Understanding Motor Controls
4th Edition
ISBN: 9781337798686
Author: Stephen L. Herman
Publisher: Delmar Cengage Learning
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Textbook Question
Chapter 9, Problem 7RQ
Refer to the circuit shown in Figure 9–7. Assume that when the forward push button is pressed the motor does not start, but when the reverse push button is pressed the motor will start in the reverse direction. When the stop button is pressed the motor stops running. Which of the following could NOT cause this problem?
- a. The forward push button is defective.
- b. The F starter coil is open.
- c. The overload auxiliary contact is open.
- d. The normally closed R contact is open.
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Chapter 9 Solutions
Understanding Motor Controls
Ch. 9 - Prob. 1RQCh. 9 - What is interlocking?Ch. 9 - Referring to the schematic shown in Figure 97, how...Ch. 9 - What would be the danger, if any, if the circuit...Ch. 9 - Prob. 5RQCh. 9 - Assume that the circuit shown in Figure 97 were to...Ch. 9 - Refer to the circuit shown in Figure 97. Assume...Ch. 9 - Prob. 8RQ
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- Refer 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_forwardRefer to the circuit shown in Figure 33–7. When the low speed push button is pressed, the motor begins to run in low speed. When the high speed push button is pressed, the motor stops running. Which of the following could cause this problem? The 1L contactor coil is open. H contactor coil is open. PR relay coil is open. The 2L contactor coil is open.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_forward
- Refer to the circuit shown in Figure 16-11. Assume that the platform is located on the bottom floor. When the UP push button is pressed the pump motor does not start. Which of the following could not cause this problem? The contacts of limit switch LS1 are open. The contacts of limit switch LS2 are open. Motor starter coil M is open. The overload contact is open.arrow_forwardRefer to the circuit shown in Figure 107. Assume that when the start button is pressed the motor does not start, but when the inch push button is pressed the motor runs at reduced speed. Which of the following could NOT cause this problem? a. The control transformer fuse is blown. b. M starter coil is defective. c. The start push button is defective. d. The stop push button is defective.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
- Refer to the circuit shown in Figure 2614. When the START button is pressed, the control transformer fuse blows immediately. Which of the following could not cause this problem? a. Control relay coil CR is shorted. b. Starter coil 1M is shorted. c. Contactor coil S is shorted. d. Contactor coil 2M is shorted.arrow_forwardRefer to the circuit shown in Figure 25–5. Assume that timer TR1 is set for a delay of 10 seconds and timer TR2 is set for a delay of 5 seconds. When the START button is pressed, the motor starts. After 10 seconds the S1 contacts open and the motor continues to accelerate, but never reaches full speed. After a delay of about 30 seconds, the motor trips out on overload. Which of the following could cause this problem? TR1 coil is open. S2 coil is open. S1 coil is open. R coil is open.arrow_forwardRefer to the circuit shown in Figure 16-11. Assume that the platform is located on the lower floor. When the UP push button is pressed, the platform rises. When the platform reaches the upper floor, however, the pump does not turn off but continues to run until the overload relay opens the overload contacts. Which of the following could cause this problem? a. The solenoid valve opened when limit switch LS1 opened. b. The UP push button is shorted. c. Limit switch LS1 did not open its contacts. d. Limit switch LS2 contacts did not reclose when the platform began to rise.arrow_forward
- Referring to Figure 1214, assume that the normally open 2M contact located between wire numbers 23 and 29 is welded closed. Also assume that none of the motors are running. What would happen if: a. The number 2 push button was to be pressed before the number 1 push button? b. The number 1 push button was to be pressed first?arrow_forwardRefer to the circuit shown in Figure 247. Assume that all timers are set for a delay of 5 seconds. When the START button is pressed the motor starts in its lowest speed. After a delay of over 10 seconds, the motor is still running in the lowest speed. Which of the following could cause the problem? a. TR1 coil is open. b. TR1 coil is shorted. c. S2 coil is open. d. S1 coil is shorted.arrow_forwardRefer to the circuit shown in Figure 33–11. Explain the action of the circuit if coil 2CR is shorted and the second speed push button is pressed.arrow_forward
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