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Term 3 - Review Tests > Incorrect Final Exam #1 > Flashcards

Incorrect Final Exam #1 Flashcards

1
Q

On single phase 3 wire circuits the correct conductor color coding could be red and black for line conductors and white for neutral. T or F?

A

True

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2
Q

The rated voltage on a run capacitor must be equal to or greater than the applied voltage to the compressor motor. True or False

A

False

MUST BE GREATER

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3
Q

The direction of rotation of a split phase induction motor can be changed by interchanging the two run winding leads. T or F?

A

True

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4
Q

You ohm a CSR compressor motor and obtain the following reading: Common to Run  one ohm, Common to Start 2 ohms, Run to Start 3 ohms, each terminal to ground you read infinity. From this data, you determine the compressor is defective for the following reason:

  • open run winding
  • grounded start winding
  • short between start and run windings
    -turn to turn short in the start winding
A

d

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5
Q

You ohm a CSR compressor and record the following resistance readings: Common to  Run one ohm, Common to Start four ohms, Run to Start five ohms, Common to  Ground three ohms, Run to Ground four ohms, Start to ground one ohm. You decide to change the compressor because:
 

-the internal thermostat is open
-the run winding is open
-the start winding is grounded
- the run winding is grounded

A

start winding is grounded because it has the least amount of resistance to ground

(easiest path)

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6
Q

A PSC compressor has a shorted run capacitor. The compressor now has similar  characteristics to which type of motor?
 
CSR
CSIR
RSIR
Three phase induction

A

RSIR

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7
Q

The voltage stamped on a run capacitor is:
 

  • the system rated voltage
  • always higher then system rated voltage
  • equal to or greater then system rated voltage
    -not significant
A

always higher than system rated voltage

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8
Q

A 240 volt three phase compressor motor is connected to the secondary of a 4 wire  Delta Closed Distribution Transformer. One transformer is center tapped and grounded.  What other voltages may be obtained from the secondary side of this transformer?
 

120/1/60, 208/1/60, 240/3/60

120/1/60, 208/3/60 , 240/1/60

120/1/60, 240/1/60, 240/3/60

120/1/60, 208/1/60, 240/1/60

A

d

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9
Q

The best trap for system contaminants as a result of a cookout is:
 

refrigerant

suction line filter drier

liquid line filter drier

refrigerant oil

A

refrigerant oil because it absorbs it and runs it through the system,

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10
Q

Which desiccant has the best ability to remove moisture?
 

methyl alcohol

activated alumina

silica gel

molecular sieve

A

molecular sieve

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11
Q

High discharge pressure can be caused by:
 

refrigerant overcharge

refrigerant undercharge

low load on evaporator

restricted cap tube

A

a and d

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12
Q

A low temperature commercial system is operating with a 10 degree f fluctuation in suction line temperature. This could be an indication of:
 

improperly adjusted metering device

undersized metering device

oversized metering device

oversized evaporator

A

oversized metering device or evap

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13
Q

An Air Conditioned computer room has problems with excessive static electricity with in  the equipment. What could be the possible cause?
 

relative humidity too high

relative humidity too low

low temperatures

high temperatures

A

low temperatures

and

RH too low

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14
Q

A water cooled condensing unit has the following readings, water outlet temperature
98 degrees f, Condensing temperature of 128 degrees f. You determine that the unit:
 

operating fine

too much water flow through the condenser

too little water flow through the condenser

condenser may be fouling

A

condenser may be fouling

OR

too little (better answer)

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15
Q

A Up Flow Furnace would most likely be installed in :

the full basement of a two story building

the crawl space of a two story building

the attic of a single story building

the location of your choice

A

the full basement of a two story building

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16
Q

A Heat Pump can be Oversized by a Max of 35 % if the SPF is:

more than 2.25

less than 2

equal to 2.25

less than 2.25

A

less than 2.25

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17
Q

A Up Flow Furnace would most likely be installed in :

the full basement of a two story building

the crawl space of a two story building

the attic of a single story building

the location of your choice

A

the full basement of a two story building

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18
Q

Normally Add on Heat Pump Systems would be Turned off at approx:

45 degrees f

35 degrees f

the temperature stipulated by the utility

the calculated balance point determined by the work sheet for equipment selection

A

the calculated balance point determined by the work sheet for equipment selection

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19
Q

Define the Term U Factor.

Coefficient of thermal resistance

Coefficient of thermal conductance

Coefficient of thermal transfer

Coefficient of thermal insulation

A

Coefficient of thermal conductance

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20
Q

A current larger than normal, but flowing outside its normal current path is referred to as:

overload

overcurrent

short circuit

ground fault

A

short circuit

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21
Q

An overcurrent condition is:
 

a current above normal

a current shorted to ground

a short circuit

all of the above

A

all of above

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22
Q

A plug fuse with a continuous current rating of 25 amps will be identified by the color:

pink

blue

green

red

A

red

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23
Q

The voltage rating of a conductor is determined by:

the size of the conductor

the type of insulation around the conductor

the application of the conductor

there is no voltage rating on conductors

A

the type of insulation around the conductor

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24
Q

The term “slip” is used to indicate:

the amount of horse power lasted due to motor resistance

the amount of efficiency lost when there is no run capacitor

the difference in motor rpm between the time the start winding circuit is opened and when the motor reaches full speed

the difference between the motor full operational rpm rating and the actual speed under load.

