Questions and Answers
An internal bimetal protection device will open the motor circuit when the temperature reaches 200°F to 250°F (93°C to 121°C).
True
To protect the transformer from overload, ____ oversizing is recommended.
125%
An AC generator uses a commutator to produce electricity.
False
External bimetal protection devices only open a motor circuit if the current is too high.
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When a TEV meters liquid refrigerant into the indoor coil, the indoor coil is functioning as a(n) ___.
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A compliant scroll compressor is able to pump liquid without sustaining damage.
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Ladder diagrams show ____.
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With an energized circuit, a multimeter set to read volts can be used to quickly and easily test switches to determine whether they are open.
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Current-limiting fuses use temperature-sensitive resistors that close the motor circuit as temperature rises.
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A clamp-on ammeter requires the circuit to be broken to take a measure of circuit current.
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When a ground fault occurs, the change in current flow creates an amperage ______________________________ between the hot and neutral wires.
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If the contact points of a thermostatic motor control were to open very slowly, electric arcing could burn the contacts.
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Unlike in-line ammeters, ohmmeters are connected in series with the circuit or load being tested.
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One horsepower is equal to ____ watts.
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A metering orifice meters refrigerant flowing in both directions.
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If the voltage in a circuit is constant, the current in the circuit ____ when the resistance is decreased.
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Single-phase alternating current induction motors offer high starting torque and high running torque without the need for a start winding, capacitors, or relays.
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The major difference between a relay and a contactor is the size of the contacts and the ____ rating.
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A time-delay fuse is selected with a rating ____ greater than the motor FLA.
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The potential relay uses a normally closed (NC) set of contacts.
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In a heat pump, the air volume is greater over the outdoor coil and less over the indoor coil than for a regular air conditioning system.
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If a thermistor's resistance increases as temperature increases, it has a positive temperature coefficient.
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A system's ____ is the number of units between the cut-out and cut-in values.
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In second-stage heating with a cold outside ambient temperature, the holdback thermostat is open.
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Motor speed is determined by dividing the number of stator poles by the number of times the current changes direction per minute.
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In cooling mode, the metering orifice on the indoor coil allows free flow through it, creating no pressure drop.
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The pickup voltage required to operate a potential relay is generated when a motor reaches around ____ of its normal operating speed.
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In a heat pump system, at least one supplementary electric strip heater is energized during stage-one heating.
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The unit of resistance defined as a one coulomb charge with a potential difference of one volt is the farad.
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Which motor uses one capacitor during starting and then operates at full speed using a different capacitor?
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The two types of current electricity are direct current and static current.
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What is the abbreviation for a sail switch?
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Dual-voltage motors are manufactured to operate on either of two supplied voltages.
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Which of the following methods is not generally used to disconnect a single-phase motor's start winding from the circuit?
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Which motor begins operation using a capacitor in series with its start winding, then de-energizes both, and runs only on the run winding?
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Which split-phase motor has a capacitor in series with its start winding and both capacitor and start winding remain energized during operation?
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To measure voltage polarity correctly in a DC circuit, a technician should place the voltmeter's red lead on the side of the load closest to ____ of the power supply.
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In the from load outward method of troubleshooting, voltage at the load device is checked first.
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In the permanent split-capacitor motor, the capacitor is a permanent part of the circuit.
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If an in-line ammeter is accidentally connected in parallel, it may blow a fuse.
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The coil on the lockout relay in a heat pump system has a higher voltage rating than the compressor contactor coil.
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Circuit protection devices are rated by amperes only.
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A clamp-on ammeter requires the circuit to be broken to take a measure of circuit current.
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A schematic diagram can be converted to a ladder diagram for troubleshooting purposes.
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High-mass boilers heat up quickly.
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The outdoor fan and defrost relay is a device used to control three things: outdoor fan, the reversing valve, and the relay controlling the auxiliary heating elements.
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A multi-zone system typically has more than one heat relay.
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The voltage drop of an electrical load is equal to the current passing through the load multiplied by the resistance of the load.
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Most reversing valves shift piston position through the direct force of ___.
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The term used to rate the energy efficiency of appliances is the energy efficiency ___.
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In general, a megohm reading of ____ or higher indicates that the motor winding insulation is in excellent condition.
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When the heat pump system enters defrost mode when the holdback thermostat is open, this indicates a _____ ambient temperature.
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A zero resistance reading between a motor terminal and its frame indicates a(n) _____.
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The capacitor-start, capacitor-run (CSCR) motor starts up as a CSIR and then runs as a PSC for the rest of normal operation.
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A uniquely designed, low-cost motor used to operate small fans is the ____ motor.
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If an overload condition is not correct, the bimetallic disc will trip repeatedly, a malfunction known as ____ on the overload.
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Contactors with ____ of contacts are used to control three-phase motor operation.
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Each section of a split air-conditioning system has its own power supply.
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What happens when the indoor blower on an air-conditioning system is in cooling mode?
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Run capacitors ____.
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What must happen in order for an individual electric strip heater to be energized?
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The airflow standard for regular air conditioning, established by the Air-Conditioning, Heating, and Refrigeration Institute (AHRI), is ____ cu.ft. per minute (cfm) per ton over the evaporator and ____ cfm per ton over the condenser.
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The polarity of electromagnets change as current alternates.
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In a ducted heating and cooling system, what happens if the equipment owner turns the fan switch on the thermostat to the ON position during the heating cycle?
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A square type axial blade is best suited for free-air applications, such as pedestal fans.
