Voltage Drop For Long Feeder

[faresos]

Hello everyone,

I have a situation where we have 1000kw generator feeding multiple buildings with emergency & standby loads and the furthest load (panel) is about 2000Ft. The loads varies but let say average of 400Amps with approximately 10% VD . Upsizing the feeders seems unparticle but will be our last reserve due to cost and termination challenges. I know I have seen designed overseas where they use transformers to boost the voltage to address voltage drop issues, not sure if that something we have here in the US. another option, is raising the generator voltage output but not sure what is the maximum setting we can do using this method. Any ideas on how to address this issue? Thanks,

 

[infinity]

Sounds like a higher voltage, smaller generator might be a better solution with transformers at the load end.

 

[faresos]

Sounds like a higher voltage, smaller generator might be a better solution with transformers at the load end.

I agree 100% with you and I thought of it as well initially but the client doesn't want MV generator for some reason.

 

[winnie]

Increasing voltage to overcome voltage drop is generally a bad choice, because when the load is low the voltage will become excessive. At most set your voltage to the maximum tolerance range of your supply.

What us the amp rating of the feeder? If you are allowing a steep 10% voltage drop, then you can go pretty far at 480V before you hit the voltage drop limit.

A 2000 foot 480V 500A three phase feeder built with 2x parallel 250kcmil Cu just hits 10% voltage drop.

Jonathan

 

[tortuga]

I agree 100% with you and I thought of it as well initially but the client doesn't want MV generator for some reason.

Whats the highest they are willing to go? I'd propose a 600V Genset.

 

[Julius Right]

According to ANSI C84.1 /2016 the Utilization voltage may be 504 V maximum for 480 V rated and 432 V minimum. So, if you may supply 504 V and if the current will be 0, the farthest point
will get 504 V it is still good. If the current decrease from 1200A to 400 A at the farthest point the voltage will be still 456V.