3- 2,500 kVA,3-phase, 3,300/400 V, 3-phase transformer is Y-connected on HV side and A- connected on LV side. The test results are as follow: SC test: HV side: 400V 219 A and 24kW OC test: LV side: 400 V 175A and 18kW Determine i). The parameter equivalent circuit referred to high voltage (HV) side ii). The percentage of voltage regulation on full-load at power factor of 0.8 lagging iii). The efficiency of the transformer on full-load at power factor of 0.9 lagging

3- 2,500 kVA,3-phase, 3,300/400 V, 3-phase transformer is Y-connected on HV side and A- connected on LV side. The test results are as follow: SC test: HV side: 400V 219 A and 24kW OC test: LV side: 400 V 175A and 18kW Determine i). The parameter equivalent circuit referred to high voltage (HV) side ii). The percentage of voltage regulation on full-load at power factor of 0.8 lagging iii). The efficiency of the transformer on full-load at power factor of 0.9 lagging

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 3.16P: A single-phase, 50-kVA,2400/240-V,60-Hz distribution transformer has the following parameters:...

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(a) An ideal single-phase two-winding transformer with turns ratio at=N1/N2 is connected with a series impedance Z2 across winding 2. If one wants to replace Z2, with a series impedance Z1 across winding 1 and keep the terminal behavior of the two circuits to be identical, find Z1 in terms of Z2. (b) Would the above result be true if instead of a series impedance there is a shunt impedance? (c) Can one refer a ladder network on the secondary (2) side to the primary (1) side simply by multiplying every impedance byat2 ?
Consider Figure 3.25 of the text for a transformer with off-nominal turns ratio. (i) The per-unit equivalent circuit shown in part (c) contains an ideal transformer which cannot be accommodated by some computer programs. (a) True (b) False (ii) In the - circuit representation for real c in part (d), the admittance parameters Y11 and Y12 would be unequal. (a) True (b) False (iii) For complex c, can the admittance parameters be synthesized with a passive RLC circuit? (a) Yes (b) No
Three single-phase transformers, each rated 10MVA,66.4/12.5kV,60Hz, with an equivalent series reactance of 0.1 per unit divided equally between primary and secondary, are connected in a three-phase bank. The high-voltage windings are V-connected and their terminals are directly connected to a 115-kV three-phase bus. The secondary terminals are all shorted together. Find the currents entering the high-voltage terminals and leaving the low-voltage terminals if the low-voltage windings are (a) Y-connected and (b) - connected.
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 ratings of a three-phase three-winding transformer are Primary(1): Y connected 66kV,15MVA Secondary (2): Y connected, 13.2kV,10MVA Tertiary (3): A connected, 2.3kV,5MVA Neglecting winding resistances and exciting current, the per-unit leakage reactances are X12=0.08 on a 15-MVA,66-kV base X13=0.10 on a 15-MVA,66-kV base X23=0.09 on a 10-MVA,13.2-kV base (a) Determine the per-unit reactances X1,X2,X3 of the equivalent circuit on a 15-MVA,66-kV base at the primary terminals. (b) Purely resistive loads of 7.5 MW at 13.2 kV and 5 MW at 2.3kV are connected to the secondary and tertiary sides of the transformer, respectively. Draw the per- unit impedance diagram, showing the per-unit impedances on a 15-MVA,66-kV base at the primary terminals.
Rework Example 3.12 for a+10 tap, providing a 10 increase for the high-voltage winding.
How many transformers are needed to make an open-delta connection?
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.
A short-circuit test was performed on a 10kVA, 2000/400 V single phase transformer. The instruments indicated 100V, 5A and 100 W. Determine the secondary voltage when operating at rated load at 80% pf lagging at rated primary voltage. Provide values in order the space provided below: Re, Xe, I1, I2, and E1, E2
3- 2,500 kVA.3-phase. 3,300/400 V, 3-phase transformer is Y-connected on HV side and A- connected on LV side. The test results are as follow: SC test: HV side: 400V 219 A and 24kW OC test: LV side: 400 V. 175A and 18kW Determine i). The parameter equivalent circuit referred to high voltage (HV) side ii). The percentage of voltage regulation on full-load at power factor of 0.8 lagging iii). The efficiency of the transformer on full-load at power factor of 0.9 lagging
The following values were seen in the measurements made separately by the primary and secondary of a 220/270 V phase transformer. R1 = 4 ohms, X1 = 4.6 ohms, R2 = 0.89 ohms, X2 = 1.79 ohms; R2T = 8.7 ohms, X2T = 8.8 ohms (total values measured on the secondary side), Xm = 60 ohms, Rfe = 750 ohms, (using a T-type equivalent circuit) c.) Active and reactive powers drawn from the transformer d.) Calculate the efficiency of the transformer.
State the common use of the following 3-phase transformer connections in electrical power transmission and distribution: Delta - Delta connection, Star - Deita connection, Delta - Star connection