medium voltage cable

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alfonso1900

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I need information on how to terminate medium voltage cables (4160v) at the supply side and at the load side. Also what to use for equipment ground.
 
I had training from a 3M rep. on their cold shrink kits. After a few they are not difficult. We have installed many in our facility without failtures. I would agree with ZOG that you should consult an expert. Ordering the correct kit for the cable and application is essential. The kits do not include compression lugs.
 
alfonso1900 said:
I need information on how to terminate medium voltage cables (4160v) at the supply side and at the load side. Also what to use for equipment ground.
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The cable we are using is shielded and the thing i need to know is if i need to ground both ends or just the supply side. If so what do i do with the other end?. Where in the NEC do i get the size for the equipment ground?. is it just based on ampacity?.
 
alfonso1900 said:
The cable we are using is shielded and the thing i need to know is if i need to ground both ends or just the supply side. If so what do i do with the other end?. Where in the NEC do i get the size for the equipment ground?. is it just based on ampacity?.
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  • Both ends.
  • Shield is NOT to be used as EGC.
  • Triplexed cables often contain EGC, otherwise size you EGC based on the main conductors ampacity.
 
Weressl did hit on the target with basic set up for MV sheilded cables and I done few of them and used the cold shrink tubing and of course you have to get the compression lugs with boots if neecesary.


what about shield currentes when both ends are grounded and the tempereture increase due to this currents?
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Again let me highlight this one.,,

Triplexed cables often contain EGC, otherwise size you EGC based on the main conductors ampacity.
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If you run single sheilded cable not in triplex format yes you must run the EGC seperated and do not use sheild as EGC at all some of them may not able handle the fault current.

And the other thing you should talk to one of the MV/HV contractors and see what they do with their producres with the types of cables they use.

I know the 3M do make cold shrink spice kits and not sure about other manufacters do have them that you have to do little digging on that one.

Merci,Marc
 
weressl said:
  • Both ends.
  • Shield is NOT to be used as EGC.
  • Triplexed cables often contain EGC, otherwise size you EGC based on the main conductors ampacity.
Click to expand...

What is EGC ?
Is that Equipment Ground Cable?
 
Here is (Attachment) the basic construction of a MV termination, while the installation is fairly easy procedure wise, the craftmanship is vital, one small error and the termination will fail.

Plus you need to test it after installation, preferablly using VLF (Or AC hipot) or Tan Delta, you will probally need a MV contractor for this anyways. You can find one in your area at www.netaworld.org
 
weressl said:
  • Both ends.
  • Shield is NOT to be used as EGC.
  • Triplexed cables often contain EGC, otherwise size you EGC based on the main conductors ampacity.
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If you terminate both ends of the sheild, exactly how do you not use it as an EGC?

Steve
 
steve66 said:
If you terminate both ends of the sheild, exactly how do you not use it as an EGC?

Steve
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The shield grounding provides the capacitive charge drain. The shield grounding also provides an equipotential stress level around the circumference - and length - of the insualtion to avoid stress points that could provide oppurtunity to develop weakening spots on the insulation.

Although it is functionally capable of carying the fault current because it is connected to ground - not necessarily to the EGC bond, you want to force as much of the fault current to the EGC as possible - by providing a low impedance fault - as the thermal stress affects the insulation and the semiconductive layer's life.
 
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