Understanding Motor Controls
4th Edition
ISBN: 9781337798686
Author: Stephen L. Herman
Publisher: Delmar Cengage Learning
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Textbook Question
Chapter 15, Problem 3RQ
Refer to the circuit shown in Figure 15-2. Why is there an overload contact symbol shown in series with the compressor contactor but not the condenser fan contactor or evaporator fan contactor?
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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
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14-26. For the circuit of Figure 14-20, what happens to the cylinders in each case?
a. Valve V1 is actuated and held.
b. Valve V1 is released and valve V2 is actuated and held. Valves V3 and V4 are
sequence valves.
Select the proper choice(s) for each of the following statements:
1) To control single-acting cylinder we just need:
double-acting cylinder we should use
A2/2-way, 5/2-way,
(C) 3/3-way, 3/4-way,
2) In
DCV.
(B) 3/2-way, 4/2-way,
(D) 4/3-way, 3/2-way.
mid poistion of DCV, we can move cylinder piston rod freely without
resistance by hand.
(A) working ports are exhausted,
(C) working ports are pressurized,
3) In pneumatics we use
A Compressor
(B) Pump,
DCV, while to control the
4) Quick exhaust valve is used to
(A) increase the cylinder return speed.
(C) meter-out the cylinder speed
(B) all ports are closed.
no one of these options.
to obtain high pressure air.
(C) Turbine,
(D) pressure relief valve.
(B) meter-in the cylinder speed,
(D) increase the cylinder extending speed.
6) Meter-in of cylinder movement is used to control the
Afluid that enters the hydraulic cylinder,
(B) fluid that exits the hydraulic cylinder,
(C) fluid that enters the DCV
(D) fluid that exits the DCV.
5) One of the…
Chapter 15 Solutions
Understanding Motor Controls
Ch. 15 - What is the common name for an air flow switch?Ch. 15 - What type of switch is contained on most flow...Ch. 15 - Refer to the circuit shown in Figure 15-2. Why is...Ch. 15 - Refer to the circuit shown in Figure 15-6. The...Ch. 15 - Refer to the circuit shown in Figure 15-6. If an...Ch. 15 - Refer to the circuit shown in Figure 15-6. If the...Ch. 15 - Prob. 7RQ
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Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, mechanical-engineering and related others by exploring similar questions and additional content below.Similar questions
- Refer to the circuit shown in Figure 15-6. If the circuit is in operation and an overload should occur on the lube oil pump and the overload contact open, would it affect the operation of the compressor?arrow_forwardRefer to the circuit shown in Figure 15-6. If an overload should occur on the compressor motor and the overload contact open, would it affect the operation of the lube oil pump?arrow_forwardA three-phase motor nameplate indicates a full load current of 362 amperes. The nameplate indicates that the heaters are to be sized for 125% of motor full load current. Current transformers with a ratio of 600:5 are used to reduce the motor current. Using the chart shown in Figure 4–7B, determine the size of overload heaters needed to protect this motor.arrow_forward
- What advantage does a reactor have when limiting in-rush current that is not available with a resistor?arrow_forwardRefer to the schematic in Figure 7-10. Assume that when the START button is pressed, the control transformer fuse blows. What is the most likely cause of this trouble? Figure 7-10 Numbers are placed beside all components.arrow_forwardName two methods of sensing the current flow through the shunt field.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_forwardWhich is not a method of low-ambient control on air-cooled equipment? A. Modulating TXV B. Fan-cycling controls C. Flooding a condenser D. Fan speed control Describe the devices in questions 10-13.arrow_forwardExamine the circuit shown below and answer the following questions: 1. How is the cylinder 3A (towards the right) fundamentally different than cylinders 1A and 2A? 2. Describe 5 key features (ways, actuator, etc.) of the directional control valve 1V1. 3. Describe 5 key features of directional control valve 3V. 4. What type of device is 1V2? 5. Here's a close up of 1V2. Is it metering-in or metering-out? How do you know? 6. Empty triangle shapes appear in many places in this schematic. What do they represent? 1A 181 182 2A 282 3A 281 381 WWE 1V2 1V3 2V2 2V3 1V1 2V1 2Y1H svos H2Y2 3Y1 V 1V3 OV] OY1 211AM OZarrow_forward
- Draw a series circuit with a thermostat,a low-pressure switch, and a highpressure switch used as safety controlsto protect a motorarrow_forwardRefer to the circuit shown in Figure 5-29. Is the thermostat contact normally open, normally closed, normally closed held open, or normally open held closed? Figure 5-29 The contactor contains both load and auxiliary contacts.arrow_forwardGive the name of the following graphic symbols or Draw the graphic symbol according to the following name 4.(a) variable displacement motor (b) Pressure reducing valve (c) Directional control valve for 4-way, 3-position, O type neutral conditions (d) check valvearrow_forward
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