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228)
228)
The most common residential control voltage is:
A)
115 V.
B)
24 V.
C)
12 V.
D)
230 V.
Answer:
B
Explanation:
A)
B)
C)
D)
229)
229)
What type of control system has the ability to measure the controlled variable and the system
output and dynamically adjust the setpoint to achieve more precise control?
A)
Proportional controls
B)
Modulating controls
C)
Two-position controls
D)
Proportional integral derivative (PID) controls
Answer:
D
Explanation:
A)
B)
C)
D)
230)
230)
When is the O terminal energized on most low-voltage thermostats?
A)
Whenever the system switch is moved to "Cool"
B)
Whenever the thermostat calls for first stage heat
C)
Whenever the thermostat calls for cooling
D)
Whenever the system switch is moved to "Heat"
Answer:
A
Explanation:
A)
B)
C)
D)
231)
231)
Pneumatic controls are most commonly used:
A)
To turn on and off small residential air-conditioning systems.
B)
To move air through the duct of forced air systems.
C)
To operate systems with programmable logic control.
D)
To control dampers and valves in large commercial systems.
Answer:
D
Explanation:
A)
B)
C)
D)
61
232)
232)
At its most basic, a control requires:
A)
A sensor, an actuator, and a linkage.
B)
A voltage source, a path, and a load.
C)
A transformer, a relay, and a motor.
D)
A thermostat and a motor.
Answer:
A
Explanation:
A)
B)
C)
D)
233)
233)
Compared to electro-mechanical controls, pneumatic controls can more easily:
A)
Provide proportional or modulating control.
B)
On-off control.
C)
Control residential air-conditioning systems.
D)
Control small appliances.
Answer:
A
Explanation:
A)
B)
C)
D)
234)
234)
A heat pump defrost control must do three things: Turn on auxiliary heat, turn off the condenser
fan motor, and:
A)
Turn off the compressor.
B)
Deactivate the thermostat.
C)
Shift the reversing valve from heat to cool.
D)
Turn off the indoor blower fan.
Answer:
C
Explanation:
A)
B)
C)
D)
235)
235)
The purpose of controls in an HVACR system is to:
A)
Protect the refrigeration cycle components.
B)
Start and stop all the electrical components.
C)
maintain the temperature in a space.
D)
Regulate HVACR equipment in response to monitored conditions.
Answer:
D
Explanation:
A)
B)
C)
D)
62
236)
236)
When first setting up a new communicating control system:
A)
The technician must enter the communicating address and function of each component in
the system.
B)
The technician enters the control code on each individual component access screen.
C)
The technician must connect a laptop to each device in the network.
D)
The system automatically scans the network for connected devices.
Answer:
D
Explanation:
A)
B)
C)
D)
237)
237)
In a communicating control system, the system components communicate over a ________
network.
A)
computer
B)
serial
C)
home
D)
commercial
Answer:
B
Explanation:
A)
B)
C)
D)
238)
238)
To view the Advanced Installer menu on Rheem and the Ruud Comfort Control System, press the
________ simultaneously for three seconds.
A)
left and right
B)
Menu button
C)
up and down
D)
Rheem and Ruud logos
Answer:
A
Explanation:
A)
B)
C)
D)
239)
239)
How many wires are needed for a communicating control system to control a three-stage heat,
two-stage cool heat pump?
A)
Five wiresone for each stage heat and cool
B)
Four wirestwo for power and two for communication
C)
Nine wiresone for each stage plus reversing valve and power
D)
No wires are required because communicating systems are wireless.
Answer:
B
Explanation:
A)
B)
C)
D)
63
240)
240)
Most residential systems that use communicating controls use:
A)
Three-phase motors.
B)
Brushless DC electronically controlled motors.
C)
Permanent split capacitor motors.
D)
Shaded pole motors.
Answer:
B
Explanation:
A)
B)
C)
D)
241)
241)
Which type of control system can control system operation based on real-time system
information?
A)
Hybrid pneumatic electromechanical system
B)
Relay logic system
C)
Communicating system
D)
Line-voltage control system
Answer:
C
Explanation:
A)
B)
C)
D)
242)
242)
________ are available for integration in communicating control systems.
A)
Zoning boards, humidifiers, and air cleaners
B)
Humidifiers, video games, and audio systems
C)
Blowers, kitchen appliances, and entertainment systems
D)
Air cleaners, dishwashers, and refrigerators
Answer:
A
Explanation:
A)
B)
C)
D)
243)
243)
The BACnet protocol is primarily used in:
A)
Commercial refrigeration systems.
B)
Residential systems.
