Running Electrical 1000 ft to power a 1000W pump?

[DB2]

I need to run cable on a farm 1000 feet to a small pump system. The pump draws roughly 8.5A at 120V when running. It will run approximately 10 minutes per hour, 24 hours a day.

How do I determine what size cable etc to run, and what other equipment is needed? The pump's controller system is 120V, so I can't run it on 240V, but could I run 240V out and then step-down the voltage to the unit to minimize the cable size?

 

[mrb]

I would definetly run 240v out there and use a step down transformer. What does the pump draw when it starts? What runs it, a timer?

 

[ForceFed70]

What's a step down transformer worth?

At 240V with a 4.25amp draw and using a 12AWG conductor, you're still looking at over 30 volts of drop.

If you do use a step down transformer, see if you can get one that will compensate for the voltage drop (not a 2:1 transformer) Something like a 2:1.1

 

[mrb]

a 1kva 240 -120 transformer is going to be cheap -you can even grab one off ebay for $50-$100. to do this circuit without a transformer its going to take #3 copper. #6 copper (or #4 AL) with the transformer.

 

[ForceFed70]

a 1kva 240 -120 transformer is going to be cheap -you can even grab one off ebay for $50-$100. to do this circuit without a transformer its going to take #3 copper. #6 copper (or #4 AL) with the transformer.

Do they not sell a 2:1.1 transformer? Just wondering why you have to go to such a large conductor if you can compensate with the transformer ratio?

 

[mrb]

Do they not sell a 2:1.1 transformer? Just wondering why you have to go to such a large conductor if you can compensate with the transformer ratio?

larger transformers have taps on the primary to match the incoming voltage. Small transformers dont. You could use a buck boost transfomer to make up for the voltage drop, but it makes more sense to just do it right with proper sized wire. #4 AL is only going to be $0.20 something a foot. Figure 2x #4 @ 0.25/ft plus 1x #6 for the ground @ $0.20/ft = $0.70/ft. Add 1-1/4" SCH40 pvc conduit (you could put this in 1" but the cost difference isnt much and it will be easier to pull in a slightly larger conduit), the transformer, and the other stuff needed and the whole thing will cost around $1200.00.

The big question is: Can you keep this under 1000ft of wire? then you can get three 1000ft spools.

The pull wont be bad, just use lots of lube and have your feed set up well.

 

[mrb]

Do they not sell a 2:1.1 transformer? Just wondering why you have to go to such a large conductor if you can compensate with the transformer ratio?

the other thing is by trying to compensate for the VD in this fashion, the voltage will be quite high when the pump isnt running which could fry the controller. Best to just do it right.

then there's the issue of energy lost from the voltage drop. i havent calculated to see if its significant or not.

 

[Aceman]

the other thing is by trying to compensate for the VD in this fashion, the voltage will be quite high when the pump isnt running which could fry the controller. Best to just do it right.

What do you think would happen with no load using the buck boost you suggested?

You could use a buck boost transfomer to make up for the voltage drop, but it makes more sense to just do it right with proper sized wire.

I think the best thing to do would be to buy a 240v pump. Personally, I'd rather spend money buying a different pump than a stepdown transformer. It doesn't make sense to buy a transformer and have one more potential failure point in the system....

 

[mrb]

What do you think would happen with no load using the buck boost you suggested?



I think the best thing to do would be to buy a 240v pump. Personally, I'd rather spend money buying a different pump than a stepdown transformer. It doesn't make sense to buy a transformer and have one more potential failure point in the system....

right, no load on the buck boost would cause the same problem. Again, using transformer to boost the voltage to make up for vd isnt the best solution here.

the OP needs to compare the cost of transformer vs new pump.

 

[larry_g]

I'm curious what you are doing? what are you pumping, how much, 24/365 days per year? Could you do the job with a 12 or 24vdc motor and put a battery in the system then only have a circuit that would run a trickle charger to keep the battery charged. If I figured right you are using less than 200w per hour. That would be 80A from a battery at 12 vdc. You would need a charger of ~15A to keep ahead of the power usage. Convert that back to 120 volts and you have ~2 amp draw on the 120vac circuit. Some thing to consider. Also can you go to a smaller pump and run longer times?

lg
no neat sig line

 

[kbs2244]

I would go solar.
Either feeding a battery and an invertor, or switch to a 12 volt pump.