A 25-kVA, 4000/400-V, 60-Hz transformer has the following parameters: R, = 18 Q, X, = 25 0, R, = 180 mQ, X, = 250 mQ, R,, = 15 kQ, and X,, = 25 kQ. If the open-circuit and short-circuit tests are performed on this transformer, what are the readings of the instruments in each case? From the data given in above, determine the rating of the transformer at maximum efficiency. What is the maximum efficiency of the transformer at unity power factor? What is the efficiency at full load and unity power factor?

A 25-kVA, 4000/400-V, 60-Hz transformer has the following parameters: R, = 18 Q, X, = 25 0, R, = 180 mQ, X, = 250 mQ, R,, = 15 kQ, and X,, = 25 kQ. If the open-circuit and short-circuit tests are performed on this transformer, what are the readings of the instruments in each case? From the data given in above, determine the rating of the transformer at maximum efficiency. What is the maximum efficiency of the transformer at unity power factor? What is the efficiency at full load and unity power factor?

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

See similar textbooks

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
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
Single phase half wave AC-AC converter has a resistance of R = 50 ohms. Input voltage is given as 230 Vrms. Transformer conversion ratio is 1:1. If T1 thyristor is triggered at 60 degrees; a)Rms output voltage? b)Output power? c)RMS load current and average load current? d)Input power factor? e)Average and RMS thyristor current?
2. The parameters of a certain transformer are to be found. Following the procedure as outlined in the introduction under the first order low frequency model section: The resistance of the primary winding of a certain transformer is found to be R1 = 388 Q, while the resistance of the secondary winding is R, = 0.9 Q. A 200 Hz, 5 volt peak-to-peak sinusoid, V1, is applied to the primary while the secondary is left open-circuited. The primary current, I,, entering at the dot is measured to be 1.07 milliamps peak-to-peak, lagging the voltage by nearly 83°. The open circuit voltage across the secondary, V20c, is measured to be 0.155 volts peak-to-peak. The sinusoid driving the primary is removed and a 200 Hz, 5 volt peak-to-peak sinusoid, V2, is applied to the secondary while the primary is left open-circuited. The secondary current, I2, entering at the dot is measured to be 206 milliamps peak-to-peak, lagging the voltage by 87°. From these measurements, estimate the self-inductances, L,…
1. A 2.4-KVA, 2400/240-V, 50-Hz, the step-down transformer has the following parameters: : RH = 1.59, :XH = 2.50, R₂ = 0.020, X₁ = 0.030, : Rc = 6k2, and: Xm = 8kQ. It is operating at 50% of its load at 0.5 power factor leading. Using the exact equivalent circuit embodying the ideal transformer, determine the efficiency of the transformer. Also, sketch its phasor diagram.
DC 200 V was applied to the primary of a transformer with a conversion ratio of 1/5. Obtained from seconderexplain the reason for this by typing the voltage value to be?
3. A 3200/400 single-phase transformer has winding resistance and reactance of 30 and 132 respectively in the primary and 0.0292 and 0.0652 in the secondary. Express these in terms of (a) primary alone, (b) secondary alone. (ans. (a) 4.282, 17.16; (b) 0.067, 0.268)
b) A lkQ resistance is connected across the secondary winding of a 200V/400V transformer with the following equivalent circuit parameters, Kleq=502, Rc = 10k2, XM =1 k2 , ^leq = 100 2. Determine the following: R i. The Open Circuit Output Voltage (Vsoc) ii. The Output Voltage under load (Vs) i1i. The Output Current (Is) iv. The Transformer Efficiency (%)
5) A flyback converter has an input of 45 V, an output of 15 V, a duty ratio of 0.4, and a switching frequency of 80 kHz. The load resistor is 15 Q. (a) Determine the transformer turns ratio. (b) Determine transformer magnetizing inductance Lm such that its maximum current is 120% of its average current.
A. What are the various causes of voltage drop in atransformer? B. A single phase transformer has arated secondary voltage of (230v).when Loaded by a purely inductive load to its rated Value of current ,its terminal voltage drops to (200 v). Calculate its regulation and efficiency.
3. An 100-KVA, 2500/125-V, 50-Hz, step-down transformer has the following parameters: R₁ = 1.50, X₁ = 2.8 2. : R₂ = 15 m , : X₂ = 20m2,: Re - 3k, and: Xm 5 KQ. The transformer delivers 85% of the rated 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 T