Science 103 Outcomes 7-12 Flashcards

1
Q

What is overcurrent?

A

when more current flows than the circuit is designed for

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2
Q

What is a short circuit?

A

When line and neutral touch, eliminating the resistance of the load

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3
Q

What is the earth fault?

A

When the line conductor comes in contact with something connected to earth

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4
Q

What is overload?

A

When too much load is connected to a circuit (where the circuit is otherwise electrically sound)

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5
Q

What is the BS number of a semi-enclosed rewireable fuse?

A

BS3036

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6
Q

What is a BS3036 semi enclosed rewireable fuse?

A

one of them old fuses with just a bare wire

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7
Q

What is the breaking capacity of a BS3036 fuse?

A

1-4kA

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8
Q

What is a cartridge fuse?

A

an element encased in a ceramic body

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9
Q

What are the BS numbers for the two different types of cartridge fuse?

A

BS1361 - big

BS1362 - baby

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10
Q

Name two advantages of the BS3036 fuse?

A
  • simple

* can see if it’s blown

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11
Q

Name two disadvantages of the BS3036 fuse

A
  • can easily mix up the size of the wire if replaced

* cable must be downgraded

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12
Q

Name two advantages of the BS1361 fuse

A
  • more accurate than BS3036

* easy to replace

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13
Q

Name two disadvantages of the BS1361 fuse

A
  • can’t see if it’s blown

* more expensive to replace than BS3036

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14
Q

What is a BS1362 fuse ?

A

a baby ceramic fuse

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15
Q

What colours indicate the different sizes for bs1362 fuses

A

RED - 3A
BROWN - 13A
BLACK - everything else

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16
Q

What size do BS1362 fuses go up to?

A

13A

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17
Q

Name two advantages of BS1362 fuses

A
  • the element doesn’t weaken with age

* easy to replace

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18
Q

name two disadvantages of the BS1362 fuse

A
  • can’t see if the fuse has blown

* have to keep a stock of replacements

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19
Q

What is the BS88 fuse?

A

A more industrial type fuse with metallic end caps

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20
Q

two advantages of BS88

A
  • work very quickly

* no mechanical moving parts

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21
Q

two disadvantages of bs88 fuses

A
  • very expensive to replace

* keeping replacements is costly and takes up space

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22
Q

What the hell does ‘diazed’ and ‘neozed’ refer to?

A

fuses (bottle neck)

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23
Q

What does H.R.C. mean

A

High Rupture Capacity

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24
Q

What does H.B.C. mean

A

High Breaking Capacity

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25
Q

Name four types of fuel

A

Coal, oil, gas, biofuel

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26
Q

What is the typical output voltage for a power station?

A

18kV-25kW

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27
Q

Name the three transmission voltages

A

132kV, 275kV, 400kV

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28
Q

Name the five distribution voltages

A

66kV, 33kV, 11kV, 400V, 230V

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29
Q

What are the two types of transformer?

A

core and shell

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30
Q

Why do we need to keep transformers cool?

A

as the temp increases so does the resistance, causing greater losses

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31
Q

what are the three methods of cooling for transformers?

A

air, oil, gas

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32
Q

Which two losses occur in the core of a transformer?

A
  • eddy currents

* hysteresis

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33
Q

What is the core of a transformer?

A

iron

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34
Q

What is the loss that occurs in the winding of a transformer?

A

heat

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35
Q

What is the winding of a transformer made of?

A

copper

36
Q

How do we reduce the losses from eddy currents and hysteresis?

A

Laminating

37
Q

In a solar PV panel circuit what increases as more panels are added in series?

A

the voltage

38
Q

In a solar PV panel circuit what increases as more panels are added in parallel?

A

output

39
Q

Name two advantages of Hydro generation

A
  • eco friendly

* low maintenance

40
Q

Name two disadvantages of a hydro generation system

A
  • high install cost

* requires flowing water

41
Q

name two advantages of wind generation

A
  • plentiful energy source

* can store electricity

42
Q

name two disadvantages of wind energy

A
  • relies on wind

* requires planning permission

43
Q

Name two advantages of heat pumps

A
  • lowers fuel bills

* fit and forget technology

44
Q

name two disadvantages of heat pumps

A
  • requires that your house is already well insulated

* high set up costs

45
Q

What is a Type B RCBO for?

A

resistive loads i.e. General loads, domestic

46
Q

What is a Type C RCBO for?

A

inductive loads i.e. for something with coils/windings like motors or transformers

47
Q

What are type D RCBOs for?

