HVAC Electircal Final Practice Exam

Which of the following is equal to 100 milliamps? A. 1.0 amperes B. 10.0 amperes C. 0.10 amperes D. 0.1 amperes

C. 0.10 amperes

Impedance in a circuit is the result of; A. Pure resistance B. Inductive reactance C. Capacitive reactance D. All the above

d. All of the above

Over current can be caused by; A. Ground Faults B. Overload C. Short circuit D. all of the above

d. all of the above

A electron has

negative charge

What is resistance?

Anything that slows the flow down/ Opposition to current flow

Relays used in the HVAC industry are generally used to control loads up to____ amps A. 100 B. 10 C. 25 D.50

C. 25

The capacitor stat- capacitior run(CSCR) motor; A. Provides high starting torque B. Provides high running torque C. Both A and B

C. Both A and B

To change the direction of rotation of a three-phase motor; A. The motor must be replaced B. Change the position of all three supply wires C. Change the position of any two supply wires D. The rotation of three- phase motors cannot be changed

C. Change the position of any two supply wires

Voltage can be calculated by; A. I divided by R B. R divided by I C. I times R D. All of the above

C. I times R

A capacitor analyzer is designed to; A. Read power factor percentage B. Diagnose an open or shorted capacitor C. Read the microfarad rating of a capacitor D. All of the above

C. Read the microfarad rating of a capacitor

The meter on a house measures the _______ passing through it. A. Voltage B. Amperage C. Wattage D. Resistance

C. Wattage

A _______ may be used on a single-phase induction motor to disconnect the start winding after the motor stats. A. Centrifugal switch B. Amperage relay C. Potential Relay D. All of the above

D. All of the above

A transducer can create a signal based on a form of energy such as; A. Pressure B. Heat C. Fluid flow D. All of the above

D. All of the above

In a series circuit, the voltage drop across each resistance (load) will; A. Always add up to equal the source voltage B. Depend on the value of each resistor C. Depend on the current flow in the circuit D. All of the above

D. All of the above

Electricity can produce A. Heat B. Light C. Magnetism D. All the above

D. All the above

If contact become dirty or pitted, it is acceptable to sand or file them as a permanent repair. True or False

False

Single phase motors are more efficient than three phase motors. True or False?

False

What is current flow?

Flow of electrons in a circuit

A 240-volt, 3 wire circuit can be split into two 120-volt circuits. True or False?

True

A three- phase system requires a minimum of three supply line too a three phase load. True or False

True

How many switches can be connected to a contactor coil control circuit?

unlimited

One horsepower is equal to ____ watts?

746

Any material that will readily release elctrons is called

A conductor

thermocouple

A device made of two unlike metals that generates electricity when there is a difference in temperature from one end to another

A parrallel circuit contains an 18 ohm and a 9 ohm resistor The total resistance equals A.6 ohms B. 27 ohms C. 8 ohms D. 10 ohms

A. 6 ohms

A capacitor opposes current flow in a circuit.This opposition is called; A. Capacitive reactance B. Inductive reactance C. Conductance D. Influence

A. Capacitive reactance

When current flows, a ____ is produced around the conductor. A. Magnetic Field B. Dielectric transmitter C. Short Circuit D. Worm hole

A. Magnetic field

The thermal overload contacts on a line starter are usually _____ reset. A. Manual B. Automatic

A. Manual

What meter is used to bench check a motor for shorts or open windings? A. Ohmmeter B. Voltmeter C. Ammeter

A. Ohmmeter

what type of meter uses its own battery? A. Ohmmeter B. Voltmeter C. Ammeter D. Wattmeter

A. Ohmmeter

The _____ drawing illustrates where the components are located on the appliance. A. Pictorial B. Schematic C. ladder diagram

A. Pictorial

In a single-phase motor, which winding has the most resistance? A.Start B. Run C. Ground D. They are all equal

A. Start

Direction of rotation of a single-phase induction motor is determined by; A. The direction of current flow through the start winding B. The direction of current flow through the run windings C. The number of poles in the motor

A.The direction of current flow through the start winding

A transformer has 1000 turns of wire in the primary coil and 2000 turns in the secondary coil. If 120 volts are applied, the output voltage will be; A.120 KV B. 620 volts C. 60 volts D. 240 volts

