Three Phase Distribution Flashcards
What voltage is derived from a substation transformer?
400/230 volt
What method is used in the secondary winding
Of the substation transformer ?
Star point
What is phase voltage?
Phase voltage is the voltage (230V) between any live line (L1,L2,&L3) and the neutral.(single phase )
What is line voltage (UL)
The voltage between two live feeds (L1&L2, L1&L3, L2&L3) it is 400volts (three phase)
What are the wire colour codes for three phase systems ?
Brown =L1 Black =L2 Grey=L3 Blue =Neutral Green/yellow= Earth
What is 3 phase 400 volt 4wire supply used for ?
Unbalanced three phase loads as they require a neutral.
What is a 3 phase 400 volt 3 wire supply used for?
It is used for balanced loads such as three phase motors which do not require a neutral.
What is 2 phase 400 volt 2 wire supply used for
Used for loads such as welders
Referred to as 1 phase 400 volt supply
What is 1 phase 230 volt supply used for ?
Used for loads such as lamps, heaters & computers.
Name the three different neutral bars that can be found in a three phase board ?
- Main neutral bar
- Single phase neutral bar
- Three phase neutral bar
What is ran into a three phase neutral bar?
Three phase sockets neutral
What should a three phase socket circuit be protected with ?
Three phase RCD
What does HBC in HBC fuses stand for ?
High Breaking Fuses.
What is another name for a high Breaking fuses (HBC)?
High Rupturing Fuses
How quick can a higher breaking fuses (HBC) break a short circuit ?
0.01 sec
What is the disadvantage of a high Breaking fuses ?
Expensive
What are the advantages of hight breaking fuses (HBC) ?
Can distiguses between over load current for motor start up and high fault current
No fire risk
Will not deteriorated with time
Capable of breaking very high value fault currents
What is the fusing factor if high Breaking fuses ?
1.25
What is a type C MCB ?
A type C MCB is used in industrial wiring.
What is the difference between a type b and type c MCB ?
Type C can detect a over current for the start of a motor and not trip but can also detect short circuits in the case of a fault
What is the magnetic tripping facto of a type C MCB ?
5-10 time it’s rated current
What is the thermal tripping factor of a type C MCB?
Between 1.13 & 1.45 the same as a type B MCB
What colour is a 110 volt plug and socket?
Yellow
What colour is a 230 volt socket and plug ?
Blue.
What colour is a 400 volt plug and socket?
Red
At what position of a clock is the earth sleeve located on a 110 volt plug ?
4 o’clock position
What position is the earth sleeve on both 230 volt and 400 volt plugs ?
6 o’clock
What is the CENELEC plug and socket standard for industrial uses ?
EN 60309