A

the difference between the motor full operational rpm rating and the actual speed under load.

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25
Q

The purpose of a run capacitor as used with a split phase motor is to:

increase power factor

make the motor more efficient

increase starting torque

increase running torque

A

make the motor more efficient

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26
Q

You could replace a defective 35 uf, 370 volt running capacitor with which of the following capacitors:

35 uf 330 volts

35 uf 390 volts

30 uf 440 volts

40 uf 370 volts

A

35 uf 390 volts

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27
Q

A dual voltage three phase motor has a current draw of 50 amps when connected to a 240 volt line. How much current will flow if the motor is connected for operation on 480 volts?

25 amps

100 amps

50 amps

12.5 amps

A

25 amps

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28
Q

The primary and secondary winding of a transformer:

are wired in series

are wired in parallel

are not electrically connected

wired in series parrallel

A

are not electrically connected

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29
Q

A series circuit consists of three resistor. If one resistor is removed, and the remaining resistors are connected in series to the same source, then the current in each of these two resistors will be:

increased

decreased

the same as before

zero

A

increased

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30
Q

If an open occurs in one branch of a parallel circuit, the line current (total current) will:

increase and the total circuit resistance will decrease

decrease and the total circuit resistance will increase

decrease and the total circuit resistance will decrease

be zero and the total circuit resistance will infinity

A

decrease and the total circuit resistance will increase

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31
Q

Given the following capacitors , circle the most correct replacement for the following  burned out start capacitor and run capacitor used on a compressor motor operating on a
208 Volts source.

Original

Start capacitor 190 - 220 Vac  
  140 - 165 MFD    
     

190 - 240 Vac      
140 - 175 MFD

400 - 440 Vac      
140 - 160 MFD

230 - 345 Vac      
140 - 165 MFD

340 Vac      
300MFD

310 Vac      
300 MFD

A

190 - 240 Vac      
140 - 175 MFD

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32
Q

During overload conditions the solder melts. During short circuit conditions the fuse link breaks open. What kind of safety device do the preceeding statments describe?

A standard circuit breaker

A standard fuse

A time delay circuit breaker

A time delay fuse

A

A time delay fuse

33
Q

When performing electrical tests of a compressor motor, what reading would you get if there was an open winding?

Low resistance

High resistance

Infinite resistance

No resistance

A

Infinite resistance

34
Q

Who enforces the Canadian Electrical Code?

Electircal Trade Board

Electrical Safety Branch

Industry Training Committee

Canadian Safety Association

A

Electrical Safety Branch

35
Q

CEC is a national code. What are the extra regulations required in BC called?

B.C. Amendments

Municiple codes

Municiple amendments

B.C. codes

A

B.C. Amendments

36
Q

A coil of wire carrying alternating current produces a type of resistance known as:

inductance

capacitive inductance

capacitive reactance

impedance

A

impedance

37
Q

Which of the following are two main types of thermostats?

extra-low and pilot duty

low and high voltage

low and line duty

extra- low and low voltage

A

extra- low and low voltage

38
Q

A dual voltage three phase motor has a current draw of 50 amps when connected to a 240 volt line. How much current will flow if the motor is connected for operation on 480 volts?

25 amps

100 amps

50 amps

12.5 amps

A

25 amps

39
Q

A current larger than normal, but flowing within its normal current path is referred to as an:

overload

overcurrent

short circuit

ground fault

A

overload

40
Q

Extra-Low voltage thermostats would normally be used for which of the following applications:

residential air-conditioning

refrigerator thermostats

commercial Walk-in freezers

window unit Air conditioning units

A

residential air-conditioning

41
Q

Which of the following is not an advantage of using pilot duty instead of line break control?
 

control cost is less

wiring costs are less

sized for light loads

large solenoids

A

large solenoids

42
Q

An ammonia receiver has the following dimensions 36 inches dia x 60 inches long. What is the correct PRV size? 
 

5 cu/ft/min.

5 lb./min.

7.5 cu/ft/min.

7.5 lb./min.

A

7.5 lb./min.

