Syncing four SW inverters [RE-wrenches]

[William Miller]

<x-flowed>
Your free subscription is supported by today's sponsor:
-------------------------------------------------------------------
Shopping for a new car? 
Pay 2-3% below invoice on a new car of your choice. 
Save thousands with our free car discount finder service!
http://click.topica.com/caaemrqbz8Qcsbz9JC9a/Dealix
-------------------------------------------------------------------







Colleagues:

I have a situation where I need to synchronize four SW inverters to achieve 
120/240.  The inverters are in an existing installation and were connected 
incorrectly.  The description of how it was done is irrelevant, but the 
result was that during generator run, the two 120 outputs would stay 180 
degrees apart.  Without the generator feed, the phase would vary slowly so 
that over about 45 minutes the voltage between phases would go from 240 to 
0 and back up to 240.  Needless to say, this is not acceptable.

I had investigated this in 2000 and I seem to recall this is not easy to do 
with the SW inverters.  I will call Xantrex again, but I wondered if anyone 
here has experience with this scenario.

Having asked the question, I think I have a solution:  Is it feasible to 
feed a pair of synchronized SW inverters with another synchronized pair of 
inverters?   Think of it-- the downstream inverter pair will think the grid 
is up and will transfer.  If the loads exceed the capability of the 
downstream set, the upstream set will kick in to assist.

If it were possible that all 4 inverters could be connected in  parallel, 
the output would be 70 AAC per phase inverting.  With this scheme, we are 
limited to 60 AAC per phase.  During generator run, the output for an all 
parallel installation would be 120 AAC instead of 60 AAC with this method.

Battery charging is a little trickier.  This is an off grid setting with 
two large generators.  My first thought is to connect the upstream set to 
the generator via the AC2 input.  The output of the upstream pair is 
connected to the AC1 input of the downstream pair.  The upstream pair is 
set to FLT to charge whenever the generator is running.  The downstream 
pair is set to SLT mode.  The SLT timer can be either defeated or set to 
occur when it is known the generator will be running.

I call this idea "Cascaded inverters."  I know it's a little hard to wrap 
your head around this concept.  I do appreciate any feedback if anyone has 
ever thought of this or tried it, (or likes to think about these kinds of 
things)  A drawing of this idea can be found at: http://mpandc.com/  Click 
on Downloads, Click on "-Cascading SW Inverters."



--
[Non-text portions of this message have been removed]

Your free subscription is supported by today's sponsor:
-------------------------------------------------------------------
Jumpstart your love life at AmericanSinglesR.com.  
Meet someone in your area today. Millions of member profiles. 
Create a profile, post photos and search for free.
http://click.topica.com/caaemrrbz8Qcsbz9JC9f/Spark Network
-------------------------------------------------------------------

- - - -
To send a message: RE-wrenches at topica.com

Archive of previous messages: http://lists.topica.com/lists/RE-wrenches/read

List rules & how to change your email address: www.mrsharkey.com/wrenches/etiquette.php

Check out participant bios: www.mrsharkey.com/wrenches/

Hosted by Home Power magazine

Moderator: michael.welch at homepower.com
--^----------------------------------------------------------------
This email was sent to: michael.welch at homepower.com

EASY UNSUBSCRIBE click here: http://topica.com/u/?bz8Qcs.bz9JC9.bWljaGFl
Or send an email to: RE-wrenches-unsubscribe at topica.com

For Topica's complete suite of email marketing solutions visit:
http://www.topica.com/?p=TEXFOOTER
--^----------------------------------------------------------------



</x-flowed>