[RE-wrenches] UPS disturbance with SMA Inverters

[Ray Walters]

Is it possible that the inverters are raising line voltage high enough 
to make the UPS respond by clicking, but not high enough to have them 
actually trip?  I'm not familiar enough with UPS control structure, but 
it might run a quick test (the click) when the voltage gets close to its 
high voltage trip off.
Just a crazed monday morning idea.....

R.Ray Walters
CTO, Solarray, Inc
Nabcep Certified PV Installer,
Licensed Master Electrician
Solar Design Engineer
303 505-8760

On 8/4/2014 8:50 AM, RE Ellison wrote:
> How about disabling one inverter at a time when the disturbances are happening?
>
> That might narrow it down to it being a single inverter.
>
> Through the process of elimination you may be able to find out if it is a single inverter or a combination of inverters that makes it do it.
>
> It might be a specific inverter or it might be a specific combination of inverters
>
> I have seen APC UPS units click but not activate, in that case it was one inverter off grid and one UPS.
>
> Somewhat irritating, I put it where I couldn't hear it to make the problem go away so to speak !
>
> Later,
> Bob ellison
>
>
>
>
> Bob Ellison
>
>> On Aug 4, 2014, at 10:29 AM, Carl Adams <swingjunkie at gmail.com> wrote:
>>
>> 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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