# Simulated 3 phase using 1 phase linked



## frank (Feb 6, 2007)

GerryL


I have tried to follow what you have said Gerry but do not fully understand. Whatever you are doing however you can't make single phase into 3 phase simply linking 3 lines together. All you get is 3 //ll phases of the same single phase. If you can explain in further detail maybe I can figuree it out for you and give a answer


Frank


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## chrisb271 (Jul 6, 2007)

GerryL

So what you are saying is that your customer has a single phase supply to his site that he wants to supply a three phase DB ( with the phases linked ) 

If the mains supply goes off then the generator ( thats three phase+neutral) with take over and supply the three phase DB with three phases ?

WOW,weird 

ok so it is possible BUT and it's a big BUT !!!!

1. it would be quite costly to set up as you would need at least three BIG contactors,mechanical interlocks,auxillary contacts and delay timers just to keep the generator from back feeding the mains supply.
( you have to take into account that if the incoming mains supply is dead then there could be someone working a substation or overhead line )

2. You could be placing your neck on the block for doing such a foolish practice.I certainly wouldn't entertain such and i don't think many other electricians would.

3. if your customer has any three phase motors etc then they wouldn't run properly anyway and would doubt if they would even start,three phases are usually 120 degrees apart,you would just end up causing a big fire.If your interlocks and aux contact fail then it would kill the alternator on the generator.

If i were you bud i would tell your customer to either run his three phase board permanantly from the generator or get a three phase supply put to it,its really not worth the hassle and maybe killing someone for a few quid.

Chris B


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## Electric Al (Mar 13, 2010)

Is it possible to use a stepdown transformer and an A.T.S.? 


What is the voltage at the generator?


Is the single phase voltage 240 volts?

:blink::blink::blink:


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## JohnR (Apr 12, 2010)

Provided you set it up correctly with a transfer switch and all,

yes it sounds like _it would work_ *but* the 3 ph panel would only have power on 2 ph normally, so when the genny started all your loads would only be on those 2 ph anyway. In a 42 ckt pnl you only are getting 28 usable breakers. 

besides that last I checked , a 3ph panel was 3-4 times more expensive to boot. besides the bolt-in breakers are way more than stabbers too. .................. how much KW are we talking here anyway?


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## AFOREMA1 (Nov 23, 2009)

What is the issue here? if you have single phase power source and want to power a 3 phase device all you need to do is by a phase converter and install but they are pricey.


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## frenchelectrican (Mar 15, 2007)

GerryL said:


> Went to job today where the customer has bought a second hand 3 phase auto start emergency generator but only has single phase supply to the site, he wants me to connect the existing supply to the gen and at a switch on the gen that would normally be for 3 phases, connect the single phase and link to the other 2 positions thereby simulating 3 Phase, then on the other side of the switch run a 3 phase cable to a 3 phase DB which would be the default operation, until the supply failed and then the gen would auto start and supply an actual 3 phase supply to said DB.
> 
> I have never had this situation before would it be legit to have a single phase feeding a 3 phase DB?
> 
> ...


 Very simple here.,,

All it depending on the windings if you have 12 leads genny then yeah it can be convertable to single phase otherwise it may be little tough but it depending on the conenctions. you have to watch the Kva rating on single phase supply I know most genneys do have reduced rating on single phase side.

Check with your nameplate on the genny to see if that can be done.

Merci,Marc


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