MV Feeder in RSC

[rayramgar]

Can anyone please comment on a situation as follows. I have a Medium Voltage feeder at 34.5KV using 3-80mmsq (AWG 3/0)XLPE cables run in 3-100mm (4inch) dia RSC. That is, one XLPE cable in a RSC. The shield of the XLPE is bonded to the ground at both ends.
Querries: What are the consequences in this installation? Will there be inductive heating considering 60Amps ruun in each cable? What are the code provision related in this installation? Any code violations?
Thanks.

 

[don_resqcapt19]

Re: MV Feeder in RSC

Ray,
Are you saying that you have a single conductor in each of the 3 raceways? That is a violation of 300.3(B) and will cause serious inductive heating of the raceways.
Don

 

[drmoody]

Re: MV Feeder in RSC

See 300.3(B) and 300.5(A). The conductors in different raceways will cause severe hysteretic effects that will cause additional heating as well as degrade your cable insulation. This happens because the magnetism that is created (greater in rigid conduit) can?t remain in the same ?time? with the alternating magnetic fields. If you cover it with concrete, the effects are worsened. I have never seen an installation like you describe and I certainly wouldn't do it.

Brian

[ March 03, 2004, 11:03 AM: Message edited by: drmoody ]

 

[roger]

Re: MV Feeder in RSC

Ray you asked a similar question yesterday, and I gave you code references as well as Don and Brian have here. may I ask what your consulting capacities are?

Medium voltages (not down playing lower voltages) should be left to the trained professionals.

Roger