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Buried ducts for medium voltage cables

vici
Hello everyone,


Is there any BS or IEC standard indicating typical configurations for multiple ducts buried in the ground? This is mainly in relation to medium voltage cables.


Specifically, I wondered if there was a standard giving guidance on typical arrangements used for multiple ducts to be laid in the ground (e.g ducts arrangement like 3 x 5 or 4 x 4) and backfilling material requirements (e.g. ducts surrounded by concrete or other back fill materials etc..). I am aware of all the minimum depths form the ground level, depending on the conditions (e.g. carriageways, footways, arable land etc..) but I wondered if there were also indications from BS or IEC documents for typical layouts / engineering solutions.


thank you
Parents
  • 0
    I am not sure if the plug-in power for London Underground trains that they use to move their trains once in depots (which for clear safety reasons wish not to have the rails as  live supply where folk are walking around trains, so they plug into cables on slider rails that run above, and isolate the pick-up shoes) will also be increased to 750V to match, or if the 630v supplies will stay for those short applications - though I imagine any change will be slow, after all each depot already has a local independaant supply anyway.


    Also the regenerative brakes mean that the voltage at the train can be 50 or so volts higher than the nominal line voltage when decelerating. Apparently regenerative braking is not permitted in a few places where there are escalator and lift motors running from the traction circuits - the fear being that if the escalator suddenly speeds up with a jerk as a train brakes to pull in to the station, it may cause injuries. In time all these will be phased out.




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  • 0
    I am not sure if the plug-in power for London Underground trains that they use to move their trains once in depots (which for clear safety reasons wish not to have the rails as  live supply where folk are walking around trains, so they plug into cables on slider rails that run above, and isolate the pick-up shoes) will also be increased to 750V to match, or if the 630v supplies will stay for those short applications - though I imagine any change will be slow, after all each depot already has a local independaant supply anyway.


    Also the regenerative brakes mean that the voltage at the train can be 50 or so volts higher than the nominal line voltage when decelerating. Apparently regenerative braking is not permitted in a few places where there are escalator and lift motors running from the traction circuits - the fear being that if the escalator suddenly speeds up with a jerk as a train brakes to pull in to the station, it may cause injuries. In time all these will be phased out.




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