Slightly OT: Plant Power Distribution

[Jieve]

Hello Guys,

I have a question thats not directly related to PLCs, but for those of you who work or have worked in contental Europe (anywhere using 230V as standard single phase AC), I was wondering what 3 phase voltage generally comes into a typical factory directly from the outside lines, and how/where that is stepped down to other voltages, and ultimately to the 230V used for powering outlets, lighter machinery, etc. I'm sure there is no single answer as higher voltage is necessary where heavy machinery is implemented, but maybe a few answers would be good. Is there often times an outside step down transformer near the plant that reduces the voltage to something above 230 used to power heavier duty machines, or is there ever a circumstance where this is actually done with step down Transformers in-plant? Or is it common to just take standard 230V from the local Distribution station? This may be a simple question, but I'd really appreciate an answer to satisfy my curiousity.

Thanks!

 

[Oceansoul]

I work on a large water treatment plant in the UK. Were supplied with 22kv from the DNO. This is fed to 5 22kv/3.3kv Transformers which we own. The 3.3kv is fed to some HV pump motors and to further substations on the plant which have 3.3kv/415v TX.

All the above is 3 phase. Obvously the 415v 3phase is 230v single phase.

 

[Jieve]

Oceansoul,

Thanks for the response. Ok, so those are pretty high voltages fed out of the lines directly into the station's own transformers. Interesting. I was kind of curious if there was a standard voltage that most plants take from the lines that is fed out, or if this is customized for every application, depending specifically on what the plant needs.

I thought the UK was on 415/240V, Germany 400/230V. But maybe I'm wrong about something here.

 

[jude]

ireland is 380V 3 phase 220v single phase

 

[Andybr]

Jieve.
Technically the supply voltage across the EU is 400/230V with a tolerance of +10% -6%. this range was a political fix to accomodate the historical voltages in Europe which ranged from 380/220V to 415/240V. In the UK larger sites have traditionally been supplied at 11KV but this seems to be changing to 33KV at the moment. Where plants are supplied at the higher voltages the actual final voltage you see in the panels depends entirely on the tap changer settings on the distribution transformers. The current fashion is to keep final voltages low to save energy on simple heating and lighting loads.
Andybr