Science 103 Outcomes 7-12 Flashcards
What is overcurrent?
when more current flows than the circuit is designed for
What is a short circuit?
When line and neutral touch, eliminating the resistance of the load
What is the earth fault?
When the line conductor comes in contact with something connected to earth
What is overload?
When too much load is connected to a circuit (where the circuit is otherwise electrically sound)
What is the BS number of a semi-enclosed rewireable fuse?
BS3036
What is a BS3036 semi enclosed rewireable fuse?
one of them old fuses with just a bare wire
What is the breaking capacity of a BS3036 fuse?
1-4kA
What is a cartridge fuse?
an element encased in a ceramic body
What are the BS numbers for the two different types of cartridge fuse?
BS1361 - big
BS1362 - baby
Name two advantages of the BS3036 fuse?
- simple
* can see if it’s blown
Name two disadvantages of the BS3036 fuse
- can easily mix up the size of the wire if replaced
* cable must be downgraded
Name two advantages of the BS1361 fuse
- more accurate than BS3036
* easy to replace
Name two disadvantages of the BS1361 fuse
- can’t see if it’s blown
* more expensive to replace than BS3036
What is a BS1362 fuse ?
a baby ceramic fuse
What colours indicate the different sizes for bs1362 fuses
RED - 3A
BROWN - 13A
BLACK - everything else
What size do BS1362 fuses go up to?
13A
Name two advantages of BS1362 fuses
- the element doesn’t weaken with age
* easy to replace
name two disadvantages of the BS1362 fuse
- can’t see if the fuse has blown
* have to keep a stock of replacements
What is the BS88 fuse?
A more industrial type fuse with metallic end caps
two advantages of BS88
- work very quickly
* no mechanical moving parts
two disadvantages of bs88 fuses
- very expensive to replace
* keeping replacements is costly and takes up space
What the hell does ‘diazed’ and ‘neozed’ refer to?
fuses (bottle neck)
What does H.R.C. mean
High Rupture Capacity
What does H.B.C. mean
High Breaking Capacity
Name four types of fuel
Coal, oil, gas, biofuel
What is the typical output voltage for a power station?
18kV-25kW
Name the three transmission voltages
132kV, 275kV, 400kV
Name the five distribution voltages
66kV, 33kV, 11kV, 400V, 230V
What are the two types of transformer?
core and shell
Why do we need to keep transformers cool?
as the temp increases so does the resistance, causing greater losses
what are the three methods of cooling for transformers?
air, oil, gas
Which two losses occur in the core of a transformer?
- eddy currents
* hysteresis
What is the core of a transformer?
iron
What is the loss that occurs in the winding of a transformer?
heat