17. Calculate: (a) F.L. efficiency at unity p.f. (b) The secondary terminal voltage when supplying full-load secondary current at p.f. (i)m 0.8 lag (ii) 0.8 lead for the 4-kVA, 200/400-V, 50-Hz, 1-phase transformer of which the following are the test figures: Open circuit with 200 V supplied to the primary winding – power 60 W. Short circuit with 16 V applied to the h.v. winding - current 8 A, power 40 W. [0.97; 383 V; 406 V]

17. Calculate: (a) F.L. efficiency at unity p.f. (b) The secondary terminal voltage when supplying full-load secondary current at p.f. (i)m 0.8 lag (ii) 0.8 lead for the 4-kVA, 200/400-V, 50-Hz, 1-phase transformer of which the following are the test figures: Open circuit with 200 V supplied to the primary winding – power 60 W. Short circuit with 16 V applied to the h.v. winding - current 8 A, power 40 W. [0.97; 383 V; 406 V]

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 3.54P: An infinite bus, which is a constant voltage source, is connected to the primary of the...

See similar textbooks

Similar questions

An infinite bus, which is a constant voltage source, is connected to the primary of the three-winding transformer of Problem 3.53. A 7.5-MVA,13.2-kV synchronous motor with a sub transient reactance of 0.2 per unit is connected to the transformer secondary. A5-MW,2.3-kV three-phase resistive load is connected to the tertiary Choosing a base of 66 kV and 15 MVA in the primary, draw the impedance diagram of the system showing per-unit impedances. Neglect transformer exciting current, phase shifts, and all resistances except the resistive load.
Consider the single-line diagram of the power system shown in Figure 3.38. Equipment ratings are Generator 1: 1000MVA,18kV,X=0.2perunit Generator 2: 1000MVA,18kV,X=0.2p.u. Synchronous motor 3: 1500MVA,20kV,X=0.2p.u. Three-phase -Y transformers T1,T2,T3,T4,: 1000MVA,500kV,Y/20kV,X=0.1p.u. Three-phase YY transformer T5: 1500MVA,500kV,Y/20kVY,X=0.1p.u. Neglecting resistance, transformer phase shift, and magnetizing reactance, draw the equivalent reactance diagram. Use a base of 100 MA and 500 kV for the 50-ohm line. Determine the per-unit reactances.
Consider the oneline diagram shown in Figure 3.40. The three-phase transformer bank is made up of three identical single-phase transformers, each specified by X1=0.24 (on the low-voltage side), negligible resistance and magnetizing current, and turns ratio =N2/N1=10. The transformer bank is delivering 100 MW at 0.8 p.f. lagging to a substation bus whose voltage is 230 kV. (a) Determine the primary current magnitude, primary voltage (line-to-line) magnitude, and the three-phase complex power supplied by the generator. Choose the line-to-neutral voltage at the bus, Va as the reference Account for the phase shift, and assume positive-sequence operation. (b) Find the phase shift between the primary and secondary voltages.
PowerWorid Simulator case Problem 3_60 duplicates Example 3.13 except that a resistance term of 0.06 per unit has been added to the transformer and 0.05 per unit to the transmission line. Since the system is no longer lossless, a field showing the real power losses has also been added to the oneline. With the LTC tap fixed at 1.05, plot the real power losses as the phase shift angle is varied from 10 to +10 degrees. What value of phase shift minimizes the system losses?
A single-phase 50-kVA,2400/240-volt,60-Hz distribution transformer is used as a step-down transformer at the load end of a 2400-volt feeder whose series impedance is (1.0+j2.0) ohm. The equivalent series impedance of the transformer is (1.0+j2.5) ohms referred to the high-voltage (primary) side. The transformer is delivering rated load at a 0.8 power factor lagging and at a rated secondary voltage. Neglecting the transformer exciting current, determine (a) the voltage at the transformer primary terminals, (b) the voltage at the sending end of the feeder, and (c) the real and reactive power delivered to the sending end of the feeder.
The motors M1andM2 of Problem 3.45 have inputs of 120 and 60 MW, respectively, at 13.2 kV, and both operate at unity power factor. Determine the generator terminal voltage and voltage regulation of the line. Neglect transformer phase shifts.
A two-winding single-phase transformer rated 60kVA,240/1200V,60Hz, has an efficiency of 0.96 when operated at rated load, 0.8 power factor lagging. This transformer is to be utilized as a 1440/1200-V step-down autotransformer in a power distribution system. (a) Find the permissible kVA rating of the autotransformer if the winding currents and voltages are not to exceed the ratings as a two-winding transformer. Assume an ideal transformer. (b) Determine the efficiency of the autotransformer with the kVA loading of part (a) and 0.8 power factor leading.
Three single-phase two-winding transformers, each rated 3kVA,220/110volts,60Hz, with a 0.10 per-unit leakage reactance, are connected as a three-phase extended autotransformer bank, as shown in Figure 3.36(c). The low-voltage winding has a 110 volt rating. (a) Draw the positive-sequence phasor diagram and show that the high-voltage winding has a 479.5 volt rating. (b) A three-phase load connected to the low-voltage terminals absorbs 6 kW at 110 volts and at 0.8 power factor lagging. Draw the per-unit impedance diagram and calculate the voltage and current at the high-voltage terminals. Assume positive-sequence operation.
A single-phase two-winding transformer rated 90MVA,80/120kV is to be connected as an autotransformer rated 80/200kV. Assume that the transformer is ideal. (a) Draw a schematic diagram of the ideal transformer connected as an autotransformer. showing the voltages, currents, and dot notation for polarity. (b) Determine the permissible kVA rating of the autotransformer if the winding currents and voltages are not to exceed the rated values as a two-winding transformer. How much of the kA rating is transferred by magnetic induction?
A 10-kVA, 2200/400 V, single phase distribution transformer has a primary and secondary winding impedances of 5 + j12 and 0.25 + j0.45 ohms, respectively. Calculate the voltage across the secondary terminals at full load, 90 % power factor lagging, when the primary is supplied with 2200 volts?
2) A three -phase transformer of 90 kVA, 13200/480 V (line to line), with connection Delta-Delta, has a resistance of 1.3% and a reactance of 8.2% per unit. a) Calculate the phase impedance of the transformer referred to the high side strain. b) Calculate the phase impedance of the transformer referred to the low side strain. c) Calculate the transformer voltage regulation into nominal conditions with F.P.0,8 in delay.
2.2. The figure below shows a radial transmission system with a generator having a per-unit voltage of 1.3 at an angle of 9 degree p.u. The load demand is 47MW at a power factor of 0.96lagging. Use the nameplate values of Transformer 2 as base values and calculate the following: Correct answers to three decimal places : 25..Per unit impedance of transformer and it's angle 26.Per unit voltage of the line and its angle 27.Per unit impedance of the line and its angle. And Reactance of the transmission line when the load consumes full-load (Ω).