Need help with a system built on UPS es.

[3Phase]

I have been given several pieces of hardware and would like some technical advice before I build it into a system.

1. A (I think unisys) 48 volt 4000 watt ups. With dead sealed lead acid batteries.

It was being used a backup for a bank main frame.

2. 4 minuteman 650 pro ups. 12 volt 400 watts each, likely modified sine wave.

They were being used for bank telephone system backups.

I was hoping to use the unisys as my primary ac source, but I don't know if it is square, modified, or full sine.  It is very heavy (two persons to lift) without the sealed lead acid in side. I think that the large transformer may have something to do with the weight. :>)

The minuteman ups es I am hoping to take out of there cases and install them all in one empty computer tower case. The reason for this is 3 of the 4 cases were damaged or modified before I got them, but all ups still work. This will also help to save space and simplify external wiring. I do not intend to combine the outputs or to get crazy with wiring. Only real combining is they will all run off of the same battery bank.

My question is will it cause problems to have all 4 of the transformers in such close proximity to each other, as the ac produced in one will likely be out of Phase with the others. Can cross induction Happen?

I also have 3 transformers salvaged from old dead battery chargers. All three transformers are identical number and all.  How can I rewind the primary or secondary to use these as a three-phase transformer to charge the 12-volt battery bank from a 48 volt 3 phase wind genny (also used to charge the 48 volt battery bank for the unisys system)?

My thoughts so far are to supply one transformer with line voltage on the secondary and check output voltage on the primary to get a ratio of the windings. Next unwind the secondary carefully counting the windings. Apply the ratio to the counted secondary windings to calculate the count of the primary windings. Rewinding the secondary with the appropriate count of windings and wire size to step the 48 volt 3 Phase down to 12-volt 3 Phase, rectify, and hopefully charge the 12-volt battery bank.  Maybe.

I do not know how to wire the three transformers to a 3-phase source for transforming.  Can some one please explain it to me?

For the 48-volt battery bank I will simply rectify to charge the batteries, Possibly with a shunt regulator on the system as well.

Are there huge holes in this idea?  Any help can be useful, as my system is not yet built. Nor is the wind genny built.  I know nothing about charge controllers. Is a controller (or two) something I might need for this proposed system? Now is the time for advice before I make expensive and stupid mistakes that can be avoided with help.

Thanks 3Phase ( don't really know all the much about 3 phase) :<(  

[ghurd]

It may be easier to think about 3 phase as 3 seperate systems.

Like imagine you have 3 seperate 48V AC wind gennys. Work on each one individually.

Keep them balanced, so what you do to one, do to all.

Rewinding a large transformer is a bugger. Efficiency, and other things, would make ME just buy the transformers. Your rewind math seems OK, but there are a couple other things to consider... resistance, V RMS to rectified V DC, reactance, etc.

For just starting out, I would use the UPS to a 120Vin 12V battery charger. Not very efficient, but it would work. It also keep you from worrying about too many details until after the basic system is up and running. The details can get overwhelming.

G-

[ThomasK]

Hello 3Phase,

look to

http://www.qsl.net/dg5sga/inverter.htm

there you will find info on constructing a inverter and also info on building the needed transformer.

This might be helpful for your thing.

Thomas

[3Phase]

Hay Thomas,

thanks for the link. It has some good Math for use in calculation of the transformer windings. Time will tell if I can Handel that kind of math.

Hay ghurd

The three transformers that I intend to use are not really that big. They have a plastic sleave that the coils are wound around that can slide of the core. I think this will make the rewinding alot simpler. I still do not understand the connection between the 3 leads coming from my Hypothetical 3-phase genny and the six leads coming from the secondary side of my transformer group.  Do I wire the transformers into a delta or star configuration to match what I use on the stator of the genny, and the same thing on the out put side of the transformers? This is where I am not sure at all.

Dose anyone have any thoughts as to weather I may have probulems with trying to keep those 4 semi-seprate ups es in one case (refer to inital posting)?

ghurd and Thomask

Thanks for your comments and help.

3Phase

[ghurd]

Sorry. That real world 'flux stuff' is about half of why I read this.

Until somebody says something better, and that shouldn't be long, I'll guess that the comercial transformer core will control and mostly contain the flux in each one.

Seems like if you double the distance between them the strength goes down to 25%?

And I wouldn't 'stack' them, like don't line up the cores with each other. (I think thats how they build particial acceleraters! LOL.)

Maybe give it a couple days. If you don't get another answer, maybe try a post about multiple out of phase transformers interfering with each other?