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WorksheetsVolume 3 URE
Total questions: 100
Worksheet time: 25hrs 0mins
What relationship between magnetic field and conductors is required to generate voltage mechanically?
No relationship exists between the two
Relative motion between the two
A direct temperature relationship
Conductors must be solid copper
Nickel and chromium alloys are used in heater elements because they
Have a very low resistance to current
Make it possible to operate the elements at high pressures without melting
Make it possible to operate the elements at high temperatures without melting
Make it possible to operate the elements at low pressures without melting
What effect does the length of a wire have on the amount of pressure needed to force the electrons the load device?
The long wire decreases the need for voltage
No pressure will be needed
More pressure will be needed
Less pressure is needed
Resistance should not be considered a bad thing because
Even conductors offer resistance to flow
A circuit reading O.L. will still allow flow
Voltage will always flow, no matter the resistance
An open circuit will allow flow
All forms of apposition to current flow are measured in
Amperes
Ohms
Volts
Watts
How is direct current produced?
By a battery or a thermocouple
Through a rotating magnetic field
Through relative motion
By an alternating current generator
The sine wave gets its name because the alternator output voltage at any one paint on the wave is the product of the sine of the
A product of the sine of the stator angle and the peak voltage
Rotor angle and the frequency
Rotor angle and the zero voltage
Rotor angle and peak voltage
What can you do to greatly increase the inductance of a coil?
Insert any non-magnetic substance
Remove the magnetic core
Add a core of magnetic material
Add of a balsa wood
Current lags the voltage in a purely inductive circuit because of the
Resistance of the circuit
Opposition of DC voltage
Opposition of impendance
Opposition by inductive reactance
When working with electrical equipment, how should you treat all electrical circuits as being
Dead
Live
Safe
Grounded
How can you prevent anyone from accidentally closing the breaker to a circuit that is under repair?
Lock the breaker in the ON position so other people will know it’s on
Lock the breaker in the OFF position and tell other technicians you plan on tagging it
De-energize the circuit by closing the switch and post a warning sign outside of the breaker box to let other technicians know you are working there.
Lock the breaker in the OFF position and tag it to indicate that the system is being repaired.
If using an aluminum-clad wire in place of a copper wire, how many sizes larger must the wire be to carry he same current safely?
One
Two
Three
Four
The type of insulation for a conductor is primarily based on
Insulation is the same for all conductors.
Where it is going to be used
The load device
The line voltage
What, if anything, does the location of a conductor affect?
Nothing, because it is insulated
The device it is connected to
Weather it is stranded or not
It’s current-carrying capacity
How is a solderless pigtail splice finished?
When applying the solder to the joint
By twisting the wire into three wires
With a wire nut
By stripping the insulation
When making a terminal loop, what will happen if the loop is not placed in a clockwise direction?
It will never connect
The screw will keep the loop tight
The screw tends to spread the loop as you tighten it
It will be looser if you turn it clockwise
How is a stranded wire pushed into a push in connection?
Insert a small screwdriver into the slot
Insert a large screwdriver into the driver
Pull the wire through with wire strippers
Pull the wire through with needle nose pliers
How do you ensure the wire is placed tightly into a push-in connection?
By pulling slightly on it
By pushing it out of the connector
By pulling hard with a needle nose plier
By pulling hard with wire stripper
When checking voltage rating, what will result if you place two hot wires to the same side of a device?
Proper system operation
Device will explode
A short to ground
A direct short
What could result if a circuit is forced to carry too much current?
Circuit will run properly
A fire or electrocution
A more efficient circuit
Circuit will exceed expectations
What is a common theme amongst schematics?
Different parts of the same component being separated
Line circuit being the biggest portion of the diagram
Load circuit being the biggest portion of the diagram
Control circuit being the smallest portion of the diagram
On the Environmental Control Unit (ECU), what component should come on after the compressor relay is energized?
Evaporator fan
Condenser fan
Compressor
Lockout relay
What should you be doing as you follow each circuit on a schematic?
Guessing the potential solution
Jumping around the schematic
Simply moving your finger left to right over the diagram
Describing in your head what is occurring with each component
What is the key to understanding complex circuits?
