2 2 c m 1 = 1 3. An 100-kVA, 2500/125-V, 50-Hz, step-down transformer has the following parameters: R₁ = 1.50, X, 2.8 Q, R₂ = 15 m Q, :X₂ = 20mQ, R = 3kQ, and : X = 5KQ. The transformer delivers 85% of the rated X, load at a terminal voltage of 110 V and a power factor of 0.866 lagging. Use the approximate circuit referred to as the primary. a. Determine the efficiency of the transformer. b. And the voltage regulation A 150-kVA transformer has a core loss of 8 kW and a copper loss of 22 kW at full load. a. What is the kVA rating at the maximum efficiency of the transformer? b. Express the load current at maximum efficiency as a percent of the rated current. If the transformer operates at a power factor of 0.9 lagging, c. Determine the maximum efficiency and d. the full-load efficiency of the transformer. ୮ L

2 2 c m 1 = 1 3. An 100-kVA, 2500/125-V, 50-Hz, step-down transformer has the following parameters: R₁ = 1.50, X, 2.8 Q, R₂ = 15 m Q, :X₂ = 20mQ, R = 3kQ, and : X = 5KQ. The transformer delivers 85% of the rated X, load at a terminal voltage of 110 V and a power factor of 0.866 lagging. Use the approximate circuit referred to as the primary. a. Determine the efficiency of the transformer. b. And the voltage regulation A 150-kVA transformer has a core loss of 8 kW and a copper loss of 22 kW at full load. a. What is the kVA rating at the maximum efficiency of the transformer? b. Express the load current at maximum efficiency as a percent of the rated current. If the transformer operates at a power factor of 0.9 lagging, c. Determine the maximum efficiency and d. the full-load efficiency of the transformer. ୮ L

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 3.7P: Consider a source of voltage v(t)=102sin(2t)V, with an internal resistance of 1800. A transformer...

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Consider an ideal transformer with N1=3000andN2=1000 turns. Let winding 1 be connected to a source whose voltage is e1(t)=100(1| t |)volts for 1t1ande1(t)=0 for | t |1 second. A2- farad capacitor is connected across winding 2. Sketch e1(t),e2(t),i1(t),andi2(t) versus time t.
An ideal transformer has no real or reactive power loss. (a) True (b) False
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
A 23/230-kV step-up transformer feeds a three-phase transmission line, which in turn supplies a 150-MVA,0.8 lagging power factor load through a step-down 230/23-kV transformer. The impedance of the line and transformers at 230kVis18+j60. Determine the tap setting for each transformer to maintain the voltage at the load at 23 kV.
For the transformer in Problem 3.10. The open-circuit test with 11.5 kV applied results in a power input of 65 kW and a current of 30 A. Compute the values for GcandBm in siemens referred to the high-voltage winding. Compute the efficiency of the transformer for a load of 10 MW at 0.8 p.f. lagging at rated voltage.
An ideal transformer with N1=1000andN2=250 is connected with an impedance Z22 across winding 2. If V1=10000VandI1=530 A, determine V2,I2,Z2, and the impedance Z2, which is the value of Z2 referred to the primary side of the transformer.
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.
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
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Consider a source of voltage v(t)=102sin(2t)V, with an internal resistance of 1800. A transformer that can be considered as ideal is used to couple a 50 resistive load to the source. (a) Determine the transformer primary-to-secondary turns ratio required to ensure maxi mum power transfer by matching the load and source resistances. (b) Find the average power delivered to the load, assenting maximum power transfer.
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
The ideal transformer windings are eliminated from the per-unit equivalent circuit of a transformer. (a) True (b) False