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Flashcards in Electricity II Final Deck (84)
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1
Q

What is an electrical device that uses electromagnetism to change voltage from one level to another or to isolate one circuit from another?

A

Transformer

2
Q

What is an electrical service in which service-entrance conductors are run underground from the utility service to the building?

A

Lateral Service

3
Q

What is a central location for troubleshooting and servicing motor control circuits?

A

Motor Control Center

4
Q

What is a graphic representation of a device, component, or object on a print?

A

Symbol

5
Q

A delta connection is a connection that has each coil connected end to end to form what kind of loop?

A

Closed Loop

6
Q

What are transformers rated in, which specifies their power output capability?

A

kVA

7
Q

What is a grounded metal enclosure that contains factory-mounted bare or insulated conductors?

A

Busway

8
Q

What is an electrical wiring sketch showing actual positions of system devices and wiring?

A

Wiring Diagram

9
Q

What shows property lines of a building lot, elevation information, compass directions, lengths of property lines, and locations of structures to be built on the lot?

A

Plot Plan

10
Q

Standard receptacles include what?

A

Long (N) slot, short (hot) slot, U-shaped ground hole

11
Q

What indicates a high-voltage location and condition that could result in death or serious personal injury from an electrical shock if proper precautions are not taken?

A

Electrical Warning

12
Q

What kind of current travels a path other than the normal operating path for which a system is designed?

A

Fault Current

13
Q

What kind of voltage tends to cause continuous muscular contractions that can prolong the individual’s attachment to a circuit and extra care should be taken around?

A

High-voltage DC

14
Q

What is the process of removing the source of electrical power and installing a lock that prevents the power from being turned on?

A

Lockout

15
Q

What are the five classes of fires, and what type of extinguisher should be used on electrical fires?

A

A, B, C, D, and K. Use C on electrical fires

16
Q

Double-insulated electric safety tools have a recommended maximum use of how many volts and are designed to meet NFPA 70E and OSHA requirements for protecting individuals working with electrical equipment?

A

1000V

17
Q

All electrical circuits include multiple points at which ___ or circuit breakers are located.

A

Fuses

18
Q

What single word is used to indicate a potentially hazardous situation that, if not avoided, could result in death or serious injury?

A

Warning

19
Q

What is done to electrical circuits to safeguard personnel and equipment against the hazards of electrical shock?

A

Grounding

20
Q

According to NFPA 70E, only qualified personnel are allowed to work on energized circuits of how many volts or higher?

A

50V

21
Q

What is a voltage decrease of more than 10 percent below the normal rated line voltage for a period of longer than 1 minute?

A

Undervoltage

22
Q

With many modern electronic components derated to save energy and operating costs, the acceptable voltage range is +5% to ___.

A

-10%

23
Q

What is a short, temporary, undesirable voltage in an electrical circuit?

A

Transient Voltage

24
Q

Every load, such as a lamp, motor, or heating element, that converts electrical energy into some other form of energy, such as light, rotating motion, or heat, uses ___.

A

Current

25
Q

What describes the relationship between voltage, current, and resistance in a circuit?

A

Ohm’s Law

26
Q

What is the state where voltage and current in a circuit do not reach their maximum amplitude and zero level simultaneously?

A

Phase Shift

27
Q

What kind of connection has two or more devices connected so there is only one path for current flow?

A

Series

28
Q

A series circuit contains 3 resistors. One is 25 ohms, another is 50 ohms, and the last is 10 ohms. What is the total resistance of this circuit?

A

85 ohms. Series: add. Parallel: 1 / 1/P1 + 1/P2 + etc

29
Q

What is the rate of doing work?

A

Power

30
Q

What is the amount of electrons passing a predetermined point in a circuit in 1 second?

A

Ampere

31
Q

What is used to verify only the presense of coltage at receptacles, switches, and fuses or circuit breakers?

A

Voltage Tester, Voltometer

32
Q

What is an electromechanical device that displays measurements using the mechanical motion of a pointer?

A

Analog Display

33
Q

Analog scales are divided using what?

A

Primary divisions, secondary divisions, and subdivisions

34
Q

How should a digital display read when measuring an open circuit?

A

OL

35
Q

How many jacks does a DMM normally have?

A

2

36
Q

What is most commonly used to measure current over 1 A and in applications in which current can be measured easily by placing its jaws around one of the conductors?

A

Clamp-on Ammeter

37
Q

In-line ammeters provide the most accurate current measurements when measuring currents less than ___.

A

1 Amp

38
Q

Megohmmeters detect what in long wire runs, motor windings, and transformers?

A

Insulation Failure

39
Q

Conductive leakage current is kept to a minimum by keeping insulation clean and what?

A

Dry

40
Q

A meter’s CAT rating indicates what type of magnitude reading a DMM or other electrical appliance can withstand when used on a power distribution system?

