Solved: AC vs DC powered switch

Anwar Safian · ‎08-05-2020

Hi expert

I would like to know what is the difference between AC vs DC powered switch.

Like performance etc.

And which situation should I use AC or DC power supply?

Joseph W. Doherty · ‎08-05-2020

The difference is, AC switches are powered by AC and DC switches powered by DC - duh. Only kidding!

Joking aside, often that's actually the only real major difference. Some switches have the option of using AC or DC power modules, some even (I recall?) even allowed redundancy using AC and DC power modules.

I believe, generally, AC power can provide more wattage. I.e. you may find you can support PoE ports using AC but not DC.

Also, generally, your switch options using DC tend to be much more limited.

Again, otherwise, no real difference in switch capabilities. (Remember, internally, the switch generally uses DC.)

A situation to use DC? If the location already uses it. Not as common now a days, but (again, I recall?) "older" TelCo equipment often ran using DC, i.e. locations where you'll find NEBS certified equipment. So, if you wanted to place a data switch in one of those racks, it made life easier if it too could be powered by the DC already provided to the rack.

A interesting problem presented to me, several years ago, was a location using mostly DC. They had extra DC capacity, but not any additional AC capacity. We couldn't find a suitable small switch that used DC. I suggested using an AC switch with a power inverter (changes DC to AC). Don't recall what they finally decided to do. The other alternative was to electrically upgrade the site's AC capacity (which required much more time and much more costly).

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marce1000 · ‎08-05-2020

- The powered-world we are living uses AC. When you buy a switch is will as your vacuum cleaner have a power supply accordingly. The conversion to DC is an internal matter.

M.

-- ' A nun once asked a penguin ' do you think the earth is flat ? ; the penguin replied :
Madam, it all depends , in Riemann geometries the earth can be perfectly flat! The nun thanked him , he tripped and fell forward : the poor animal had forgotten that he might be living in a Riemann geometry too!

Joseph W. Doherty · ‎08-05-2020

The difference is, AC switches are powered by AC and DC switches powered by DC - duh. Only kidding!

Joking aside, often that's actually the only real major difference. Some switches have the option of using AC or DC power modules, some even (I recall?) even allowed redundancy using AC and DC power modules.

I believe, generally, AC power can provide more wattage. I.e. you may find you can support PoE ports using AC but not DC.

Also, generally, your switch options using DC tend to be much more limited.

Again, otherwise, no real difference in switch capabilities. (Remember, internally, the switch generally uses DC.)

A situation to use DC? If the location already uses it. Not as common now a days, but (again, I recall?) "older" TelCo equipment often ran using DC, i.e. locations where you'll find NEBS certified equipment. So, if you wanted to place a data switch in one of those racks, it made life easier if it too could be powered by the DC already provided to the rack.

A interesting problem presented to me, several years ago, was a location using mostly DC. They had extra DC capacity, but not any additional AC capacity. We couldn't find a suitable small switch that used DC. I suggested using an AC switch with a power inverter (changes DC to AC). Don't recall what they finally decided to do. The other alternative was to electrically upgrade the site's AC capacity (which required much more time and much more costly).