Breaking down the line circuits into smaller circuits
Keeping the complex circuits as large circuits and working through each in a logical manner
Breaking down the complex circuits into smaller circuits and skipping circuits you don’t
Breaking down the circuit into smaller circuits and working through them in a logical manner
What are you checking for when you troubleshoot a circuit using voltage?
Proper resistance at one point
The amperage between two points
The potential difference between three points
The potential difference between two points
How should you connect a voltage meter when checking AC voltage?
In parallel
In series
With one lead connected to the circuit
In a way that recognizes the polarity
When testing equipment for high voltage, when should you connect your meter?
While the compressor is running
After selecting the voltage setting
Before turning on power
After turning on power
What should you do to the multimeter before checking for ohms?
Turn it off and on
Insert thermistor attachment
Remove battery because it creates voltage
Zero it out by touching the leads together
What does it mean to isolate the part of the circuit you are testing?
Check it with a meter
Physically remove the entire component
Remove the components electrical and non-electrical hardware
Electronically disconnect the part being tested
What tool should you use when testing insulated material?
A megometer
A meter set to volts
Clamp-On ammeter
A regular meter set to ohms
When taking current readings using the clamp-on ammeter, you squeeze the trigger assembly to
Close the clamping jaws and place the open jaws around one of the circuit leads.
Open the clamping jaws and place the open jaws around one of the circuit leads.
Close the clamping jaws and place the jaws around two of the circuit leads.
To open the clamping jaws and place the open jaws around two circuit leads
What effect does an open circuit have on the load device? The load device will
Run intermittently
Run more efficiently
Not operate
Operate continuously
What should you do if you are having problems troubleshooting?
Ask for help
Stress out
Close out the job and return to the shop
Stay on the job site for hours even if you get nowhere
What is the next step after a part has been replaced?
Close out the job
Run an operational test
Disconnect electrical circuit
Tell your supervisor the job is complete
Where is a permanent distribution panel mounted?
At a construction site
Outside of a tent in the desert
At a forwarding operating base only
In a wall or other frame structure in a facility or home
What happens to the circuit when a fuse blows?
It creates a short
It creates an open
It creates a ground
It closes the circuit
How does a magnetic-type circuit breaker open the circuit?
Automatically after 8 seconds
Automatically after 10 seconds
Through delay action
Instantly
In a push-button switch, why are the push buttons insulated from the movable contact?
To prevent the switch from closing when it is pushed
To avoid injury from electrical shock
To create heat from the current
To complete the circuit
How must a snap-action switch close to avoid excessive arcing?
Quickly or slowly
Quickly
Slowly
Within one minute
Which coil of a transformer is always connected to the incoming power?
Both coils
Primary coil
Secondary coil
The control side
What is generated around the coil if AC blows through it?
Conduction
Relative motion
DC voltage
An alternating magnetic field
What happens when an alternating magnetic field is generated by one coil and cuts through the turns of a second coil?
DC current will flow
DC voltage is created
A magnetic field stays in the primary coil
Voltage is induced in the second coil
What happens when 24 volts is applied to a relay coil?
Contacts change positions
Contacts will only close
Contacts will only open
Contacts will maintain their position
What is the principle cause of a solenoids coil malfunction?
Excessive heat
Refrigerant
The amature
Technician negligence
In a split-phase motor, if the start winding is not disconnected after a short period of time, it will
Burn up
Increase efficiency
Increase running torque
Open after five additional minutes
How does the split-phase motor operate after the start winding is removed?
By the rotating magnetic field produced by the run winding and endbell
By the rotating magnetic field produced by the run winding and rotor
By the rotating magnetic field produced by the run winding and stator
By the rotating magnetic field produced by the DC sine wave
How is a toggle switch wired with the hot conductor in the circuit?
Wired to create an open
Directly to the neutral
In parallel
In series
What prevents the contactor chatter?
Shaded rings
Solenoid
Rubber gaskets
Control voltage
When replacing a heater, how are they identified?
