Cord Management on Grid-Connected Electric Tractors and Mobile Equipment

[MossRoad]

Maybe they could set up some Tesla Towers like Wardenclyffe?

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[herm0016]

I wonder how much heat is generated in a KM long spool of wire with that much juice flowing through it? Wouldn’t it become a huge electromagnet?

Forget the cord, go microwave

Wireless power transfer - Wikipedia

en.m.wikipedia.org

yes, but not a strong one. the insulation keeps the charge density down.

we run 25000 feet of steel cable with a copper conductor down the center for servicing oil wells, wound up on a big steel drum. The drums can become weekly magnetic, but its never presented any issues. we run dc and ac power up to about 400 volts and fairly high current depending on the tools we are running in the well. there are either a single conductor or 7 depending on the services and such.

 

[Phil Timmons]

That's a 13 year old discussion. Technology has advanced. GPS is extremely accurate. The reel system VS a pivot or overhead wire system seems much simpler to control, less moving parts, no or less wear items on cables, etc.

We can't drag cables from a center pivot in row crops.

One more thing about overhear wiring systems. Crop dusting.

Yeah, have worked some variations over the years. Even some stuff with CAT (Caterpillar), JD, and others.

GPS has some applications, but so far just polar coordinates (circle, angle, radius) covers thing pretty well. Limitation on the all Cord, Cable, Hose methods is the Cord Management itself . . . which is sort of what this topic was started as.

The pivot is optimal for some sites -- especially where pivots already exists or will exist for irrigation. The power is already there and covers 100% of the area under the pivot. It drops pretty easy at or near the location needed.

As far as various spraying . . . most of what we are doing is heading for Organic rating -- so not so much. But you may know that Center Pivots and Tractor Booms are both used for this, as well.

 

[Phil Timmons]

With an overhead system, you'd need the additional costs of 4 towers, 1 at each field corner, 4 motor/winches for the overhead device, 4 cables that are long enough to span the entire field each, those cables would have to be strong enough to support wire that is heavy enough to provide the voltage to the tractor, and a 5th motor/winch to reel up the voltage cable. You'd also need electrical connections to each corner of the field. Then you'd need all of the controllers to operate all of it. And you'd need it at each field.

Whereas you'd only need 1 electrical connection at each field, 1 motor/winch on the tractor, and 1 electric cable if you did it the way in the original video.

Simpler is better, in this case.

Understood. Entertaining the various ideas for the purposes of brain-storming as it were.

Focus for the cord application (at least on our project(s)) are the irregular sites that not work well with other methods. Biggest torment are obstacles and how work around them. The reel methods offer some help for that, but this may become like the old Drag Line power cables -- sometimes you just have to go out and hand-drag things.

 

[cqaigy2]

I vote for the big Tesla towers with arcs going every which way. Might keep pest out of the field too. Operator would just have to remember to put on the faraday cage suit, clip on the big grounding wire, hop on the tractor, turn on the tower and hold on. Just remember to turn the tower off before unclipping.

 

[Phil Timmons]

I wonder how much heat is generated in a KM long spool of wire with that much juice flowing through it? Wouldn’t it become a huge electromagnet?

Forget the cord, go microwave

Wireless power transfer - Wikipedia

en.m.wikipedia.org

Good question and good caution.

I have been lazy at times when doing site "jumper" wires -- like maybe needing 200 feet and a having 500 roll of single wire -- so I just roll out some, leave most on the reel and jump from the ends -- hooking that in a circuit -- and YEAH! it makes a Choke / Induction Coil -- hums, gets warm, creates a voltage drop.

BUT -- that is not what is happening with a Cord. With a cord, BOTH legs (or sides, or hot + return) -- however you want to say this -- are coiled together with each other inside a cord -- so the field(s) created by the wires being in a coil shape pretty much cancel each other out. If you think about with signal wires you may played with -- they are sometimes even twisted together (called "twisted pair") -- that is make the overall loop(s) really tiny, and cancel out induction.

But as far as the overall Voltage Drop (the heat part of your question) is there whether stretched out straight or all rolled up. It is partly from the resistance of the wire, but much more so from the Amps (or Current or "I") going through the wire. Since we are trying to get power down range (Volts X Amps = Watts) -- we crank the Voltage UP, so we can keep the Amps DOWN. The heat loss equation is also in Watts (Amps ^2 X Resistance = Watts -- due to Heat Loss). Since Amps is squared in this case -- it is a HUGE factor.

That is why John Deere is running theirs at 2400 Volts. When Volts go UP, Amps can come DOWN.

Not sure if this one means 2400V Phase-to-ground, but if so, that means about 4000 Volts phase-to-phase. (always need to check that stuff when Europe is involved) And if that is 3 phase, we use SQRT(3) to average it out, 4000 V X 1.73 = 6900 effective volts. So going back to the JD claim of 200,000 watts at the tractor end (about 200 HP) -- means they are sending less than 30 amps down the cord (Watts = Volts X Amps) --> (200,000 = 4000 X 1.73 X Amps) . . . Amps = 28.9. So the low amps mean low heat loss in the cord, overall.

 

[herm0016]

the cord reel on the tractor makes sense. seems like there are other solutoins though. for the reel, does the tractor have to reverse the same path to reel it up without damaging crops? this seems like a huge waste of time.

 

[Phil Timmons]

the cord reel on the tractor makes sense. seems like there are other solutoins though. for the reel, does the tractor have to reverse the same path to reel it up without damaging crops? this seems like a huge waste of time.

That is one heart burn. If you look at the "app" that they are showing (inside the fake screen frame video ) that cord recovery path is part of what they are doing.

Part that is goofy to me is the travel from the barn to the field. You see they drive it out of the garage / barn on a cord. Mkay. And then they are somehow in a field -- probably edge of the field connected. Here is my question . . . when they got from the barn to field -- how did the unplug from the barn and then (what? drag? hand-carry?) the cord to plug-in site at the field? Or did they run this all from the barn and that is WHY they need a Kilometer of cord?

 

[MossRoad]

the cord reel on the tractor makes sense. seems like there are other solutoins though. for the reel, does the tractor have to reverse the same path to reel it up without damaging crops? this seems like a huge waste of time.

No, it doesn't have to reverse to reel it up. Let's say you're going forward. It lays the cable down on the right side outside of the path of the following implement. When you get to the end of the row, you turn 180 degrees to the right, and head back in the opposite direction, reeling up the cable as you go.

Watch the video in the first post. It shows how that works.

 

[MossRoad]

That is one heart burn. If you look at the "app" that they are showing (inside the fake screen frame video ) that cord recovery path is part of what they are doing.

Part that is goofy to me is the travel from the barn to the field. You see they drive it out of the garage / barn on a cord. Mkay. And then they are somehow in a field -- probably edge of the field connected. Here is my question . . . when they got from the barn to field -- how did the unplug from the barn and then (what? drag? hand-carry?) the cord to plug-in site at the field? Or did they run this all from the barn and that is WHY they need a Kilometer of cord?

A kilometer of cord is only 6/10 of a mile. Up here in northern Indiana, for example, most fields are divided into 80 acres. They're 1/2 mile long by 1/4 mile wide. So there's 8 - 80 acre fields in a square mile, or 640 acres. You could put 1 tap in the center of the square mile and hit all of the 640 acres with a 1 mile long cable if you went straight to an edge, then 90 degrees in either direction.

You'd only need 1 tap for every 640 acres.

Deere said in that video that the length of the cable is scalable. So it's very doable.