A

highly inductive loads e.g. X rays

48
Q

Name two advantages of a tungsten filament lamp

A

simple, cheap

49
Q

Name two disadvantages of a tungsten filament lamp

A
  • only 5% efficient

* fairly short life

50
Q

Name two advantages of a tungsten halogen lamp

A
  • better colour rendition

* higher efficacy than a filament lamp

51
Q

Name two disadvantages of a tungsten halogen lamp

A
  • low efficacy

* low lamp life

52
Q

What are the two types of tungsten halogen lamp?

A

Linear and capsule

53
Q

Name two advantages of a high pressure sodium vapour lamp

A
  • excellent lumen maintenance

* long lamp life (24k hrs)

54
Q

Name two disadvantages of a high pressure sodium vapour lamp

A
  • requires a ballast

* colour rendition is golden white

55
Q

Name two advantages of a low pressure sodium vapour lamp

A
  • long lamp life

* high efficacy

56
Q

Name two disadvantages of a low pressure sodium vapour lamp

A
  • poor colour rendering

* expensive to install

57
Q

Name two advantages of a high pressure Mercury vapour lamp

A
  • more efficient than fluorescents

* intense illumination

58
Q

Name two disadvantages of a high pressure Mercury vapour lamp

A
  • unflattering bright colour rendition

* requires a warm up period

59
Q

Name two advantages of an L.E.D.

A
  • saves up to 25x more energy than a traditional incandescent lamp
  • long lamp life up to 39k hrs
60
Q

Name two disadvantages of an L.E.D.

A
  • high upfront cost

* can change colour as a result of age and temperature

61
Q

Name two advantages of a metal halide lamp

A
  • high efficacy

* life span of 6k-15k hrs

62
Q

Name a disadvantage of a metal halide lamp

A

•the life span can be shortened as a result of the oils on your hands if you’re not careful during installation

63
Q

Briefly describe the operation of a solenoid

A
  • the solenoid has a winding which creates a magnetic field when current passes through it
  • an iron rod is placed partly inside
  • when the circuit is energised, the rod is pulled into the solenoid fully which should operate the system
64
Q

Briefly describe the operation of a relay

A
  • in a relay there is a coil which is used to attract a contact to operate a switch
  • when the coil has no current thru it, the switch stays open
  • then when it is energised, the coil creates a magnetic field which attracts the ferrous contact, closing the switch and completing the circuit.
65
Q

What is a fault current?

A

a current which flows through a circuit under fault conditions

66
Q

What is meant by the term ‘protective conductor current’?

A

a current that flows thru a protective device

67
Q

Three advantages of a BSEN60898 circuit breaker

A
  • easy to see when it’s tripped
  • can quickly restore the supply
  • every breaker is set to manufacturers standard
68
Q

Three disadvantages of a BSEN60898 circuit breaker

A
  • expensive
  • must be regularly tested
  • ambient temp can affect performance
69
Q

Describe the basic operation of an RCD

A
  • An RCD monitors the current going out compared with the one coming in
  • if there is an imbalance, a magnetic flux is produced by the toroid which energises the trip coil.
  • this opens the double pole switch
70
Q

What is a cold tail?

A

The part of the underfloor heating mat or cable which does not heat up because it is the electrical connection.

71
Q

What are the two types of heat transfer in space heating?

A

convection and radiation

72
Q

What is economy 7?

A

Economy - cheap

7- for 7 hours, between 12-7am

73
Q

What are the two main types of water heaters?

A

Stored and instantaneous

74
Q

What temp should the thermostat of an immersion heater be set to?

A

55-60 degrees

75
Q

What stops you from being scalded in an instantaneous water heater?

A

a scald guard thermostat

76
Q

Why should water in heaters never get too hot or too cold?

A

too hot - risk of scalding

too cold - risk of legionella

77
Q

What is the usual temp for a room thermostat?

A

20 degrees

78
Q

What does the programmer do in terms of heating ?

A

it makes the decision of when the heating will run

79
Q

What are two valves commonly used in central heating systems? (electrical )

A

zone valve, three-port valve

80
Q

What is the unit and symbol for luminous intensity?

A

candelas, I

81
Q

What is the unit and symbol for luminous flux

A

Lumen F

82
Q

What is the unit and symbol for illuminance

A

lux E

83
Q

What is colour rendering

A

a lamps ability to show colours as they truly are

84
Q

How is a lamps efficiency measured?

A

in lumen watts

85
Q

What does GLS mean?

A

General Lighting Service