Electrical Exam - Exit

In a schematic, what voltage would be found across the contacts in line #8

0 volts

In the schematic, what voltage would be found from terminal Y to the input side of the coil on line #11?

0 volts

Which of the following is equal to 100 milliamps?

0.10 amps

Relays used in the HVAC industry are generally used to control loads up to ____ amps.

100

In the schematic, what voltage would be found across the condenser fan motor?

240 volts

The symbol for a transformer is represented by diagram ______

B

When troubleshooting the A/C system in the schematic, the following conditions are found. The thermostat contacts are closed. The compressor and condenser fan motors are short cycling. The blower motor is not running. This could be caused by? A. a faulty coil on line #11 B. blown fuse on line #10 C. a faulty blower motor or blower relay D. all of the above

C. a faulty blower motor or blower relay

Single phase motors are more efficient than three phase motors?

False

When testing a motor with an ohmmeter, one winding shows 1000 ohm continuity to the motor frame. This is an indication of a good safety ground?

False

Like charges will?

Repel each other

Transformers are rated according to?

VA at the secondary

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

W=E times I

Two 120 volt motors are wired in series, one is a 60 watt motor, the other is a 4 watt motor. The results would be?

neither motors would operate normally

Technician #1 says that an open transformer coil is indicated by a reading of 0 ohms on an ohmmeter. Technician #2 says that a shorted transformer coil is indicated by a reading of infinity on an ohmmeter

neither technician #1 or #2 are correct

What type of meter uses it's own battery?

ohmmeter

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

unlimited

To discharge a capacitor prior to ohmmeter testing?

use a 20,000 ohm, 2 to 5 watt resistor across the terminals.

A setup transformer increases?

voltage

The meter on a house measures the ___________ passing through it.

wattage

In the schematic, the crankcase heater will operate?

when the compressor is off.

Fuses are used to protect what?

wires

Three 300 ohm resistors are wired in parallel. The total resistance equals?

100 ohms

The synchronous speed for a four pole, 60Hz single phase motor is?

1800 rpm

Which of the following is equal to 2.1KV?

2,100 Volts

How many Watts of power are used by a heater operating at 460 volts and drawing 5 amps?

2300 watts

In the schematic, what voltage would be found across the fuse in line #10?

24 volts

In the schematic, what voltage would be found from terminal R to terminal G on the thermostat?

24 volts

In the schematic, what voltage would be found from terminal Y to the input side of the coil on line #11?

24 volts

A transformer has 1,000 turns of wire in the primary coil and 2,000 turns in the secondary coil. If 120 volts are applied, the output voltage will be?

240 volts

I'm the schematic, what voltage would be found across L1 to L2

240 volts

Utility companies usually supply residential homes with _________ service

240V, single phase, three wire

Three resistors are wired in parallel. Two of the resistors have a value of 12 ohms, one resistor has a value of 6 ohms. What is the total resistance of the circuit?

3 ohms

A parallel circuit contains a 18 ohm and a 9 ohm resistor the total resistance equals?

6 ohms

A parallel circuit consist of three resistors. R1 = 30 ohms. R2 = 15 ohms. R3 = 10 ohms if the current through R2 = 4 amperes, what is the source voltage?

60 volts

A transformer has 1,000 turns of wire in the primary coil and 500 turns in the secondary coil. If 120 volts are applied, the output voltage will be?

60 volts

Three resistors are wired in series. Each has a value of 300n ohms. What is the total resistance of the circuit?

900 ohms

The symbol for a thermal overload is represented by diagram _____

A

Any material that will readily release electrons is called?

A conductor

When troubleshooting the A/C system in the schematic, the following conditions are found. The thermostat contacts are closed. The compressor and condenser fan motors are short cycling. The blower motor is not running. When the fan switch at the thermostat is moved from the AUTO position to the FAN ON position, the blower runs. This could be caused by;

A faulty thermostat- AUTO/FAN ON switch

What is generally considered to be the maximum allowable (plus or minus) supply voltage variation? A. 5% B. 15% C. 20% D. 30%

A. 15%

How much resistance must be placed in a 110 volt circuit in order to limit the current to 2 amps? A. 55 ohms B. 110 ohms C. 30 ohms D. none of the above

A. 55 ohms

One horsepower is equal to ________ watts. A. 3.415 B. 746 C. 1200 D. 208

B. 746

The symbol for a pressure switch is represented by diagram ______

C

A thermocouple can? A. generate small electrical current, depending on temperature. B. become hot or cold when current is passed through, depending on the direction of current. C. both A and B are correct D. neither A OR B are correct

