Electrical distribution system + one line diagram

Hi,
I'm hoping someone may give me a hand in something probably quite straightforward.

I'm wanting to know roughly what a typical single line diagram of a typical office block (pc's, lighting, air conditioning, heating) would look like.

If anyone could do a rough sketch then this would be awesomely (is that a word??) useful. This isn't an assignment or any work which needs to be handed in. I am already graduated. I just want to get more familiar with such areas.

I've looked at several books etc but I haven't seen any useful examples of one line diagrams.

I realise its extremely vague questions and it can vary hugely, but I just want to get a feel for how you'd put the info into a diagram.

For instance I would assume an office block wouldn't have much to it in terms of the electrical distribution system. So it would just be a case of taking power from the grid, downsizing the voltage (eg: 11kV input to a 1000KVA transformer). This would then be distributed to the areas I mentioned above.

So you'd need transformer to take power down to standard 240V for pcs. With AC and heating it would also be a case of a transformer down to a typical rating for these types of equipment).

On the otherhand a factory might be a whole lot more complicated, especially if the factory has a load of variable speed drives, motors and switch mode power supplies. Am I right in believing that all pc switch mode power supplies are required by specific standards to have built in power factor correcting stages. Therefore the above office plant I spoke of would not require any additional stages.

However a factory with switch mode power supplies for equipment and with all the motors etc would require additional power factor correction circuitry such as Static Var compensators in order to ensure their PF was good (not below 0.9) in order to avoid any surcharges by the electricity supplier due to high reactive power demands.

If anyone has anything to add to this then I'd be hugely appreciative. If someone could confirm/deny anything I've said it would also help.


Thanks a lot guys,
ADEng