C)
Small appliances.
D)
Building automation control.
Answer:
D
Explanation:
A)
B)
C)
D)
64
244)
244)
Which type of control system can more easily control multiple indoor coils?
A)
Line-voltage control system
B)
Hybrid pneumatic electromechanical system
C)
Relay logic system
D)
Communicating system
Answer:
D
Explanation:
A)
B)
C)
D)
245)
245)
Communicating systems operate by:
A)
Sending 24 V to each component that must be energized.
B)
Sending serial computer communications down a small number of wires.
C)
Sending control signals over telephone wires.
D)
Connecting to the manufacturer's website via satellite connections.
Answer:
B
Explanation:
A)
B)
C)
D)
246)
246)
Most communicating systems are wired with four wires. They are:
A)
Two wires for 24 V power and two for communication.
B)
One wire for power, one for cooling, one for heating, and one for fan.
C)
Power lines 1, 2, 3, and 4.
D)
Communication lines 1, 2, 3, and 4.
Answer:
A
Explanation:
A)
B)
C)
D)
247)
247)
In communicating systems, fault history, system run time, system status, and other helpful service
information are normally:
A)
Available at the LCD screens on the side of the equipment.
B)
Available on the manufacturer's website for each installed system.
C)
Always shown on the main thermostat display.
D)
Available through the service screens of the communicating thermostat.
Answer:
D
Explanation:
A)
B)
C)
D)
65
248)
248)
The ________ popularity of communicating systems lies in their ability to ________ overall system
efficiency and comfort by matching the system capacity to the heat load.
A)
increasing; improve
B)
increasing; decline
C)
decreasing; improve
D)
decreasing; decline
Answer:
A
Explanation:
A)
B)
C)
D)
249)
249)
Poor ________ are the most common cause of communication errors.
A)
voltages
B)
pressures
C)
cooling
D)
connections
Answer:
D
Explanation:
A)
B)
C)
D)
250)
250)
A control protocol is:
A)
An internationally recognized energy efficiency code.
B)
An agreed way to approach a service call.
C)
A type of communicating system specific to a particular manufacturer.
D)
An agreed standard set of rules that are used for communication over a network.
Answer:
D
Explanation:
A)
B)
C)
D)
251)
251)
In refrigeration and air conditioning, loads are normally wired:
A)
Either in series or in parallel with each other.
B)
In parallel with the switches controlling them.
C)
In parallel with each other.
D)
In series with each other.
Answer:
C
Explanation:
A)
B)
C)
D)
66
252)
252)
Electric current that regularly reverses direction is called:
A)
Ellipsoidal current.
B)
Direct current.
C)
Potential current.
D)
Alternating current.
Answer:
D
Explanation:
A)
B)
C)
D)
253)
253)
The three general types of materials used in electrical control systems are:
A)
Wood, concrete, and oil.
B)
Protons, electrons, and neutrons.
C)
Wire, electrical tape, and batteries.
D)
Conductors, semiconductors, and nonconductors.
Answer:
D
Explanation:
A)
B)
C)
D)
254)
254)
The three essential requirements for a useful electric circuit are:
A)
A magnetic field, a path for current flow, and a switch.
B)
A power source, a path for current flow, and a switch.
C)
A power source, a path for current flow, and an electrical load.
D)
A power source, a magnetic field, and a path for current flow.
Answer:
C
Explanation:
A)
B)
C)
D)
255)
255)
What are free electrons?
A)
Electrons that flow without any energy input
B)
Electrons that are no longer bound to their atoms
C)
Electrons that escape from conductors into the surrounding air
D)
Electricity that the power company does not charge for
Answer:
B
Explanation:
A)
B)
C)
D)
67
256)
256)
What is the current draw of a 120-V circuit with a resistance of 20?
A)
120 V × 20 = 2,400 A
B)
120 V + 20 = 140 A
C)
20/120 V = 0.17 A
D)
120 V/20 = 6 A
Answer:
D
Explanation:
A)
B)
C)
D)
257)
257)
In refrigeration and air conditioning, switches are normally wired:
A)
In either series or parallel with the load they control.
B)
In series with the load they control.
C)
In parallel with the power supply.
D)
In parallel with the load they control.
Answer:
B
Explanation:
A)
B)
C)
D)
258)
258)
Alternating current frequency is measured in:
A)
Bandwidth (BW).
B)
Hertz (Hz).
C)
Gigabytes (GB).
D)
Power Width Modulations (PWM).
Answer:
B
Explanation:
A)
B)
C)
D)
259)
259)
What is the total circuit resistance of three heat strips wired in parallel if each strip has a resistance
of 12?
