Long feed-line calculation
Long feed-line calculation
(OP)
Hi eveybody, I am new to this site and I really like the feedbacks of all involved. My question is: One of our customer wants to supply 240v to a remote (1200ft) location in open terrain using underground approved wiring to supply (2) 7 1/2 hp pumps located a few hundred feet apart. He has no 600v available, only a 600Amps 240v main. He wanted to buy (2) 600v to 240v transformers and connect the two 600v winding together to boost his voltage to 600v and down again to 240v to minimize line losses but I`m not sure it`s the best way to do it. I was inclined to suggest a big feedline but maybe somebody has a better idea.
Thank you all
Maurice442
Thank you all
Maurice442






RE: Long feed-line calculation
You may be able to get a transformer-manufacturer’s rep to help you with comparative calculations. Don't forget that starting and running are figured separately. Make sure you understand the figures he provides, and exactly what assumptions he made in the process.
Then do your own cost comparison versus "large" conductors. Aluminum cable may be cost effective, but I would not install any without hydraulic-compressed terminations.
Fifteen horsepower is not a large load compared to standard sizes of drytype transformers.
RE: Long feed-line calculation
Mike
RE: Long feed-line calculation
RE: Long feed-line calculation
I think the method to boost the voltage is better ,the current will be 23A for two pumps,and the distance (1200ft)is relevative long,you have to think about the line losses and voltage losses,the two pumps maybe not work propperly because of the voltage losses .and there maybe another choice ,the voltage you boost can be higher just depending on the prices of the transformer the line and future need of your client.
Jhone
RE: Long feed-line calculation
1. voltage drop during motor starting, about 6 time running curent, at low power factor starting conditions may not provide adequate torque to start the motors.
2. Transformers with taps provied some insurance of obtaining adequate voltage for operations.
3. Transformers decrease the operating and starting voltage drop with smaller wire due to the higher voltage.
Larger conductors without the step-up transformers fot this small loae will probably be less expensive to install and own.
You should consider open delta connection of transformers to reduce transformer cost if these are three phase motors. This may reduce transformer cost.
RE: Long feed-line calculation
Mike
RE: Long feed-line calculation
Depending on which voltage drop calculator i use it comes up to about 10-12 volts at 80 amps.
Thsi would work best a soft start for the pumps and that would take care of starting currents and water hammer. Your going to need some kind of starter anyway so buy one that does some good.
I the pumps are not already purchased the Soft starts have the capability to use three phase motors - which are cheaper and more reliable than single phase.
RE: Long feed-line calculation
If you are talking about three phases you may be ok with 3#6AWG
You MUST also THINK about GROUNDING that becomes a problem at this distance, adding transformer will let you ground the power at the remote location, which is vital for safety. You will safe $$ on grounding wire and have perfectly safe installation.
There is also a cost associated with sending electricity over 1200ft.
Use voltage drop calc from
http://members.rogers.com/g.cygalski/vdrop.htm
that will aid you do the math, and has built in all the data you will need
RE: Long feed-line calculation
RE: Long feed-line calculation
Best regards,
AAK
RE: Long feed-line calculation