3 phase 240/416 military surplus 15k generator

[Sedgehammer]

Question is - Can I run 2 phase 220 - 240 on the 2 legs and just ignore the third leg?

[sawguy21]

I think you mean single phase which is most common, 2 ph is obsolete. Frequency becomes a problem, there are members here much more familiar than I.

[Sedgehammer]

Yes, correct. single phase. thanks

[mike_belben]

Yes.  Sawguy is right thats 230VAC 1PH.

You will have an "unbalanced load"  on the alternator by the unused winding.. but for whatever youre doing i bet its inconsequential. 

Look up "split phase electric power" to learn a bit more.  I am thinking your two phases will be 120* apart relative to neutral where split phase is 180* out of phase leg per leg.  


But yeah.  Two 120VAC legs of a 4wire 3ph 230VAC system will run 220v 1ph junk every single time i have ever tried it which is quite a few now.  No smokeshows yet.


Measure the leg voltages.. Beware of 277vac aka "highleg"

[Gary_C]

Not a good idea at all to use two phases of the three to substitute for single phase. I don't know exactly what it will do but you will certainly have some strange things going on. As Mike said the two phases will be 120 degrees out of phase instead of 180 degrees. So your phase to phase voltage will not be correct and meters will not measure the correct voltages because they measure RMS or root mean squared voltages which will give you different readings with two points 120 degrees out of phase. I suspect the most damage will be done to sensitive electronics. Also there is the question of is the generator delta or Y connected. What you are doing is risky so consider the cost of a failure before you decide.  

[Southside]

If it's a 12 wire alternator you should be able to change the taps to 240V single phase or, you could pick up a dry transformer and have clean voltage.

[mike_belben]

I wouldnt try it on my EKG or space shuttle comms set, but ive done it for a jetwash, a welder, heater elements, pumps, and a sunnen hone which is just an electric motor really.  

[Ed_K]

 On a 220 single phase welder cable can I hook to one leg and the neutral wires and get 110 volts without ruining a 110 volt motor?

[mike_belben]

Yes but you should also have an independant ground wire so that if the neutral is lost the conduit and motor housing doesnt become energized.

[Sedgehammer]

Not a good idea at all to use two phases of the three to substitute for single phase. I don't know exactly what it will do but you will certainly have some strange things going on. As Mike said the two phases will be 120 degrees out of phase instead of 180 degrees. So your phase to phase voltage will not be correct and meters will not measure the correct voltages because they measure RMS or root mean squared voltages which will give you different readings with two points 120 degrees out of phase. I suspect the most damage will be done to sensitive electronics. Also there is the question of is the generator delta or Y connected. What you are doing is risky so consider the cost of a failure before you decide.  

I did a bit more research and if just a motor running it wood prolly be ok, but as you said sensitive or load changing it woodn't be good. I found a vid that shows exactly how to convert it and change the instrumentation to also work.
Thanks everyone 

[mike_belben]

Glad to hear it. 

disclaimer:  i am not a licensed electrician and have just enough experience to be dangerous.  Please do not risk your life, liberty or property on anything ive said in this thread, and do consult with a pro before proceeding. 

[Sedgehammer]

Glad to hear it.

disclaimer:  i am not a licensed electrician and have just enough experience to be dangerous.  Please do not risk your life, liberty or property on anything ive said in this thread, and do consult with a pro before proceeding.