PDA

View Full Version : Inteference of Lighting Ballast



Kevin Yeo
20-08-2007, 05:58 PM
Hi all,

I've recently installed some showcases in a supermarket with danfoss ekc 202 controller c/w RS485 Lon card. I also used a logger AKA245 to link up all controllers with Lapp screened cable. (Screened cable runs separately from power cable and is grounded individually)

However, whenever i turn on the lighting (with electronic ballast), communication between showcases with lighting 'disappeared' from the monitoring station.

Have been trying to upload for days and there's no progress...anyone faces this problem before?

rgds.
Kev

Brian_UK
20-08-2007, 08:11 PM
My only comment would be - is the grounding done at only one end/

If both ends are grounded then the shield becomes an aerial.

Can't help on the rest because I don't know enough on those items, sorry.

frank
20-08-2007, 08:23 PM
My only comment would be - is the grounding done at only one end/

If both ends are grounded then the shield becomes an aerial.
You beat me to it - damn. ;) Double earth path

Lowrider
20-08-2007, 09:25 PM
Is my best gues too! Just earth the cables at one end! Seen it a thousand times! And if I'm not mistaken it would also be in the manual!

Brian_UK
20-08-2007, 11:04 PM
Is my best gues too! Just earth the cables at one end! Seen it a thousand times! And if I'm not mistaken it would also be in the manual!
Ahh! R T F M:D

Kevin Yeo
21-08-2007, 07:09 PM
Today I took out the ballast and moved it away further from the controller, i managed to retrieve 70%. still struggling...

750 Valve
04-09-2007, 01:17 PM
Move it further then :D

This, as has been said before is likely an earth/shield problem. It may even be an earthing problem with the fixture the ballast is on. Have you actually checked the RS485 shield is earthed at one end only? Is the network terminated at BOTH ends with resistors?

frank
04-09-2007, 09:40 PM
Move it further then :D

This, as has been said before is likely an earth/shield problem. It may even be an earthing problem with the fixture the ballast is on. Have you actually checked the RS485 shield is earthed at one end only? Is the network terminated at BOTH ends with resistors?
Got called back to Sheffield today (Meadowhall) as the Fire Alarm engineer got a belt from the earth cable within the FA Interface box. Seems that the 3 core cable from the 2 cassettes I had just re-commissioned after the recent floods were experiencing a mega volt induction as they were not earthed at source.

A little crimp and screw soon sorted it :D