[RE-wrenches] Inverter 1741 Listing Process

[Exeltech]

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

    

    

  

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