Helo: phase transform 3-phases, 380V (40 KW max) to 1-phase, 230V, 50Hz outlets?

[leigh8959]

Hello,
long time reader, first time poster.

I'm installing equipment in Venice, Italy where they use 230V 50hz power. We have access to a 40kW line that is 380V and 3-phase.

I need to transform that to 230V, 50hz and I need at least 90 outlets total. I'm assuming I need a phase transformer and a breakerbox.

I'm guessing that 45 230V 10A breakers will do the trick, but I don't know how to do the phase transform.

What's the best way to do this? I have an electrical engineer and an electrician helping me, but their english is not that great and I need to have a really clear set of specs for them. (I'm a mechanical engineer who also does some power electronics, firmware and software design/management).

thanks!
Leigh

 

[ScottyUK]

Is the available supply 380V 3-wire or 3-phase 4-wire? If you have a neutral plus three phases then this is fairly straightforward because 380V line-line is 230V line-neutral. If you don't have a neutral then you'll need that transformer.

I have no idea what the regulations relating to electrical wiring are in Italy, but I suggest you allow the locals to do their work to their codes unless you are intimately familiar with the requirements. You can't specify what you don't understand, regardless of whether the reason that you don't understand is lingual or technical. The more detail you put in the spec the greater your understanding needs to be.

You might want to check whether it really is 380V, or 400V. Italy adopted 400V as the standard LV utilisation voltage, along with the rest of Europe. It has been that way for quite a while, although there probably is some legacy 380V equipment still in service.

 

[waross]

380V / 1.73 = 220V, 400 / 1.73 = 230. Close enough.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[Mbrooke]

Is a neutral available? Most European equipment can run on a tolerance of +6 -10%. If a neutral is available, this can provide 220 volts which is the standard mains supply in most of Italy. If no neutral can be obtained such as an IT earthed system or simply one was not run a transformer would be used. Check the main incomer first though. 220/380 and 230/400 is a very common supply in Italy.

 

[leigh8959]

@Mbrooke and @scottyuk

thanks for the replies. I understand much better now.

But if the incoming line is 40kW, and I only use one phase, does that mean I only have access to 1/3 of the power? Will I be limited to 13kW?

thanks!

 

[ScottyUK]

Yes, that's correct - if the 3-phase line is rated for 40kW then one phase will be rated for 13.3kW. But you can run three sets of single phase loads from a TP&N supply. It is done all the time.

 

[Skogsgurra]

No, you will be using L1-N for one set of outlets, L2-N for the other set and L3-N for the third. Balance the number of outlets and the power consumed. It is being done all the time, in EU and in the US. All over the world, in fact. Nothing new or mysterious.

BTW
The grid is probably 400 V with 230 V from line to neutral.
It used to be 380 V with 220 L-N. The "Harmonization" in EU (where the Brits had 240 V L-N and the rest of Europe had 220 V) led to the 400/230V compromise. Most countries have "harmonized" and use 230 V, but if you go to the UK, you will still find 240 V. Brits are conservative...

Gunnar Englund

http://www.gke.org

--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.

 

[ppedUK]

Slightly off thread........

I believe that the EU voltage "harmonization" was mainly to permit manufacture of equipment for use anywhere in the E.U., that's what the voltage tolerance was changed to -6% / +10%. The actual system voltages AFAIK didn't actually change, I don't remember the DNOs in the U.K. changing the taps on their transformers to suit the harmonization. The changes to the voltage tolerances permitted Euro 380/220V systems and UK 415/240V systems to remain as was and the tolerances actually allow U.K. 440/250V systems (which I often come across) still to be used. Most distribution transformers are still manufactured with 415V (433V No Load) secondaries.

There may be another reason, I suspect, why the existing system voltages in the U.K. were not actually reduced, and that is because Earth Loop Impedances (Zs) of many circuits were calculated (as per BS7671 15th/16th Edition) for 415/240V operation before the "harmonization" and it is possible that some circuits may not be compliant with the Regs if the voltage was reduced to 400/230V. Just my theory though!

New distribution circuits in the U.K. are now (since BS7671 17th Edition) designed with Loop Impedances using 400/230V, so we might see an actual change in future system voltages on new schemes.