[RE-wrenches] Grid-Connect Inverter with battery, AND auto backoff?

Christopher Freitas cfreitas at outbackpower.com
Wed Jun 24 12:22:16 PDT 2009


All of the OutBack inverters have a programmable mode for the AUX OUTPUT
which will turn off AC loads when the inverter reaches its AC output
current limit or if it gets too hot (i.e. is overloaded).  This mode is
called "DIVERT-AC" and is in addition to a "DIVERT-DC" mode which is
similar except the DC mode does not consider the AC output current level
or over-temperature of the inverter.  

The DIVERT-AC system was developed based on a problem Bob-O had many
years ago - he was using the AUX OUTPUT to control an electric water
heater as a dump load for his hydro system.  When he ran the clothes or
maybe dish washing machine with hot water the combination of the water
heater's electric elements and the start surge of the washer was over
loading the inverter.  Once we added this mode his problem was solved
(or at least he never said anything any more...)  

To use the DIVERT-AC system - set the "DIVERSION ON SETPOINT" at a
relatively low battery cutout level - then the load will operate nearly
all the time (except when the battery voltage gets low or when a large
load is placed on the battery system).   I just checked on a system here
and lowest I could set it at was 24.0 VDC (on a 24V system of course).
This might be a little high but is probably acceptable.  

There is a second setting called "DIVERSION OFF DELAY" which can be set
up to 255 seconds which is how long the load is kept off once it is
turned off.  I would think a long time period would be best for this
setting.  

If you have a large system like a quad stack - then you can use each
inverter's AUX OUTPUT to control a different set of loads.  By
staggering the DC voltage setting and the time delay the load shedding
system can be staggered slightly to improve operation and reduce
cycling.  

As was also mentioned - the generator start system can also be used to
help with heavy load conditions - in conjunction with the load shedding
system - I always advise using the FNDC with doing a generator start
system and using the built in AUX relay that is included with the FNDC
for the generator start system control.  

Christopher

Christopher Freitas
Director of Research and Development 
OutBack Power Systems, Inc.
cfreitas at outbackpower.com
Tel 360 435 6030
Cell 360 202 4239
19009 62nd Ave NE 
Arlington WA 98223 USA
www.outbackpower.com

-----Original Message-----

BTW, Outback inverters also have a loadshed relay  
control function built in.

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