Mindtap Electrical, 4 Terms (24 Months) Printed Access Card For Herman's Delmar's Standard Textbook Of Electricity, 6th (mindtap Course List)
6th Edition
ISBN: 9781305634312
Author: Herman, Stephen L.
Publisher: Cengage Learning
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Chapter 29, Problem 2PA
To determine
The minimum kVA rating of each transformer.
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Students have asked these similar questions
In the circuit in Figure 2, the capacitor connected to the a-b terminals of the transformer anda circuit consisting of resistance is defined as a load circuit.
a)Find the average power spent by the load circuit?
b) How much of the average power calculated in a) by the resistance in the load circuit and how muchspent by the capacitor? Comment on the results obtained?
Three single phase transformers are connected in a Delta-Wye configuration. Each transformer is rated 12kV/56kV. The transformers are connected to a 3 phase 12kV (L-L) supply and the balanced three phase load is 763KVA.
What is the current magnitude in the secondary winding of each transformer?
[Answer in amps. No units required. One decimal point]
explain the steps too please
The rated voltages of a single-phase transformer are 2000 V and 200 V in its
primary and secondary respectively. The shunt impedance can be modelled with a
resistance of 14000 ohms in parallel with a reactance of 1100 ohm, both refer to
primary side. The primary and secondary series impedances are (0.12+j 0.35) ohms
and (0.0012+j 0.0035) ohms respectively. A load is connected to the secondary
side of transformer, draws 810 KVA with a lagging power factor of 0.85. The load
voltage is same as rated voltage, that is 200 V.
▪ Use per unit method for analysis and find the voltage on primary side in pu.
Chapter 29 Solutions
Mindtap Electrical, 4 Terms (24 Months) Printed Access Card For Herman's Delmar's Standard Textbook Of Electricity, 6th (mindtap Course List)
Ch. 29 - How many transformers are needed to make an...Ch. 29 - Two transformers rated at 100 kVA each are...Ch. 29 - How does the NEC specify that the high leg of a...Ch. 29 - An open-delta three-phase transformer system has...Ch. 29 - If a single-phase load is connected across the two...Ch. 29 - A three-phase transformer connection has a...Ch. 29 - A three-phase transformer connection has a...Ch. 29 - A three-phase transformer bank has the secondary...Ch. 29 - A three-phase transformer bank has the primary and...Ch. 29 - Referring to the transformer connection in...
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- Consider the three single-phase two-winding transformers shown in Figure 3.37. The high-voltage windings are connected in Y. (a) For the low-voltage side, connect the windings in , place the polarity marks, and label the terminals a, b, and c in accordance with the American standard. (b) Relabel the terminals a, b, and c such that VAN is 90 out of phase with Va for positive sequence.arrow_forwardFor an ideal transformer, the efficiency is (a) 0 (b) 100 (c) 50arrow_forwardThe 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.arrow_forward
- The symbol shown is a(n) a. iron core transformer. b. auto transformer. c. current transformer. d. air core transformer.arrow_forwardA single-phase step-down transformer is rated 13MVA,66kV/11.5kV. With the 11.5 kV winding short-circuited, rated current flows when the voltage applied to the primary is 5.5 kV. The power input is read as 100 kW. Determine Req1andXeq1 in ohms referred to the high-voltage winding.arrow_forwardIn per-unit equivalent circuits of practical three-phase transformers, under balanced thr-phase operation, in which of the following connect ions would a phase-shifting transformer come up? (a) Y-Y (b) Y- (c) -arrow_forward
- 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.arrow_forward(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 ?arrow_forwardAn ideal transformer has no real or reactive power loss. (a) True (b) Falsearrow_forward
- A bank of three single-phase transformers, each rated 30MVA,38.1/3.81kV, are connected in Y- with a balanced load of three 1, Y-connected resistors. Choosing a base of 90MVA,66kV for the high-voltage side of the three-phase transformer. spify the base for the low-voltage side. Compute the per-unit resistance of the load on the base for the low-voltage side. Also, determine the load resistance in ohms referred to the high-voltage side and the per-unit value on the chosen base.arrow_forwardFor an ideal 2-winding transformer, an impedance Z2 connected across winding 2 (secondary) is referred to winding 1 (primary) by multiplying Z2 by (a) The turns ratio (N1/N2) (b) The square of the turns ratio (N1/N2)2 (c) The cubed turns ratio (N1/N2)3arrow_forwardThree 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.arrow_forward
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