B. 240 volts

Utility companies usually supply residential homes with _____ service. A.115V, single phase, three wire B. 240V, single phase, three wire C. 240V, three phase, three wire D. 480V, three phase, three wire

B. 240V, single phase, three wire

The terminals T1, T2, & T3 are located at the _____ of a contactor. A. Top B. Bottom C. Middle D. Side

B. Bottom

Contactors are rated according to the maximum amperage through the; A.Coil B. Contacts C. Thermostat D. Fuse

B. Contacts

When the temperature of a negative temperature coefficient(NTC) thermistor increases, its resistance will; A. Increase B. Decrease C. Remain the same

B. Decrease

When testing a capacitor with an analog or digital ohmmeter, the meter should? A. Show no deflection and remain on an infinite reading B. Deflect towards zero then return to infinite reading C. Deflect to zero and stay there D. Deflect halfway between zero and infinity and stay there

B. Deflect towards zero then return to infinite reading

If the conductor in an AC circuit is wound into a coil, the resulting EMF opposes the supply voltage. This opposition is called? A. Capacitive reactance B. Inductive reactance C. Conductance

B. Inductive reactance

Single phase motor speed is determined by the A. Size of the wire used in the windings B. Number of stator poles C. Supply voltage D. Al the above

B. Number of stator poles

Transformers are rated according to; A. VA at the primary B. VA at the secondary C. Ohms at the primary D. Ohms at the secondary

B. VA at the secondary

A step-up transformer increases; A. power B.voltage C.resistance D.Amperage

B. voltage

Capacitors are always connected ______ to the start winding. A. parrallel B. In series C. Through a relay D. Through a diode

B.In series

Two 120-volt motors are wired in series, one is a 60-watt motor, the other is a 4 watt motor. The result would be; A. Both motors operate normal B. Neither motor would operate normally C. Only the 60-watt motor operates normally D. Only the 4-watt motor operates normally

B.Neither motor would operate normally

Fuses are used to protect A. People B. Loads C. Wires D. Switches

C.Wires

A ohmmeter should never be connected to; A. A Resistor B. A Coil C. A motor winding D. A live circuit

D. A live circuit

Ampeeres can be calculated by; A. e divided by r B. W divided by E C. The square root of W divided by R D. All of the above

D. ALL of the above

When replacing a capacitor; A. Use a replacement with the same value as the original B. If a duplicate of the original is not available, a capacitor that is up to 10% over capacity is OK C. Never use a capacitor that is under capacity D. All of the above

D. All of the above

Capacitors are rated in? A. Amperes B. Microfarads C. Volts D. Both B and C

D. Both B and C

Which of the following statements about current is true? A. Current flow is the same as voltage B. Current flow will increase when voltage increase C. Current flow will increase when resistance increases D. Current flow will decrease when voltage increases

D. Current flow will decrease when voltage increases

The total resistance of a parrallel circuit will be; A. The sum of all resistance B. Equal to the largest resistance C. Equal to the smallest resistance D. Less than the smallest resistance

D. Less than the smallest resistance

What is the term used to describe the output side of a transformer? A. low inductive side B. High inductive side C. Primary side D. Secondary side

D. Secondary side

A device used to control a motor is a; A. Relay B. Contactor C. Line starter D. All the above

D. all the above

The synchronous speed of a four pole, 60 Hz single phase motor is; A.3600 RPM B. 1500 RPM C. 3450 RPM D. 1800 RPM

D.1800 RPM

How are fuses sized? A: By amperage B: By microfarads C: By voltage D: Both a and c

D: Both a and c

Resistance can be calculated by...

E divided by I

A selenoid valve operates on the priciple of;

Electromagnetism

The symbol for current is A.E B. I C. R D. W

I (amps)

When the temperature of a positive temperature coefficient (PTC) thermistor increases, its resistance will; A. Increase B. Decrease

Increase

What is impedance?

Opposition to alternating current

In electrical wiring, a black colored wire usually indicates; A. hot conductor B. neutral conductor C. Ground conductor

The hot conductor

The safety ground conductor is usually color coded.

green

Like charges will,

repel each other

Which of the following is the correct formula for determining wattage in an electrical circuit?

watts=volts x Amperes