Understanding Motor Controls
3rd Edition
ISBN: 9781305498129
Author: Stephen L. Herman
Publisher: Cengage Learning
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Textbook Question
Chapter 41, Problem 1RQ
To answer the following questions refer to the circuit in Figure 41–6.
The pressure switch is shown as:
- a. Normally open
- b. Normally closed
- c. Normally open held closed
- d. Normally closed held open
Expert Solution & Answer
To determine
The state of the pressure switch used in the circuit shown in Figure 41-6.
Explanation of Solution
Refer text book Figure 41-6.
The pressure switch shown in the circuit has its movable contact above the fixed contact. Hence, the pressure switch is normally closed and kept open for the circuitry purpose. This switch is called a “normally closed held open switch”. The schematic of normally closed held open pressure switch is shown in Figure 1 below:
Thus, the correct answer is “option d. normally closed held open”.
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Section 5-2: Line Diagrams-Signals,
Decisions, and Actions
In the following application, a temperature switch controls a heating contactor and a flow switch is used to
ensure there is enough air flow. If there is not enough air flow, an alarm is sounded. Complete the required
information.
1. List all the signal devices in the circuit.
2. List all the action devices in the circuit.
3. List the decision part of the circuit that automatically sounds the alarm if there is a problem.
4. When the heating element is on during normal operation, is the flow switch open or closed?
CIRCULATING
2
L1
FAN
TEMPERATURE
SWITCH
TR
HEATING
ELEMENTS
FLOW
SWITCH
-HOT AIR
PADDLE
AIR FILTER
NORMALLY CLOSED
FLOW SWITCH
65
ALARM
(SOUNDS IF NO FLOW FOR
15 SECONDS OR MORE)
Date
HEATING
CONTACTOR
TR
ON-DELAY
TIMER
SUPPLY AIR
COLD AIR
(3) TIME SET= 15 SEC
© 2014 American Technical Publishers, Inc.
All rights reserved
In a tap set, the plug tap is the final one and is also known as taper tap.
Select one:
True
False
Chapter 41 Solutions
Understanding Motor Controls
Ch. 41 - To answer the following questions refer to the...Ch. 41 - To answer the following questions refer to the...Ch. 41 - Prob. 3RQCh. 41 - To answer the following questions refer to the...Ch. 41 - To answer the following questions refer to the...Ch. 41 - Prob. 6RQCh. 41 - To answer the following questions refer to the...Ch. 41 - To answer the following questions refer to the...Ch. 41 - Prob. 9RQCh. 41 - Prob. 10RQ
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- 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_forwardTo answer the following questions refer to the circuit in Figure 416. What is the purpose of the rotary switch connected after the pressure switch?arrow_forwardRefer 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_forward
- Refer to the circuit shown in Figure 15-6. The STOP button is shown to be an emergency STOP button. What does the symbol used for the STOP button actually represent?arrow_forwardThe symbol shown is: a. Double acting push button b. Two-position selector switch c. Three-position selector switch d. Maintained contact push buttonarrow_forwardTo answer the following questions refer to the circuit shown in Figure 41–10. Assume that the third speed push button is pressed. Explain the sequence of operation for the circuit.arrow_forward
- 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_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_forwardRefer to the circuit shown in Figure 310. When would the amber pilot light be turned on? a. When the manual/automatic switch is set in themanual position. b. When the float switch contacts are closed. c. Anytime the manual starter is turned on. d. Only when the manual/automatic switch is setin the manual position.arrow_forward
- Refer 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 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_forwardWhat is the primary use of a limit switch?arrow_forward
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