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ISA Utility Specialist 2019 > Chapter 5 - Electrical Knowledge > Flashcards

Chapter 5 - Electrical Knowledge Flashcards

1
Q

disruption of electrical supply

A

Interruption

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2
Q

measure of electric force or pressure. Analogous to pounds per square inch or kilopascals in a hydraulic system.

A

Volt (V)

Electromotive force

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3
Q

difference in electric energy between an energized conductor and another energized conductor, the ground, or other object.

A

Electrical potential (voltage)

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4
Q

a measure of current. One is the charge carried by 6.25x10(to the 18th) electrons moving past a given point in one second.

A

Ampere (amp, A)

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5
Q

the flow of electricity.

A

Current

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6
Q

a measure of electric power; one amp flowing at one volt. Calculated by multiplying volts and amps.

A

Watt (W)

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7
Q

one million watts

A

Megawatt

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8
Q

the ratio of voltage to current, measured in ohms. Analogous to friction or drag.

A

Resistance

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9
Q

measure of electrical resistance consisting of one volt flowing at one amp.

A

Ohms

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10
Q

the sum of resistance-inductive reactance and capacitive reactance.

A

Impedance

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11
Q

capacity of a material to transmit electricity.

A

Conductivity

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12
Q

electrical network consisting of a conductor or series of conductors through which electricity flows, including a return path to the source.

A

Circuit

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13
Q

interruption to the electrical supply.

A

Outage

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14
Q

amperages in a conductor that are larger than those for which it is rated.

A

Overcurrent

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15
Q

unintentional and undesirable conducting path or blockage of current in an electrical system.

A

Fault

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16
Q

current that is bypassing a designed conducting path.

A

Short circuit

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17
Q

fault that affects the dielectric properties of a system for an instant, and no longer exists after the power has been restored.

A

Transient fault

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18
Q

repeated momentary interruptions in the same place due to the same cause.

A

Intermittent fault

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19
Q

inrush of electricity caused when electrical devices, such as motors or transformers, are first switched on, at which time they can draw several times their normal operating electrical load; often occurs when circuits are first reenergized following an outage.

A

Current surge

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20
Q

electrification of a wire by passing it through a moving electromagnetic field.

A

Inductance

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21
Q

force field comprising electric and magnetic elements associated with electric charge in motion.

A

Electromagnetic field

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22
Q

in an electric utility system, a single primary energized conductor affixed to a pole or cross arm. Technically refers to the synchronized movement of electrical energy and pertains to common designs of electric supply lines, such as single (one primary conductor), two (two primary conductors), or three (three primary conductors).

A

Phase

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23
Q

system that automatically collects data and enables remote control switching operations.

A

Supervisory Control and Data Acquisition (SCADA)

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24
Q

electric facility equipped with transformers, switching equipment, and protection and control devices such as circuit breakers, automatic line reclosers, capacitors, or voltage regulators. Voltage is changed here.

A

Substation

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25
Q

region where transmission or extra-high transmission lines are connected. Allows utilities to transfer electricity both within their systems and among one another.

A

Transmission interconnect

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26
Q

the value (such as MW, Mvar, amperes, frequency, or volts) derived from, or a subset of the System Operating Limits, which if exceeded, could expose a widespread area of the Bulk Electric System to instability, uncontrolled separations or cascading outages.

A

Interconnection reliability operating limit (IROL)

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27
Q

electric facility that does not change voltage, but is used to route power through various circuits. May be strategically designed to compensate for portions of a system that are experiencing power failures, protecting circuits through disconnect switches, circuit breakers, relays, and communications systems.

A

Switchyard

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28
Q

high-voltage lines generally energized between 69 and 161 kV. They can be as low as 35 kV. Connect bulk transmission substations to industrial customers or distribution substations.

A

Subtransmission lines

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29
Q

in an electric utility system, the portion that delivers electricity to end-users. Includes distribution substations, primaries, distribution transformers, secondaries, and service lines.

A

Distribution network

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30
Q

in an electric utility system, electric supply lines usually energized between 2.4 and 23 kV

A

Distribution lines

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31
Q

in an electric distribution system, electric potential above a designated level, generally upstream of transformers.

