Hotwire environment

[Rossco]

Has anyone had any installations with cbus in a large farming environment with hotwires.
We have a job to install cbus all over a property using under ground cables.
The property has 9KV hotwires running all over the place.
We are doing tests at the moment with cbus cable tied to a 9KV hot wire, all seems fine so far after a few hicups.
We found that when a PCI was on the network near the hotwire the network would not work when the unit pulsed its voltage, moving the PCI away or off the network fixed this problem.

[UncleDick]

Hi Rossco,
I 'm willing to bet that the disturbence caused by the Hot Wire (and I presume we are talking about an electric fence for security or stock control here) pulsing on (not to mention when someone/something provides a path to ground) is in excess of the international standard on emf emmissions that most electrical/electronic products have to comply with so some effect is to be expected.

I recall from basic physics that the field strength from this interference is going to reduce at a rate that is the square of its seperating distance (or something along those lines) from the C-bus so any additional distance will help.

I wonder if any one can advise if burying the C-bus (use underground Cat5) will provide additional attenuation over plain air gap. Depending on the run distance and number of units/networks involved fibre may be the go.

[Charlie Crackle]

Where do you get the CBUS Cat5 to fibre Converters !!!!! ;)

Could do over 2 CNI with fiber to ethernet conveters but you can not bridge over 2 CNI. Please add bridging over 2 CNI interfaces to which list please. :)

Charles

[Rossco]

We will be running cbus over fibre on the long runs (1 to 2 Km) with half bridge and pci units with ethernet to serial converters.
Our tests have been running now for a week and every thing seems fine and working well.

[allgo]

Your method of installation does not meet cbus installation segregation requirements therefore you may have problems gaining assistance if any is required further down the track.

[znelbok]

I am on a farm with an electric fence unit in the shed, mounted about 1m away from a 12ch c-bus relay. the cable runs vertically up the wall about 20cm from the fence wire.

We appear to have no problems at all. A network bridge exists between the shed/house and my shed/house (duplex arrangement). My network is nowhere near the fence wire and both scan about the same.

The CNI is mounted on my network and I configure the remote network via the bridge. There is however a PCI on the remote network for the alarm panel (not installed yet) so things may change in the future

[UncleDick]

Rossco
Just had another concern pop up: If you run the Cat 5 near enough to the High voltage wire there may be a high voltage induced on to the Cat 5 conductors. Now as long as you have used the correct pairs the mutual twist should cancel out any common mode voltage so that if the C-bus +ve goes up to 6kV then the C-bus -ve will also go up to ~6kV and the C-bus electronics will only 'see' the 34Vdc difference that is the C-bus power supply. But the isolation (via opto-isolators, double wound transformers, pcb layout and air gaps etc) to earth and between mains and C-bus on C-bus units is 3.5kV so there would be a possibility that voltages above this could leap the barrior and cause damage to electronic components. You will have to ensure that the C-bus is sufficiently seperated to limit the induced voltages to below this figure (easy for me to say - not sure how you can test for this other that putting a storage CRO across C-bus and Earth and looking to see what voltage any spikes get up to at various seperations.

[Rossco]

The cbus will be installed underground in conduit using under ground cat 5e,
the runs may end up parallel with the hot wires but will have 300mm segregation.
In our test we have cable tied it to the hot wire for 100m to give us a worst case senario.
In situations where we will be running in parallel for at least 1 to 2 Km we will be using fibre.