[RE-wrenches] Connecting Two Grid-Battery Backup Inverters to 120/208

[Darryl Thayer]

This is solvable, first is your needs are for back up at 120-208  3 phase, or can you get by with 120 back up?  Or a William suggests 120-240 derived from 120 volt system?  The question is do you need 3 phase?  Outback using 3 inverters can produce 3 phase.  HOWEVER I have never seen two SW generate 3 phase.    


________________________________
 From: lance barker <lance.b at centurytel.net>
To: RE-wrenches <re-wrenches at lists.re-wrenches.org> 
Sent: Thursday, November 29, 2012 8:29 AM
Subject: Re: [RE-wrenches] Connecting Two Grid-Battery Backup Inverters to 120/208
 
I'm up
On Nov 28, 2012, at 8:30 PM, William Korthof wrote:

> You could use a 120:120volt, with both the first and second inverters using the same phase, but the xfmr secondary used to supply 120 volts out of phase from the primary for the slave. Voila, auto-transformer 120:240 split phase power. Downsides are the heavy loading all on one phase and neutral, and xfmr losses... 
> 
> Alternate option is to get an isolation transformer with 208 primary and 120/240 secondary. Bond the midpoint. 
> Better phase balance, but xfmr losses.
> 
> /wk
> 
> William Korthof
> 714.875.3576
> Sustainable Solutions
> #956904 
> 
> -------------------------
> From: Christopher Warfel 
> 
> We were asked to replace two failed Trace SW4048 inverters with two 
> Outback GT3048 inverters. Upon start up the slave inverter would not 
> connect.  We did not realize that the building service is 208, 3 phase. 
> The bypass is 120/240 which the SW4048s could connect to without a 
> problem. Outback says their inverters will not connect to this system 
> because of the phase angle of 120 and their software.
> 
> The phases are always going to be at this rotation, so I don't see a 
> transformer helping solve the problem, but this is something I am really 
> unfamiliar with.
> 
> So the input at the inverter panel is two 120 volt phase at 120 degrees. 
> The output to the EP is 120/240.
> 
> I am asking if anyone has an idea of how to fix this problem? 
> ------------snip---------------
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