William - You're correct, I was confused - thanks for setting me straight!
Regards, Gary
On 3/1/13 1:05 PM, William Miller wrote:
Gary:
I think you are a little confused about the operating modes of the XW
inverter:
In the AC Passthru mode, no battery charging occurs. Below is the
passage from the manual that describes this:
/The AC connected to the AC1 or AC2 input is passing directly through
the Xantrex XW
Series Inverter/Charger to the loads. The batteries are not being
charged in this state.
/In the normal transfer mode, battery charging does occur. It is my
clear understanding that the Xantrex SW and XW inverters and the
Outback FX and Radian inverters will regulate battery charging so that
the charger circuit uses only excess amperage available. For
example: If the input breaker size is programmed for 60 amps and
there is 60 amps of load, 0 amps of AC will be used for battery
charging. If the load decreases to 50 amps, 10 amps of AC will be
used for battery charging, etc.. Therefore, the OCPD does _not_ need
to be sized to accommodate both uses of input AC.
Below is a passage from the XW Operating Manual that describes this:
/In addition, the battery charger can reduce its charging current to
the batteries
so the combined charge AC current and total load current does not
exceed the
capacity of the generator or trip its output breakers or fuses.
/Extending this discussion beyond the current topic (pun intended), we
need to understand what happens if the connected loads exceed the
input breaker rating. Here the game changes. The FX inverter can not
prevent the overload from passing to the input breaker, possibly
tripping it. The SW, XW and Radian inverters can provide "Generator
Support." Do not confuse Generator Support with Generator Remote
start functions. Generator Support allows the inverter to sync to,
and assist the AC input source in powering loads. To use the example
above: If the load rises to 70 amps, the inverter draws energy from
the batteries to provide the last 10 amps.
Below is the passage from the XW manual that describes this:
/AC2 Breaker: Sets the AC2 (Gen) breaker size, based on the size of
the installed AC breaker. The
breaker size must not exceed the capacity of the generator. The
Xantrex XW Series
Inverter/Charger limits the maximum input current to this setting by
derating its charging
current to an equivalent of 80% of the AC breaker size. If the
connected loads exceed the
AC2 breaker setting, the AC breaker trips. The breaker may not trip if
Gen Support is
enabled and Gen Amps is configured not to exceed the generator's rated
output current.
/I hope this information is relevant, correct and helpful.
Sincerely,
William Miller
At 08:24 AM 3/1/2013, you wrote:
Larry:
In the case of the Xantrex XW Series, while in the "AC Pass-Thru"
Mode, the internal transfer switch relay connects the protected loads
directly to the AC1 grid input. The XW internal battery charger is
then activated to recharge the battery bank.
The OCPD(s) through which the protected load amps and charging amps
are passing must be sized to accommodate both at the same time.
Regards,
Gary Willett
Icarus Solar
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