[RE-wrenches] Put on your detective hats - what can cause this Outback and Morningstar damage?

[Ross Taylor]

Hi gang,

I was at an off-grid site today and found damaged components.  It's one of four identical sites and the configuration is proven.  But, at one of the sites, there's some neighborhood opposition to the installation and I suspect vandalism.  The opposition results from the locals' fondness for pilfering diesel fuel from the on-site generator.  With the RE installation, diesel access is way down.  Energy theft is also a problem, but I think not an issue here. The system has an Outback FX, a Morningstar TriStar TS-60 (as a diversion controller) and a suitable diversion load.  I've used the TS-60 many times and found them, and the Outback, to be about bullet proof.  So, here's what I know:

The DC buss bar to which the Outback and the TriStar are connected is protected by a 100A DC breaker mounted in the side of the Outback FlexWare cabinet.  Nothing odd there.  But the breaker is fused or locked in the open position.  The breaker toggle does not move freely.  The TriStar was visibly charred - some small components from the back side of the card, near the +, were melted and laying inside the bottom of the cabinet.  And, after replacing the TriStar, I bypassed the cabinet-mounted breaker (ONLY because there's another breaker on the line feeding this breaker) for a test.  But, there's a direct short inside the Outback so it's clearly fried.  So, with one fried TriStar, one fried Outback, and one fried breaker (that's a new one for me) I did some further inspection and found signs that someone had been inside the DC FlexWare cabinet and there's an arc weld on the POS buss bar.  And, someone had removed one of the screws from the AC line buss in the AC FlexWare cabinet.  The screw was laying inside the cabinet - not something I did when installing it 3 weeks ago.

I'm guessing that, if someone was simply in the DC cabinet with a screwdriver and shorted across the +/- busses, I'd be looking at only a tripped breaker.  And, of course, another arc weld/scorch on another buss or cabinet part (which is NOT present).  So, given the observations above, I have a question - if someone fed 240V AC into the DC buss side of this system, could that account for the three damaged components?  There is 240V available close by and some wiring found at the site makes me suspicious.   Or, does anyone have any experience with similar failures caused by "natural" means and I'm way off base?

Thanks much,

Ross
[Description: http://www.windenergy.com/_images/email-signature-logo-150x55.gif]

Ross Taylor
International Training Manager
Telecom Systems Project Manager - EMEA

Southwest Windpower GmbH
Mannesmannstr. 6
50996 Köln Deutschland
ross.taylor at windenergy.com<mailto:ross.taylor at windenergy.com>
www.windenergy.com<http://www.windenergy.com/>
Office:  +49 (0) 221/ 16 53 94 50
Mobile: +49 (0) 15779554879

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