Long Distance Power Run

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138lawfull

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I have an oppertunity to bid a job on on some pumps that require 480V, 3 Phase. The run is 1 mile 5300 feet (+ -). I was thinking dirrect burrial 250MCM AL. Anybody have any experiance doing such a job? Found a great site for voltage drop(www.csgnetwork/voltagedropcalc.html). Anyone ever trench that far in easy soil?
How long do you think it may take to trench that far? Any imput would be helpful.
Thanks,
Terry.
 
I would be curious on size of pumps as well and is it multiple along the 5300ft run or are they at the end... I have done some in the past not quite a mile but pretty close however they were not permanent.
 
1.6 KM ?? that pretty loooonnnggggg strech run there.

any chance there is a POCO grid near by that loaction ??

sometime it can be much cheaper just get the POCO to drop a line. it will really reduce the voltage drop very easly espceally with that kind of distance.

Merci, Marc
 
138lawfull said:
I have an oppertunity to bid a job on on some pumps that require 480V, 3 Phase. The run is 1 mile 5300 feet (+ -). I was thinking dirrect burrial 250MCM AL. Anybody have any experiance doing such a job? Found a great site for voltage drop(www.csgnetwork/voltagedropcalc.html). Anyone ever trench that far in easy soil?
How long do you think it may take to trench that far? Any imput would be helpful.
Thanks,
Terry.
Click to expand...

Why would you even think of doing by hand ?
 
Long Distance Power Run

I need to run a 480 volt, 3 phase, line 5500 feet (1 mile). The load is 100 amp. Anybody with any experience in long runs?
 
I just assumed he meant with a ditch witch. For me to dig a trench a mile long by hand would take the rest of my life.
 
well seeing that this is a duplicate post.
In your first post you said 100amps at 480 volt , this would mean 250 mcm AL. is not going to cut it.

3 conductor(s) per phase utilizing a 1000 kcmil Aluminum conductor will limit the voltage drop to 2.67% or less when supplying 100 amps for 5500 feet on a 480 volt system.

For Engineering Information:

445 Amps Rated ampacity of selected conductor
0.027 Ohms Resistance (Ohms per 1000 feet)
0.037 Ohms Reactance (Ohms per 1000 feet)
14.4 volts maximum allowable voltage drop at 3%
2.67 Actual voltage drop loss for each cable at 2.67%
38.52 volts Total maximum allowable parallel voltage drop loss for the circuit
0.9 Power Factor
 
The last time I had to deal with that type of distance, we stepped up the voltage to 600V (higher voltage = lowercurrent = less voltage drop) and then back down once we got to the load. We also used a soft-start to further reduce the voltage drop during start-up. A VFD may also be able to run with a voltage as low 400V, it depends on the model.
 
Looks like you have some expert help with the engineering part. Need some more information on the trenching part.. What kind of climate are you in( possible frozen ground)? Will you need to cross any streams or roadways? Don't forget seed and straw... Always use a Rock Clause and get Utilities Marked before you dig.
 
Terry, I think I would sub it out and put 30% on top, If I got the job good, if

not, oh well.

Also, have you thought about Pole Line Construction, the reason I ask is once

that wire is buried there's no recourse, I can see a MV line with a trans. at

the end to feed your pumps. JMO
 
Even at only 100 amps, that'd be pretty good sized wire. And expensive!! Consider xfmrs at both ends. 480 to 4160, then back down at the other end. 75KVA will do. (90 amps at 480 3PH). The 5KV wire will be #8. It'll pull easy, and might make up the cost of huge 600V wire. Especially if labor is factored in. Very common at airports, where the distance can exceed 2 miles.

If the load is constant, you could design in substantial voltage drop, and boost it up at the supply end to compensate. this will only work with a constant load though.
 
I realize you are new to the Forum, Welcome !!, along with that I'll say it's

not cool to ask the same question in different Forum sections, O.K.

thanks
 
Keep in mind that a motor is a transformer; you can step the voltage up and then use a higher voltage motor rather than stepping back down.

-Jon
 
micromind said:
Even at only 100 amps, that'd be pretty good sized wire. And expensive!! Consider xfmrs at both ends. 480 to 4160, then back down at the other end. 75KVA will do. (90 amps at 480 3PH). The 5KV wire will be #8. It'll pull easy, and might make up the cost of huge 600V wire. Especially if labor is factored in. Very common at airports, where the distance can exceed 2 miles.

If the load is constant, you could design in substantial voltage drop, and boost it up at the supply end to compensate. this will only work with a constant load though.
Click to expand...

The transformer would need to be larger then 75KVA unless you put on either a reduced voltage starter or VFD. Which one will depend on your starting torque. Pad mounted transformers are relatively inexpensive, as it goes. Also could use poles at about $5k a pop, but OP didn't say whether it had to be UG or not.
 
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