Delmar's Standard Textbook Of Electricity
7th Edition
ISBN: 9781337900348
Author: Stephen L. Herman
Publisher: Cengage Learning
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Textbook Question
Chapter 28, Problem 1RQ
How many transformers are needed to make an open-delta connection?
Expert Solution & Answer
To determine
The number of transformers needed to make an open delta connection.
Answer to Problem 1RQ
Two transformers are needed to make an open delta connection.
Explanation of Solution
The open delta connection is used when the amount of three-phase power needed is not excessive. From the figure it can be seen that the open-delta transformer connection can be made with only two transformers. The total output power is 86.6% of the sum of the power rating of the two transformers when an open-delta connection is used.
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For a band-rejection filter, the response drops below this half power point at two locations as visualised in Figure 7, we need to find these
frequencies. Let's call the lower frequency-3dB point as fr and the higher frequency -3dB point fH. We can then find out the bandwidth as
f=fHfL, as illustrated in Figure 7.
0dB
Af
-3 dB
Figure 7. Band reject filter response diagram
Considering your AC simulation frequency response and referring to Figure 7, measure the following from your AC simulation. 1% accuracy:
(a) Upper-3db Frequency (fH) =
Hz
(b) Lower-3db Frequency (fL) =
Hz
(c) Bandwidth (Aƒ) =
Hz
(d) Quality Factor (Q) =
P 4.4-21 Determine the values of the node voltages V1, V2, and
v3 for the circuit shown in Figure P 4.4-21.
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1. What is the theoretical attenuation of the output voltage at the resonant frequency? Answer to within 1%, or enter 0, or infinity (as “inf”)
Attenuation =
Chapter 28 Solutions
Delmar's Standard Textbook Of Electricity
Ch. 28 - How many transformers are needed to make an...Ch. 28 - Two transformers rated at 100 kVA each are...Ch. 28 - How does the NEC specify that the high leg of a...Ch. 28 - An open-delta three-phase transformer system has...Ch. 28 - If a single-phase load is connected across the two...Ch. 28 - A three-phase transformer connection has a...Ch. 28 - A three-phase transformer connection has a...Ch. 28 - A three-phase transformer bank has the secondary...Ch. 28 - A three-phase transformer bank has the primary and...Ch. 28 - Referring to the transformer connection in...
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- Vs(t) + v(t) + vi(t) ZR ZL Figure 1: Second order RLC circuit Zc + ve(t) You are requested to design the circuit shown in Figure 1. The circuit is assumed to be operating at its resonant frequency when it is fed by a sinusoidal voltage source Vs (t) = 2sin(le6t). To help design your circuit you have been given the value of inductive reactance ZL = j1000. Assume that the amplitude of the current at resonance is Is (t) = 2 mA. Based on this information, answer the following to help design your circuit. Use cartesian notation for your answers, where required.arrow_forwardWhat is the attenuation at the resonant frequency? You should use the LTSpice cursors for your measurement. Answer to within 1% accuracy, or enter 0, or infinity (as "inf") (a) Attenuation (dB) = dB Check You may have noticed that it was significantly easier to use frequency-domain "AC" simulation to measure the attenuation, compared to the steps we performed in the last few questions. (i.e. via a time-domain "transient" simulation). AC analysis allows us to observe and quantify large scale positive or negative changes in a signal of interest across a wide range of different frequencies. From the response you will notice that only frequencies that are relatively close to 100 kHz have been attenuated. This is the result of the Band-reject filter you have designed, and shows the 'rejection' (aka attenuation) of any frequencies that lie in a given band. The obvious follow-up question is how do we define this band? We use a quantity known as the bandwidth. A commonly used measurement for…arrow_forwardV₁(t) ww ZRI ZLI ZL2 ZTH Zci VTH Zc21 Figure 8. Circuit diagram showing calculation approach for VTH and Z TH we want to create a blackbox for the red region, we want to use the same input signal conditions as previously the design of your interference ector circuit: Sine wave with a 1 Vpp, with a frequency of 100 kHz (interference) Square wave with 2.4Vpp, with a frequency of 10 kHz (signal) member an AC Thevenin equivalent is only valid at one frequency. We have chosen to calculate the Thevenin equivalent circuit (and therefore the ackbox) at the interference frequency (i.e. 100 kHz), and the signal frequency (i.e. 10 kHz) as these are the key frequencies to analyse. Your boss is assured you that the waveform converter module has been pre-optimised to the DAB Receiver if you use the recommended circuit topology.arrow_forward
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