Re: Re: Power supply efficiency on older model Sun equipment

On Mon, 1 Sep 2008, Brian Costello wrote:

> This got me thinking about my setup that runs 24/7 which is a Sunfire
> V100 along with a Cisco 2950 10/100 switch as shown here:
> http://costello.mine.nu/private/mysun.html  . The V100's uptime is 540
> days (today) so reliability is clearly not an issue.
>
> The second V100 is a cold spare and the SS20 and external SCSI drive are
> now decommissioned. I also have an APC Smart UPS 2200 that protects both
> of these and my DSL modem from power outages. I un-plugged the UPS and
> reconnected it with a short extension cable in which I can access the
> individual wires. I used a clamp meter to see how much current it was
> pulling. With everything running it was consuming 2.15A @120V or 258W. I
> figured that the Cisco 2950 was probably pulling a fair share so I
> pulled the plug on it. The reading only went down to 1.95A so the Cisco
> 2950 is consuming about 24W. The V100 only has an 80W power supply and
> based on the system handbook it should only be pulling about 60W based
> on what is in it. Therefore the UPS and DSL modem are pulling about 170W
> which seems hard to believe.
>
> Does anyone have any experience on the power consumption/efficiency of
> UPS's? You could consider me fairly UPS crazy here with 2 PC with their
> own. One on my wireless phone system base station, one on my Wireless
> router & Vonage box, and one on each of my 2 replay TV units. Needless
> to say, power outages are only a problem if they are longer than an hour
> or so.

Is the UPS running warm/hot to the touch? My experience of running
APC UPS's at a low load is that they are not too efficient and run
warm.

If the ADSL modem/router is 'brick' powered, then a guesstimate of
the load can be easily made, mine has a 9V 2A AC output and
allowing 10% transformer loss it will draw ~20W.

I would be inclined to run the APC UPS at as close to full load as
I can for improved efficiency and cater for extended run time by
more batteries (if it will allow them).

Geoff
-- 
    Geoff Blake G8GNZ      located  near  Chelmsford,  Essex,  U.K.
    Please reply to:      geoff(at)palaemon(dot)demon(dot)co(dot)uk
    Using Linux on  Intel & Linux  or NetBSD on Sun Sparc platforms

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