(b) A 110 kVA, 2300:230 V, 50 Hz, single-phase transformer has the following parameters: Resistance of the primary (high-voltage) winding: Resistance of the secondary (low-voltage) winding: Leakage reactance of the primary (high-voltage) winding: Leakage reactance of the secondary (low-voltage) winding: Core loss resistance (referred to the primary): Magnetising reactance (referred to the primary): R₁ = 0.15 Ω R₂ = 0.0015 2 Ω X₁ = 0.32 2 X₂ = 0.0032 2 Ω Rc = 18.6 k Xm = 3.4 k The transformer is delivering full (rated) load at a rated secondary voltage of 230 V and 0.88 power factor lagging. (i) Draw the equivalent-T circuit (including component values) for the transformer with all quantities referred to the primary (high-voltage) side. (ii) Draw the phasor diagram which relates the primary voltage V₁ to the referred secondary voltage V2. (Notes: Ignore the exciting current. Make sure you label all phasors clearly numerical values are not required.) (iii) Calculate the phasor load current 72, referred to the primary. (iv) Calculate the phasor primary voltage V₁ (you may ignore the exciting current).

(b) A 110 kVA, 2300:230 V, 50 Hz, single-phase transformer has the following parameters: Resistance of the primary (high-voltage) winding: Resistance of the secondary (low-voltage) winding: Leakage reactance of the primary (high-voltage) winding: Leakage reactance of the secondary (low-voltage) winding: Core loss resistance (referred to the primary): Magnetising reactance (referred to the primary): R₁ = 0.15 Ω R₂ = 0.0015 2 Ω X₁ = 0.32 2 X₂ = 0.0032 2 Ω Rc = 18.6 k Xm = 3.4 k The transformer is delivering full (rated) load at a rated secondary voltage of 230 V and 0.88 power factor lagging. (i) Draw the equivalent-T circuit (including component values) for the transformer with all quantities referred to the primary (high-voltage) side. (ii) Draw the phasor diagram which relates the primary voltage V₁ to the referred secondary voltage V2. (Notes: Ignore the exciting current. Make sure you label all phasors clearly numerical values are not required.) (iii) Calculate the phasor load current 72, referred to the primary. (iv) Calculate the phasor primary voltage V₁ (you may ignore the exciting current).

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 3.9P

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Similar questions

For a short-circuit test on a 2-winding transformer, with one winding shorted, can you apply the rated voltage on the other winding? (a) Yes (b) No
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.
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
For developing per-unit equivalent circuits of single-phase three-winding transformer, a common Sbase is selected for all three windings and voltage bases are selected in proportion to the rated voltage of the windings (a) True (b) False
The ideal transformer windings are eliminated from the per-unit equivalent circuit of a transformer. (a) True (b) False
A single-phase, 50-kVA,2400/240-V,60-Hz distribution transformer has the following parameters: Resistance of the 2400-V winding: R1=0.75 Resistance of the 240-V winding: R2=0.0075 Leakage reactance of the 2400-V winding: X1=1.0 Leakage reactance of the 240-V winding: X2=0.01 Exciting admittance on the 240-V side =0.003j0.02S (a) Draw the equivalent circuit referred to the high-voltage side of the transformer. (b) Draw the equivalent circuit referred to the low-voltage side of the transformer. Show the numerical values of impedances on the equivalent circuits.
For an ideal 2-winding transformer, the ampere-turns of the primary winding, N1I1 is equal to the ampere-turns of the secondary winding, N2I2 (a) True (b) False
An ideal transformer has no real or reactive power loss. (a) True (b) False
The direct electrical connection of the windings allows transient over voltages to pass through the auto transfonner more easily, and that is an important disadvantage of the autotransformer. (a) True (b) False
Consider a bank of this single-phase two-winding transformers whose high-voltage terminals are connected to a three-phase, 13.8-kV feeder. The low-voltage terminals are connected to a three-phase substation load rated 2.0 MVA and 2.5 kV. Determine the required voltage, current, and MVA ratings of both windings of each transformer, when the high-voltage/low- voltage windings are connected (a) Y-, (b) -Y, (c) Y-Y, and (d) -.
Three single-phase two-winding transformers, each rated 25MVA,54.2/5.42kV, are connected to form a three-phase Y- bank with a balanced Y-connected resistive load of 0.6 per phase on the low-voltage side. By choosing a base of 75 MVA (three phase) and 94 kV (line-to-line) for the high-voltage side of the transformer bank, specify the base quantities for the low-voltage side. Determine the per-unit resistance of the load on the base for the low-voltage side. Then determine the load resistance RL in ohms referred to the high-voltage side and the per-unit value of this load resistance on the chosen base.
With the American Standard notation, in either a Y-or-Y transformer, positive- sequen quantities on the high-voltage side shall lead their corresponding quantities on the low-voltage side by 30. (a) True (b) False