Can someone familiar with Cat 7 cable comment on this question? Thanks. My question is, can I confidently use Cat 7 cable in the following application? Or should I follow a more laborious special loom construction?
I am making wiring looms for a test arrangement with a sensor which is noise sensitive, where the manufacturer has recommended multipair, individually shielded pairs with an overall shield. The shields from the individual pairs are to be terminated to the 0V terminal of the control system, while the overall shield is to be terminated to the system chassis (= building ground, eventually). This is a reputable manufacturer and I trust their experience.
I can make up these looms as a bundle of single shielded twisted pair (STP) cables, each of which has its own shield underneath external insulation, then insert these into a copper braid and cover with tubing. This will meet the spec as I can terminate the overall braid to chassis and it will be well isolated from the signal circuit 0V. That's a fair amount of work and a colleague has said to me, just use Cat 7 ethernet cable, that has individual STP plus an overall shield.
My concern is, in a Cat 7 cable, does the coating on foil screens of the STP provide sufficient isolation so that the STP and overall shields can be terminated to these two separate grounds? Or are the STP foil shields effectively the same point as the external shield, so that I will be creating a path between the signal circuit 0V and the building ground?
It seems like a good idea to follow the simpler assembly method but I don't want to splash out on a reel of Cat 7 cable just to poke it with a DMM and find the individual STPs are the same electrical point as the external braid. Also a more swotty colleague suggests the capacitive coupling between the STPs in cat 7 could be more significant.
I am making wiring looms for a test arrangement with a sensor which is noise sensitive, where the manufacturer has recommended multipair, individually shielded pairs with an overall shield. The shields from the individual pairs are to be terminated to the 0V terminal of the control system, while the overall shield is to be terminated to the system chassis (= building ground, eventually). This is a reputable manufacturer and I trust their experience.
I can make up these looms as a bundle of single shielded twisted pair (STP) cables, each of which has its own shield underneath external insulation, then insert these into a copper braid and cover with tubing. This will meet the spec as I can terminate the overall braid to chassis and it will be well isolated from the signal circuit 0V. That's a fair amount of work and a colleague has said to me, just use Cat 7 ethernet cable, that has individual STP plus an overall shield.
My concern is, in a Cat 7 cable, does the coating on foil screens of the STP provide sufficient isolation so that the STP and overall shields can be terminated to these two separate grounds? Or are the STP foil shields effectively the same point as the external shield, so that I will be creating a path between the signal circuit 0V and the building ground?
It seems like a good idea to follow the simpler assembly method but I don't want to splash out on a reel of Cat 7 cable just to poke it with a DMM and find the individual STPs are the same electrical point as the external braid. Also a more swotty colleague suggests the capacitive coupling between the STPs in cat 7 could be more significant.
