[RE-wrenches] UPS disturbance with SMA Inverters

[Jerry Shafer]

It would be good to put a volt meter at the input to the UPS confirm input
voltage is within range at the time there is an issue. If volts are high
there is a problem between that location and as far as the transformer. A
scope would help to see noise on the AC side but an old AM radio may do the
same to detect noise on the line.
On Aug 4, 2014 1:30 PM, "Chris Mason" <cometenergysystems at gmail.com> wrote:

> Is it possible that the UPS issue is raised voltage, causing the UPS
> voltage regulator to switch settings? A large amount of solar on a circuit
> can raise the voltage in the system at full sun. I would rent a Fluke
> Energy Analyzer and leave it in place for a number of days to see how the
> voltage, current and power factor varies with the inverter output.
>
>
> On Mon, Aug 4, 2014 at 5:11 PM, Carl Adams <swingjunkie at gmail.com> wrote:
>
>> 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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>>
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>
>
> --
> Chris Mason
> NABCEP Certified Solar PV Installer™
> Solar Design Engineer
> Generac Generators Industrial technician
>
> www.cometsolar.com <http://www.cometenergysystems.com>
> 264.235.5670
> 869.662.5670
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>
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