EBK ELECTRIC MOTOR CONTROL
10th Edition
ISBN: 9780100784598
Author: Herman
Publisher: YUZU
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Chapter 49, Problem 1SQ
To determine
Explain the reason for using magnetic brakes.
Expert Solution & Answer
Explanation of Solution
An electric brake also known as magnetic brake which consists of two friction surfaces or shoes that can be made to bear on a wheel on the motor shaft. Refer to Figure 49-1 in the textbook, the shoes are held by the spring tension on the wheel. Due to the friction between the wheel and shoes, the braking is achieved.
Magnetic brakes provide a smooth braking action and used for high inertia loads. Since these brakes apply and remove the braking pressure in either direction, it is recommended to use in cranes, hoists, elevators, and to increase the production of the industrial machinery. These magnetic brakes can limit the shock of braking.
Conclusion:
Thus, the reasons for using magnetic brakes are 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),
as follows:
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
w
t=0
The relative tolerance for this problem is 10 %.
+
www
R₂
Vit
R3
+
Vc1(t)
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
i(∞0) =
Rth
=
i(1.5 sec)
Ω
A
R₁
L
i(t)
VS2
R2
w
The relative tolerance for this problem is 9 %.
+
V S1
Chapter 49 Solutions
EBK ELECTRIC MOTOR CONTROL
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