Trace PS2512 drop out problems [RE-wrenches]
Christopher Freitas --- OutBack Power
cfreitas at outbackpower.com
Tue Dec 16 15:25:18 PST 2003
The issue here, I believe, is how an inverter/charger detects a line
disturbance that causes the AC to not completely be gone (as when
throwing a breaker switch) but is 1/3 off - such as the grid dropping to
80 vac or so... Many "older" inverter/chargers watch the RMS voltage
(i.e. the average of a whole cycle of AC power) which can make them too
slow in responding to some situations. Unfortunately, the typical spec
provided for the UPS/AC transfer time does not include the detection
time for these situations.
Real UPS systems (and some brands of newer sinewave inverter/charger
systems) use much faster methods to detect an AC disturbance - such as
comparing the actual grid voltage to a syncronized digitized sinewave
and dropping the grid instantly if a significant difference occurs
between the real grid and the reference waveform. This allows detection
of subcycle AC voltage disturbances - with detection AND transfer times
of 2 milliseconds or less.
If you could supply the customer with my email address - I would
consider using this as a good test case for comparing the performance of
our new 12 volt VFX2812 units.
Christopher Freitas
OutBack Power Systems, Inc.
cfreitas @ outbackpower.com
www.outbackpower.com
Arlington WA USA
Tel 360 435 6030
Richard Perez wrote:
>
> Hello Wrenches
>
> Quoted below is a problem that an Home Power reader is having with
> his Trace PS2512. I am at a loss as to how to help him. Perhaps one
> of you Wrenches have solved this problem.
>
> Richard
> Home Power
>
> At 12:10 -0700 12/16/2003, Jim wrote:
> >We've been fighting with a problem involving a Trace PS2512
> >inverter. I thought perhaps you might offer some insight into what
> >is causing the problem and what (if anything) we can do about it.
> >
> >Our Moab, UT office experiences power interruptions lasting anywhere
> >from under a second to several hours. While relatively infrequent,
> >they can be quite costly to our programming effort. So, using my
> >experience at Ray Mesa Power & Light, we built a grid-tied
> >uninterruptible power supply for our software development
> >environment. Currently, the system relies entirely on the grid for
> >charging -- although we anticipate adding solar to it next year.
> >
> >The system (dubbed "MOAB", Mother Of All Backups -- see attached
> >photo) consists of a Trace PS2512 and about 675 AH in a 12v battery.
> >It's sourced from a single 30 amp circuit breaker thru the inverter
> >and back to a secondary breaker panel with two smaller circuits: one
> >for our server room and one for the programming office. We calculate
> >the system will carry us for about 8 hours under worst case
> >conditions. All in all, it works as intended. When we pull the 30
> >amp breaker, the inverter kicks in with no visible interruption --
> >not even a screen flicker. Cut-over is seamless and never fails;
> >we've never had a computer go down in this situation.
> >
> >On the other hand, we have had several instances in which the office
> >fluorescent lights barely flicker, the inverter kicks in and 10 out
> >of 12 computers in the programming office instantly go dead. The two
> >computers that seem to ride through (both Macs) are always the same
> >two. Other nearly identical Macs on the same circuit leg as well as
> >all PC's always go down.
> >
> >We have called Xantrex tech support and although they admit to
> >having had the problem reported, they are unable to offer either an
> >explanation or a solution. They claim that there is no firmware
> >upgrade available (the unit is 18 months old) and don't know what to
> >suggest. I hinted that maybe they could furnish some means for us to
> >perform line monitoring to see what was actually triggering the
> >problem -- they didn't bite. We had already tightened up the grid
> >voltage limits in the hopes of catching the outage as early as
> >possible -- no help. Xantrex suggested since tightening the grid
> >voltage limits doesn't seem to work, maybe we should try widening
> >the limits. Since there's nothing to lose, we'll probably try it but
> >I'm hardly optimistic.
> >
> >We have discussed adding small consumer grade UPS's throughout the
> >office to provide short term ride-through but this defeats the
> >intent of our original $3000 investment. It just seems illogical to
> >us that the inverter is able to cut-over without so much as a
> >flicker when power is cut entirely but can't seem to handle short
> >blips.
> >
> >Have you heard of this problem? Do you have any idea what causes it
> >and if so, any suggestions for dealing with it?
Christopher Freitas
OutBack Power Systems, Inc.
cfreitas @ outbackpower.com
www.outbackpower.com
Arlington WA USA
Tel 360 435 6030
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