DC contactor [RE-wrenches]

[William Miller]

Kurt:

The Trace SW4000 series can take as much as 60 amps on AC1 and AC2 inputs.
In the LBX mode, when the battery array voltage gets low enough to
transfer, the AC input will need to power any loads and any extra (up to 35
amps) will be used for battery charging.

One can program the SW inverter to require less current from the AC inputs,
all the way down to 1 amp in 1 amp increments.  Theoretically, one can put
a 30 amp breaker in front of the AC1 or AC2 inputs, program that input for
30 amps and use a 30 amp contactor to switch that input.  The problem I see
is that if the inverter were ever to lose its programming and reset to
default values, the AC1 input could draw 60 amps and the AC2 could draw 33
amps (the book says 30 but it's really 33).  The 30 amp breaker will open
and protect the contactor, but you will have a client without grid power to
their system with the possibility of a power outage and damage to the
batteries.

I have had inverters reset to default mysteriously and I've always wondered
if the client has been experimenting.  Because of the potential for the
inverter to reset to default values, I try to never limit the power input
to an on-grid inverter.  I suggest you find a 60 amp contactor if you can.

By the way I find this idea of switching AC inputs off intriguing.  I'm
trying to see if this might be good for my few LBX mode clients.  I have
come to the conclusion that for maximum use of PV resources, line tie is
the way to go.  It eliminates battery cycling and if set up properly, the
PV panels can work close to full efficiency all the time (especially with
maximum power point tracking).

I know this is complicated but there are these ramifications.  I hope this
explanation makes sense.



At 07:19 PM 10/14/00 -0700, you wrote:
>R. Sparks Scott wrote:
>> 
>>         Kurt;
>> 
>>         Do you want/need the full 60 amp pass through on the Trace? 
>
>Hey Sharkey,
>
>Thanks for all the extra input on the Trace Effeciency Improvement issue
>(TEI).  I personally have a number of systems that need improvements in
>their solar to grid ratio, and on a broader scale if we could all add a
>hundred bucks worth of equipment that would increase efficiency by 20 to
>60 percent??? lets work on it.  
>
>In regards to the 60 amp rating on the relay/contactor, I was (still am)
>trying to remember what the amperage rating was on the pass through
>transfer switch in the Trace.   I may be wrong on that rating, but if
>not I know the code guys are gonna want to see any current switching
>device rated at or above highest possible values.  If the inverter was
>set into the LBX mode, and the inverter transfers over to power loads
>with the grid, can't it draw 60 amps? 
>
>If what I am saying is true, would it be possible to use a 30 amp power
>relay if AC1 was tied into the utility with a 30 amp breaker?  I have
>always used a 60 amp breaker and # 6 wire to maximize pass through and
>make code.
>
>Thanks for your thoughts.
>
>Kurt
>
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William Miller
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For info contact list moderator by email:
 michael.welch at homepower.com
___________________________________________________________
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