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Re: Re[2]: telehouse - 25 broadway

  • From: David Lesher
  • Date: Sun Sep 16 11:15:30 2001

Unnamed Administration sources reported that Leo Bicknell said:
> I think "limited" here is a bit misleading.  Most of these engines
> are continuous duity rated, which means within the bounds of
> maintenance items (oil changes, gasket changes, and other routine
> maintenance) they can run non-stop.  Most gensets are essentially
> the same components that power diesel-electric locomotives that
> routinely run for weeks at a time without shutdown.

They may be continuous duty rated, but in this application?

I.e. - the ones I have worked on (to limited extents;
change filters, oil, repair FUBARs in the control systems
design [1] had two rating: N kw continuous duty; {say} 1.4N
intermittent. Intermittent may well be 24H or less; I 
bet the 1.4 is a f(run time/week) or such.  
> Here in ice storm country every few years power is out for 3-4 days
> in some areas after bad storms.  Generators routinely run for 3-4
> days and cause no concern over their condition, other than to move
> up routine maintenance due to the additional run time.

> I suspect dust is going to be the largest problem for all generators
> in the area.  It will reduce radiator effectiveness, wear on external
> parts (fans and the like), clog air and oil cleaners.  Again, these
> devices are made for some fairly harsh environments so 48 hours is
> no concern, I would think expecting 2 weeks of reliable power if
> they are attended to even in these conditions is reasonable.

This is just as much a case of matching equipment to application
as is buying a new backbone router. Do you buy based on a "100 year
flood" peak; the "Mothers Day calling" peak or the "105% of >1hr"
model. Justify your decision the the beancounter. 25 points.

I do not know what all the Ma specs [Sean: is this p/o the FCC
regs, NEBS, or ??] call for, but I'd guess 2-3 days tops.

[1] Engines are big noisy devices. When you use high impedance
input logic (from slow crude mechanical sensors such as
oil pressure and water temp switches) that responds in a few
microseconds, and have no filtering debounce on them; duh, you get
lots of false alarms. Slow things down to a 500ms time constant,
and they work far better. Filter the power supply {Hello! The
generator just started -- yep, the line WILL spike...} well as
well, and hey, it does work after all. I hope other folks did
better design work than those guys.

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