Use the same one you are replacing
Catalog number
By size
By color
The first step in removing an electric motor is to ensure the circuit breaker
Or disconnect switch is closed
is closed and the disconnect switch is open
Is open and the disconnect switch is closed
Or disconnect switch is open
When using a external-drive motor starts but hums, what is the probable cause?
A bad capacitor or centrifugal switch
A bad motor
A bad stator
A bad rotor
When troubleshooting motor failure, how do you determine if a motor is overloaded?
Take an ohm reading
Take a megohm reading
Take a current draw with an ohmmeter
Perform a current draw with an ammeter
What should the motor shaft be check for when troubleshooting motor failure?
Depth
Width
Length
Any up or down play
What does a meter reading of ohms mean when checking a circuit to a grounded surface?
An open
A ground
The circuit is not grounded
There is no resistance to ground
What could create excessive noise from the motor?
Rotor is aligned
Motor is disconnected
Belts are at proper deflection
Motor not be being securely mounted
How can motor accessory noise be eliminated?
Placing tape over wire nuts
Tightening the wire nuts
Tightening the oil well cover and connection box cover
Placing electrical tape over connection box
When checking coupling alignment, what should you do if any part of a coupling is damaged?
Use coupling glue to fix it
Tape it together
Refurbish it
Replace it
How must the run windings be connected, to operate a dual-voltage motor on high voltage?
Directly to the transformer
Directly to the thermostat
In parallel
In series
How do you change the rotation of a three-phase motor?
Change all three power leads
Change any two power leads
Connect one lead power leads
Wire it for a single-phase application
Where are the load terminals connected in a three-phase controller?
T1, T2, and T3
L1, L2, and L3
L1 and L2
T1 and T2
What contacts must close for supply power to be sent to the load circuit?
The normally open main contacts
The normally open line contacts
The normally closed main contacts
The normally closed line contacts
If an air compressor runs for an extended period of time, the oil in it will
Cool down and vaporize
Heat up and liquify
Cool down and sludge
Heat up and turn into a vapor
When oil from an air compressor carbonizes and solidifies, what problems, if any, can it cause downstream?
None
Line voltage issues
Too large of an increase in airflow
Valves and air tools to malfunction
When you push the test button on the automatic drain of an air compressor, there should be a blast of air and
No moisture
A little moisture
3 pounds of moisture
5 pounds of moisture
What happens to the vapor pressure inside a sensing bulb when the surrounding air temperature increases?
It leaves the bulb and capillary
It explodes
It decreases
It increases
What could occur if the system throttling range is too small?
Operator hunting
Controller sensitivity will be adjusted
Complete loss of control of the system
Very efficient control of the system
In a timed on-off control, when does the heating anticipator cause the system to turn off?
After the space temperature reaches set point
Early before the space can overheat
Two degrees above set point
Ten degrees below set point
In proportional control, if the room is very cold, how much will the system provide?
One hundred percent heat every time
A minimum of 35 percent heat
An amount in proportion to the need
An amount in proportion plus 25 percent integral action
What is added to proportional control to correct its poor control and energy usage?
Timed on-off control
Floating control
Integral action
On-off control
How do valves and dampers move through their complete range of motion?
By on-off control
By loosening the linkages
By free flowing linkages
By an actuator that drives them
In times on-off control, what is the result of the controller not having to wait until it can detect change in the control variable?
A 25-percent increase in lag
A 75-percent increase in lag
The system is constantly lagging
Control system lags have no significant effect
In floating control, how does the controller move in relation to the deviation of the controlled variable?
Its movement corresponds to the direction of deviation of the controlled device
It’s movement is the inverse to the direction of deviation of the controlled device
There is very minimal relation between the controller and the controlled variable
It’s movement floats the controller
What does a microprocessor do after inputs and stores them?
Creates its own creative output
Creates a pre-programmed output
Holds on to them for up to 45 years
Creates an output for the sensor
What causes the temperature changes sensed by an averaging bulb?
Stratification
Motor efficiency
External static pressure
Pre-programmed output
What does a minimum position selector use to select its output?
