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IBEW 125 JL Test > Miscellaneous > Flashcards

Miscellaneous Flashcards

1
Q

Name the two types of Underground Distribution Systems.

A

Duct and Vault
Direct Bury

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2
Q

Duct banks are usually made with?

A

Polyvinyl Chloride/PVC plastic or fiberglass, existing could be tile, concrete or steel.

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3
Q

What are the various paint markings and their corresponding meanings?

A

Red - Electrical
Yellow - Gas, oil, steam
Blue - Water
Orange - Communications
White - Proposed Structure
Green - Sewer
Purple - Irrigation
Pink - Temporary Survey Tape

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4
Q

At what depth is red caution tape laid out?

A

1 foot and above the underground cable

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5
Q

A bare ground wire/tracer wire can be laid along with cable for what purpose?

A

To locate the cable in the future. Or gather stray ground current.

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6
Q

The maximum tension for pulling cable is dependent upon what two factors?

A

Conductor size and how a pulling eye is attached.

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7
Q

What are the two methods of pulling wire

A

A crimp on or mechanical connected pulling eye will allow a higher pulling tension. Or a kellum or wire mesh grip around the jacket of cable. Kellum rated at less than 1000 lbs typically.

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8
Q

Define ampacity.

A

Is the current in amperes that a conductor can carry continuously without exceeding it’s temperature rating.

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9
Q

What is a thermal barrier? And name some.common examples.

A

Anything that is in direct contact with underground wire and impedes its ability to cool.

Conductor insulation, soil surrounding cable, poor air circulation in duct.

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10
Q

On high voltage transmission lines a minimum diameter conductor is required to avoid ______.

A

Corona Loss

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11
Q

With underground cable the voltage rating is based on what?

A

The property of the insulating material.

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12
Q

An electrical field around a conductor can be strong enough to break down or ionize the molecules in the air. This is referred to as what?

A

Corona

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13
Q

It takes energy to make corona, and corona loss results in power loss. Also radio and television interference. What are ways to minimize these issues?

A

Increase spacing between conductors and or ground

Increase surface area of conductors (bundle, or corona rings/grading rings)

Keep rough edges to a minimum to reduce voltage stress points

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14
Q

Aeolian Vibration is also known as what?

A

Wind vibrations

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15
Q

What is galloping by conductors?

A

The rise and violent drop of conductors caused by ice loading or moderate winds.

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16
Q

What is the conductivity of aluminum compared to copper?

A

62%

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17
Q

Properties to consider in conductor design include.

A

Weight per unit length, thermal expansion, elasticity, surface shape drag, fatigue resistance, dampening ability/resist galloping.

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18
Q

What is ACSR, AAC, AAAC, ACAR, AACSR

A

Aluminum Conductor Steel Reinforced
All Aluminum Conductor
All Aluminum alloy conductor
Aluminum Conductor Aluminum Alloy Reinforced
Aluminum Alloy Conductor Steel Reinforced

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19
Q

What size wire tongs should you use on conductors up to 1/0 and what size for conductors 1/0 and larger?

A

2” and 2 1/2”

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20
Q

Identify some MAD distances for various voltages.

A

5.1 to 15
2’2 phase to ground and 2’3” phase to phase

15 - 36
2’7” p to g and 3’ p to p

46.1 - 72.5
3’3” p to g and 4’ p to p

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21
Q

Where is a pole most likely to decay? And what is the typical life expectancy?

A

1 foot below ground level.
Typically 35 yrs.

22
Q

What is the unit of measurement for capacitance?

A

Farads, however farads are an extremely small unit so line workers use kilovolt amperes reactive. kVAR

23
Q

Voltage to the customer should be within this percentage plus or minus?

A

6%

24
Q

Fault currents are highest near what?

A

The source, either substation or transformer.

25
Q

Induced voltage is always in a direction that _______ the direction of the current.

A

Opposes

26
Q

What does SCADA stand for? And what is its function?

A

Supervisory Control And Data Acquisition.
It is the communication system used to operate a distribution system.

27
Q

Trenches or vaults deeper than ___ feet are considered confined spaces.

A

4

28
Q

Define Capacitance

A

The ability of an electrical apparatus to hold a charge.

29
Q

Can a line without a load carry current? And if so how much?

A

Yes it can carry a charging current of as much as 20 amps.

30
Q

Name the colors for these various Guy Performs.
5/16”
3/8”
7/16”
1/2”

A

Black, Orange, Green, Blue

31
Q

What are the 4 types of switches?

A

Air - circuit breakers, air break, disconnect
Oil - oil switches, OCB, OCR, and sectionalizer
Vacuum - vacuum circuit breakers, vacuum recloser
SF6 - circuit breaker, circuit switch, recloser

32
Q

What are the two types of distribution voltage regulators?

A

Induction and step

33
Q

What color are your truck/trailer connections?

A

Red Emergency
Blue Service
Green Electrical

34
Q

At what depth is sloping, shoring or benching needed?

A

5 Feet

35
Q

What are three types of loads fed by an AC circuit?

A

Resistive, Inductive, Capacitive

36
Q

A step voltage regulator is basically a what?

A

Auto Transformer

37
Q

Which way does electrical current flow?

A

Negative to positive

38
Q

What must be done to the secondary side of a CT before heating up the primary side?

A

Short, shunt or hookup up to prevent high circulating current

39
Q

When should a fuse interrupt the fault current?

A

Within the first 1/4 cycle

40
Q

Can a sectionalizer open under load?

A

No!

41
Q

When properly sharpened a gaff should not have a spike point but should function as a ?

A

Chisel

42
Q

What is the definition of power?

A

The rate at which work is done.

43
Q

What does a sectionalizer do?

A

It senses the operation of a back up device (recloser) and locks out when it is open.

44
Q

Name two types of faults?

A

Temporary and permanent

45
Q

Why does the recloser hold the line open for 60 or more cycles before it recloses?

A

To allow the sectionalizer to open while no current is flowing.

46
Q

The ______ or equivalent span, is an assumed uniform span that most closely represents the various lengths of spans that are in the section of line being sagged.

A

Ruling

47
Q

Two things to consider when sagging a conductor?

A

Temperature and span length

48
Q

What is the minimum depth a pole should be set?

A

5 feet

49
Q

Name some various factors that determine pole strength.

A

Diameter, weight, type (concrete, laminate, wood)

50
Q

Poles are divided into how many classes depending on top circumference and circumference 6 feet from the butt.

A

Class 1 - 10 for normal strengths and
H1 - H6 for higher strengths

51
Q

At what current does a recloser normally open?

A

Two times normal line current.

IBEW 125 JL Test (5 decks)

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