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Old 09-18-2016, 09:52 AM   #1
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Default 13.8kv stress cones

Here's the install of 13.8KV @ source. Here's the thing... I don't have a complete understanding of each component of this cable.
We have the porcealen mount, lugs to cable, the stress cone to elevate the immense flux which is made of this grey putty I don't know its composition. Then I do and don't know exactly which each layers job is so any explanation would be fantastic!

We have the outer jacket, the stranded grounds, the semiconductor, the dielectric, a layer under it and the conductor.
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Old 09-18-2016, 10:12 AM   #2
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Here's a pretty good write-up of all the components..
http://www.openelectrical.org/wiki/i...e_Construction
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Old 09-18-2016, 12:56 PM   #3
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The point where the shield terminates puts a whole lot of focused stress in the cable because there is a huge difference in capacitance between the shielded and unshielded sections of cable and this occurres over a very short length.

The idea is to reduce the stress on that insulation gradually and this is what the putty or tape-buildup in a stress cone do. Very often the material is a semiconductor that gradually dissipates the lines of electric stress across its length.

You guys gonna ground your shields, though?
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Old 09-18-2016, 03:29 PM   #4
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Yes! At the switch gear end. Could you explain why only the switch gear end? The picture is of the peckerhead I terminated, and in it we isolated each run using mica board. Then switch gear side we braided the grounds. Thank you for the write up I was hoping for this kind of an answer. And I appreciate the link as well very good information!
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Old 09-18-2016, 04:49 PM   #5
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Originally Posted by Kadenselect View Post
Yes! At the switch gear end. Could you explain why only the switch gear end...?
The only time I see that done is when the cable shielding is not suitable to carry the current that may flow during a ground-fault. In those cases only one end of the shield is grounded because this still allows the shield to create uniform stress control on the cable insulation without completing a circuit.

My concern is that you still need a fault clearing path, and this would be in the form of a separate equipment grounding conductor pulled with the cables, but I don't see that in your photos.
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Old 01-08-2017, 03:00 PM   #6
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Quote:
Originally Posted by Kadenselect View Post
Yes! At the switch gear end. Could you explain why only the switch gear end? The picture is of the peckerhead I terminated, and in it we isolated each run using mica board. Then switch gear side we braided the grounds. Thank you for the write up I was hoping for this kind of an answer. And I appreciate the link as well very good information!
if your not grounding those braids tape them up. engineers sometimes only want you to ground one end to reduces recirculating currents on ground paths, usually this is desired where cathodic protection is being used in the vicinity. it's best for the cable and safety to ground both ends. my source of information on this is okonite engineering design book. yeah and wheres your ground?
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Old 02-17-2017, 02:45 PM   #7
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That looks an awful lot like concentric neutral on that cable. Depending on the rating of the shield wires, they may serve as the ground.
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