Size of generator for a large electric motor

[David Standing 1Participant @davidstanding1]

Posted by JasonB on 18/09/2017 20:00:43:

Posted by David Standing 1 on 18/09/2017 19:54:21:

Jeff

Ah, but is it grain crushing, or milling? Two totally different things………

As I said above, the requirement is far from clear, so this just becomes a thread of endless guessing

Does it matter what the use is. Original question was what size generator is required for a 200Kw motor. That would require a 300KVA genny to give a bit to play with.

Jason

As I do have some farming background, yes it quite possibly might. They are totally different operations.

What would be really nice would be a clear understanding of the actual requirement, then the OP might get some accurate suggestions for a solution

[Peter G. ShawParticipant @peterg-shaw75338]

David,

A subsoiler. Not a big deal, every farm has one

Well, if he goes around using one, then that suggests that farms up here in Cumbria don't all have one.

Muzzer,

They do indeed have at least one John Deere

They've had a number of tractors – Same, McCormick, John Deere that I know of. My understanding is that the expected life of a tractor is 5000 hours and after that it's worn out. I don't know what the current situation is – all I know is that occasionally either of the grandsons may turn up at their home on one when I'm there and when I go and look they are huge. After all, with rear tyres approaching my rather meagre height of 5'6" and a set of steps to get into the cab. I was surprised a short time ago to find that one of them had either two generators or two hydraulic pumps, I forget which, but it shows what the power requirements can be to require two because one isn't enough.

Interestingly, they do all sorts of agricultural jobs and travel far and wide to do it. Which suggests to me that there is obviously a demand for the services they offer.

Cheers,

Peter G. Shaw

[Peter G. ShawParticipant @peterg-shaw75338]

Well, I see that a few more replies have arrived since my last post.

I've always had it described to me as "crushing". And Jamie himself said "Grain Crusher" earlier this evening. I've no recollection of hearing the term "milling". There is one other phrase which I think I may have heard in connection with this, and that may be "drying". Perhaps someone might know if this machinery can also dry the grain? In which case might this be the reason for the high power requirements.

Jeff,

At the moment, it's just an idea. Now fair enough, the costs of setting it up may well put it out of bounds, but if he doesn't look into it, he'll never know.

I have to say that ever since his Dad set up the company, I've been amazed at the equipment he's amassed and used. As I said above, there is obviously a demand for their services and they are never short of work so in this instance, either local (define local!) fixed milling/crushing firms are overloaded or there are insufficient, but whatever it is, they are making a go of it, and have done for quite afew years now.

Jamie has been advised of this thread. I'm hopeful that once he's read it, he will come back and supply more details, HINT, HINT, JAMIE!

Regards, and thanks,

Peter G. Shaw

[David Standing 1Participant @davidstanding1]

Peter

Grain does indeed get dried to reduce the moisture content (which can make the grain rot if not reduced), but the equipment for this is not directly connected in any way to that for crushing or milling……….

As to travelling far and wide, a number of farming contractors farm on behalf of tenant or owner farmers, who, for a whole number of reasons, do not, or cannot, farm their own land; and in that process can cover a wide area.

[Peter G. ShawParticipant @peterg-shaw75338]

David,

Thanks for the clarification. The fact that I've heard about it suggests that they either have had, or still have such a machine.

In respect of your 2nd paragraph, I don't think that's the case as I know they have done work for what could be described as non-agricultural organizations. Also, I've never heard them saying anything along those lines. But who knows, I certainly am not aware of all that they do.

Peter G. Shaw

[Steve PaveyParticipant @stevepavey65865]

As a (former) agricultural engineer, working in the machinery field, and for the Electricity Council for some of that time, this is typical of the problems faced when powering large items of static agricultural machinery. To be honest, Paul Whitley has hit the nail on the head with his suggestion of using a static Diesel engine to replace the tractor pto if we are actually talking about a single item of machinery.

