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General Knowledge Flashcards

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1
Q

What is the purpose of an iron core within a TX?

A

To direct and channel the magnetic field

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2
Q

How do you find full load rating of a TX?

A

Full load rating=KVA/ sec voltage
I=P/E

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3
Q

Core loss in a TX comes from_________ set up by the constant reverssing of the magnetic field

A

Eddy currant losses

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4
Q

Copper loss in a TX is due to the ______ of the windings

A

Resistance

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5
Q

What is corona ?

A

Alluminous discharge of ionized particles

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6
Q

An electrical device that allows currant to flow only in one direction

A

Diode

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7
Q

Voltage read on a meter before it is connected to an electrical circuit produced by magnetic field

A

Ghost voltage

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8
Q

A ____________ is a temporary undesirable voltage in an electrical circuit

A

Transient voltage

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9
Q

An explosion that occurs when the air surrounding electrical equipment becomes ionized and conductive

A

Arc blast

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10
Q

A system that has a common connection for all three windings is ________ connected

A

Wye

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11
Q

Windings and three phase generation are _______ apart

A

120’

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12
Q

What is a capacitor, what does it do?

A

Two conductors separated by a di-electric material
Used to balance power factor

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13
Q

The _________ voltage value is measured from zero to the highest value obtained in either direction

A

Peak

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14
Q

What is the speed of light?

A

186, 282 miles/second

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15
Q

The time required for one cycle is called the ______?

A

Period

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16
Q

Formula: length of guy estimate

A

Height of attachmentment above ground + 1/2 distance pole to anchor

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17
Q

Formula: Guy tension

A

Line tension x (length of guy/distance to anchor)

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18
Q

Formula: structure tension

A

Distance from adjacent structure to adjacent structure x conductor weight per thousand ft/ 2

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19
Q

____________ are connected in parallel to improve power factor

A

Shunt capacitors

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20
Q

If a transformer with no connected load is energized, the exciting current may be as high as ______ of the transformer full load current

A

5%

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21
Q

Where does the potentially lethal third harmonic voltage come from

A

The difference between primary and secondary neutrals if the two are not connected

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22
Q

Transformers that have a rating over ______kVA or primary voltage over ______ are subtractive

A

200 KVA
8600 volts

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23
Q

5 musts for parralleling transformers

A
  1. Identical voltage ratings
  2. Identical tap settings
  3. Identical frequency ratings
  4. Impedance + or - 7.5
  5. Tapped on the same phase
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24
Q

The primary coil in a dual voltage transformer(clicker) can be connected in ________ or________ depending on incoming voltage

A

Series or parallel

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25
Q

Definition of a nuetral

A

A current carrying conductor at ground potential that acts as a return for unbalanced load

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26
Q

Definition of a transformer

A

A transformer is a ratio in device operating on the principal of mutual induction

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27
Q

A CSP primary lead should be taken off-line before working the secondary because?

A

The secondary coil might have enough capacitance to hold a charge
No visual open

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28
Q

The emergency control handle on a CSP should be used as a _______[?

A

Temporary fix to an overload situation

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29
Q

The primary fuse link of a CSP protects ______ from an internal fault

A

The system

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30
Q

If the nameplate conveys the secondary 240/120 or 208/120 what does that mean 

A

The coils are permanently connected in center tap series, can not be connected in parallel

31
Q

If the nameplate coveys the secondary 120/240 what does that mean

A

Means the coil can be connected in series, parallel, or center tapped series

32
Q

What does it mean if there is a slash (/) between primary voltages on the transformers nameplate

A

Both H1 and H2 are insulated
Suitable for delta connection 

33
Q

If the name plate has an X between the listed voltages what does that mean?

A

The coil may be connected in series or parallel but never center tapped

34
Q

If the nameplate has “Grd” along with the primary voltage the transformer ____?

