Understanding Motor Controls
4th Edition
ISBN: 9781337798686
Author: Stephen L. Herman
Publisher: Delmar Cengage Learning
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Textbook Question
Chapter 26, Problem 4RQ
Refer to the circuit shown in Figure 26–9. Assume that timer TR is set for a delay of 10 seconds. When the START button is pressed, the motor starts with its windings connected in wye. After a period of 1 minute, the motor has not changed from wye to delta. Which of the following could cause this condition?
- a. TR timer coil is open.
- b. S contactor coil is open.
- c. 1M starter coil is open.
- d. The control transformer fuse is blown.
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1 To enable actuator A2 to advance, it is necessary to switch valve V2 to the leftmost position and ensure that valve V1 is in its initial (intermediate) position.
2 Switching valve V2 to the leftmost position allows actuator A2 to advance, but for this to happen, valve V1 must also be switched to the leftmost position.
3 When activating valve V1, using the locking lever installed on the left side of it, the two actuators (A1 and A2) are allowed to advance.
4 Hydraulic pump B1 is a simple variable displacement type.
5 Valves V1 and V2 have a TANDEM center.
State four advantages of a pre-engaged starter when compared with an inertia type.
The supply frequency is 50 Hz. What will be
the rotor voltage frequency if the motor
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Chapter 26 Solutions
Understanding Motor Controls
Ch. 26 - Name two requirements that must be met before a...Ch. 26 - Prob. 2RQCh. 26 - Prob. 3RQCh. 26 - Refer to the circuit shown in Figure 26–9. Assume...Ch. 26 - Refer to the circuit shown in Figure 269. Assume...Ch. 26 - Prob. 6RQCh. 26 - The motor nameplate of a wye-delta started motor...Ch. 26 - Prob. 8RQCh. 26 - Refer to the circuit shown in Figure 2614. What is...Ch. 26 - Refer to the circuit shown in Figure 2614. When...
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- Refer 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 241. Assume that timer TR is set for a delay of 10 seconds. When the START button is pressed, the motor starts in low speed. After a delay of 30 seconds the motor is still in its lowest speed and has not accelerated to normal speed. Which of the following could not cause this condition? a. The START button is shorted. b. Timer coil TR is open. c. Contactor coil R is open. d. Timed contact TR did not close after a delay of 10 seconds.arrow_forwardRefer to the circuit shown in Figure 269. Assume that timer TR is set for a delay of 10 seconds. When the START button is pressed, the motor does not start. After a delay of 10 seconds, the motor suddenly starts with its stator windings connected in delta. Which of the following could cause this problem? a. TR timer coil is open. b. 2M contactor coil is open. c. S contactor coil is open. d. 1M starter coil is open.arrow_forward
- Refer 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 4221. Assume that the THIRD SPEED push button is pressed. The motor starts in second speed, skipping first speed. After 5 seconds, the motor accelerates to third speed. Which of the following could cause this problem? a. S1 contactor coil is open. b. CR1 contactor coil is open. c. TRl timer coil is open. d. S1 load contacts are shorted.arrow_forwardRefer 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_forward
- Refer to the circuit shown in Figure 252. Assume that timer TR is set for a time delay of 10 seconds. When the START button is pressed, the motor does not start. After a period of 10 seconds, the motor starts with full line voltage applied to it. Which of the following could cause this condition? a. Timer TR coil is open. b. CR coil is open. c. Contactor S coil is open. d. Contactor R coil is open.arrow_forwardTo answer the following questions refer to the circuit shown in Figure 4110. Assume that the third speed push button is pressed and the motor starts in its first or lowest speed. After a delay of 3 seconds, the motor accelerates to its second speed, but never accelerates to its highest or third speed. Which of the following could cause this problem? a. CR coil is open. b. Coil 2TR is open. c. Coil 1TR is open. d. Coil 1S is open.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 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_forwardRefer to the circuit shown in Figure 97. 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.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_forward
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