[mythtv-users] Uninterruptible Power Supply

Raymond Wagner raymond at wagnerrp.com
Tue Dec 22 07:19:01 UTC 2009

On 12/22/2009 2:09 AM, Jerome Yuzyk wrote:
>  From times I've had a monitoring UPS (or
> bothered to set up monitoring), living in older houses, or even
> apartments, power can vary widely around 120VAC. A nice battery smoothing
> out those variances can help your electronics last longer.

UPSs are generally passive systems.  That means the battery is kept 
charged offline, and only swapped into place during a power outage.  The 
unit itself only ends up having a couple milliseconds of power left 
internally to allow the transfer without interruption of power.  While 
active systems do exist, they are only ever used for very large systems 
designed for server rooms, and significantly shorten the life of the 

High end consumer and small office units may come with voltage 
regulation, but the vast majority of units do not.

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