43
Q

The gauge manifold set is a very important piece of equipment for the HVAC & R technician and may include:

compound gauge, high pressure gauge, manifold, hoses and manifold valves

either two or five valves

a five valve design including separate valves for evacuation and refrigerant charging

micron gauge

A

compound gauge, high pressure gauge, manifold, hoses and manifold valves

44
Q

The hole drilled in sheet metal for a tapping screw should be the approximate size of:

the thread diameter

the thread root diameter

the shank diameter

hole diameter

A

the thread root diameter

45
Q

A common aceptable filler material used for soft soldering is composed of:

50/50 tin-lead

95/5 tin-antimony

60/40 tin-lead

60/40 aluminium-tin

A

95/5 tin-antimony

46
Q

A flux must be used when brazing:

copper to aluminum

copper to steel

steel to tin

copper to copper

A

copper to steel

47
Q

The Code of Practice states that a brazing material will have a melting temperature between:

800-1600 °F

600-1200 °F

1100-1300 °F

600- 1200 °C

A

800-1600 °F

48
Q

The crankcase pressure regulator (CPR) is installed in the suction line:

down stream from the suction accumulator under all conditions

down stream from the suction accumulator under certain conditions

up stream from the suction accumulator under all conditions

as close to the compressor as possible downstream of any other ancillaries in the system

A

down stream from the suction accumulator under certain conditions

49
Q

Refrigeration systems frequently use liquid line filter driers to help remove any moisture trapped with the system after servicing. There are four common desiccants used in this accessory, but only two of the four are capable of also removing acids from the system. Which of the following are capable of acid removal?
 

activated alumina/silica gel

charcoal/silica gel

activated alumina/charcoal

molecular sieve/charcoal

A

activated alumina/charcoal

50
Q

The setting (cutout) for a high pressure switch used on water cooled condensers should be higher than normal condensing temperature:
 

35%

10%

20%

depends on ambient temperature

A

20%

51
Q

Which of the following materials are suitable for joining refrigerant piping?
 

silfos/silver solder (melting temperatures above 800 degrees f)

silfos/silver solder(melting temperatures below 800 degrees f

any material may be used (temperature has no relevance)

silver/95-5

A

silfos/silver solder (melting temperatures above 800 degrees f)

52
Q

Choose the statement that describes latent heat of vaporization for a refrigerant.

it varies from refrigerant to refrigerant

it is a constant value for all refrigerants

its value is determined by the boiling point of the refrigerant

its value determines solidification

A

it varies from refrigerant to refrigerant

53
Q

When examining a Psychrometric chart moving from left to right will on the chart will:
 
increase dry bulb temp and decrease relative humidity

increase dry bulb and increase relative humidity

decrease dry bulb and decrease relative humidity

decrease dry bulb and increase relative humidity

A

increase dry bulb temp and decrease relative humidity

54
Q

The low voltage contacts on a room thermostat are:
 
in series with the load

in series with the cooling anticipator

in parallel with the cooling anticipator

in parallel with the heating anticipator

A

in series with the load

55
Q

The purpose of a liquid line solenoid on a refrigeration system is:
 

to provide for pump down

to prevent liquid slugging

to prevent liquid flooding

to allow for the proper use of box thermostat

A

prevent liquid slugging

56
Q

If you reduce the size of a water line supplying a water cooled condenser the result will be:
 

velocity will increase and pressure will remain the same

velocity and pressure will decrease

velocity and pressure will increase

velocity will increase and pressure will decrease

A

velocity will increase and pressure will remain the same

57
Q

A chilled water system is equipped with two centrifugal pumps one for supply water the other for return water one of the pumps is leaking thought the packing gland. You decide to:
 

replace the pump gland

replace the other pump

tighten the gland packing

do nothing

A

do nothing

58
Q

Which setting is adjusted first on a low pressure switch?

cut out
cut in
differential

A

cut out

59
Q

Variable resistor such as a rheostat control current flow in a circuit? Yes or No

A

No

60
Q

Rheostat is there to make a _______ drop not adjust current

A

voltage drop

61
Q

Is a rheostat a load?

A

Yes

62
Q

When installing evap train a liquid trap must be installed within the inside space. This is will limit heat infiltration from entering space. T or F?

A

False

63
Q

When testing motor windings what scale would you use?

rx100
rx1000
rx10,000

A

rx10,000

64
Q

How many leads for a part winding start motor compressor?

A

9 lead

65
Q

If compressor is dead, but otherwise testing electrically OK. You may assume you have what kind of failure?

A

turn to turn short

66
Q

TD on a high efficient condenser ?

A

15F

67
Q

TXV valve may be + or - 25%-30%. True or False

A

True

68
Q

TXV valves can be over or under sized within ___% - ___%

A

25% - 30%

69
Q

Water cooled condensing unit temp TD is ___f average

A

10f

70
Q

CPR is on which line?

A

suction line

71
Q

CPR is downstream of suction accumulator and the purpose is to protect the compressor during hot pull down when discharge temp is high. True or False?

A

True

72
Q

EPR is located on the suction line at outlet of warmest evap coil, upstream of controls/accessories. True or False?

A

True

73
Q

EPR ____ on a rise of inlet

A

opens

74
Q

CPR ______ on a rise of outlet to protect comp

A

closes

75
Q

Set CPR based on compressor ____ during hot pull down

A

RLA

76
Q

Best desiccants for acid removal? (2)

A

Charcoal and Activated Alumina

77
Q

Best desiccant for moisture removal?

A

Molecular sieve

78
Q

What letters represent these?

1.Coefficient of thermal resistance
2.Coefficient of thermal conductance
3.Coefficient of thermal transfer
4.Coefficient of thermal insulation

A
  1. R value
  2. U value
  3. ?
  4. ?

Term 3 - Review Tests (9 decks)

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