CNI and external power???

Looking at my install today and I still cant understand why a CNI has an external power supply. The unit is built to be mounted in a panel, hence the din rail enclosure, but it come with one of those horrible plug packs (its not bus powered for those who have not used one).

Where do you plug the plug pack into, a GPO next to the board. If there is 240V in the board I believe you cant use cable not rated for the maximum votlage within the board (ie 240V or 230 is you prefer what is in the AS standards), so you cant run the cable from the plug pack into the board, similarly the network cable cant be inside the board (unless you substitute c-bus cable for network cable).

You would say then that a seperate enclosure is required for ELV only, but this still means that you need a GPO near it and a hole for the cable to enter in by.

Does anyone know of a din rail 12VDC power supply that will fit in the boards nicely like the CNI and all other din rail module ie protrude through the cut-out of the board.

Mick

 

Mick

This has to do with the Ethernet module, the current it consumes and isolation. If the unit was to be permanently powered from C-Bus it would consume 250+mA of current from C-Bus which is approximately equivalent to 14 key units. The unit would probably have to go into an 8M enclosure or even a 12M enclosure to handle the heat dissipation and to fit all the components for a C-Bus power supply of that size. The plug-pack power supply also means that a decent level of isolation can be maintained between Ethernet and C-Bus. Trust me when I say that it's cheaper and smaller the way it is.

Would there be any value in designing a CNI in a new enclosure type?

There definitely are a range of DIN power supplies available for just about any application you can think of, I just can't think of a brand off the top of my head at the moment!

 

Don't do it

I would suggest that the problem shouldn't arise as the CNI really shouldn't be put in the switch board with all that nasty mains. Never mind the ELV power from the plug pack the concern would be the CAT 5 from the eithernet. I would have thought that the CNI should be mounted in the DataComms rack rather than the switch board. Anyone had practical experience of this on site?

 

i dont believe that the noise issue is a real one.

If you run the cable away far away from the power (I run them all down one side and power down the other) and only within the board you should be OK. After all the c-bus net is a data network and it is in with the power.

While I can find many din rail power supplies, they appear to be larger than the cut out on the panel of the boards, but I may be wrong. I will look into it further.

If anyone knows af a power supply that will fit in a clisap 4C48FD board, plesae post it here

Thanks

 

My CNI is mounted in my wiring closet next to my PCI on a short bit of din rail. C-Bus is available in a Krone box right next door. All my DC requirements are met by a home made battery backed regulation/distribution system. I have 8 x 12V 2.1mm, 4 x 5V, 2 x 9V and 2 x 8V, all in 2.1mm coaxial DC sockets. I use this for my broadband router, switches, wireless AP's, StarServe TV stuff and now also my CNI. I made this up cause I was sick of my PC's not being able to communicate during a blackout (the PC's have UPS backup) due to the network support devices loosing power. It also gets rid of about EIGHT plug pack power supplies (yuck!). You can see some of my stuff here :-
http://www.users.on.net/~michaelcarey/pics/network/DSC02396.JPG
I try to keep my C-Bus support units (IR, CNI & PCI) away from the mains powered units.
*note* Some of the images in the folder are pre DC distribution days and still show plug pack and associated cabling...
Regards,
Michael.


Edit: URL for folder : http://www.users.on.net/~michaelcarey/pics/network/

 

Hi Michael
I distribute my 12v same way as you ,via 2.1mm sockets from a common box so just make up male leads to leads.....Like your idea about distrib the other voltages as well as i have currently 3 ethernet / serial devices which each have their own power pak and run off 5v the would free up some gpos...

Bought a 13.8v 10a power unit from Jaycar so could use that...Are you using individual regulators foe each 5v out ???

Nice Pic

Frank

 

I use a small switchmode power supply for the 5V rail, 9-18V in, 5V @ 5A out. I bought it from RS components. Each of the 8V and 9V rails each have a 7808 and 7809 1A regulator. I have an Imark 12V power supply with a simple float charger and change over relay. It works quite well.

 

The CNI fits perfect onto the Din rail in the Starserve Pro or Home Network enclosure with a power rail to supply the 240v and my ethernet switch mounted above.
Unit fits like a glove.

Regards,
Rossco