Title: Final Exam
Course: HET 119 HVACR Electricity II > Section: HET 119 HVACR Electricity II

Q: The automatic control of a system is intended to ____.
- maintain the working conditions of the equipment with a controllable device
- prevent overloading situations
- maintain stable or constant conditions with a controllable device
- maintain safe operations for service technicians
A: maintain stable or constant conditions with a controllable device

Q: Modulating controls are used to ____.
- start motors
- stop motors
- vary the speed of the motor
- stop the flow of a liquid
A: vary the speed of the motor

Q: When a control is required to control space or product temperature, it is called a____.
- safety device
- thermostat
- pressure control
- speed control
A: thermostat

Q: A thermal system overload may occur if a specific electrical or mechanical component is not cooled properly, resulting in ____.
- underload
- failure
- overheating
A: overheating

Q: The control that stops the condensing unit if the head pressure climbs too high is classified as a ____.
- safety control
- thermostat
- temperature control
- speed control
A: safety control

Q: The overload device mounted in the compressor terminal box would be classified as a ____.
- safety control
- capacitor
- pressure control
- speed control
A: safety control

Q: The metals most commonly used in a bimetal temperature control are ____.
- copper and brass
- copper and steel
- brass and steel
- brass and aluminum
A: brass and steel

Q: An example of a bimetal device is a ____.
- snap-disc
- mercury-filled tube and diaphragm
- thermistor
- Bourdon tube
A: snap-disc

Q: The Bourdon tube ____.
- tends to straighten out with an increase in voltage
- tends to curl inward with an increase in vapor pressure
- tends to straighten out with an increase in electrical current
- tends to straighten out with an increase in vapor pressure
A: tends to straighten out with an increase in electrical current

Q: A thermocouple is a device that ____.
- converts heat to mechanical movement
- converts heat to current flow
- converts heat to electrical energy
- couples two temperature controls together
A: converts heat to electrical energy

Q: A motor's speed is determined by ____.
- size
- voltage
- amperage
- number of motor poles
A: number of motor poles

Q: Start windings are placed ____ with the run windings.
- 180 degrees out of phase
- in phase
- slightly out of phase
- in series
A: slightly out of phase

Q: The start windings have ____.
- fewer turns than the run windings
- more turns than the run windings
- the same number of turns as the run windings
- larger diameter wire than the run windings
A: more turns than the run windings

Q: A thermal system overload may occur if a specific electrical or mechanical component is not cooled properly, resulting in ____.
- start, run
- failure
- overheating
A: overheating

Q: When a general duty split-phase motor reaches approximately 75% of its operating speed, the start winding is de-energized by a ____.
- circuit board
- capacitor
- centrifugal switch
- dual voltage switch
A: centrifugal switch

Q: A split-phase motor that has a current relay and a start capacitor is called a(n) ____ motor.
- start, run
- start, common
- common, run
- run, common
A: start, common

Q: When a Capacitor Start Induction Run (CSIR) motor is running and up to speed, what is the total capacitance acting on the motor? (Assume the run capacitor is 5 microfarads and the start capacitor is 20 microfarads, if present.)
- 4 microfarads
- 5 microfarads
- 20 microfarads
- 25 microfarads
A: 5 microfarads

Q: A permanent split capacitor (PSC) motor that is running and up to speed will have the start winding ____.
- energized
- de-energized
- in series with the run winding
- removed from the circuit
A: energized

Q: When a Capacitor Start, Capacitor Run (CSCR) motor initially starts, what is the total capacitance acting on the motor? (Assume the run capacitor is 5 microfarads and the start capacitor is 20 microfarads, if present.)
- 4 microfarads
- 5 microfarads
- 20 microfarads
- 25 microfarads
A: 25 microfarads

Q: Capacitors wired in series with the starting winding provide a(n) ____.
- longer starting time
- greater starting torque
- aid in starting three phase motors
- more efficient operation at full load speed
A: greater starting torque

Q: The shaded pole motor ____.
- has little starting torque
- has excessive starting torque
- has greater efficiency than most split-phase motors
- will start against a heavy starting load
A: has little starting torque

Q: Three phase motors have ____.
- 1hree start and three run windings for each phase
- one start and one run winding for each phase
- run windings only
- a start switch in each phase circuit
A: run windings only

Q: A current magnetic relay opens and closes its contacts based on the ____.
- current in the start winding
- voltage across the start winding
- voltage across the run winding
- current in the run winding
A: current in the run winding

Q: The starting device usually used on single phase, fractional horsepower motors requiring low starting torque is the ____.
- potential relay
- current relay
- centrifugal switch
- differential relay
A: current relay

Q: The positive temperature coefficient resistor start device is a type of ____.
- capacitor
- variable resistor
- switching device
- diode
A: variable resistor

Q: A permanent split-capacitor motor has a ____.
- start and run capacitor
- start capacitor only
- run capacitor only
- split phase capacitor
A: run capacitor only

Q: Which of the following voltages are not safe for a 208-V motor to operate?
- 170 volts
- 220 volts
- 238 volts
- both a and c
A: both a and c

Q: If the voltage supplied to the motor is well below the motor rated voltage, the current draw will be ____ it should be.
- lower than
- the same as
- higher than
- in reverse polarity than
A: higher than

Q: The voltage tolerance of a standard electric motor is ____.
- +5% -10%
- +10% -5%
- 10% -10%
- +15% -15%
A: 10% -10%

Q: The locked-rotor amperage is normally ____ times as great as the run-load amperage.
- two
- three
- five
- ten
A: five

Q: Why are explosion-proof motors not normally used on standard equipment?
- They are too large.
- They are too noisy.
- They are too expensive.
- They cannot be replaced.
A: They are too expensive.

