magnitudes of the generator current, transmiss ion-line current, load current, and line-to-line load voltage. Also, find the three-phase complex power delivered to the load.
A single-phase three-winding transformer has the following parameters: Z1=Z2=Z3=0+j0.05,Gc=0, and BM=0.2 per unit. Three idenucal transformers, as described, are connected with their primaries in Y (solidly grounded neutral) and with their secondaries and tertiaries in . Draw the per-unit sequence networks of this transformer bank.
The ratings of a three-phase, three-winding transformer are Primary: Y connected, 66kV,15MVA Secondary: Y connected, 13.2kV,10MVA Tertiary: connected, 2.3kV,5MVA Neglecting resistances and exciting current, the leakage reactances are: XPS=0.09 per unit on a 15-MVA,66-kV base XPT=0.08 per unit on a 15-MVA,66-kV base XST=0.05 per unit on a 10-MVA,13.2-kV base Determine the per-unit reactances of the per-phase equivalent circuit using a base of 15 MVA and 66 kV for the primary.
In developing per-unit circuits of systems such as the one shown in Figure 3.10. when moving across a transformer, the voltage base is changed in proportion to the transformer voltage ratings. (a) True (b) False
Consider the adopted per-unit system for the transformers. Specify true or false for each of the following statements: (a) For the entire power system of concern, the value of Sbase is not the same. (b) The ratio of the voltage bases on either side of a transformer is selected to be the same as the ratio of the transformer voltage ratings. (c) Per-unit impedance remains unchanged when referred from one side of a transformer to the other.
Consider the single-Line diagram of a power system shown in Figure 3.42 with equipment ratings given: Generator G1: 50MVA,13.2kV,x=0.15p.u. Generator G2: 20MVA,13.8kV,x=0.15p.u. Three-phase -Y transformer T1: 80MVA,13.2/165YkV,X=0.1p.u. Three-phase Y- transformer T2: 40MVA,165Y/13.8kV,X=0.1p.u. Load: 40MVA,0.8PFlagging,operatingat150kV Choose a base of 100 MVA for the system and 132-kV base in the transmission-line circuit. Let the load be modeled as a parallel combination of resistance and inductance. Neglect transformer phase shifts. Draw a per-phase equivalent circuit of the system showing all impedances in per unit.
The leakage reactance of a three-phase, 300-MVA,230Y/23-kV transformer is 0.06 per unit based on its own ratings. The Y winding has a solidly grounded neutral. Draw the per-unit equivalent circuit. Neglect the exciting admittance and assume the American Standard phase shift.
Three single-phase, two-winding transformers, each rated 450MVA,20kV/288.7kV, with leakage reactance Xeq=0.10perunit, are connected to form a three-phase bank. The high-voltage windings are connected in Y with a solidly grounded neutral. Draw the per-unit equivalent circuit if the low-voltage windings are connected (a) in with American standard phase shift or (b) in Y with an open neutral. Use the transformer ratings as base quantities. Winding resistances and exciting current are neglected.
Using the transformer ratings as base quantities, work Problem 3.13 in per-unit.
Reconsider Problem 3.64 with the change that now Tb includes both a transformer of the same turns ratio as Ta and a regulating transformer with a 4 phase shift. On the base of Ta, the impedance of the two comp onents of Tb is jO.1 per unit. Determine the complex power in per unit transmitted to the load through each transformer. Comment on how the transformers share the real and reactive pors.