A

Primary voltage

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32
Q

voltage leaving a transformer in the intended direction. On distribution systems in North America, is 120 to 240 volts.

A

Secondary voltage

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33
Q

stationary part of an electric generator. Contains field windings.

A

Stator

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34
Q

electric current that reverses its direction many times per second at regular intervals, typically used in power supplies.

A

Alternating current (AC)

35
Q

graph of the changing intensity and direction of alternating current.

A

Sine wave

36
Q

in electric generation, the number of cycles, or revolutions of spinning generation magnets, per second. Alternating current periodically varies in amplitude in conjunction with spinning generation magnets, intensifying from zero to a maximum value in a positive direction back to zero, and minimum value in the negative direction before returning to zero. The changing intensity and direction of alternating current is graphed in a sine wave. The time it takes for a magnet to complete a revolution is a cycle.

A

Hertz (Hz)

37
Q

energized cable constructed from aluminum wire stranded around a steel core. Lightweight and relatively low-cost aluminum is often used as a conductor. However, it has a tendency to stretch when it heats, as it does when subject to high electric loads and elevated ambient temperatures. To minimize stretching and add strength, aluminum wire is stranded around a steel core in this cable construction.

A

Aluminum conductor steel reinforced (ACSR)

38
Q

common return path for an electrical system.

A

Neutral wire

39
Q

common return path for an electrical circuit or physical connection to the earth.

A

Ground wire

40
Q

electric distribution configuration with three phases, but no common neutral wire. There is no fixed difference between phase-to-phase and phase-to-ground voltages.

A

Delta construction

41
Q

in an electric utility system, a distribution secondary line that carries electricity from a transformer to a home or business.

A

Service drop

42
Q

secondary wire, which has two insulated conductors and a neutral wrapped around a supportive cable. In North America, a single conductor typically carries 120 V, and the two together total 240 V.

A

Triplex

43
Q

in an electric transmission or distribution system, the activation of a protective device.

A

Operation

44
Q

wire connection between energized conductors and other electrical equipment, such as transformers.

A

Taps

45
Q

permanent operation that requires manual closure of automatic line reclosers.

A

Lockout

46
Q

transient fault in an electrical system, lasting from 33 to 133 milliseconds.

A

Momentary interruption

47
Q

protective device mounted on distribution poles or crossarms that isolates line sections or protective zones in order to limit the number of customers who lose service as the result of a fault. They cut off current when an upstream recloser operates, isolating a fault in the line beyond it.

A

Line sectionalizer

48
Q

device installed to protect electric facilities from voltage surges caused by sudden electrostatic discharges during electrical storms (lightning).

A

Lightning arrestor

49
Q

material with poor conductivity— such as fiberglass, glass, polymers, and porcelain—used to separate energized conductors from poles or other objects or structures that must not be energized.

A

Insulator

50
Q

electrical device that raises or lowers voltage through induction.

A

Transformer

51
Q

device that increases voltage (e.g., from distribution to transmission).

A

Step-up transformer

52
Q

device that reduces voltage (e.g., between primary distribution and secondary distribution).

A

Step-down transformer

53
Q

electric flow in an unintended direction through a process whereby de-energized lines become energized from an external source, such as a home generator.

A

Back feed

54
Q

ratio between the two wire coils in a transformer; identical to voltage ratio.

A

Turns ratio

55
Q

the proportion of primary to secondary voltage of a transformer. It is identical to the turns ratio such that if the primary winding has 10 times the number of turns as the secondary coil, the turns ratio is 10 to 1; the voltage will be stepped down by a factor of 10.

A

Voltage ratio

56
Q

electrical device that functions like an adjustable transformer, capable of either increasing or decreasing the circuit voltage.

A

Voltage regulator

57
Q

a measure of the number of outages experienced by the average customer over a year’s time (or any specific time period): [total number of customer interruptions / total number of customers].

