Understanding Motor Controls
4th Edition
ISBN: 9781337798686
Author: Stephen L. Herman
Publisher: Delmar Cengage Learning
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Question
Chapter 4, Problem 13RQ
To determine
The size of the overload heater that should be used to protect the motor.
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Give an example of the Resistance Factor?
Question 5
The blower requires 20 kW to run at 350 rpm. The power is
transmitted by a v-belt shown in Figure 4 from an electric motor. The
diameter of the machine pulley is 650 mm and that of the motor
pulley is 330 mm. The centre distance between the pulleys is 1.2 m.
The contact angle of the belt is 150°. The safe pull in each belt is
900 N and the mass of the belt is 0.46 kg per meter length. The
coefficient of friction between the belt and the pulley is 0.25. The
belt should not exceed the speed of 1 800 m/min.
X1 = 16 mm
H= 6 mm
B
X2 = 7 mm
Figure 4: Cross sectional view of the v-belt
5.1. Calculate the velocity of the belt in m/s.
Determine the length of the belt.
Calculate the belt tensions.
5.2.
5.3.
In a given DC motor, the output power is 45 HP, and the copper losses are 2.005 KW.
If the rotational losses is one tenth of the output power,
find the converted power and the efficiency of the motor.
Select one:
O a. None
O b. Pcony = 33.57 KW and % efficiency = 89.2 %
%3D
O C. Pcony = 39 KW and % efficiency = 75.8 %
O d. Peony = 36.927 KW and % efficiency = 86.2 %.
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Chapter 4 Solutions
Understanding Motor Controls
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Similar questions
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