Electric Motor Control
10th Edition
ISBN: 9781133702818
Author: Herman
Publisher: CENGAGE L
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Chapter 27, Problem 1SQ
Why is it desirable to remove the autotransformers from the line when the motor reaches its rated speed?
Expert Solution & Answer
To determine
Explain the reason why it is desirable to remove the autotransformer starters from the line when the connected motor reaches its rated speed.
Explanation of Solution
Autotransformer starter is placed between the motor and supply power lines to limit the supply voltage that is provided across the terminals of the motor during accelerating of the connected motor. With the lower accelerating voltage, motor draws less current and produces less torque in motor. Taps are provided on the autotransformer starters to permit the user to initiate the motor at an increasing speed from 50 percent, 60 percent, 75 percent or 85 percent of the line voltage.
The autotransformer starters are removed from the line connection when the motor attains the rated speed to obtain the required electrical energy by removing the magnetizing current, iron, and copper losses. Generally, the insulating life of the autotransformers may extend due to reduced heat and voltage applications.
Conclusion:
Thus, the reason why it is desirable to remove the autotransformer starters from the line when the connected motor reaches its rated speed is explained.
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Chapter 27 Solutions
Electric Motor Control
Ch. 27 - Why is it desirable to remove the autotransformers...Ch. 27 - What is meant by an open transition from start to...Ch. 27 - Which of the following applies to an...Ch. 27 - How are reduced voltages obtained from...Ch. 27 - Prob. 5SQCh. 27 - What is a disadvantage of starting with...Ch. 27 - What is one advantage of using an autotransformer...
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