Q: The motor that should be used in a potentially wet area is a(n) ____ motor.
- enclosed
- drip proof
- explosion proof
- open
A: drip proof

Q: When referring to motors, to what does the "insulation class" relate?
- the noise level of the motor
- the type of base on which the motor is mounted
- the normal operating temperature of the motor
- both a and b
A: the normal operating temperature of the motor

Q: A sleeve bearing would typically be used in a motor that operates with a ____.
- light load and where noise is a factor
- heavy load and where noise is a factor
- heavy load in a dirty atmosphere
- heavy load in a moist atmosphere
A: light load and where noise is a factor

Q: A slotted screw at the bottom of the bearing housing is called a ____.
- drain plug
- purge screw
- relief plug
- retaining screw
A: relief plug

Q: A direct-drive motor is usually connected to a load with a ____.
- cradle mount
- rigid base mount
- pulley
- coupling
A: coupling

Q: Grounding straps are required on resilient mounted motors to ____.
- prevent rotation of the motor in the mount
- help reduce motor vibration transfer to the object on which the motor is mounted
- ground the motor in case of winding failure
- act as the position for locating the motor leads
A: ground the motor in case of winding failure

Q: The width of a drive belt is classified as ____.
- large or small
- narrow or wide
- A or B
- 1 or 2
A: A or B

Q: The alignment of a motor and the driven mechanism must be done at room temperature and ____.
- after heating with a torch
- at operating temperature
- after running for one minute
- again after several days of operation
A: at operating temperature

Q: A common practice in condensing units is to use a contactor with only one set of contacts opening only one side of the power to the unit. This is to ____.
- reduce the cost of the contactor
- make it easier to wire the unit
- teach the service technician not to put hands in the unit with the power on
- provide off-cycle heat to the compressor
A: provide off-cycle heat to the compressor

Q: Beside maintaining pressure on the contacts for current carrying capacity, the pressure springs have a second important function. This is to ____.
- keep the contacts in line
- help obtain equal contacts against the stationary contacts
- slow down the pull of the armature into place to reduce the noise
- increase the power required to close the contacts
A: help obtain equal contacts against the stationary contacts

Q: When a contactor's coil is energized, how much resistance should be measured between terminal "L1" and terminal "T1"?
- zero ohms
- 50-3000 ohms
- 5000-6000 ohms
- infinite
A: zero ohms

Q: Technician “A” says that if you take a voltage reading from terminal "L1" to terminal "T1" on a contactor whose coil is energized, you should read zero volts. Technician “B” says that contactors can only have normally open contacts. Which of the following statements is correct?
- Technician "A" is correct. Technician "B" is correct.
- Technician "A" is correct. Technician "B" is incorrect.
- Technician "A" is incorrect. Technician "B" is correct.
- Technician "A" is incorrect. Technician "B" is incorrect.
A: Technician "A" is correct. Technician "B" is incorrect.

Q: An inherent motor protector is a ____.
- circuit breaker
- motor starter overload
- thermally activated device in the motor winding
- line fuse
A: thermally activated device in the motor winding

Q: The service factor of an electric motor is determined by ____.
- National Electrical Code
- National Electrical Manufacturers Association code
- motor's reserve capacity
- he required wire size supplying power to the motor
A: motor's reserve capacity

Q: Standards for motor overload protection are set by the ____.
- United States Department of Transportation
- National Electrical Code
- Environmental Protection Agency
- American National Standards Institute
A: National Electrical Code

Q: A solder pot is part of a ____.
- one-time fuse
- resettable circuit breaker
- time-delay fuse
- plumber's tool kit
A: resettable circuit breaker

Q: Which of the following overload devices is not affected by ambient temperature?
- solder pot
- magnetic
- bimetal
- time-delay fuse
A: magnetic

Q: Most electrical problems with an electric motor are ____.
- short circuited windings, closed windings, and grounded windings
- short circuited windings. open windings, and grounded windings
- all of the above
- none of the above
A: short circuited windings. open windings, and grounded windings

Q: A technician needs to check a single-phase compressor. He labels the three terminals "A," "B," and "C" and takes resistance readings of the windings. He reads 10 ohms from "A" to "B," infinity from "B" to "C," and infinity from "C" to "A." Identify the terminals.
- . A: common B: start C: run
- Cannot identify terminals: winding grounded
- A: start B: run C: common
- Cannot identify terminals: open winding
A: Cannot identify terminals: open winding

Q: Technician "A" says that while checking the windings of a compressor, a reading of 10 ohms or less from the common terminal to ground indicates that the motor is okay. Technician "B" says that the resistance of the start winding should always be less than the resistance of the run winding. Which of the following statements is correct?
- Technician "A" is correct. Technician "B" is correct.
- Technician "A" is correct. Technician "B" is incorrect.
- Technician "A" is incorrect. Technician "B" is correct.
- Technician "A" is incorrect. Technician "B" is incorrect.
A: Technician "A" is incorrect. Technician "B" is incorrect.

