3 Phase Wiring

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engineer1000

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I have looked at serveral 3 phase inputs at factories in the uk, They appear to have  the 3 phases and an earth line. I understand that I could fit a 1 phase 240v  unit across the neutral and one of the phases. If I don't have a neutral how can I do it?? 

I have a system  running an inverter that controls a 3 phase motor, If

engineer1000 said:
I have looked at serveral 3 phase inputs at factories in the uk, They appear to have  the 3 phases and an earth line. I understand that I could fit a 1 phase 240v  unit across the neutral and one of the phases. If I don't have a neutral how can I do it?? 

I have a system  running an inverter that controls a 3 phase motor, If i wanted to fit a 240v lamp how could i do it?
 
It's not the factory that's missing the neutral, just some machines are designed that way.

A 400V to 230V transformer of appropriate rating would give you a single phase feed for controls and lighting etc.

 
It's not the factory that's missing the neutral, just some machines are designed that way.

A 400V to 230V transformer of appropriate rating would give you a single phase feed for controls and lighting etc.
Hi Prodave thanks for that. My next question  is this the 3 phases are going through a 3 phase mcb and then into a 3 phase contactor. Should I take the the lines to the transformer after the mcb and should i fit fuses between the phases and the transformer

 
Hi There,

You are waaaaaaaayyyyyyyyy out of your depth on this one. Please get someone that knows what they are doing as you will be very likely to hurt yourself...

Anyway, we cannot answer your question unless you explain more about what you are trying to do, but, yes, you do need overcurrent protection in the feed to the transformer.

What are you trying to connect up????

john..

 
The transformer primary would go between two phases and yes it would need over current protection in BOTH lines.  Also a pretty damned good idea to have over current protection on the secondary circuit as well.

Please be very careful, you don't sound very knowledgeable on 3 phases stuff, and 400V is a lot more dangerous than 230V. 

 
what, you mean you can get worse than dead, like really really dead. I'll have to watch out for really dead it might hurt more!!! :slap
Oh yes, there are many levels of dead!

For example.....a Mother in Law's scowl can deaden anything MUCH more than just putting yourself across 11kV

Do not forget the Domestos advert....."Domestos kills,99% of household germs, dead"

Just waffling on about nothing in particular

 
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