Motor amperage
Compressor amperage
System control points
The minimum output selected for the controller
Where does an electronic actuator receive its direct current (DC) voltage?
From the sensor
From a controller
From the controlled device
From the motor controller
What gives the engineers flexibility when creating customer comfort?
Air handling equipment or pumps
Minimum output controllers
Variable frequency drives (VFD)
Dampers
Where does the variable frequency drive (VFD) receive its feedback control?
From the refrigerant gauges
From the controlled device
Internally or externally
Internally only
What is required for the energy monitoring control systems (EMCS) and direct digital control (DDC) components to communicate?
A modem from your shop
A modem at the DDC
A modem at EMCS
A modem at both locations
Where can a technician make changes to a direct control (DDC) system?
From a computer in the shop or laptop in mechanical rooms
From a government computer at your house
Only in mechanical rooms
By setting linkages
What should be the state of outdoor air dampers during preoccupancy warm-up periods for optimum start?
Inactive
Active
100 percent open
75 percent open
What air source does early morning purge use to precool a building?
Mixed air
Return air
Outdoor air
Supply air
What will a direct digital control (DDC) processor probably do after it receives its input and processes the information?
Produce its own input
Produce an output
Control the sensor output
Control the sensor input
What proportional plus integral plus derivative (PID) action acts as a brake to stop the controller at set point and prevent overshoot?
Derivative action
Floating control
On-off control
Integral control
What is a modulating signal from a direct control (DDC) to a particular device?
Digital output
Analog output
Digital input
Analog input
When the direct digital control (DDC) sends a small amount of current through the thermistor circuit, what does it then do to the input current coming back from the thermistor?
Preforms a derivative action
Translates it into a temperture
Discards it to the floating control
Translates it to a signal back to the sensor
Why would you choose to install electric reheat over reheat water coils?
Electric reheat is more expensive to install but more efficient to operate
Reheat coils are less expensive to install but more costly to repair
Electric reheat is the industry standard
Electric reheat is cheaper to install
On a central air-handling unit, which components turns on with the fan and also provides an emergency shutdown feature?
Firestats and freezestats
Closed oil pressure switches
Freezestats and closed oil pressure switches
Firestats, smoke detectors, and airflow switches
How many degrees Fahrenheit (F) above the normally expected temperature are supply duct Firestats set?
10
30
50
150
Roll-feed media filters may be automatically controlled by
The variable air volume (VAV) temperature
Pressure-activated timer circuit
Temperature-activated timer circuit
The technician removing the filter
In a mixed-air system, if outdoor air temperature is higher than the conditions where free cooling can be obtained, what will the outdoor air controller do?
Shut the damper
Open the damper 50 percent
Open the damper 25 percent
Shut the damper 60 percent
For space and zone control, where can the control of a coil come from?
Dampers
Valve actuators
The controlled device
The controlled space
What type of relationship occurs if the reset variable increases and the primary reset point goes down?
Observed
Reverse
Offset
Inverted
What two things does a reheat subsystem control depend on?
Wet bulb temperature
Specific and relative humidity
Temperature and relative humidity
Temperature and specific humidity
Besides cooling the air, what other function does the chilled-water coil do?
Heat
Humidify
Dehumidify
Increase grains of moisture
What must be used as the result of low relative humidity in the condition space?
Chilled water cooling and dehumidifying
Steam coils to reheat air
Dehumidifier
Humidifier
What can be used to prevent relative humidity in the duct from rising too high?
Actuators
Dampers
Sensor/controller
Controlled device
In a multiple-zone system, how can each zone draw as much hot or cold air as it requires?
By using a dependently controlled set of mixing dampers provided for each zone
By using an independently controlled set of mixing dampers provided for each zone
By using the set of mixing dampers provided for all zones
By using bypass zoning
In a multiple-zone system, the zone discharge temperatures are based on the
Return air temperature of one zone
Average building temperature
Worst case zones (the largest heating and cooling loads)
Best case zones (the smallest heating and cooling loads)
By what percent can a hot deck increase operating cost if it was 10 degrees Fahrenheit warmer than needed?
30
40
50
60
