Electric Motor Control
10th Edition
ISBN: 9781133702818
Author: Herman
Publisher: CENGAGE L
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Question
Chapter 35, Problem 1SQ
To determine
Whether the motor in Figure 35-1 is started in medium or high speed and explain why.
Expert Solution & Answer
Answer to Problem 1SQ
No, the motor in Figure 35-1 cannot be started in medium or high speed.
Explanation of Solution
Refer to Figure 35–1 in the textbook shows the push-button speed selection for a wound rotor motor permits three steps of speed. In this circuit, the motor must be allowed to start at low speed and progress to second speed and then, to high speed. When the motor is operating at high speed, the motor speed can be reduced to a slower speed by pushing the suitable speed push button.
The motor is started at low speed by pressing a low speed push button and the coil M gets energized. This causes the power to be supplied to the stator winding of motor through the load contacts M. Due to that, the motor starts slowly with full resistance available in the secondary circuit. In Figure 35-1, the motor cannot be started in high or medium because it is interlocked with the low push button and the maintaining contact M.
Conclusion:
Thus, the motor in Figure 35-1 cannot be started in medium or high speed.
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