[RE-wrenches] Backup System Blues

[Ray Walters]

Hi All;

I'm in the process of finishing a grid tie with battery backup system, 
and besides the many pitfalls of this type of work, I destroyed a Tripp 
lite surge suppressor when I turned on the system.
The system has a pair of the new Outback VFXR 3524 inverters wired in 
120/240 series config. with Mate 3.
I measured before and after, and the output was a steady 120vac (240 
between them), frequency was 59.99 to 60.00 Hz.
I also measured THD at about 2.5%, which is much better than the grid 
here ( about 5%)
The system was in off grid mode, running several lights and other loads, 
when I switched on the breaker to the office.  Immediately the slave 
inverter shut down with an AC short circuit error.
Upon examining the computer equipment, I was greeted with the classic 
"smoke let out of the box" scent, and traced it to the Tripplite surge 
suppressor.  This morning, I opened it up to examine, and one set of 
capacitors had blown.  The Triplite (which I'm not that familiar) has 
several outlets each with an inductive coil and cap, each is labeled 
with a higher level of protection.
The one that blew was labeled 120 dB ( or max) protection.
So the question is:  Did this just blow randomly, or is there something 
with the Outback power output that isn't right?
I don't have an Oscilloscope, but I could better isolate the various 
harmonic Distortion to its separate components to see if maybe there is 
a harmonic spike somewhere the Tripplite didn't like?
I didn't notice what was plugged into that outlet, but I will check 
today.  The actual equipment is just the usual home collection of ink 
jet printers, and lap tops.  The Tripp lite however looks pretty high 
end ( and old) and was immediately my suspect, as soon as I looked under 
the desk.  The model is Tripp Lite Isobar Ultra 8, and is apparently 
still available.
https://www.tripplite.com/isobar-8-outlet-surge-protector-12-ft-cord-3840-joules~ISOBAR8ULTRA/
This is venturing outside my normal area of expertise and into the Murky 
world of what's actually inside those electronic gizmos.

As always, thanks in advance for all your sage advice,

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