[mythtv-users] Power outages and UPSs

[Brian Wood]

David Brodbeck wrote:
> On Jul 30, 2007, at 3:25 PM, f-myth-users at media.mit.edu wrote:
>> If you want -maximal- isolation, you hook a motor to a generator
>> and you can get better isolation than even an isolation transformer
>> will give you... :)
> 
> And there are sites that do that.  But it has its own unique issues.   
> Now instead of the massive impedance of the power grid to smooth out  
> quirks in your loads, you have a relatively small generator.  You  
> become vulnerable to spikes created on your OWN site by big loads  
> turning on and off.  Small generators can also easily lose voltage  
> regulation in the presence of highly capacitive loads, which happen  
> to include many computer power supplies.  Third-order harmonics  
> created by switching supplies can wreak their own unique kind of  
> poorly-understood havoc, as well.

When I was working at a broadcast facility we used a fairly large
(300KW) motor-generator made by Piller, a German company whose
technology is in fact the descendant of the motor-generators used in
WWII vintage U-Boats. The Generator was driven by a DC motor, powered by
batteries that were continuously charged from the power line. The
batteries could supply 20-30 minutes of full-load power, the assumption
being that at least one of the pair of Cat diesels would be up to speed
and online charging the batteries before that time was up.

Another supplier of commercial size/quality UPS systems is Leibert, also
well-known for Air conditioning systems.

Perhaps of intellectual interest to folks here, but certainly not
practical for a typical Myth installation.

BEWW