Telecom Netonix DC powered switch - looking for input

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ste
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Re: Telecom Netonix DC powered switch - looking for input

Sat Dec 15, 2018 4:11 am

Older Post but i have the same Problem now. Is it neccesary to use an isolated DC-DC converter for every +48V device? Wouldnt it work to put the negative Output of the DC-DC converter to ground to get a grounded +48V System from the converter? Ordered a DDR-240C-48.

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sirhc
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Re: Telecom Netonix DC powered switch - looking for input

Sat Dec 15, 2018 12:30 pm

ste wrote:Older Post but i have the same Problem now. Is it neccesary to use an isolated DC-DC converter for every +48V device? Wouldnt it work to put the negative Output of the DC-DC converter to ground to get a grounded +48V System from the converter? Ordered a DDR-240C-48.


I am not really sure what your asking.

If you have a NEGATIVE 48V DC SITE you must use the WS-26-400-IDC or you can use an ISOLATED DC2DC power supply and then use the WS-12-DC and WS-26-DC.
Most telecom sites bond POSITIVE to the rail/earth ground since positive is 0V reference.
If your using the WS-26-400-IDC with NEGATIVE DC site then you can power POE devices normally.

You can NOT use any other of our DC switch with NEGATIVE DC power by simply flipping the DC cables. Yes the switch will power up and appear to run normally and if you only powered devices like the NanoStation M5 you would be OK as the radio is completely isolated being inside an insulated plastic housing. But as soon as you try and power any device that has access to tower steel (Ground) poof.

Reason why:
Netonix bonds DC negative to chassis/earth rail.
Most devices (radios) WISPs use also bond DC negative to chassis/earth rail which if it is a connectorized radio will have access to tower ground through the antenna.

So with Negative 48V DC positive is the reference voltage of 0V and DC negative is -48V to reference.
In say a UBNT Rocket radio negative is 0V reference and positive is +24V to reference.
Since UBNT and most WISP equipment bond DC negative to chassis/earth rail which is bonded to the outside of the N-Type or SMA connector it gains access to tower ground through the antenna.
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ste
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Re: Telecom Netonix DC powered switch - looking for input

Sat Dec 15, 2018 12:59 pm

sirhc wrote:
ste wrote:Older Post but i have the same Problem now. Is it neccesary to use an isolated DC-DC converter for every +48V device? Wouldnt it work to put the negative Output of the DC-DC converter to ground to get a grounded +48V System from the converter? Ordered a DDR-240C-48.


I am not really sure what your asking.

If you have a NEGATIVE 48V DC SITE you must use the WS-26-400-IDC or you can use an ISOLATED DC2DC power supply and then use the WS-12-DC and WS-26-DC.
Most telecom sites bond POSITIVE to the rail/earth ground since positive is 0V reference.
If your using the WS-26-400-IDC with NEGATIVE DC site then you can power POE devices normally.

You can NOT use any other of our DC switch with NEGATIVE DC power by simply flipping the DC cables. Yes the switch will power up and appear to run normally and if you only powered devices like the NanoStation M5 you would be OK as the radio is completely isolated being inside an insulated plastic housing. But as soon as you try and power any device that has access to tower steel (Ground) poof.

Reason why:
Netonix bonds DC negative to chassis/earth rail.
Most devices (radios) WISPs use also bond DC negative to chassis/earth rail which if it is a connectorized radio will have access to tower ground through the antenna.

So with Negative 48V DC positive is the reference voltage of 0V and DC negative is -48V to reference.
In say a UBNT Rocket radio negative is 0V reference and positive is +24V to reference.
Since UBNT and most WISP equipment bond DC negative to chassis/earth rail which is bonded to the outside of the N-Type or SMA connector it gains access to tower ground through the antenna.



>I am not really sure what your asking.



I have multiple devices at this Telecom powered site which need +48V. A MT 10G Switch, a Netonix, and a media converter (more to come). So my idea is to use an isolated DC-DC Converter and put the negative output of this Converter to the positive Input/Site Ground.

So I have:
Input A Negative power
Input B Positive Power/GND

After DC-DC converter:

Output C Negative Power/GND
Output D Positve Power

So between A und D is 96V. B and C are connected.

So I should be able to put all +48V devices to C and D and use GND (no Floating)

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