[RE-wrenches] Conductor Sizing for Supply Side Connection

[Gary Willett]

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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