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dicklaxt
Guest
Here's the scenario.
Powerhouse, housing 13.8 Switchgear, elevated 6' above finished grade.
Okay so how do you want to run the feeder cables from the Switchgear to transformer HV chambers. This will be 3 phase 13.8KV shielded cable,the 6 transformers are 13.8-4.16 KV @ 20MVA each with a full height chamber from grade to above HV Bushings,removable door/cover.
Max feeder length to transformer #6 is 150' with 2 vertical 90's and 1 horizontal 90 when going UG,AG conduit run would probably have 2 additional 90's.Quick calcs on load at 125% is 1050 amps
Your options are :
1.Overhead in cable tray triplexed or multiconductor.
2.Rigid UG conduit with singles or multicondutor out the bottom of gear,UG encased in concrete and stubbing up into the HV chamber.
3.Direct buried cable either triplexed or multi conductors stubbing up into HV chamber using rigid conduit sleevs at both ends.
4.Overhead in rigid conduit out the bottom of bldg or thru wall,dropping down into the HV chamber.
I don't usually have these type options available as the plant specs always direct the design to be to their standards. This contract is very cost conscious and after safety and code requirements are met its potluck ,get it done, quick and cheap.The client has not specified a preference.
You as the field guy probably don't usually have this latitude either so lets make it easy on you too.
dick
Powerhouse, housing 13.8 Switchgear, elevated 6' above finished grade.
Okay so how do you want to run the feeder cables from the Switchgear to transformer HV chambers. This will be 3 phase 13.8KV shielded cable,the 6 transformers are 13.8-4.16 KV @ 20MVA each with a full height chamber from grade to above HV Bushings,removable door/cover.
Max feeder length to transformer #6 is 150' with 2 vertical 90's and 1 horizontal 90 when going UG,AG conduit run would probably have 2 additional 90's.Quick calcs on load at 125% is 1050 amps
Your options are :
1.Overhead in cable tray triplexed or multiconductor.
2.Rigid UG conduit with singles or multicondutor out the bottom of gear,UG encased in concrete and stubbing up into the HV chamber.
3.Direct buried cable either triplexed or multi conductors stubbing up into HV chamber using rigid conduit sleevs at both ends.
4.Overhead in rigid conduit out the bottom of bldg or thru wall,dropping down into the HV chamber.
I don't usually have these type options available as the plant specs always direct the design to be to their standards. This contract is very cost conscious and after safety and code requirements are met its potluck ,get it done, quick and cheap.The client has not specified a preference.
You as the field guy probably don't usually have this latitude either so lets make it easy on you too.
dick
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