Understanding Motor Controls
3rd Edition
ISBN: 9781305498129
Author: Stephen L. Herman
Publisher: Cengage Learning
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Chapter 3, Problem 3RQ
To determine
The reason for using two load contact starter to control a single-phase motor operates on 240 volts.
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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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- A 150-horsepower motor is to be installed on a 480-volt three-phase line. What is the minimum size NEMA starter that should be used for this installation?arrow_forwardA manual motor starter controls a single phase 120 volt motor. The motor is not running, and theswitch handle on the starter is found to be in thecenter position. What does this indicate?arrow_forwardRefer to the schematic diagram in Figure 318. Assume that the motor is not running. When the third speed push button is pressed, the motor starts in its lowest speed. After a delay of 3 seconds, the motor accelerates to second speed and 3 seconds later to third speed. After a period of about 1 minute, the fourth speed push button is pressed, but the motor does not accelerate to fourth speed. Which of the following could cause this problem? a. Control relay CR2 coil is open. b. S2 contactor coil is open. c. CR3 coil is shorted. d. S3 contactor coil is open.arrow_forward
- What is the speed of operation of the Holtz motor?arrow_forwardWhat does the code letter on a motor nameplate indicate about the motor?arrow_forwardTo answer the following questions refer to the circuit in Figure 416. When the pressure switch closes, which starter will energize first, 1M or 2M? Explain your answer.arrow_forward
- When a repulsion-start induction-run motor reaches about 75% of rated full-load speed, it stops operating as a repulsion motor and starts operating as a squirrel-cage motor. What must be done to cause the motor to begin operating as a squirrel-cage motor?arrow_forwardAssume that all three motors shown in Figure 12–14 are running. Now assume that the STOP button is pressed and motors #1 and #2 stop running, but motor #3 continues to operate. Which of the following could cause this problem? STOP button is shorted. The 2M contact between wire numbers 31 and 32 is hung closed. The 3M load contacts are welded shut. The normally open 3M contact between wire numbers 23 and 31 is hung closed.arrow_forwardAn open single-phase motor with a centrifugal starting switch may not be used in A. an air-conditioning condenser fan motor. B. an air-conditioning indoor air handler. C. an area where explosive gases exist. D. a ventilating fan motor.arrow_forward
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