The problem lies with the inversion - inverters are horrendously inefficient and require a
significant amount of standby current to run, even with no load.
From: Philip D'Ath [pid(a)ifm.net.nz]
Sent: Tuesday, 1 July 2008 10:03 AM
To: Andrew Hooper; NZNOG
Subject: Re: [nznog] Vector, did you try turning it off and then on again
Speaking from a Cisco perspective; this is not the case.
The typical AC power supply in Cisco kit is around 93% efficient. The
DC power supply option (which you can purchased for direct connection)
is around 70% to 80% efficient. So those people who elect to use DC
only for power will need a lot more power.
The reason for this is it is more efficient to convert 240VAC (or
110VAC) to 12VDC, 5VDC (and sometimes 3.3VDC and 48VDC), than it is to
convert 12/48VDC to those same voltages.
Most military network equipment is not DC powered. If you have a tight
power budget you need to go AC.
UPS and Battery Backup are a joke, I often wonder why critical systems
employ external direct connections to battery systems rather than having
used PSU's, UPS's and Inverters. Granted these are often packaged in
housings but they are still not as efficient as running a device off the
power it was designed to work with.
Take a leaf out of the Military's book. Most of their gear has an
DC option so it can be connected to something in the field and will run
NZNOG mailing list