Electric Motor Control
10th Edition
ISBN: 9781133702818
Author: Herman
Publisher: CENGAGE L
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Textbook Question
Chapter 48, Problem 1SQ
In Figure 48–2, what is the purpose of normally closed contact F?
Expert Solution & Answer
To determine
Explain the scope of normally closed (NC) contact (F) in Figure 48-2.
Explanation of Solution
Refer to Figure 48-2 in the textbook shows that plugging the motor to stop from one direction only. In this figure, the normally closed (NC) contact F is mentioned as an interlock.
In Figure 48-2, while the stop button is pressed, the forward contactor will drop out and the coil (F) is a de-energized normally closed (NC) contact F. This contact in turn, energizes coil (R) to operate the motor in the reverse direction through the closed plugging switch.
Conclusion:
Thus, the scope of normally closed (NC) contact (F) in the given figure is explained.
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The following circuit is at steady state for t<0. At t=0 sec, the switch is open. Let R₁ =14 ohms, R₂=14
ohms, R3-4 ohms, C₁-1 F, Vx-16 V and Ix-7 A. Find Vc1 (0.8 sec) and voltage across resistor R3 = v(1.4 sec),
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Vc1(0) in volts=
Vc1(00) in volts=
Rth in ohms=
Vc1(t-0.8 sec) in volts=
v(t-1.4 sec) in volts=
Vx
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t=0
The relative tolerance for this problem is 10 %.
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R₂
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R3
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C₁
For the circuit shown, the switch opens at t=0 sec. Find i(t=1.5) value as follows.
Let R1-12 ohm, R₂-8 ohm, L=0.6 H, V≤1-10 V and V2-8 V, and determine:
i(0) =
A
A
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You must have noticed that, when a major appliance is turned on (such as an AC unit, garbage disposal,
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Electric Motor Control
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