C. both A and B are correct

When troubleshooting the A/C system in the schematic, the following conditions are found. the thermostat contacts are closed. The compressor and condenser fan are not running. The blower motor is running this could be caused by? A. the HP, LP, overloads, or oil pressure switch are open( line #11) B. the contactor coil may be faulty ( line #11) C. either A or B could be correct D. neither A or B are correct

C. either A or B could be correct

A device used to control a motor is a? A. relay B. contactor C. line starter D. all of the above

D. all of the above

A solenoid valve operates on the principle of? A. pressure differential B. temperature differential C. electromagnetism 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

Electricity can produce? A. heat B. light C. magnetism D. all of the above

D. all of the above

In the schematic, the coil on line #11 controls? A. the compressor B. the condenser C. the crankcase heater D. all of the above

D. all of the above

Overcurrent can be caused by? A. grounded faults B. overload C. short circuit 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 !0% over capacity is ok C. never use a capacitor that is under capacity D. all of the above

D. all of the above

How are fuses sizes? A. amps B. volts C. watts D. both A and B

D. both A and B

Capacitors are rated in? A. amperes B. microfarads C. volts D. both B and C

D. both B and C

Resistance can be calculated by?

E divided by I

Amperes can be calculated by?

E divided by R

The symbol for current is?

I

Voltage can be calculated by?

I times R

What is impedance?

Opposition to alternating current flow

What is resistance?

Opposition to flow

An ohmmeter should never be connected to?

a live circuit

An electron has?

a negative charge

When checking the windings of a three phase motor?

all three terminals should show the same resistance.

In a series circuit, the voltage drop across each resistance (load) will?

always add up to equal the source voltage

The capacitor start-capacitor run(CSCR) motor? A. provides high starting torque B. provides high running torque C. both A and B D. neither A or B

both A and B

When testing the windings in a single phase motor, Technician #1 says that the common and the run terminals show the lowest resistance. Tech #2 says that the pair of terminals with the highest resistance will indicate that the other terminal is the common. Who is correct?

both technicians #1 and #2

The terminals T1, T2, & T3 are located at the _______ of a contactor.

bottom

A capacitor opposed current flow in a circuit. This opposition is called?

capacitive reactance

Impedance in a circuit is the result of?

capacitive reactance

A ______ may be used on a single phase induction motor to disconnect the start winding after the motor starts

centrifugal switch

To change direction of rotation of a three phase motor;

change the position of any two supply wires

Contactors are rated according to the maximum amperage through the?

contacts

Which of the following statements about current is true?

current flow will increase when voltage increases

When the temperature of a negative temperature coefficient(NTC) thermistor increases, it's resistance will?

decrease

When testing a capacitor with an analog ohmmeter, the needle on the meter should?

deflect towards zero then return to infinite reading

If the contact become dirty or pitted, it is acceptable to sand or file them as a permanent repair?

false

With a motor running at full load, voltmeter leads are placed on each side of the relay contacts. The voltmeter indicates no measurable voltage. This is an indication of?

good clean contacts

The safety ground conductor is usually color coded?

green

What would be the result of three defrost heaters, each 12.5 ohms. Wired in series to a 115 volt power supply, if the heater were to supply a 360 watt heating load

heaters operate normally

When the temperature of a positive temperature coefficient(PTC) thermistor increases, it's resistance will?

increase

If the conductor in an AC circuit is wound into a coil, the resulting EMF opposes the supply voltage. This opposition is called?

inductive reactance

The total resistance of a parallel circuit will be?

less than the smallest resistance

When current flows, a _________ is produced around the conductor.

magnetic field

The thermal overload contacts on a line starter are usually ______ rest.

manual

Single phase motor speed is determined by the?

number of stator poles.

What meter is used to bench check a motor for shorts or open windings?

ohmmeter

The _______ drawing illustrates where the components are located on the appliance.

pictorial

A capacitor analyzer is designed to?

read the microfarad of a capacitor

What is the term used to describe the output side of a transformer?

secondary side

In a single phase motor, which winding has the most resistance?

start

In the schematic, the coil on line #12 controls?

the blower motor relay

Direction of rotation of a single phase induction motor is determined by?

the direction of current flow through the start winding

What is current flow?

the flow of electrons in the curcuit

In electrical wiring, a black colored wire usually indicates?

the hot conductor

When resistors are wired in parallel?

the voltage drop across each resistor will be the same as the applied source voltage

Capacitors are always connected ____________ to the start winding.

through a relay

A 240 volt, 3 wire circuit can be split into two 120 volt circuits.

true

A three phase system requires a minimum of three supply lines to the three phase load.

true

In the schematic, if the fuse in L2 is blown, the blower motor will continue to operate.

true