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Hello,

I am looking to have a WS-26 switch with an external power supply and no battery backup or solar for the switch. Is there a difference between the WS-26-400-IDC and the WS-26-DC to use, and would would be the best external DC power supply to purchase for the switch?

Thanks!

Basically looking if something like this would work?

http://www.meanwellusa.com/webapp/produ ... od=SDR-480

Did you read the Descriptions?

WS-26-DC
24 Port Managed POE Switch + 2 SFP Uplink Ports
Designed to receive positive 48V-54V conditioned power.

WARNING: This switches is not designed to operate on negative 48V site, using -48V DC will damage the switch as it does not have isolated input output power.

WS-26-400-IDC
24 Port Manged POE Switch + 2 SFP Uplink Ports
400 Watt ISOLATED DC power supply accepts 32V to 72V DC variable input while providing uninterrupted 24V and 48V POE
NOTE: This switch is designed to operate on negative or positive 36V-72V sites.
NOTE: Does not allow monitoring of DC input voltage

The WS-26-DC to be powered by a power supply as it does not have its own power supply and must be fed 48V-54V "positive" conditioned power and can NOT be used at negative 48V sites like Telco sites.

The WS-26-400-IDC can be powered with a power supply and has its own "ISOLATED" power supply which is a must for sites that have NEGATIVE 48V like Telco sites. It can use positive or negative 36V to 72V DC input.

You have to understand the difference between NEGATIVE and POSITIVE DC voltage. Voltage is measured as the difference from the reference voltage.

With POSITIVE 48V DC negative is 0V (the reference voltage) and positive is plus 48V from 0V (the reference voltage)

With NEGATIVE 48V DC positive is 0V (the reference voltage) and negative is minus 48V from 0V (the reference voltage)

At most sites 0V is binded to the rail which in the case of a Telco site that is positive 0V, at normal WISP sites which are positive DC negative which is 0V is bonded to the rail.

So if you do not use am ISOLATED switch at a negative DC site like the WS-26-400-IDC you will create a dead short through your radio because UBNT and most other WISP radios bind DC negative to their rail / tower so if you simply used a WS-26-DC and powered with negative 48V by flipping the power leads you would create a dead short and POOF if powering say an airFIBER or airMAX radio on the the tower as.

The WS-26-500-DC is also only designed to work with POSITIVE DC sites and can accept 9V to 72V and power 24V and 48V radios. DO NOT USE AT NEGATIVE DC SITES

Hello Everyone,
in our NOC there is a power supply that power at 56V all gears; can I power a WS-26-DC with 56V and not 54V as you write on technical specs ?

Thank you.

f.cucci@el-com.it wrote:Hello Everyone,
in our NOC there is a power supply that power at 56V all gears; can I power a WS-26-DC with 56V and not 54V as you write on technical specs ?

Thank you.

You will not damage the WS-26-DC with 54V input BUT if you feed the WS-26-DC 54V that is what it will put out for the 48V option minus 1V or 2V that it will drop across its circuits on the board.

So if you feed it 54V it puts out 54V to 55V for 48V and 48VH which will fry some radios like the new AF5XHD (anything above 52V) but you could power the AF5XHD radio with the 24VH POE option which the WS-26-DC would put out 24V for 24V and 24VH regardless of input volts.

Plus you also have cable voltage drop as well which on long cables is 1 to 2 volts.

If you feed a WS-26-400-IDC 54V it will put out 50V as the the 48V and 48VH POE option.