There are several reasons for not pursuing the home-brew generator – obviously the generator / electric motor appear to be redundant additions, but also there is the added cost of the electrical control gear and cabling, plus the cost of ensuring it is electrically safe in what is usually a fairly hostile environment. Against that, there may be reasons for wanting an electric motor – maybe the power and torque characteristics, or the ease of control, or the need for more than one motor – all could be compelling enough to warrant the extra cost of a generator setup.

As others have said, much more information is required. I have a feeling that the application is more involved than just a simple engine-generator-motor setup.

Edited By Steve Pavey on 18/09/2017 21:44:53

[Bodger BrianParticipant @bodgerbrian]

Posted by Muzzer on 18/09/2017 19:41:11:

(Some) farmers are funny buggers and stick to one brand.

Eminently sensible, I would say. When you're in the thick of harvest or some such time/weather dependent operation and something breaks, you need a local dealer for your particular make of machinery, not someone 2 hours away. When I was growing up on my father's farm, the majority of farms in the area had Fords, as that was what was available without going stupid distances.

Brian

[FarmboyParticipant @farmboy]

Doesn't seem a great idea to have to two stages of power-sapping conversion between engine and machine, unless the generator will be running several other things too.

In that part of the country I would guess they're crushing grain, probably on a daily basis, to feed livestock.

The simplest and cheapest way to get a large diesel is often to buy an oldish tractor. The engines usually go on for ever if they've been reasonably well maintained because they generally work as they were intended to, under load for long periods at proper working temperature. You often see pensioned off tractors driving stationary machines like mills, pumps, etc. And in an emergency you can always swap in a different tractor to keep things running . . . livestock don't appreciate 'downtime', they like their meals on time . . .

[J HancockParticipant @jhancock95746]

If access to the pto is the problem, try a hydraulic drive motor , then flexy pipes to the tractor pump outlet.

[MuzzerParticipant @muzzer]

Posted by David Standing 1 on 18/09/2017 21:24:05:

Peter

Grain does indeed get dried to reduce the moisture content (which can make the grain rot if not reduced), but the equipment for this is not directly connected in any way to that for crushing or milling……….

As to travelling far and wide, a number of farming contractors farm on behalf of tenant or owner farmers, who, for a whole number of reasons, do not, or cannot, farm their own land; and in that process can cover a wide area.

My cousin in the Scottish Borders exclusively grows barley and it ends up in beer. It's essentially sold before it's even planted, as long as the moisture content is below the required threshold. Harvest it too soon and it's too moist, leave it too late and you can get wind and rain damage. It's not unusual to need some drying which requires little more than a few piddly fans blowing air through the grain piles.

The combines (contractors) gradually work their way up the country from the South, following the grain as it matures. Finally they arrive at the Borders sometime around August IIRC and they put in long stints until the job is done. It's very seasonal work and he certainly used to have a fair bit of time for rugby etc.

Murray

[Neil WyattModerator @neilwyatt]

Posted by Jeff Dayman on 18/09/2017 19:51:22:

Whatever way you slice it, to build a high HP machine such as is being discussed is likely not going to be cheap. Unless they are in a very remote area or have an enormous qty of crop to process, I'd recommend getting quotes from local milling firms for the grain crushing.

If it frees up a tractors a £5K motor is cheap…

[Neil WyattModerator @neilwyatt]

Posted by Peter G. Shaw on 18/09/2017 20:51:00:

They've had a number of tractors – Same, McCormick, John Deere that I know of. My understanding is that the expected life of a tractor is 5000 hours and after that it's worn out.

One of the strangest jobs I have ever done is telephone interviewing dozens of farmers about their tractors.

Most of them had several tractors but the one thing that stuck in my mind was that a few of them were reporting old tractors (usually fergies) with upwards of forty thousand hours. That's four years of continuous running…!

Neil

[Phil WhitleyParticipant @philwhitley94135]

A search on "grain crusher" brings up nothing but the standard two types of agricultural milling machine, the rolling mill,and the hammer mill, usually about 3hp requirement, They can produce about 2 tons per hour of crushed grain for animal feed. I worked on some milling and mixing plant at Bradshaws animal feed mill, and the mixer had the biggest power requirement. It mixed animal feed in 10 ton batches, and was powered by a 175 hp motor. The tractors used on farms to do the really heavy work are getting more and more powerful, but when you see the size of the implements they attach, it is not surprising that they need that power. Most of the rock crushers we used to service at the now defunct Hoveringham Gravels, were between 40 and 100 HP. Can we see a pic of this machine?