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There are multiple fan motors on most window air-conditioning units.
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Voltage across any load in a series circuit is equal.
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The ____ method of troubleshooting is used to determine the location of an open switching device.
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A shorted capacitor occurs when one of the terminals separates from its coil.
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A PTC relay has a low resistance when the motor circuit is first energized, so it is easier for the current to pass through the PTC relay than through the run capacitor.
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Which of the following substances is a semiconductor?
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The GFCI opens the circuit whenever the imbalance reaches about ____.
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In a DC circuit, an in-line ammeter's black lead is placed on the side of the load closest to the positive terminal of the circuit's power supply.
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On large heat pump systems, each coil requires a TEV and a(n) ____ line.
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A control system's ____ is the set of numbers between and including cut-in and cut-out values.
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Cartridge fuses are available as ordinary fuses or as time-delay, dual-element types.
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After a PTC relay increases its resistance, the motor current seeks the path of least resistance, which is through the run capacitor.
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A conductor is a substance with no free electrons in its structure.
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After internal motor overload protection opens the motor circuit due to overheating, a technician should ____ to speed up compressor cooling.
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A flat bimetal strip deforms or bends as temperature rises because the copper expands more than the steel.
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By widening the groove of a variable-pitched pulley, a technician ____ the speed of a belt-driven blower or fan.
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Because a heat pump's refrigerant flow is reversible, the volume of airflow through each coil (indoor and outdoor) must be the same.
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A time-delay fuse may allow a motor to be damaged from high current before the time delay is over.
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Which of the following motors has only a start winding installed in the stator to produce a magnetic field out of step with the main winding?
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The difference between the desired condition and the present condition is called the ____.
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A wattmeter is connected in parallel with the circuit being measured.
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A diode must be replaced if a meter registers a voltage for both meter lead configurations.
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Which of the following formulas is used to calculate the current flowing through a circuit?
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The temperature of the hottest part inside a motor should not be more than ____ above the ambient temperature.
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If a thermistor's resistance decreases as the temperature increases, the thermistor has a positive temperature coefficient.
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The squirrel cage rotor is the most common rotor type used in induction motors.
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An above-atmospheric-pressure element is used to control heating units.
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On a low-mass boiler on a single-zone heating system, when the water reaches the cut-out temperature on the limit switch, the circulator pump immediately shuts off.
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Motors rated less than one horsepower are called integral horsepower motors.
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In a series circuit, the load with the lowest resistance has the highest ____.
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Motors rated less than one horsepower are called ____ horsepower.
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A heat pump with a COP of 3.00 produces ____ as many Btu of heat for the same electrical energy input as electric resistance heating elements.
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A ____ fuse will not blow unless an overload condition exists for a certain period of time.
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The term electromotive force can be used interchangeably with the term voltage.
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Study Notes
Ladder Diagrams
- Ladder diagrams indicate the physical layout of devices and how to connect electrical devices in a unit.
- They do not represent wire colors or other details.
Multimeter Use
- A multimeter set to volts can test switches in an energized circuit to verify if they are open.
Fuses and Circuit Protection
- Current-limiting fuses do not use temperature-sensitive resistors; this statement is false.
- Time-delay fuses allow for brief overloads without blowing, possibly damaging motors during that time.
Circuit Measurement Tools
- Clamp-on ammeters can measure circuit current without breaking the circuit.
- Ohmmeters are not connected in series with the load being tested.
Electrical Concepts
- One horsepower equals 746 watts.
- Voltage remains constant while current increases as resistance decreases.
- GFCIs open the circuit at an imbalance of 4 mA to 6 mA.
- The thermal properties of materials influence motor control and circuit design.
Capacitors and Motors
- Capacitor-start, capacitor-run motors utilize two different types of capacitors during operation.
- Permanent split-capacitor motors always use the capacitor in the running circuit.
Thermostats and Controls
- The holdback thermostat is open during second-stage heating with cold outside temperatures.
- In troubleshooting, the method used is the "from load outward" technique, verifying the voltage at the load first.
Energy Efficiency and Ratings
- Energy efficiency is rated using a ratio, indicating performance compared to input energy.
- Motors less than one horsepower are classified as fractional horsepower motors.
Various Electrical Devices
- Dual-voltage motors can operate on two supplied voltages.
- Shell elements like PTC relays have variable resistance based on motor current.
- A diode reads a voltage for both lead configurations, indicating it needs replacement.
Operational Principles
- A PTC relay initially offers low resistance, facilitating easier current flow.
- Bimetal protection devices trip the motor circuit at specific temperature thresholds (200°F to 250°F).
Refrigeration and HVAC Systems
- Heat pumps require proper airflow through indoor and outdoor coils, often with supplemental heating during cold conditions.
- TEV meters refrigerant into the indoor coil, where it operates as an evaporator.
- High-mass boilers do not heat up quickly compared to other types.
Troubleshooting and Electrical Measurements
- Voltmeter leads must be positioned correctly to measure voltage polarity in DC circuits.
- In troubleshooting, circuitry should be methodically examined to locate faults effectively.
Miscellaneous Insights
- A shorted capacitor occurs due to terminal separation, not functioning as intended.
- Axial blade types are suited for various applications, particularly fans.
- The airflow standard for air conditioning systems is 400 cfm per ton over the evaporator.
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Description
This quiz focuses on key concepts related to electrical test procedures and circuit components. Learn about ladder diagrams, multimeter usage, and safety measures in electrical applications. Perfect for students and professionals looking to reinforce their understanding of electrical testing.
