[RE-wrenches] Gen set problems

[Jeff Wongstrom]

William,

I am having the same problem with a newly installed 8.5RES with a  
single VFX3648.  The problem was somewhat corrected for a auto start  
shutdown by setting the generator cool down to one minute.  This  
unloads the generator before the generator is shut down and  
eliminates the nasty relay chatter in the inverter followed by a surge 
(indicated by a flash in the lighting) . There is still however a  
'hammering' in the step down transformer.

With a MAN-OFF there there is still a chatter and surge before the  
inverter and generator say goodbye to each other.

I am planning on adding a contactor to disconnect the generator input  
with the generator start relay unless another solution exists.

I am wondering if Kohler has changed something and the two no longer  
get along?  The next time that I go to the job site I am going to  
check the shutdown of the generator with the OB system disconnected.   
I am also going to try a second backup generator.


Thirsty Lake Solar
Jeff Wongstrom
NABCEP Certified Solar Installer
University of Montana College of Technology
Renewable Energy Instructor
406-219-1119
thirstylakesolar
energytechnology

On Jun 14, 2010, at 11:31 PM, William Miller wrote:

> Wrenches:
>
> I have a customer that has a problem with a new generator.  He has  
> two VFX3648 inverters in Outback stacking.  He acquired a new  
> generator, a Kohler 12RES, a reputable make and model.  Below is a  
> description of the problem:
>
> The 12RES seems to be operating OK except for one problem.  At the  
> end of a charging cycle, when the gen automatically shuts down and  
> load goes back to the inverters, all lights, TVs, etc., flash, one  
> TV shuts off, and a GFI trips.  This has happened every time.  It  
> did not happen with the 15RES or the smaller back-up gen (which was  
> disconnected manually).  With the 15RES the same GFI would  
> occasionally trip while the unit was charging and handling house  
> load, but never at the auto shutdown point.  I replaced the GFI,  
> but it still trips.  There are three GFIs in the house, but only  
> one--always the same--trips.
>
>
> I suggested he adjust the AC2/Gen transfer delay to a lower  
> number.  He reduced it to minimum and this did not resolve the  
> problem.  I also had him verify that the AC source is selected as  
> generator, which it is.
>
> Do you have any suggestions?
>
> Thanks in advance,
>
> William Miller
>
>
> Please note new e-mail address and domain:
>
> William Miller
> Miller Solar
> Voice :805-438-5600
> email: william at millersolar.com
> http://millersolar.com
> License No. C-10-773985
>
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