Ground fault [RE-wrenches]

Fri Nov 15 22:24:44 PST 2002

Well explained! Obviously, no one wants a fire. Trace ground fault
protection problem stories and rumors were rife for a while, and I suppose I
got my opinion from others, not first-hand Thank Heavens. It's all part of
the concern you develop when using equipment that's going through
development pains I guess.

So, in the interest of preventing just a few fires, why leave the choice of
to protect, or not protect up to the buyer? If they're cheap and effective,
what's the harm in building them into the controller?

Matt
----- Original Message -----
From: "Christopher Freitas - OutBack Power" <cfreitas at outbackpower.com>
To: <RE-wrenches at topica.com>
Sent: Friday, November 15, 2002 8:18 PM
Subject: RE: Ground fault [RE-wrenches]

> > Your comments suggest that nothing will prevent some problems from
> > occurring, if GFIs and fusing aren't able to provide protection.
>
> Yes - nothing can prevent some problems from occurring - if you make
> something idiot proof they will make a better idiot... The ultimate
> solution would ground fault protection, fuses in the positive and
> negative and all of the circuit breakers locked in the OFF position at
> all times!
>
> >In over 20 years of installing battery-based power systems, I've
> >never installed a GF protection device at the PV or battery primary
> >>wiring, seen one installed by anyone else, or seen any damage as a
> >>result of not installing one.
>
> You probably install systems well and live a charmed life...
>
> >for this occurrence to trigger mass installations of ground fault
> >protectors, which are problematic in themselves
>
> I hardly would say that the PV ground fault protection system is
> problematic (which was first offered by Trace and then copied by Pulse,
> AEI GC1000/MultiMode and SMA Sunnyboy inverters).  Its an extremely
> simple design, uses very solid, well protected components (usually) and
> is non-electronic (so is reliable).  For someone who has never installed
> one or seen one you have a pretty strong opinion ...
>
> When we first started shipping them at Trace, I said I would answer all
> of the tech calls on them myself - I was amazed at the number of people
> who were having problems with them - but it turned out to be not the
> PV-GFP design but was that the systems had real legitimate installation
> problems... of course we only heard from the people who had problems...
>
>
> > If this issue is so all-fired important, why not include ground
> >fault protection in and for ALL DC control and conversion devices as
> >standard, from the factory? Hmmmmm?---
>
> Gee - that is what SMA and AEI decided to do in their inverters.  We
> aren't doing this at OutBack because you do not need to have one for
> each inverter - just one for the system with a disconnect pole for each
> charge controller.  Its an easy option to add into our PSDC enclosure.
> We let you decide if you want it that way.  With our design you can also
> utilize multiple OBDC-GFP/2 units for larger systems with more than two
> charge controllers.
>
> The design of the GFP system handles both DC and AC ground faults.  I
> have more than once found AC voltage/currents mixed with the the DC
> voltage/current - improper installation and internal inverter faults
> were the cause usually.  A GFP system would have stop it and alerted the
> customer.  But I usually am out in the field with a O-scope and check
> for such problems,  so I find them.  These systems were often normal
> operating systems with no signs of problems.
>
> The GFP system we use will in fact respond to a ground fault anywhere in
> the DC system - not just from the PV array wiring.  This is really nice
> when part of the system is batteries which can deliver large amount of
> power into a fault. I had a friend who's GFP was tripping due to a
> leaking cell in a high voltage battery bank - try to find that one
> without killing yourself doing it.
>
> I suspect that a good portion of PV systems are installed even today
> with DC, AC or DC/AC ground faults and no one notices - and I
> acknowledge that only a few will result in fires.  Including a GFP will
> find these problems 99% of the time, I bet.  I think stopping a few
> houses from burning down is pretty important to me.
>
> The bottom line it is cheap and fairly easy to install.  A PV system is
> a LOT safer with it included.  It can save your butt if something does
> go wrong or a problem with a product occurs.  It assures you that the
> install is ok when you open your beer at the end of the day. I just feel
> better with them on the systems I am involved with.
>
> Seems like a no-brainer to me...
>
> Christopher Freitas
> OutBack Power Systems, Inc.
> cfreitas at outbackpower.com  www.outbackpower.com
> Tel 360 435 6030  Arlington WA USA
>
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