Question regarding 400V three phase lighting connected in Delta, without Neutral.

[Lucien Nunes]

If there is such a thing as a 400V LED driver, then yes. There's no need for a neutral and no need for loads to be balanced. Just connect them between any two lines and that's that. I'm not familiar with units that take 400V AC input though. And, uh, why?

 

[The Ghost]

And, uh, why?

Well indeedy, why? Why not just the normal driver etc. What would the manufacturers say.

 

[telectrix]

they'd say you've put 400v across our 230V driver. warranty is void.

 

[westward10]

the singlephase load requires 240V. the only way to get that from a 3 phase 415V supply is Ph -N, N being the star point.

Agreed but the star point requires no connection to neutral. I regularly used to demonstrate this by having three 60w lamps connected across three phases and the neutrals floating and just connected together.

 

[The Ghost]

neutrals floating

Sorcery!

 

[westward10]

I think this hole thread is a fishing exercise from previous posts. It is not uncommon in large commercial or industrial installations to have three phase lighting circuits which incorporate a single neutral conductor provided you have a linked triple pole protective device.

 

[LankyWill]

Enlighten me fellas, how does it work without a neutral? i thought a neutral was required to create a potential difference thus allow the current to flow. Be gentle...

 

[static zap]

Enlighten me fellas, how does it work without a neutral?. Be gentle...

The whole basis of the three opposing phases is they always add to zero , making their own neutral when stared , saving on 3x Line currents flowing up return !

Hence the preoccupation with balanced loads so neutral , doesnt get cooked up.

 

[AReynolds]

Thanks for the replies, although I'm not sure why people are saying that this thread is an attempt at a 'wind up' or 'Fishing'- I am simply asking a question in good faith, as an electrician who has worked overwhelmingly in domestic installations and is trying to progress to commercial and industrial installations as well as design. Anyway, I realise that 400V, 3 Phase LED lighting is probably overkill in this case. Single Phase would indeed do the job well, if it wasn't for the length of the cable run, which would be about 50m from the Consumer Unit to the last light fitting, which may entail unacceptable voltage drop, and in turn require the use of 2.5 or 4mm conductors, which could be rather difficult to terminate in lighting accessories. As for the existence of 400V LED Drivers, they do exist (Although someone made a good point about them likely requiring neutral connection)- try Google if you don't believe me! Your responses have made me rethink the 400V three phase option- especially the fact that a malfunction of one or more of the lights could unbalance the loading of the circuit.

 

[static zap]

"cable run, which would be about 50m"
Tighter specs on lighting volt drops ,doesn't help !

 

[marconi]

'As for the existence of 400V LED Drivers, they do exist (Although someone made a good point about them likely requiring neutral connection)- try Google if you don't believe me! '

Out of curiosity I did a google search and found this example:

LPFH-60-54 - MEAN WELL - TRC Electronics - http://www.trcelectronics.com/View/Mean-Well/LPFH-60-54.shtml

I note though that the input voltage specification is 200 - 400V ac to 'Meet 277Vac and 347Vac input requirements of North America'. At first glance then, the manufacturer has in mind two operating voltages lower than the upper figure of 400V. The three phase supply in my road in London is 242 x square root of 3 = 420V.

 

[Andy-1960]

As was stated earlier, if you are planning to switch them all on at the same time, beware of the inrush current, as this may cause nuisance tripping of the protective device. I recently looked at some 140w led fittings .. inrush current was 10.2A per fitting!

 

[The Ghost]

potential difference

Think water heater 3 phase, or motor. P.D. between the phase angles. So Phase 1 peaks, phase 2 rising P.D. between the two etc. Ph. 3 as well. Thats how I (mis?)understand it.

 

[westward10]

Think water heater 3 phase, or motor. P.D. between the phase angles. So Phase 1 peaks, phase 2 rising P.D. between the two etc. Ph. 3 as well. Thats how I (mis?)understand it.

No you nailed it in #20, sorcery.

 

[The Ghost]

I don't know quite why, but every time I get an alert from @westward10 I get worried.