[RE-wrenches] Inverter 1741 Listing Process

[Matt Lafferty]

Thanks for the info Dan and boB.
 
What production tests required to maintain listing? Do you happen to know if
there is a different regimen for micro vs string vs central inverters? 
 
I'm working on developing a detailed commissioning procedure. Detailed yet
generic. There will be at least two versions for inverters. One for string
and one for central. In my book, central inverters have re-combiners
(standalone or integral) and string inverters don't. I'm trying to
understand which functions are tested in the factory on every unit so I can
avoid unnecessary duplication by the commissioning people.
 
Thanks in advance for any light you can shed on the subject!
 
Matt Lafferty
  _____  

From: re-wrenches-bounces at lists.re-wrenches.org
[mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Exeltech
Sent: Monday, October 11, 2010 10:04 AM
To: RE-wrenches
Subject: Re: [RE-wrenches] Inverter 1741 Listing Process


Matt,

The 5-minute delay is verified in the group of inverters sent to the test
laboratory.  Then, as long as the software and hardware don't change, it's
presumed the delay in all production units meets the value(s) measured in
the tested units.

An alteration in either hardware OR software can result in a unit being
required to completely re-test (as Bob pointed out).  NRTLs get copies of
the source code and can and do periodically compare their copy as submitted
with the original test units to the software being programmed into the
inverters during production to verify it's the same.

NRTLs conduct unannounced "field audits" by simply showing up on site and
randomly selecting various aspects of the product for verification --
including the software.

The overall UL1741 certification process is extremely complex, very time
consuming, and quite expensive.


Dan



--- On Fri, 10/8/10, boB Gudgel <boB at midnitesolar.com> wrote:




From: boB Gudgel <boB at midnitesolar.com>
Subject: Re: [RE-wrenches] Inverter 1741 Listing Process
To: gilligan06 at gmail.com, "RE-wrenches" <re-wrenches at lists.re-wrenches.org>
Date: Friday, October 8, 2010, 9:26 PM


On 10/8/2010 6:04 PM, Matt Lafferty wrote: 

Hola Wrenches,
 
Does anybody know off the top of their head if the
"5-minute-wait-to-interconnect" function is tested on 100% of inverters
produced? (i.e. every single inverter is tested with AC & DC within the
start parameters of the unit for at least 5 minutes)
 
Thanks!
 
Matt Lafferty


Good question.  I bet it's not 100% tested because if the software does not
change, then they may just not wait the extra 5 minutes in order to save
money on testing.

Or, maybe they do a random sampling for this test.

Theoretically, it shouldn't matter as long as the software does not change
and the hardware is tested enough in other ways, like, timers and clocks
etc.

BTW, Nowadays, there are two options for manufacturers of grid interactive
inverters....

And the UL spec has gotten more stringent.

One option  is that you have to have  the  code (software) blessed by the
NRTL in a separate process (another UL specification, (UL 1998 -Software in
Programmable Components")

OR, if they don't go for that option, then if software changes need to be
done to the inverter, the inverter must (technically) go through the UL1741
listing process all over again.

boB


-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org/attachments/20101018/35dc48b8/attachment-0003.html>