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
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
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
I wonder if the UPS is grumbling about high voltage as the inverters push back
current...
Glenn
-Original Message-
From: Carl Adams swingjun...@gmail.com
Sent: 8/4/2014 10:29
To: RE-wrenches re-wrenches@lists.re-wrenches.org
Subject: [RE-wrenches] UPS disturbance with SMA Inverters
Wrenchers,
The Ct Utility company CLP requires the following as part of the verification
test.
Because this is a three-phase service, the witness test must also demonstrate
that the inverter shuts down upon loss of each individual phase
Any recommendations on how to do this test safely?
Al
Al,
I have witnessed this test in NC several times, but with medium voltage
connected systems, not systems connected to a building service. A medium
voltage subcontractor used a disconnect stick to open one phase at a time
at the fused cutout point of delivery to the distribution network (on the
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
Hello Carl,
The egauge may be a good monitoring unit for this application. You can
monitor 12 CT's at a time, and everything is time-stamped. The egauge is
actually its own server, so it can be monitored remotely or on a site
computer on the same network. It can give you power factor, phase
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,
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
If you using a AC disconnect shut off power to it install a jumper on two
of the legs just testing once inverter is back on line pull the switch and
see what happens. Swap jumper location and tetest, once you tesy all legs
remove jumper wires.
On Aug 4, 2014 7:43 AM, Rebekah Hren
If you are using a load center to aggregate the inverter outputs, swap the
3 pole breaker for three single poles. Hopefully you can demonstrate only
one inverter works.
If the UL listing tests and certifies for this, why do they need to do it
in the field? Next they will want you to set up a full
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