A)
36
B)
4
C)
12
D)
3
Answer:
B
Explanation:
A)
B)
C)
D)
68
260)
260)
In a series circuit:
A)
The current stays the same throughout the circuit.
B)
The voltage stays the same throughout the circuit.
C)
The resistance stays the same throughout the circuit.
D)
The wattage stays the same throughout the circuit.
Answer:
A
Explanation:
A)
B)
C)
D)
261)
261)
What is the voltage drop across a 30- resistor with a current draw of 5 A?
A)
5 A + 30 = 35 V
B)
30/5 A = 6 V
C)
30 × 5 A = 150 V
D)
5 A/30 = 0.17 V
Answer:
C
Explanation:
A)
B)
C)
D)
262)
262)
An electric circuit without a complete path is called:
A)
A fundamental circuit.
B)
A short circuit.
C)
A grounded circuit.
D)
An open circuit.
Answer:
D
Explanation:
A)
B)
C)
D)
263)
263)
Protons are:
A)
Positively charged particles located in the center of the atom.
B)
Positively charged particles located in the outer part of the atom.
C)
Negatively charged particles located in the center of the atom.
D)
Negatively charged particles located in the outer part of the atom.
Answer:
A
Explanation:
A)
B)
C)
D)
69
264)
264)
Electrical conductors listed in order of best to worst are:
A)
Aluminum, gold, silver, copper.
B)
Gold, silver, copper, aluminum.
C)
Copper, gold, aluminum, silver.
D)
Copper, aluminum, silver, gold.
Answer:
B
Explanation:
A)
B)
C)
D)
265)
265)
In an AC inductive circuit:
A)
The voltage and current are in phase.
B)
Voltage leads current.
C)
Current leads voltage.
D)
Voltage lags current.
Answer:
B
Explanation:
A)
B)
C)
D)
266)
266)
Three-phase AC power is used:
A)
In both residential and commercial buildings.
B)
Only in commercial buildings.
C)
Only in residences.
D)
Only in Europe.
Answer:
B
Explanation:
A)
B)
C)
D)
267)
267)
The electrical power supplied to houses is usually:
A)
240 V, single-phase power.
B)
440 V, single-phase power.
C)
230 V, three-phase power.
D)
208 V, three-phase power.
Answer:
A
Explanation:
A)
B)
C)
D)
70
268)
268)
A wye three-phase power supply provides:
A)
120 V between the legs.
B)
240 V between the legs.
C)
208 V between the legs.
D)
24 V between the legs.
Answer:
C
Explanation:
A)
B)
C)
D)
269)
269)
Three-phase transformers are available in:
A)
Delta and omega configurations.
B)
Alpha and omega configurations.
C)
Delta and wye configurations.
D)
Alpha and wye configurations.
Answer:
C
Explanation:
A)
B)
C)
D)
270)
270)
What part of an analog scale gives the most accurate reading?
A)
Typically, analog meters are equally accurate across the entire scale.
B)
The midpoint of the scale
C)
The first 25% of the scale
D)
The last 25% of the scale
Answer:
B
Explanation:
A)
B)
C)
D)
271)
271)
What scales on analog meters require battery power to operate?
A)
Only the volts scale
B)
Only the milliamps scale
C)
Only the ohms scale
D)
All scales on an analog meter require battery power.
Answer:
C
Explanation:
A)
B)
C)
D)
71
272)
272)
How does a weighted average meter measure alternating current?
A)
It takes an average over a short period of time.
B)
It measures the current's ability to lift a small weight inside the meter.
C)
It calculates the root mean square value of the current.
D)
It reads the current at the test point and applies an averaging factor.
Answer:
A
Explanation:
A)
B)
C)
D)
273)
273)
Meter functions commonly used for air-conditioning troubleshooting include:
A)
Frequency, inductance, and impedance.
B)
Watts, frequency, and phase angle.
C)
Volts, amps, and ohms.
D)
Inductance, capacitance, and impedance.
Answer:
C
Explanation:
A)
B)
C)
D)
274)
274)
When using a meter with a manual scale setting, always:
A)
Set the scale based on what you expect the reading to be.
B)
Start with the lowest scale and work up to get an accurate reading.
C)
Start with the highest scale and work down to get an accurate reading.
D)
The scale setting does not affect the reading.
Answer:
C
Explanation:
A)
B)
C)
D)
275)
275)
What category of electric meter is intended only for measurement inside an appliance?
