SQ D HU 362 A Ratings? [RE-wrenches]

[William Miller]

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Mark:

The SMA white paper is on my web site:

http://mpandc.com/resources/resources.html

You can hook as many strings as you want to a single pole of a disconnect 
as long as the result complies with the code section 690-9 (A) Exception b.

On a related subject, I attended a day-long training session hosted by 
Fronius.  I like and use their inverters.  I do disagree with the notion 
that the built-in DC and AC disconnect switches obviate the need for 
external switches.  Fronius spent an inordinate amount of time justifying 
the notion that all you need to do to remove an inverter is to cover the 
modules feeding the inverter.

The last time I used Fronius inverters we installed 6 4500 watt units.  To 
render one of the units safe to remove, one would have to set up a 24 foot 
ladder, figure out which 30 of 180 modules needed to be covered and then 
produce an opaque tarp measuring 30 feet by 30 feet to cover those 
modules.  I say this is ridiculous.  The inverters we install all have 
external AC and DC disconnects.

William Miller





At 07:51 AM 10/11/2006, you wrote:

>During my time in solar, I have consistently seen the HU used to
>disconnect multiple strings leading to a single inverter.  The bulletin
>uses the term string and inverter interchangeable.  However, strictly
>speaking, Diagram 2 does not show multiple strings.
>
>As far as the backfeed current, I am pretty sure that any UL1714 listed
>inverter will not backfeed DC current during a fault.
>
>There is a white paper from SMA that talks about the need for fusing on
>multiple string inverters, but their site has been re-built and I can't
>yet find the document.
>
>I personally use a UL 1714 inverter (not the one starting with an X)that
>has an integrated DC disconnect and use a fused combiner box whenever I
>have more than two strings.
>
>Clear as mud as usual.
>
>
>
>
>


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