SW-series inverters hazard? [RE-wrenches]

[Bob Maynard, Energy Outfitters]

Hi Joel and all,
We can expect a response from Xantrex on their website tomorrow.  Hopefully
this unfortunate situation can be rectified quickly.
Regards,
Bob Maynard

Joel Davidson wrote:

> Did you all see the UL notice about SW-series inverters?
> Does Xantrex have a solution to this problem?
>
> http://www.ul.com/about/newsrel/alert111601.html
>
> ALERT: PHOTOVOLTAIC INVERTERS MAY POSE HAZARD
>
> November 16, 2001 -- Underwriters Laboratories Inc. (UL) is notifying
> electric utility companies, installers and authorities having
> jurisdiction (AHJs) that Xantrex Technology or Trace Engineering
> photovoltaic inverter models SW3512, SW4024, SW4048 and SW5548 may: 1)
> support an unintentional island in the presence of a balanced load, when
> utility power is interrupted; and, 2) exceed the output current total
> harmonic distortion limit.
>
> Results of operational tests recently conducted by UL during field
> investigations revealed that SW series inverters may not cease to export
> power to the utility grid when power from the grid is interrupted in the
> presence of a balanced load. The SW series inverters may continuously
> sustain an unintentional island condition under multiple balanced test
> load conditions while exporting power at the tested 25%, 50% and 100%
> power levels.
>
> Unintentional islanding occurs when a utility interactive inverter
> energizes a portion of the utility grid system when power from the grid
> is interrupted. Unintentional islanding may create a risk of electric
> shock for utility line personnel by causing a utility line to remain
> energized when it is assumed to be disconnected from all energy sources.
> This islanding condition may also cause damage to utility equipment,
> interfering with the operation and or restoration of normal utility
> service.
>
> In addition, the SW series inverters' output current total harmonic
> distortion may exceed the 5% limit required by UL 1741, the Standard for
> Inverters, Converters and Controllers for Use in Independent Power
> Systems and IEEE929, the Recommended Practice for Utility Interface of
> Photovoltaic (PV) Systems when the inverter is exporting power onto the
> utility grid. This problem is most apparent when the SW inverters are
> connected to low impedance utility lines.
>
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