A)
Category IV
B)
Category I
C)
Category II
D)
Category III
Answer:
B
Explanation:
A)
B)
C)
D)
72
276)
276)
Root-mean square (RMS) is a mathematical formula for:
A)
Determining the price of a replacement compressor.
B)
Determining the physical resistance of an AC motor.
C)
Measuring the pressure drop across an air filter.
D)
Calculating the electrical power passing through a alternating current circuit.
Answer:
D
Explanation:
A)
B)
C)
D)
277)
277)
What is a transient voltage?
A)
A momentary surge or spike of voltage that can be several times the normal circuit voltage
B)
A voltage that affects only the moving, or transient portions of the circuit
C)
A voltage that temporarily transforms to current or resistance
D)
A voltage that is traveling from one part of the circuit to another part of the circuit
Answer:
A
Explanation:
A)
B)
C)
D)
278)
278)
Which type of thermostats provide the closest temperature control?
A)
Mechanical line voltage thermostats
B)
Electronic low-voltage thermostats
C)
Mechanical low-voltage thermostats
D)
There is no difference in the ability of different thermostats to maintain close temperature
control.
Answer:
B
Explanation:
A)
B)
C)
D)
279)
279)
Which of the following describes a dual-element fuse?
A)
It provides a time delay for starting motor loads.
B)
It provides each fuse with a second chance with a spare element.
C)
It works with two different voltages.
D)
It allows field calibration of the fuse trip point.
Answer:
A
Explanation:
A)
B)
C)
D)
73
280)
280)
An electrical component that stores energy when an electric charge is forced onto its plates is
called a:
A)
Diode.
B)
Capacitor.
C)
Resistor.
D)
Triac.
Answer:
B
Explanation:
A)
B)
C)
D)
281)
281)
The purpose of an electrical overload device is to protect against:
A)
Excessive voltage.
B)
Power surges.
C)
Excessive resistance.
D)
Excessive current.
Answer:
D
Explanation:
A)
B)
C)
D)
282)
282)
The purpose of a standard control transformer is to:
A)
Regulate the power supply voltage in an air conditioner.
B)
Control the amount of power consumed by electric motors.
C)
Increase line voltage from 208 V to 230 V.
D)
Reduce line voltage to 24 V for HVACR control systems.
Answer:
D
Explanation:
A)
B)
C)
D)
283)
283)
What is the maximum safe secondary current for a 40 VA transformer that has a primary voltage
of 240 V and a secondary voltage of 24 V?
A)
40 VA ÷ 24 V = 1.67 A
B)
240 V ÷ 40 VA = 6 A
C)
24 V ÷ 40 VA = 0.6 A
D)
240 V ÷ 24 V = 10 A
Answer:
A
Explanation:
A)
B)
C)
D)
74
284)
284)
Compared to mechanical thermostats, digital thermostats:
A)
Are less expensive.
B)
Maintain closer temperature control.
C)
Are generally less flexible in application.
D)
Allow for wider swings in the controlled temperature.
Answer:
B
Explanation:
A)
B)
C)
D)
285)
285)
Why are manufacturers replacing relay logic systems with solid-state logic systems?
A)
Solid-state logic systems operate faster, use less power, and can control more functions.
B)
Solid-state systems are less prone to problems dues to noisy voltage signals.
C)
Most HVACR technicians are already trained on solid-state logic systems.
D)
Solid-state systems are simpler in design.
Answer:
A
Explanation:
A)
B)
C)
D)
286)
286)
Compared to relay logic systems, solid-state logic systems:
A)
Consume about the same amount of power to operate.
B)
Use more power to operate.
C)
Use less power to operate.
D)
Consume no power to operate.
Answer:
C
Explanation:
A)
B)
C)
D)
287)
287)
What is the most common temperature sensing element used for mechanical thermostats?
A)
Magnets
B)
Warped discs
C)
Bimetal coil
D)
Mercury bulb
Answer:
C
Explanation:
A)
B)
C)
D)
75
288)
288)
A control that responds to changes in pressure is called a:
A)
Time clock.
B)
Thermostat.
C)
Pressure switch.
D)
Humidistat.
Answer:
C
Explanation:
A)
B)
C)
D)
289)
289)
The twisting force that must be developed by a motor to turn its load is called:
A)
Horsepower.
B)
Torsion.
C)
Torque.
D)
Wattage.
Answer:
C
Explanation:
A)
B)
C)
D)
290)
290)
The rotor of an ECM motor is composed of:
A)
Layers of laminated soft iron.
B)
Copper windings coiled around layers of laminated soft iron.
C)
A solid bronze casting.
D)
Permanent magnets.
