On 10/18/2010 9:53 PM, Matt Lafferty wrote:
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?
You mean, a difference between the two when UL, ETL, CSA comes by for
their pop inspection ??
Off hand, I don't see why one inverter would be given any different
kind of attention than the other
type. The UL/ETL followup inspections are basically to make sure you
are following the proper
manufacturing and testing processes such as, software version,
verification that you are using
UL recognized sources of parts and materials, hi-potting at the correct
voltages, etc.
They are both grid-tie inverters so the testing processes are very similar.
I'm sure that Dan will pick up on anything important that I forgot.
boB
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:* [email protected]
[mailto:[email protected]] *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 /<[email protected]>/* wrote:
From: boB Gudgel <[email protected]>
Subject: Re: [RE-wrenches] Inverter 1741 Listing Process
To: [email protected], "RE-wrenches"
<[email protected]>
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
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