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Electrical Grid 1 > Electrical Grid 1: Chapter 9 - Distribution - Possible Test Questions > Flashcards

Electrical Grid 1: Chapter 9 - Distribution - Possible Test Questions Flashcards

1
Q

1) Distribution lines are typically not longer than __ miles, while transmission lines may be several hundred miles long.

A
  • 50 miles
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2
Q

2) How would you best visualize the distribution system when delivering power directly to the customer?

A
  • as a series of local streets
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3
Q

3) Distribution lines are typically separated by an average of how many feet?

A
  • 300 feet
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4
Q

4) What is the primary function of the distribution system?

A
  • To receive electrical power from the transmission system and distribute it to customers at voltage levels that can be utilized by various types of customers.
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5
Q

5) True or false: The distribution system is almost entirely an alternating current system.

A
  • True
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6
Q

6) Why is the design of the circuit important?

A
  • It can have a big impact on the reliability to customers.
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7
Q

7) An energized wire is referred to as a _____.

A
  • phase
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8
Q

8) A mainline distribution circuit is composed of either three phases, or __________________________.

A
  • three phases and a neutral
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9
Q

9) Circuits consist of what?

A
  • main lines

- tap lines

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10
Q

10) Main lines are also referred to as:

A
  • feeder mains
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11
Q

11) Main lines will have larger conductors than:

A
  • tap lines
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12
Q

12) Circuits that consist of four wire, three phase with a neutral conductor are called:

A
  • WYE or star systems
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13
Q

13) On WHY systems it is also common to tap two phases and the neutral to serve light three-phase loads. This is sometimes referred to as what:

A
  • “V” Phase Construction
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14
Q

14) When working in Distribution, define Primary:

A
  • Primary is the high voltage portion of a distribution line.
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15
Q

15) When working in Distribution, define Secondary:

A
  • Secondary is low voltage (120-480) and runs from pole to pole on overhead systems or padmount to pedestal in underground systems.
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16
Q

16) When working in Distribution, define Services:

A
  • Services are also low voltages, but run from pole to customer on overhead systems or pedestal to customer in underground systems.
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17
Q

17) What is commonly known as a Loop Design?

A
  • Underground systems that serve many customers or commercial customers are normally designed so that each transformer can be served from two directions.
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18
Q

18) The number of customers on the circuit is determined by what?

A
  • The density of the area, the type of customers, and the capacity of the circuit.
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19
Q

19) List the different types of customers:

A
  • Residential
  • Commercial
  • Agriculture
  • Industrial
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20
Q

20) Residential Customers:

A
  • Customer dwellings
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21
Q

21) Commercial Customers:

A
  • Stores, shopping centers, medical facilities, etc.
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22
Q

22) Agricultural Customers:

A
  • Irrigation pumps, grain storage, dairies, etc.
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23
Q

23) Industrial Customers:

A
  • Large manufacturing plants, refineries, etc.
24
Q

24) Utilities are obligated to:

A
  • provide voltage at the meter in an acceptable range (114 to 126 volts) so customer equipment will run efficiently and not be damaged.
25
Q

25) How much more expensive are underground systems compared to overhead construction for every miles of line?

A
  • Four times more expensive
26
Q

26) How tall are the majority of distribution poles?

A
  • 35 to 55 feet
27
Q

27) Typical nomenclature of a distribution line?

A
  • Poles
  • Supporting Brackets/Crossarms
  • Insulators
  • Primary Conductor Size
  • Transformers
  • Protective Equipment
  • Capacitors
  • Gang-Operated Switches
28
Q

28) Post Insulators offer more:

A
  • contact area at the point of attachment than pin insulators and are used with larger conductors.
29
Q

29) Over the years, why have conductor sizes increased?

A
  • Due to to the need to deliver larger amounts of power and reduce line losses.
30
Q

30) Why are smaller conductors almost always found on tap lines?

A
  • Because tap lines usually serve a limited amount of customers.
31
Q

31) Most faults that occur on a circuit are:

A
  • minor and temporary
32
Q

32) Distribution systems are designed so that:

A
  • when an outage occurs, as few customers as possible are affected, and outage time to those affected customers are minimal.
33
Q

33) Protective equipment mainly consist of:

A
  • Fused Cutout Switches
  • Reclosers
  • Sectionalizers
  • Lightning Arresters
34
Q

34) Fused Cutout Switches:

A
  • Are designed to protect equipment, and the main line from faults that occur on a tap line.
35
Q

35) Reclosers:

A
  • Are devices that “reclose” the line after a temporary fault, which minimizes outage time.
36
Q

36) A recloser has the ability to reclose up to ____ times to determine if a fault is permanent or temporary.

A
  • four
37
Q

37) Sectionalizers are installed to:

A
  • Clear faulted sections from the line, and are coordinated with a recloser.
38
Q

38) What is one of the main causes of damage to distribution lines and equipment?

A
  • Lightning
39
Q

39) Lightning or Surge Arresters are installed:

A
  • to protect lines against equipment by diverting lighting to the ground
40
Q

40) Voltage Regulators:

A
  • automatically adjust the voltage levels up or down by 10% depending on the condition
41
Q

41) Capacitors

A
  • Improve the efficiency of the circuit and reduce the flow of power that does not perform any useful function.
42
Q

42) Gang-Operated Switches

A
  • Strategically placed throughout a main line to redirect power or to sectionalize a portion of line. They break load and all three phases open at the same time. (This prevents damage to customer three-phase equipment.)
43
Q

43) Underground equipment is commonly classified as:

A
  • padmounted or subsurface
44
Q

44) Padmounted Equipment

A
  • Above ground
45
Q

45) Subsurface Equipment

A
  • Below grade
46
Q

46) Nomenclature of a cable (Out to In)

A
  • Polyethylene (PE) Jacket
  • Concentric copper shield wire (or neutral)
  • Ethylene propylene rubber (EPR) insulation
  • Semi conduction conductor shield
  • Conductor
47
Q

47) Most utilities instal underground cables in:

A
  • conduit
48
Q

48) Enclosures is a term:

A
  • used to classify various types of concrete, fiberglass, or composite-type housings, which are used to splice cables, terminate cables, or to house equipment such as switches and transformers.
49
Q

49) Manholes:

A
  • Larger concrete structures, which are typically installed in lager cities to house heavy cables and equipment.
50
Q

50) Pedestals:

A
  • above ground and are used to splice low voltage secondary and service conductors.
51
Q

51) Padmount transformers are installed:

A
  • on a pad of either concrete or some form of polyurethane.
52
Q

52) Subsurface type transformers are installed:

A
  • either in an enclosure or a manhole.
53
Q

53) Radial:

A
  • Circuits are independent and radiant into the service area.
54
Q

54) Radial Tie:

A
  • Circuits can be connected automatically or manually at one or more points.
55
Q

55) Network Grid Design:

A
  • circuits are connected together, and the step-down transformers are connected together to form a low voltage grid network.
56
Q

56) The network design is:

A
  • the most reliable but also the most expensive.
57
Q

57) Almost all distribution circuits:

A
  • are four-wire: three phase conductors and one neutral conductor.

Electrical Grid 1 (5 decks)

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