[RE-wrenches] Conext xw+ 6848 inverter 1.5 minute voltage increase

[Drake]

This problem might be due to a neutral connection 
problem in the electrical system. Loose neutral 
connections can put 120 V loads in series.  It 
puts loads on both line 1 an line 2 in series for 
240 V. The high resistance load (the one with the low draw) gets high voltage.


At 06:23 PM 8/11/2018, you wrote:
>I am placing this inquiry out to see if anyone 
>else has experienced a similar experience. An 
>electrician friend near Taos, NM, installed a 
>Conext XW+ 6648 inverter on a large 2nd seasonal 
>(remote stand alone PV supplied) vacation home, 
>(used less than 10 weeks per year), it has a 
>large 48 VDC AGM battery (40+kW-Hr) and almost a 
>7.0 kW PV Array and a back-up LP gen-set. It has 
>a Xantrex accessories : Com-Box, charge 
>controllers, bat monitor, etc. The anomaly this 
>system exhibits is that - when the owners are 
>infrequently present - during each evening, for 
>about 90 seconds -  the 120vac lights get 
>noticebly brighter. After this brief event, the 
>lights exhibit normal behavior. No lights or 
>appliances are functionally damaged. It is more 
>of a nuisance than an actual problem. This 
>usually happens between 9:30 and midnight. The 
>timing seems to be arbitrary - as no known load 
>either turns on or turns off in conjunction with 
>this event. Xantrex has been consulted and the 
>inverters firm ware has been upgraded and they 
>even sent a replacement inverter control board, 
>which after its replacement nothing changed. As 
>this is quite late at night and has been 
>happening both in winter and in summer months, 
>it is not presently believed to be associated 
>with the PV modules or charge controller. 
>Conventional wisdom implies, that if there is 
>some significant load was cycling in the 
>background - the lights would dim - not 
>brighten. I have never heard of anything like 
>this and was wondering- if any had. There are no 
>known large capacitive loads on the system. Any 
>one seen anything similar, I was asked - as I 
>have been doing systems in New Mexico since 1995 
>and I guessed it was a well/ water pressure 
>bladder tank system related issue  . . .  but 
>the installer has witnessed this, at night when 
>the water pump and well remained off.   ? Item 
>2) some weeks ago, it was noted on this 
>RE-Wrenches thread that some ballast blocks, 
>4” x  8” x 16” were starting to suffer 
>decomposition and a solution was sought, I 
>guessed that this might be due to water seepage 
>and repeated freezing and thawing. Has anyone 
>used an inexpensive masonry sealer painted on 
>the blocks, to stop water wicking to the 
>concrete ballast blocks? There is very thick 
>cinder block paint (UGL) for cinder block 
>foundations that would be quite expensive and 
>polyurethane is very pricey too - I would like 
>to recommend that works successfully and is 
>economical for existing installations rather 
>than replacing hundreds of blocks? Thanks, 
>Daniel O. Duffield NABCEP Certified PV 
>Installation Professional (2005) NM licensed 
>Commercial Electrical Contractor EE98/ER01 IEEE 
>member 23 years 
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