EBK MINDTAP FOR HERMAN'S DELMAR'S STAND
7th Edition
ISBN: 9781337900614
Author: Herman
Publisher: VST
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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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Students have asked these similar questions
The input reactance of an infinitesimal linear dipole of length A/60 and radius a=A/200
is given by
Xin = – 120
[In(€/a) — 1]
tan(ke)
Assuming the wire of the dipole is copper with a conductivity of 5.7 x 10' S/m,
determine at f = 1 GHz the
(a) loss resistance
(b) radiation resistance
(c) radiation efficiency
(d) VSWR when the antenna is connected to a 50-ohm line
Example
Solve the octic polynomial
2x⁸-9x⁷+20x⁶-33x⁵+46x⁴-66x³+80x²-72x+32=0
Solution
Divide by x⁴
2x⁴-9x³+20x²-33x+46-66/x + 80/x² - 72/x³ + 32/x⁴=0
Combine and bring terms
2(x⁴+16/x⁴) - 9(x³+8/x³) +20(x²+4/x²)-33(x+2/x) + 46= 0
Let use substitution
Let x+2/x =u
(x+2/x)²= u²
x²+2x*2/x + 4/x² = u²
x²+4/x²= u²-4
(x+2/x)³= x³+8/x³+3x*2/x(x+2/x)
u³= x³+8/x²+6u
x³+8/x³= u³-6u
(x²+4/x²)²= x⁴+2x²*4/x² + 16/x⁴
(u²-4)²= x⁴+16/x⁴ + 8
x⁴+16/x⁴ = (u²-4)²-8
x⁴+16/x⁴ = u⁴-8u²+8
2(u⁴-8u²+8)-9(u³-6u)+20(u²-4)-33u+46=0
Expand and simplify
2u⁴-9u³+4u²+21u-18=0
After checking
(u-1)(u-2) Are factors
Then
2u²-3u-9=0
u=3, u=-3/2
Assignment question
Solve the octic polynomial
2s⁸+s⁷+2s⁶-31s⁴-16s³-32s²-160=0 using the above example question, please explain in detail
b)
Another waveform g(t) is defined by
=0
t≥0, α>0
otherwise
g(t)= At exp(-at)
and is plotted in Figure 1 (for representative values of 4 = 1 and α = 1).
g(t)
0.4T
0.3+
0.2
0.1+
2
0
2
Figure 1
8
c)
Show that its amplitude spectrum is |G(@)| = -
A
(a²+0²)²
Describe briefly, with the aid of labelled sketches, how changing a affects
the waveform in both the time and frequency domains.
d) Deduce the Fourier transform H(@) of h(t) = g(t)+g(t+b)+g(t-b) and
calculate its DC amplitude H(0).
Chapter 28 Solutions
EBK MINDTAP FOR HERMAN'S DELMAR'S STAND
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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