Hi, i hope someone can help or point out calculations that i need to do. The task is to transfer from a 6kV substation feeder to another feeder (client/user feeder), need to find out how to calculate the right cable sizing and a new switchgear for clients/user feeder. The outgoing feeder - 6kV, 630 A, vaccum switch; substation: 3 phase, 50hz, 6,3 kV, 4000A, 31,5 kA/3s.
I need to calculate the cable sizing, cable lenght 2 km (1,24 miles). And i wanted advice on choosing a right switchgear. If someone could give me the right formulas to calculate, that would be great. Sorry if this might sound stupid, im just a student who needs a bit of advice/help. Thanks! The base values are taken from a diagramm/scheme.
Hi Thearx
I don't know how your engineering curriculum is administered in Estonia.
Here in US, power distribution which includes power transmission, power generation that include high voltage in several hundred thousand volts are usually taken up on the senior years in Electrical Engineering.
I almost opted out on it, but when I realized I have to take the PE test which cover its fundamentals, it left me with no other options. This lukewarm attitude did not give me the motivation to seek work in transmission design work—although I have this training.
From your request, it is obvious that there is a lot missing to even formulate an answer.
Giving us information like what kind of proposed load you are trying to provide for, is important. The distance you've mentioned would entail determining the size of aluminum wires and the impedance characteristics of your chosen size of conductor.
The separation distance between conductors on top of the pole is also important.
Having this minimum information could provide head start for a designer.
Again, I have this superficial knowledge but I 'm in no way an expert. There was an engineer here who regularly answers this type question but I haven't seen him post any comment for some time.
Are you taking this course at Tallinn University or Tallinn U of Technology?
The reason I asked is, I am scheduled to be in the Baltic Region (Finland, Netherlands, Sweden) which includes Estonia, this year.
I'll buy you a cup of coffee if you hunt me down.
There are books that will give you the calculation methods:
Westinghouse Electrical Transmission and Distribution Reference Book.
This is now publish in your region by ABB. Asea Brown-Boveri, headquartered in Zurich, Switzerland.
The other is published by: Areva Network Protection and Automation Guide.
There is a section in the above handbook that explains in details about Equivalent Circuits and Parameters of Power System Plant-Overhead Lines and Cables.
The above is down-loadable for free.
And lastly, keep in mind (and I hope that this will motivate you) that there is no such thing as stupid question. . . only stupid answers.
Good Luck.
