Jeff,
The TWACs signal is a nasty beast. It is low frequency and thus very
hard to filter. It seems to cause problems with a large variety of devices.
Unless someone has taken the time to check, how do they know if the
other inverters aren't offline for 5 of every 15 minutes?
I think the time sync signal may be broadcast from the substation only
with no reply from the individual meters. The problems I've seen have
always been when the local meter is sending data; that only takes a few
seconds but it takes the inverter offline for five minutes. So if you
are seeing problems with the time sync signal, I'd guess that the
installation must be close to the substation where the signal originates.
Kent Osterberg
Blue Mountain Solar, Inc.
www.bluemountainsolar.com
t: 541-568-4882
On 10/9/2012 9:20 AM, Jeff Wongstrom wrote:
Kent,
I just talked with Mike in the meter department. The utility does
indeed use Aclara TWACs AMR. The meter reading signal can vary but is
usually done at midnight or it could be set to every 8 hours, 1 hour,
etc. However, a time sync signal is sent every 15 minutes. This
correlates with the problem inverter going into state 104's at various
times after connecting to the grid observed from 1-11 minutes.
Unfortunately I was informed that the time sync signal can not be
changed.
Mike told me that there are two or three other Fronius inverters on
their system without problems, he did not know if they are IG or IG+.
Jeff
Jeff Wongstrom
NABCEP Certified
406.291.3416
thirstylakesolar.com <http://www.thirstylakesolar.com>
On Oct 8, 2012, at 7:38 PM, Kent Osterberg wrote:
Jeff,
Is there any chance the utility has recently implemented a remote
meter reading system? The Aclara TWACs
<http://www.aclaratech.com/AclaraPLS/specsheets/TWACS_UMT-R.pdf>
remote meter reading system communicates by putting a pulse on the
line that is very near the zero crossing of the voltage waveform.
Unfortunately the zero crossing is easily and often used as a
reference point for frequency measurements. Devices that watch the
zero crossings are often confused by the TWACS signal. The signal
isn't there constantly -- only when the local kWr meter has been
asked to send data.
Kent Osterberg
Blue Mountain Solar, Inc.
www.bluemountainsolar.com
t: 541-568-4882
On 10/8/2012 9:34 AM, Jeff Wongstrom wrote:
Hello wrenches,
We have a Fronius IG3000 that chronically and frequently cycles into
and out of a state 104(grid frequency not within admissible range).
The utility has monitored the supply and claims to have found no
frequency or supply issues. Fronius sent a replacement inverter
but the error persists. The tie in point was moved from the critical
loads sub panel to the main distribution panel. The state 104
persists with ALL other breakers open. A Fluke DMM min/max function
captures no frequency readings outside of the inverter frequency
window-same with voltage readings.
Any suggestions or recommendations?
Thanks,
Jeff
<Mail Attachment.jpeg>
Jeff Wongstrom
NABCEP Certified
406.291.3416
thirstylakesolar.com <http://www.thirstylakesolar.com/>
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