Q: An open winding in an electric motor means that ____.
- the winding is making contact with the motor frame
- one winding is making contact with another winding
- a wire in a winding is broken
- the centrifugal switch to the start winding is open
A: a wire in a winding is broken

Q: Technician "A" says that a shorted winding will result in an increased current flow through the winding. Technician "B" says that if a motor is to be replaced, a motor with a lower horsepower rating should always be used. Which of the following statements is correct?
- Technician "A" is correct. Technician "B" is correct.
- Technician "A" is correct. Technician "B" is incorrect.
- Technician "A" is incorrect. Technician "B" is correct.
- Technician "A" is incorrect. Technician "B" is incorrect.
A: Technician "A" is correct. Technician "B" is incorrect.

Q: If the resistance of the run winding decreases, the ____.
- motor probably will not start
- motor will draw too much current while it is running
- centrifugal starting switch will not start the motor
- oad on the motor is probably too great
A: centrifugal starting switch will not start the motor

Q: If a condenser fan motor grounds out, it will usually ____.
- trip a circuit breaker to shut off the unit
- keep running as the current is only going to ground
- run a little faster because the amperage draw will increase
- cause the evaporator to ice up
A: trip a circuit breaker to shut off the unit

Q: A megger ____.
- is an ammeter that can measure very small amounts of current
- is a digital voltmeter that measures very high resistances
- measures high voltage direct current
- measures very high resistances
A: measures very high resistances

Q: If a motor hums but does not start, there is a potential problem ____.
- with the starting components
- with an open winding
- with insufficient supply voltage
- all of the above
A: all of the above

Q: The recommended way to discharge a capacitor is to ____.
- place a screwdriver across the terminals
- assume it will discharge itself over a period of time
- use a 20,000 ohm 5 watt resistor that has had insulated leads soldered to it
- use an ohmmeter
A: use a 20,000 ohm 5 watt resistor that has had insulated leads soldered to it

Q: The wiring and connectors that carry the power to a motor must be in good condition. When a connection becomes loose, oxidation of the copper wire occurs. The oxidation ____.
- has no effect on the electrical connection
- acts as an electrical resistance and causes the connection to heat more
- decreases the resistance
- none of the above
A: acts as an electrical resistance and causes the connection to heat more

Q: What is the best method to repair a fractional horsepower motor that has bad bearings?
- Replace the bearings.
- Replace the bearings and shaft.
- Add a capacitor to the circuit for added torque.
- Replace the entire motor.
A: Replace the entire motor.

Q: Bimetal devices can be used to sense excessive current in a circuit.
- True
- False
A: True

Q: In order to change the direction of rotation of a split-phase motor, the technician must change the direction of current flow through the start winding.
- True
- False
A: True

Q: The centrifugal switch mounted on the shaft of a split-phase motor has a normally closed contact.
- True
- False
A: True

Q: The contact(s) in a potential type starting relay are normally closed.
- True
- False
A: True

Q: A Capacitor Start Capacitor Run (CSCR) motor that is wired with a potential relay will have the start winding energized when the relay's contacts open.
- True
- False
A: True

Q: A drip-proof motor is designed to prevent any lubricating oil from leaving any of the bearings.
- True
- False
A: False

Q: There is a definite relationship between the speed of the motor and the speed of the blower.
- True
- False
A: True

Q: The locked rotor amperage, LRA, of a motor is typically five times higher than the full load amperage, FLA, of the motor and can be as high as seven times the FLA.
- True
- False
A: True

Q: A set of contacts are closed when the relay is energized. These contacts are classified as normally closed.
- True
- False
A: False

Q: Contractor contacts that are badly pitted can cause the motor to burn out.
- True
- False
A: True

Q: Contractor contacts that are badly pitted can cause the motor to burn out.
- True
- False
A: True

Q: Bimetal and solder pot overload devices are thermally operated.
- True
- False
A: True

Q: If the cost of repairing the motor is close to the cost of replacing the motor, it would definitely pay to repair the motor if the new component carries a one-year warranty and the repaired motor carries only a 90-day guarantee.
- True
- False
A: False

Q: Open winding will not affect the resistance reading of the start winding as well as the resistance reading between the Run and Start terminals.
- True
- False
A: False

Q: If a resilient-mounted motor develops a short to the frame, the technician can simply cut the ground strap wire as a permanent repair.
- True
- False
A: False

Q: The electrical components for a fully welded hermetic compressor are checked at the disconnect box for the compressor unit.
- True
- False
A: False