Post by paterson00 on Jul 11, 2010 12:04:14 GMT
On the project I am currently on they are installing concentric cable to the signal heads. Its the first time I have come across it and by all accounts its causing some problems in that it is acting as a capacitor holding a charge after the feed to the head has been removed leaving residual voltage of 70vac after a 110vac feed at the asset. I wondered if anyone had come across the cable before and knew anything about it like what the benefits are? We are told that the main benefits are that the maintenance schedule of the cable is far less often so the cost of the installation is re-cooped via the maintenance.
To overcome the residual voltage they are installing resistors across the cores at the asset end but in the future if the resistors fail wont there be an issue of false clears etc?
Just wondered if anyone else had any experience with concentric cable and did you have any issues? I'm told that it was used on the Heathrow project and the same result was found there and that they put a capacitor across the cores again at the asset end to overcome it. I cant see how that would work as, surely that would simply add to the problem...?
To overcome the residual voltage they are installing resistors across the cores at the asset end but in the future if the resistors fail wont there be an issue of false clears etc?
Just wondered if anyone else had any experience with concentric cable and did you have any issues? I'm told that it was used on the Heathrow project and the same result was found there and that they put a capacitor across the cores again at the asset end to overcome it. I cant see how that would work as, surely that would simply add to the problem...?
