Perry E. Metzger wrote:
I believe that most of the country switched from direct to alternating
current late in the last century, and that by now it should be
expected that most commercial equipment in the world will either
operate at 120VAC or 220VAC, and not on direct current.
I realize that the phone world that MFS is part of operates
differently, but this is networking equipment we are talking about,
not phone switches, and UPSes are very old tech at this point.
In other words, its silly for them not to have UPSed AC available.
Take the following current paths:
A. Commercial AC -> [transformer, rectifier] (DC) -> [battery] (DC) ->
[inverter] (AC) -> [your equipment] (AC) -> [transformer, rectifier] (DC)
B. Commercial AC -> [transformer, rectifier] (DC) -> [battery] (DC) ->
[your equipment] (DC)
The internal compenents of any transitorized equipment will need DC.
It makes sense for the telco companies to use B. Otherwise they would just
be adding ineffiencies. One could think of the telco's power system as
a HUGE power supply that is just external :-).
It is much more efficient to transmit AC at high voltages over long
distances than DC.
Given the fact that lots of networking equipment other than routers only
support AC power, MFS should provide battery/generator backed AC power.