Answer:
D
Explanation:
A)
B)
C)
D)
291)
291)
When operated with the same power source, which induction motor will have a higher RPM: a
four-pole motor or a six-pole motor?
A)
The number of poles does not affect the speed of the motor.
B)
The six-pole motor will turn faster.
C)
The four-pole motor will turn faster.
D)
The four-pole when turning clockwise, the six-pole motor when turning counterclockwise.
Answer:
C
Explanation:
A)
B)
C)
D)
76
292)
292)
The part of an AC induction motor that turns is called:
A)
The flywheel.
B)
The rotor.
C)
The stator.
D)
The field.
Answer:
B
Explanation:
A)
B)
C)
D)
293)
293)
What is the primary purpose of the start capacitor?
A)
To increase the motor operating current
B)
To increase the motor efficiency
C)
To increase the motor starting current
D)
To increase the motor starting torque
Answer:
D
Explanation:
A)
B)
C)
D)
294)
294)
The rotor turns because of:
A)
The directional spin of the electrons in the stator windings.
B)
The repulsion and attraction between the poles of the rotor and stator.
C)
The directional spin of the electrons in the rotor winding.
D)
The induced cyclonic effects created by the proximity of the rotor to the stator.
Answer:
B
Explanation:
A)
B)
C)
D)
295)
295)
The start capacitor is removed from the circuit of a CSCR compressor by:
A)
A high-pressure switch.
B)
A centrifugal switch.
C)
The start capacitor does not drop out on a CSCR compressor.
D)
A potential starting relay.
Answer:
D
Explanation:
A)
B)
C)
D)
77
296)
296)
What is the primary purpose of the run capacitor?
A)
To increase the motor operating current
B)
To increase the motor efficiency
C)
To increase the motor starting torque
D)
To increase the motor starting current
Answer:
B
Explanation:
A)
B)
C)
D)
297)
297)
The most common type of single-phase motor used in HVACR equipment is:
A)
Repulsion start induction run (RSIR).
B)
Capacitor start induction run.
C)
Series wound universal DC motor.
D)
Permanent split capacitor (PSC).
Answer:
D
Explanation:
A)
B)
C)
D)
298)
298)
Compared to single-phase motors, three-phase motors are:
A)
More versatile because they can be operated on either single-phase or three-phase power.
B)
More complicated and use more electricity.
C)
More common in small, fractional horsepower applications.
D)
Stronger starting with a higher operating efficiency.
Answer:
D
Explanation:
A)
B)
C)
D)
299)
299)
Motors are rated in either ________ or ________ operation.
A)
instantaneous, interrupted
B)
instantaneous, intermittent
C)
intermittent, continuous
D)
interrupted, continuous
Answer:
C
Explanation:
A)
B)
C)
D)
78
300)
300)
Most indoor blower motors are ________ motors.
A)
multi-speed PSC
B)
multi-speed shunt field
C)
single speed shunt field
D)
single speed PSC
Answer:
A
Explanation:
A)
B)
C)
D)
301)
301)
Belt tension should be checked every:
A)
Year.
B)
2 months.
C)
Month.
D)
6 months.
Answer:
D
Explanation:
A)
B)
C)
D)
302)
302)
The most common types of single phase compressor motors are:
A)
Split phase capacitor (SPC), semi-permanent split capacitor (SPSC), capacitor start (CS), and
shaded pole types
B)
Permanent split capacitor (PSC), capacitor start (CS), capacitor start/capacitor run (CSR),
and split phase
C)
Split phase capacitor (SPC), capacitor start (CS), capacitor start/capacitor run (CSR), and
semi-permanent split capacitor (SPSC)
D)
Capacitor run (CR), permanent split capacitor (PSC), and capacitor start (CS), and shaded
pole types
Answer:
B
Explanation:
A)
B)
C)
D)
79
303)
303)
Motors with shunted field windings:
A)
Are hard to detect.
B)
Will not run at full speed or strength.
C)
Will draw higher than normal amps.
D)
Can be detected by comparing the actual winding resistance to the motor manufacturer's
data.
E)
All of these.
Answer:
E
Explanation:
A)
B)
C)
D)
E)
304)
304)
What type of drive would move the driven device at the same speed as the motor?
A)
Direct drive
B)
Overdrive
C)
Gear drive
D)
Belt drive
Answer:
A
Explanation:
A)
B)
C)
D)
305)
305)
Open motor winding failures can be identified by:
A)
Measurable resistance reading.
B)
Zero resistance reading.
C)
Infinite resistance reading.
D)
All of the above.
Answer:
C
Explanation:
A)
B)
C)
D)
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