A

SAIFI (System Average Interruption Frequency Index)

58
Q

a measure of the number of minutes the average customer is out of power over a year’s time (or any specific time period): [total duration of customer interruptions / total number of customers].

A

SAIDI (System Average Interruption Duration Index)

59
Q

electrical potential over a specified distance. In the context of tree-caused electrical faults, it is determined by the voltage and spacing of the lines, as well as stem diameter and species of tree. Greater branch diameter and closer phase spacing create higher gradients. The higher the gradient, the more likely a tree is to cause a fault.

A

Voltage gradient

60
Q

a series of power interruptions on a transmission system whereby one interruption increases vulnerabilities and causes additional interruptions, which in turn cause further interruptions, potentially resulting in widespread blackouts.

A

Cascading outage

61
Q

not-for-profit international regulatory authority whose mission is to assure the reliability of the bulk power system in North America.

A

North American Electric Reliability Corporation (NERC)

62
Q

Transmission Vegetation Management reliability standard for vegetation management along transmission lines, released by the North American Electric Reliability Corporation (NERC).

A

FAC-003

63
Q

calculated minimum distance between conductors and vegetation to prevent spark-over, for various altitudes and operating voltages, that is used in the design of transmission facilities.

A

Minimum vegetation clearance distance (MVCD)

64
Q

A / An __________ is a measure of electrical current.

A

amp

65
Q

Voltage used by North American utilities generally ranges from _____ V for end users (customers) to _____ kV for the largest transmission lines.

A

120

765

66
Q

A __________ is a blocked current or a bypass of an intended conducting path.

A

fault

67
Q

Transmission lines terminate at __________, where voltages are changed using transformers to step up or step down the voltage in the lines.

A

substations

68
Q

Primary distribution lines have lower __________ than transmission lines, which is safer and easier to work with.

A

voltage

69
Q

Fiberglass, glass, polymers, and porcelain are good __________; aluminum and copper are good __________.

A

insulators

conductors

70
Q

__________ is used on distribution lines in densely forested areas to provide some protection from faults caused by branches.

A

Tree wire

71
Q

__________, the principal protective devices in distribution substations, are designed to operate in as little as 10 cycles.

A

Circuit breakers

72
Q

Electrical flow in an unintended direction is called __________.

A

back feed

73
Q

Three tree and electrical system characteristics that influence the likelihood of a tree-related service interruption are __________, __________, and __________.

A

voltage gradient
stem diameter
species

74
Q

Two indices used to quantify reliability are SAIFI and SAIDI, which measure the __________ and __________ of interruptions experienced by the average customer over a given period.

A

frequency

duration

75
Q

The most common cause of the tree-related service interruptions is __________ failure.

A

mechanical tear down

76
Q

The utility system’s __________ allows the efficient transmission of electricity to areas of greatest need at a particular moment, which also makes the system more susceptible to __________.

A

interactivity

blackouts

77
Q

The __________, or MVCD, is a calculated distance inside of which vegetation may not encroach.

A

minimum vegetation clearance distance

78
Q

The capacity of a material to transmit electricity is referred to as

A) electrical fault
B) electromagnetic field
C) conductivity
D) inductance

A

C) conductivity

79
Q

A transformer that is intended to reduce voltage is known as a

A) capacitor
B) step-down transformer
C) step-up transformer
D) voltage regulator

A

B) step-down transformer

80
Q

Which of the following is not true of aluminum wire?

A) it is light weight
B) it is low cost
C) it has more conductivity than copper
D) it can span longer distances than copper

A

C) it has more conductivity than copper

81
Q

Which of the following is true of guy wires?

A) they are intended for support, rather than electrical conduction
B) they are made of steel and are therefore conductive
C) they can become energized by direct or indirect contact with energized wire
D) all of the above

A

D) all of the above

82
Q

True or false:

Electricity seeks the path of least resistance to the ground.

A

True

83
Q

Transmission circuit breakers operate in response to all of the following irregularities, except

A) abnormally high amperage
B) abnormally high voltage
C) abnormally low voltage
D) unequal current

A

B) abnormally high voltage

ISA Utility Specialist 2019 (7 decks)

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