Electricity HVAC Questions and Correct Answers
how much resistance must be placed in 120V curcuit in order to limit the current to
2Amps -answer 60 Ohms
when current flows in a 2 wire circuit such as 120v, if a clamp on amp meter is clamped
around both wires what measurement would you expect. -answer 0 amps - due to
cancellation of 2 fields
Current flow is? -answer The flow of electrons in the circuit.
What is the symbol for impedence in an AC CIrcuit. -answer Z
Impedence is? -answer Oppostion to Alternating current flow.
If contacts become badly pitted, it is acceptable to? -answer Replace the contacts or
control.
Relays are generally used to control inductive loads up to? -answer 10 Amps
When resistors are wired in parallel: -answer The voltage drop across each resistor will
be the same as the applied source voltage.
Contactors are rated according to the maximum amperage through the? -answer
Contacts.
The ________ Drawing illustrates where the components are located in small
appliances -answer Pictorial
When the Positive Temp coeffiecent thermistor increases, its resistance will -answer
Increase
Which meter is used to bench check a motor for shorts or open windings? -answer
Ohmmeter
Capacitor start capacitor run motor provides -answer Eating running and high starting
torque
When testing a motor with an ohmmeter, the following measurements are recorded:
common to run 4 ohms, common to start 6.2 ohms, run to start 10.2 ohms. Common to
ground 20.4; this indicates a -answer A grounded condition
Which of the following is an acceptable temporary replacement for a run capacitor rated
at 35 MFD at 440 VAC -answer 37.5 MFD at 440 VAC
With a motor running at full load, voltmeter leads are placed on l1 and T12 terminals of
the contactor. The voltmeter indicates no measurable voltage. This is an indication of -
answer Good clean contacts
, Electricity HVAC Questions and Correct Answers
How to discharge a capacitor prior to ohm meter testing -answer Use a 15000 or 20000
ohm, 225 watt resistor across the terminals
A __________ is commonly used on a single phase fractional horsepower capacitor
motor to disconnect the start winding after the motor starts -answer Current relay
Utility companies usually supply residential homes with________ service -answer 240v,
3-phase, 3-wire
If the conductor in a AC circuit is wound into a coil, the resulting EMF opposes the
supply voltage. This opposition is called -answer Inductive reactance
What connects to the terminal t1, t2, and t3 on a contactor or motor starter? -answer
Load connections
A solenoid valve operates on the principle of -answer Electromagnetism
Circuit breakers and fuses are primarily used to provide -answer Protection from an
overload of current
To change direction of rotation of a 3-phase motor -answer You must change the
position of any two supply wires
Which of the following motors is most energy efficient -answer ECM
Which of the following is equal to 2.1 KW -answer 2100 Watts
Which of the following statements about current is true -answer Current flow will
decrease when voltage increases
Capacitors are rated in -answer Microfarads and volts
The total resistance of a parallel circuit will be -answer Less than the smallest
resistance
A parallel circuit consists of three resistors. R1 equals 30 ohms, are two is equal to 15
ohms, are 3 is equal to 10 ohms. If the current through r2 is 4 amperes, what is the
source voltage -answer 60 volts
Which of the following meters must use its internal power to check a load or circuit -
answer Ohm meter
Which of the following is the correct formula for determining wattage in a electrical
circuit -answer W=E times I
how much resistance must be placed in 120V curcuit in order to limit the current to
2Amps -answer 60 Ohms
when current flows in a 2 wire circuit such as 120v, if a clamp on amp meter is clamped
around both wires what measurement would you expect. -answer 0 amps - due to
cancellation of 2 fields
Current flow is? -answer The flow of electrons in the circuit.
What is the symbol for impedence in an AC CIrcuit. -answer Z
Impedence is? -answer Oppostion to Alternating current flow.
If contacts become badly pitted, it is acceptable to? -answer Replace the contacts or
control.
Relays are generally used to control inductive loads up to? -answer 10 Amps
When resistors are wired in parallel: -answer The voltage drop across each resistor will
be the same as the applied source voltage.
Contactors are rated according to the maximum amperage through the? -answer
Contacts.
The ________ Drawing illustrates where the components are located in small
appliances -answer Pictorial
When the Positive Temp coeffiecent thermistor increases, its resistance will -answer
Increase
Which meter is used to bench check a motor for shorts or open windings? -answer
Ohmmeter
Capacitor start capacitor run motor provides -answer Eating running and high starting
torque
When testing a motor with an ohmmeter, the following measurements are recorded:
common to run 4 ohms, common to start 6.2 ohms, run to start 10.2 ohms. Common to
ground 20.4; this indicates a -answer A grounded condition
Which of the following is an acceptable temporary replacement for a run capacitor rated
at 35 MFD at 440 VAC -answer 37.5 MFD at 440 VAC
With a motor running at full load, voltmeter leads are placed on l1 and T12 terminals of
the contactor. The voltmeter indicates no measurable voltage. This is an indication of -
answer Good clean contacts
, Electricity HVAC Questions and Correct Answers
How to discharge a capacitor prior to ohm meter testing -answer Use a 15000 or 20000
ohm, 225 watt resistor across the terminals
A __________ is commonly used on a single phase fractional horsepower capacitor
motor to disconnect the start winding after the motor starts -answer Current relay
Utility companies usually supply residential homes with________ service -answer 240v,
3-phase, 3-wire
If the conductor in a AC circuit is wound into a coil, the resulting EMF opposes the
supply voltage. This opposition is called -answer Inductive reactance
What connects to the terminal t1, t2, and t3 on a contactor or motor starter? -answer
Load connections
A solenoid valve operates on the principle of -answer Electromagnetism
Circuit breakers and fuses are primarily used to provide -answer Protection from an
overload of current
To change direction of rotation of a 3-phase motor -answer You must change the
position of any two supply wires
Which of the following motors is most energy efficient -answer ECM
Which of the following is equal to 2.1 KW -answer 2100 Watts
Which of the following statements about current is true -answer Current flow will
decrease when voltage increases
Capacitors are rated in -answer Microfarads and volts
The total resistance of a parallel circuit will be -answer Less than the smallest
resistance
A parallel circuit consists of three resistors. R1 equals 30 ohms, are two is equal to 15
ohms, are 3 is equal to 10 ohms. If the current through r2 is 4 amperes, what is the
source voltage -answer 60 volts
Which of the following meters must use its internal power to check a load or circuit -
answer Ohm meter
Which of the following is the correct formula for determining wattage in a electrical
circuit -answer W=E times I