A

Single bushing
H2 must be connected to system nuetral

35
Q

Class II gloves
Tested: _______
Rated: ________
Color: ________

A

Tested: 20,000 v
Rated: 17,000 v
Color: Yellow

36
Q

Class III ruber gloves
Tested: ______
Rated: _______
Color:______

A

Tested: 30,000 v
Rated : 26,500 v
Color: Red

37
Q

Class IV rubber
Tested: ______
Rated:_______

A

Tested: 40,000 v
Rated: 36,000 v

38
Q

Angular displacement
Y-Y: ________
Y-delta:_______

A

Y-Y: 0, 180 degrees
Y-delta: 30’ (sub) , 210’ (add)

39
Q

IBEW history
First president:______
Year formed:______
City formed in:_______

A

Henry Miller
1890
St. Louis

40
Q

Minimum approach distance phase to phase
1-15 kv= _____
15-36 kv=_____

A

NWE
27”
33”

41
Q

How do you field test for polarity?

A

1) energize H1 at 120 V
2) Connect jumper from H1 to adjacent secondary bushing
3) Measure between H2 and it’s adjacent secondary bushing

If voltage is greater than 120 its additive, less than 120 its subtractive 

42
Q

How does an open delta bank share load?
3{}
1{}

A

Power pot Lighter pot
3{} Equally @ 57.7% of total KVA
1{} 100%

43
Q

How does a close Delta Bank share load?
3{}
1{}


A

3{} 1/3 each
1{} power pot 1/3 each
Lighter pot 2/3

44
Q

How does a closed Y Bank share load?

A

3{} 1/3 each
1{} 1/3 each

45
Q

What is power factor?

A

The ratio of true power(watts) to that of aparent power(volt amps) or
Total current to useful working current

46
Q

What is a PT?

A

Transformer used to reduce voltage to a safe measurable level for purpose of metering and checking primary voltage accurately
PT-Parallel 

47
Q

What is transposition?

A

When all three phases change position to cancel excess induction that interfere with open wire telephone circuits

48
Q

What is a CT?

A

A transformer that reduces current to a measurable value for metering
CT-Series

49
Q

What does SF6 stand for?
What does it do?

A

Sulfer hexafluoride
A non conducting gas

50
Q

What does a transformer fuse protect against?
What are two design purposes?

A

Over currant
1. Protect our equipment from over load
2. Isolate faulted TX before upstream protection opens

51
Q

What does an emergency control handle on a CSP do?

A

Increases full load capability temporary

52
Q

Four functions of a CSP transformer?

A
  1. Externally mounted arrester
  2. internal primary fuse link
  3. secondary breaker
  4. overload indication light
53
Q

What is most power generated at?

A

13,800- 24,000

54
Q

ratings
Knots:
Hitches:
Splices:

A

50%
75%
85%

55
Q

What is a bowline rated for?

A

65%

56
Q

Three parts of a rope?

A

Fibers, yarn, strands

57
Q

Lowering a tap _______ customer voltage

A

Raises
-less primary windings
-lower turns ratio

58
Q

Raising a tap _______ customer voltage

A

Lowers
- more primary windings , increases turns ratio

59
Q

What does a regulator do?

A

A regulator corrects variations of voltage by steping up or down in small incremental steps by adding or reducing turns to the primary coil

60
Q

The conductivity of aluminum is about ____% that if copper

A

62

61
Q

What is the max amount of stretch a overhead lifting chain can have?

A

3%

62
Q

Two types faults in an electrical system?

A

Short circuit and open circuit

63
Q

A distrobution system is exposed to what three faults?

A

Over-currant, over-voltage, and open circuit

64
Q

When are Fault indicators activated?

A

Over currant situation

65
Q

Purpose of a stress cone/pothead?

A

To distribute voltage stress over a larger area, reducing stress at semi-con edge

66
Q

What is PCB

A

Polychlorinated biphenyl

67
Q

Transformers larger than ____ KVA have four secondary bushings

A

100 KVA

68
Q

Open Wye-Open delta bank efficiency rating

A

86.6% of the two TX

69
Q

A __________ is a slave device that cannot interrupt fault currant, and opens during a specified interval of recloser operation

A

Sectionalizer

70
Q

What is the efficiency rating of a Wye Delta open bank?

A

86.6% of the total KVA of the two TX

71
Q

What is the efficiency rating of a Y-Delta bank if it has been converted from closed to open?

A

57.7% of the original closed bank
Or 86.6% of the remaining two TX

72
Q

What is SCADA?

A

Supervisory control and data acquisition

73
Q

On a three phase Y-Y pad mount, the three primary coils and secondary coils share what?

A

Common core

General Knowledge (1 decks)

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