[RE-wrenches] UPS disturbance with SMA Inverters

[Glenn Burt]

I would look up the specs on the UPS and see if it has a buck feature. Then see if you can identify what this voltage level is.

>From there you can use a dmm to check voltage at the input to the UPS with the inverters off, then on a high output day to see if this is an issue.

Good luck!

Glenn  

-----Original Message-----
From: "Carl Adams" <swingjunkie at gmail.com>
Sent: ‎8/‎4/‎2014 17:11
To: "RE-wrenches" <re-wrenches at lists.re-wrenches.org>
Subject: Re: [RE-wrenches] UPS disturbance with SMA Inverters

Bob, Ray, Glenn,

Thanks for the responses.  We could cycle through the inverters and see if
it is one, or some combinations of inverters, which is causing the problem.
 This results in a minimum of 6 trials.  If it is a combination of
inverters  many more.

Any feedback on the idea of monitoring the AC circuits; computer feed and
combined inverter output?  Seems to me this might provide a one step
correlation between the event and the cause.  Just not sure what equipment
to suggest for this.

Could be there is some other cause, unrelated to the inverters.  AC unit
kicking on, etc.  Though they do not see any lights dimiming/brightening,
or any other notable change in electrical equipment at the sight.



On Mon, Aug 4, 2014 at 1:03 PM, Glenn Burt <glenn.burt at glbcc.com> wrote:

>  I wonder if the UPS is grumbling about high voltage as the inverters
> push back current...
>
> Glenn
>  ------------------------------
> From: Carl Adams <swingjunkie at gmail.com>
> Sent: ‎8/‎4/‎2014 10:29
> To: RE-wrenches <re-wrenches at lists.re-wrenches.org>
> Subject: [RE-wrenches] UPS disturbance with SMA Inverters
>
> Hello Wrenches,
>
> I have a site which is experiencing nuisance disturbance of the computer
> UPS systems at the site.  The site owner "suspects" this is due to the PV
> system which is a 50 kW system using 6 SMA SunnyBoy inverters.  The
> nuisance disturbance is a clicking noise in the UPS units.  The disturbance
> is not enough to cause the UPS to engage, so it seems to be a small
> disturbance on the AC power.   The site owner "suspects" the inverters are
> the source of this disturbance since 1) It seems to only occur when we have
> a good solar day.  2) If the inverters are shut down the problem goes away,
> and if you start up the inverters the problem exhibits again.
>
> The site was commissioned in March of 2012 and has had no problems till
> this issue last month.  In reviewing the event log on Sunny Portal there
> are no inverter anomalies.  SMA tech support had not run into this issue
> and had no ideas, they too agree the inverters are not reporting any
> anomalies.
>
> The problem is not persistent but rather intermittent making this harder
> to troubleshoot.
>
> So my questions are
> 1) Has anyone else seen this sort of issue before, related to SMA SunnyBoy
> inverters.
> 2) Can you recommend an AC power monitoring tool which would support
>  frequency and voltage monitoring on the AC line.  Perhaps one data set on
> the circuit feeding the computers and another on the inverter output
> circuit.
>
> For clarity the six SunnyBoys feed into an AC Combiner panel which
> backfeeds into the building main distribution panel.  The service is 240V
> single phase.
>
> With Regards
> Carl Adams, SunRock Solar
> NABCEP Certified PV Installer
>
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