Feeder for shore power

[nickelec]

I'm trying to calculate the size of a wire I would need for a feeder. I need to run about 2500 ft at 277 480 volts to a step down 120 208 transformer and get 200 amps on the secondary

I'm having a brain fart on how to calculate the size of the primaries

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[zbang]

That's a looong run at 480. I assume you mean to calc the size with only maybe a 5% drop?

 

[tom baker]

Find the primary current, use it to calculate primary wire size and adjust for voltage drop

 

[nickelec]

That's a looong run at 480. I assume you mean to calc the size with only maybe a 5% drop?

Yes 5% and it's a very long run 480 is the only thing that's available there

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[nickelec]

Does it pay to use the step up transformer and then another step down at the end

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[tom baker]

We have seen similar long circuit questions before and often the solution is to use MV

 

[nickelec]

Could that even be done 480 stepped up to MV. I've never done that before..

Just trying to help a customer out with some viable options

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[zbang]

Could that even be done 480 stepped up to MV. I've never done that before..

Not uncommon and for half a mile, might well be worth it, but you have to do the pricing exercise to know. Also depends on whether you can/are allowed to run MV around, could be a local restriction or no good place to put the cables.

Is this going in pipe or overhead? Much easier to do MV if it's overhead.

 

[augie47]

"Shore Power" = Marina or Dock
55.4 in the '17 prohibits over 1000 volt