Ethical dilemma [RE-wrenches]

[Ezra Auerbach, Trace Engineering]

William,

I think you are doing the right thing, safety in schools is paramount.  Bill
Hoffer is correct in his posting, Xantrex does not offer a "quad" SW
configuration.  My personal suggestion would be to get the loads separated
into two panels and feed them from SW series pairs.  On my rock the PTA
would cough up the dough if the school was too strapped to do it...It's not
really that much work.
Ezra
----- Original Message -----
From: "William Miller" <wrmiller at slonet.org>
To: <RE-wrenches at topica.com>
Sent: Monday, August 13, 2001 9:37 PM
Subject: Ethical dilemma [RE-wrenches]


> Fiends:
>
> Here's a dilemma and how I dealt with it.  I am still wondering if there
is
> a better solution.  Your thoughts are appreciated:
>
> I was called by the operations director for an off-grid elementary school
> to replace fans on an SW inverter.  While on site, I took some time to
> learn how the system was built.  There are 4 SW inverters with outputs
> summed through 2 levels of transformers.   They run their generator during
> the school day and ran on batteries and inverters during the afternoon and
> evening for extra curricular, janitoring and etc.  The system runs great
> while fed by the generator, but when the generator shuts down, inverters 1
> and 2 are not synced to inverters 3 and 4.  You can measure the voltage
> from phase to phase and over a half hour or so it goes from 240 to 0 and
> then back up.  The output of the equipment room is two hots and a shared
> neutral.  When the inverters are out of phase, the neutral is properly
> shared.  When the inverters drift in phase, the neutral current will
> increase, possibly until the current is double the rated current.  It is
my
> understanding that power is distributed throughout the school in this
> manner.  At any point where a neutral is shared--on a feeder or multi-wire
> branch circuit--this condition is possible.
>
> I wrote a report describing this problem as clearly as I could.  I
followed
> up with phone calls to the operations director.  Last conversation I was
> told that there was no money to correct this problem and that all they
> could do is, "conduct extra fire drills."
>
> I wrote to the school and told them I could not work for them until this
> issue is addressed.  I do not want to be even associated with a system in
a
> public school that has an obvious design defect.  I feel pretty
comfortable
> about this decision, but I am curious what others might have done.
>
> William
>
> __________________________________________________________________
> William Miller
> SLO Communications: Communications and Power Systems Consulting
> PO Box 50, Santa Margarita, CA 93453
> Voice :805-438-5600 Fax: 805-438-4607 VMail: 805-546-4875
> email: wrmiller at slonet.org
> License No. C-10-773985
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