Understanding Motor Controls
4th Edition
ISBN: 9781337798686
Author: Stephen L. Herman
Publisher: Delmar Cengage Learning
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Chapter 3, Problem 1RQ
A manual motor starter controls a single phase 120 volt motor. The motor is not running, and the switch handle on the starter is found to be in the center position. What does this indicate?
Expert Solution & Answer
To determine
The indication of center position of switch handle of a manual motor starter.
Explanation of Solution
Manual motor starter is simple and common motor starter. Operator involvement is must to change the state of a manual motor starter. A manual motor starter is looks like a simple toggle switch. In addition, the manual motor starters are come up with overload protectors. Thus, the manual motor starter has three positions namely ON, OFF, and over load protection.
The two end positons of the toggle lever of a manual motor starter indicates ON and OFF positions. The center position indicates that the motor is tripped due to over load. Whenever the current flows in a circuit, a proportionate heat is generated in a conductor. When a motor is over loaded, more current will flow, heat generation is high. If this continues, the motor will fail. Thus, the overload heater (protector) is involved. The over load protector is designed for normal operating condition. When a motor runs abnormally (over loading), the over load protector stops the power supply to the motor. Thereby, the toggle lever (switch handle) moved to center position.
Hence, the center position of switch handle of a manual motor starter denotes that the motor is tripped due to over load.
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Chapter 3 Solutions
Understanding Motor Controls
Ch. 3 - A manual motor starter controls a single phase 120...Ch. 3 - Prob. 2RQCh. 3 - Prob. 3RQCh. 3 - A push button manual starter has tripped on...Ch. 3 - What is meant by the term line voltage on some...Ch. 3 - Explain the difference between manual motor...Ch. 3 - Prob. 7RQCh. 3 - Prob. 8RQCh. 3 - Refer to the circuit shown in Figure 310. When...Ch. 3 - Prob. 10RQ
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