Just a matter of curiosity, irrigation

around here there use to be a couple diesel powered pumps ... but any more they drop a 480v line to a  base where the pump / electric motor and control panel set..

Edited by steve(ill) - 19 hours 25 minutes ago at 1:11pm

That's why they have people smarter than me. If I did it it would look like a coiled snake taking a wizz!

Poor Ole farmers,,,,, getting those checks,,

Edited by DougG - 15 hours 10 minutes ago at 5:26pm

To keep it simple, I'll start off by saying there are exceptions to most everything, and newer control systems that use computing power. Most in my area run on 480v 3 phase with a transformer to supply a 110v control circuit. The 480 is swapped at the pivot to run either forward or reverse. There are seperate wires that go out for the forward and reverse control circuits, and each span has a control box with a contactor for the 480 and two microswitches that run on a cam that is attached by linkage to the next span. one of the microswitches has the forward and reverse conrol cicuits wired into the normal open and normal closed posts, and the common runs the contactor. When the next span out moves far enough it trips the switch so it moves until the switch is open again. The other microswitch is the safety circuit, if for some reason things don't move it opens the circuit and the machine shuts down. Most machines 20 years ago(when I took classes) were built so if 110v was sent back to the pivot on the control circuit that wasn't being used it would reverse the machine. Speed used to be controlled by a simple timer, most made now use a computer and can be set up to change the speed in different areas of the field.
T-L macines run on hydraulic, and have flow control valves on each span to keep them aligned, and the only one I had much experience with used a flow control valve at the end to control the speed.
Again most of my information is from many years ago, and there are several exceptions. I hope this answers your question.

Ted