48V DC - what does that mean?

[Steve]

48VDC is the voltage used in telephone exchanges and large ISPs. This is
usually provided from a battery bank which is constantly on charge (or
some more clever arrangement) so that it is effectively a UPS. The cost
of providing the power required for a telephone exchange with mains
UPS type supplies are too high. I have seen the battery banks for an
exchange and they are huge room sized things.

Most high quality stuff has 48VDC options.

You can get 48VDC supplies but unless you already have one I would
forget it. They can be expensive and you probably don't need the hassle
in a school.

The only option option would be to get mains AC supply for the kit but
again it could end up costing a lot more than its worth.

Hope this helps,

Steve

 

[JJ]

I'm a computer software guy and I don't know much about electronics.
I need to buy a network switch for my children's school where I
volunteer as a network admin.

I found one on Ebay that meets my needs, except it says that it is the
"48V DC" version of the switch. The manufacturer of this switch sells it as
two different models, and this one is the "48V DC" version.

What does that mean? Am I going to need to get something else to get
power to it?

 

[Larry Fisk]

48 volts (V) Direct Current (DC) as opposed to AC (alternating current)

 

[JJ]

Thanks, but I know what the letters stand for - but what does it mean in
layman's terms to me? Am I going to be able to plug the thing in to a
standard 110V line? Why would they sell a separate DC version of it? In
other words, why would one want the DC version?

 

[Larry Fisk]

Sorry I mis-understood the question.
most electronic equipment runs on DC
they often use a ac adapter to rectify AC to DC
Or the rectifier could be built into the device.
the switch on ebay may or may not come with an ac adapter.
Do a google search with the brand name and model of the switch and you will
find
documentation maybe even the manual.
Or post the brand /model here or a link to the ebay auction and someone may
be familar with the switch
and can help.

 

[Jim Douglas]

Don't bother with this one, look at Fry's Electronics and you could get a
switch for practically nothing that does plug right into the wall.