A

Transient Voltage

41
Q

Standard and isolated-ground receptacles can be tested using a voltage tester or what?

A

DMM

42
Q

A temperature rise of how many degrees or higher requires immediate attention in an electrical system?

A

100 degrees, 50 degrees requires investigation

43
Q

When converting energy, electrical loads use what?

A

Power

44
Q

Although fuse and circuit breaker conductors are rated for a maximum operating current, they should not be operated continuously at more than how many percent of their rating?

A

80%

45
Q

A temperature rise above ambient temperature is expected on electrical equipment carrying current, and the higher the temperature rise, the greater the possibility of equipment what?

A

Failure

46
Q

A neutral to ground measured voltage difference of how many volts or higher indicates that the branch circuit is overloaded?

A

5V

47
Q

Current unbalances should not exceed how many percent?

A

10%

48
Q

In addition to clamp-on ammeters and DMMs, electrical measurements can be taken at a power or distribution panel with power quality meters and what?

A

Megohmmeters

49
Q

Fuses and circuit breakers are sized so that they are what type of link in the circuit when the circuit is overloaded or there is a short circuit?

A

Weakest

50
Q

Voltage on the secondary of a transformer should not drop below how many percent of the transformers rated output?

A

10%

51
Q

What are the three main types of electric motors?

A

DC, Single-Phase AV, Three-Phase AC

52
Q

What specifies the operating voltage range in the electrical specifications provided with an HVAC system or motor?

A

OEM

53
Q

When measuring voltage, a high voltage fluctuation is an indication of what?

A

The system is overloaded

54
Q

What type of motors are small and inexpensive and normally replaced when they fail?

A

Shaded-pole

55
Q

What type of switches operate their contacts when a preset temperature is reached?

A

Thermal Switch

56
Q

What occurs when voltage at the terminals of an electric motor or other three phase load are not equal?

A

Voltage Unbalance

57
Q

What is a common problem associated with heating elements?

A

No heat, inadequate heat, electrical shock

58
Q

What is the acceptable voltage percentage range for equipment and receptacles?

A

Plus 5% to Negative 10%

59
Q

If low voltage is present out of a control circuit transformer but not into it, the problem is that the transformer if ___ or faulty?

A

Deteriorated

60
Q

Motors used in HVAC systems have been selected and installed by the OEM to operate for how long?

A

An indefinate period of time

61
Q

When magnetic motor starters are used to control motors, the current and voltage levels have to match what rating on the motor?

A

Nameplate

62
Q

The high-voltage side of a transformer is marked with an H and the low voltage side is marked with what?

A

X

63
Q

In a basic AC system, a step-down transformer is normally used to reduce the incoming voltage to ___ VAC for the control circuit components.

A

24VAC

64
Q

What is an electronic device that controls the direction, speed, torque, and other operating functions of an electric motor, in addition to providing motor protection and monitoring functions?

A

Motor Drive, VSD, VFD

65
Q

What type of transformer is the interface used to reduce the voltage from the power circuit to the control circuit?

A

Step-down

66
Q

While troubleshooting motor power circuits, what measurements should be taken when a motor is running?

A

Voltage and Current

67
Q

What is similar to a clamp-on ammeter in that they both measure the strength of the magnetic field around a conductor?

A

Current Transformer

68
Q

Most new motor control applications use what?

A

Fuses

69
Q

Dangerous voltage levels exist when?

A

A motor drive cover is removed and the drive is energized

70
Q

T/F, Electrical symbols are always shown in their off or de-energized position.

A

T

71
Q

T/F, Schematic diagrams show components in their electrical sequence without regard for physical location.

A

T

72
Q

T/F, Components used to provide a function of stop are generally wired normally open and in series.

A

F

73
Q

T/F, Schematic diagrams are usually harder to read and understand than wiring diagrams.

A

F

74
Q

T/F, When a relay is energized, all of its contacts change position.

A

T

75
Q

T/F, Wiring diagrams show components mounted in their general location with connecting wires.

A

F, Pictorial Diagrams

76
Q

T/F, The way a control symbol is drawn indicates how it is to be connected in a circuit.

A

T

77
Q

T/F, Schematics are not important to understand when performing troubleshooting.

A

F, show logic of circuit not location.

78
Q

T/F, Electrical symbols all follow a set standard developed by the industry.

A

T

79
Q

T/F, Relay contact symbols are laveled in the same manner as the relay coils that control them.

A

T

80
Q

When testing a circuit or component with an ohm meter, assuming there is an open, what should your meter display?

A

OL

81
Q

What type of diagram shows components in their electrical sequence?

A

Line Diagram

82
Q

Dashed lines on a schematic are used to represent which of the following?

A

Field wiring

83
Q

Referring to schematics, all symbols are usually shown how?

A

De-energized

84
Q

Referring to schematics, components used to provide a function of stop are shown how?

A

Wired NC and connected in series