I am currently designing a control system to operate in power stations where I will gather information from Relays. Power is available at 125 VDC and I would like to find a fibre HUB to operate at that voltage. Does anyone know of any manufacturers of this product.

 

Hi we usually use cisco or 3com hubs/switches in the control LAN. They have a 12V/5V input for redundancy or stand alone power supply. A DC/DC coverter that fits can be found on the market (e.g. HALTEC or POWERTRONICS) or of course from the hub manufacturer. If you don't use Ethernet we can produce a modular glass or plastic fiber hub which connects to a RS 232 or FO master and up to 36 FO slaves. Speed can be 19200 baud. Commonly used to connect Protection relays to a IEC 103 master, but the hub is tranparent so it would work for any protocol.

 

Tom-

Try Dymec. http://www.dymec.com/ethernethub.html Their power supply is
90 -250 Vac or Vdc.

I haved used their products in several power station applications with
success.

Regards,

Scott Olson
Power Engineers
[email protected]

 

Have you tried?

Many devices nowdays have switching power supplies capable of accepting a wide range of input voltages, ok they are all specified for AC, but in reality most of them run as happily on DC (but at a little bit higher voltage) as on AC. The reason: the first step is a rectifyer, and provided that two diodes of the input bridge can handle the needed power without beeing to hot then there would be no problem.

/Johan Bengtsson

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Although with a fibre hub, you may not want to do the "plug it in and see if it doesn't blow up" approach. If it is not high current, you may want
to try stepping your 125VDC down to 12VDC and picking up an inverter like what is used in campers or truck's to invert it up to 120VAC. I picked one up for 60USD that can run a television with no trouble. Finding a specialty hub to run on DC, or testing one and seeing if it melts may end up costing more than that...

HTH,

--Joe Jansen