Author Topic: 110 or 220 on an ST-5? Need some basic information.  (Read 12113 times)

sailawayrb

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Re: 110 or 220 on an ST-5? Need some basic information.
« Reply #15 on: May 25, 2008, 09:45:19 AM »
     
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So, a 3KW gen, can give 1.5 KW per winding in 240v config, (3KW total)
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Yes, exactly so.

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but if you swap leads around to make 120V, you can get 3KW per winding, for a total of 6KW ??? ???
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No way!  You can only get 3KW total.  However, you can feed a given 120V branch circuit the full 3KW and not be limited to 1.5KW.  So if you think you will ever need more that 1.5KW at 120V for a given branch circuit (eg., to power a microwave oven, hair dryer, etc.), then wire for 120V.

IMO, the only reason to ever wire for 240V is if you actually need to power something that REQUIRES 240V.  Even then, I think I would still wire for 120V and use a step up transfomer to get 240V.  As others have stated, wiring for 120V avoids all the load unbalance issues.
« Last Edit: May 25, 2008, 10:50:04 AM by sailawayrb »

mike90045

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Re: 110 or 220 on an ST-5? Need some basic information.
« Reply #16 on: May 25, 2008, 09:56:14 PM »
OK, I've got George's CD, but I have not found the ST head wiring section. Help me understand how the 120/240 wire happens.

 My original thought was each 120V winding, was out of phase with the other one, and you could use off either phase till you reached max load per phase.  This is what load balancing is about.  If you have 1 high current device that only comes on once in a while, you have to have it on it's own winding, and throw everything else onto the other winding. This leaves one winding carrying half the load, nearly all the time, and the other winding idles 90% of the time.

I also thought if wired for 240, both windings would be in use, out of phase, and a 240:120 step down transformer could be used to supply loads as needed, and 240 would be avaib all the time.  This would split the entire load, evenly over all the windings, and the transformer (easily replaceable if fried) would both equalize loads for 120, and the mass of iron and copper would "even up" the waveform to something closer to pure sine.

mobile_bob

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Re: 110 or 220 on an ST-5? Need some basic information.
« Reply #17 on: May 26, 2008, 12:19:01 AM »
for what its worth

both windings are in phase with one another

you have 4 poles on the rotor and
you have 2 poles on the stator in series to provide 120
and another 2 poles 90 degree's (or between the first two poles) that provide the other 120

together they can be parallel connected for high amp 120, or connect them both in series for lower amp 240volt.

because both poles of the stator have corresponding poles on the rotor at the same time they are in phase with one another.

a 240 to 120 transformer will work just fine if you wanna connect the st stator in series and run it as 240 all the time.

if you have one go ahead and connect it up and go for it.

if you dig on the cd, there should be a section on the st heads, their connections, brgs, rectifiers, issues and fixes etc.

bob g

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lowspeedlife

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Re: 110 or 220 on an ST-5? Need some basic information.
« Reply #18 on: May 26, 2008, 05:57:08 PM »
Mike, you are right & wrong in your thinking about the 120volt legs. if you wire for 240 volt you get 2 legs of 120volt at 1.5 kw each.  if you wire for 120 volt only you get 1 leg, & only 1 leg, of 120 volt at 3 kw.  I believe that this info is in the generator section of the forum .

Reno, the savings on wire costs are misleading, if you are supplying 120volt you will need three conductors of a larger size as the total amperage is larger. if you wire for 240 volts you can use smaller wire because the amperage will be half of the 120v, but that lower cost will be mostly offset because you will need a fourth conductor.

And in Residential power both legs are "in phase". Residential power is derived from Three phase power by taking one leg of the three phase power & running it thru a transformer that is center tap grounded giving you the two legs of 120 volts, but because it is derived from one leg of the three phase supplied by the power company it is in phase with itself & called "single phase".
 I hope that is clear enough, i've had trouble explaining it to electricians, with years of experiance, in person.
                                 Scott R.
Scott R.

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