inverter GFI regs [RE-wrenches]

[John Berdner]

Marco:
 
The original GFDI requirement was only for rooftop mounted arrays on
dwellings.
(Dwellings also includes hotels by the way).
 
About a year or so ago there was a ground fault in a commercial system
which resulted in an arcing fault inside a metal conduit.
The fault burned though the conduit and this brought light on a
potential problem, i.e. potentially large ground fault currents flowing
in unintentional ground conductors (like conduits, support structure,
etc.)
The GFDI requirement for all inverters was added to interrupt the fault
current in unintentional conductors. 
The addition of a GFDI circuit is a very straight forward design
effort.
I suspect that many of the other changes in May 7, 2007 version of UL
1741 (IEEE 1547, more comprehensive temperature testing, more
anti-islanding testing, etc.) were responsible for the decision to
discontinue a specific model.
The new requirements roughly doubled the cost of UL testing and I
suspect this simply made it uneconomic to retest lower volume and/or
older inverter models.
 
Best Regards,
 
John Berdner
 

>>> marco at pvthawaii.com 8/7/2007 10:44:33 PM >>>

It's been my understanding that all grid-tie inverters manufactured
after
May 1, 2007 must come with an integrated GFI function, whether or not
the
inverter is meant for residential or commercial applications. Some
inverter
manufacturers, in fact, elected to drop certain models rather than
bring
them up to this new standard. 

Do others have the same understanding?

thanks,
marco

Marco Mangelsdorf, Ph.D., President
Electrical Contractor License C-26351
69 Railroad Avenue, A-7
Hilo, Hawai'i 96720
(808) 969-3281, 934-7462 facsimile
www.provisiontechnologies.com 



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