[FarmboyParticipant @farmboy]

Continuing with the pointless speculation it is possible the machine is currently driven by a 200+HP tractor but only actually using a fraction of that power. We've all done it.

[Andrew TinsleyParticipant @andrewtinsley63637]

Blimey this is the other end of engineering, hardly model engineering, but interesting to follow.

Andrew.

[Howard LewisParticipant @howardlewis46836]

Second for direct drive. In that way you eliminate the losses in the Alternator, and in the Electric Motor. Likely scenario is that about 65% of what comes out of the flywheel will actually find way to the machine using Diesel/Electric drive. (Assuming circa 80% efficiency in each electrical machine) Only advantage is that, if needed the genset can be remote from the machine.

So for direct drive,( to replace a 200Kw Electric Motor) you are looking at about 160 -170Kw from the engine. This should be achievable with a turbocharged / chargecooled engine of about 7 -8 litres, running at 2,000 or more rpm, with speed reduced by gearing or multiple belts, to the 500 rpm required by the machine. If it has been driven by a tractor, it must have been quite a big one (possibly V8 engined?) to have that sort of power available at the PTO, (which was probably 540 rpm PTO shaft speed).

If you persist with Diesel/Electric power, since the motor is AC, the engine and hence the Alternator speed will need to be controlled to within 5%, to maintain a reasonably stable frequency, and therefore motor speed. So any old engine won't do, it will need to be more closely governed than even a Combine Harvester engine. Literally, a tight governed genset control set up. Changing the fuel pump, high pressure pipes and injectors to achieve this could be an expensive, and possibly not totally straightforward, job.

A new purpose built genset of this power would be even more costly. (It would have to have a bigger engine, something of the order of 250Kw at 1,500 rpm, for 50Hz, to compensate for the electrical losses)

Howard

[Peter G. ShawParticipant @peterg-shaw75338]

Hi folks,

I get the impression that Jamie, when he's employed on crushing, spends a lot of time doing nothing while the machine works away by itself, and hence he started wondering about the requirements to free up a tractor. Apparently his idea would be to mount the electric motor on the crusher with the genny as a standalone piece of kit. He rang me just to try his thoughts on me, and of course it's way outside my realm of knowledge, hence my suggestion of asking the question that I did here. I did this, and this is in reply to Andrew Tinsley, because one thing I've learned is that there are a lot of very knowledgable people frequenting this forum, and although I freely admit it's nothing to do with model engineering, it's quite obvious that these knowledgable people do not seem to mind giving their thoughts. I'll go further, and say that in my experience over the last 50+ years, most people do not mind sharing their knowledge. True, there are some awkward people who wouldn't give their grandma the time of day but then I wouldn't expect them to appear on a forum such as this.

Jamie's had a read of this thread, and gone away to ponder further! I really don't know now what he'll do, so really, that's the end of it for me.

Now, there has been talk of the actual requirements for building it. This may help. Jamie is 22 and on leaving school went to Newton Rigg Agricultural College for two years where he learnt all about servicing and repairing agricultural machinery. (And other stuff I believe.) His brother, nearly 20, on leaving school obtained a job as a trainee mechanical engineer. He is in the third year of a mechanical engineering college course leading, I think to HNC. Amongst other things he has learned welding, and last year he got this: "Pearson BTEC Level3 Diploma in Operations and Maintenance Engineering". Both lads have been/still are members of the local Young Farmers and have been involved in making all sorts of strange items. It seems to me that between them, other than the electrical connection side of things, they will be quite capable of building this thing themselves, that is, if it comes off.

On a personal note, I've been rather surprised at the response my initial post has generated. I'd like to thank all of you for your thoughts.

Neil,

Little Grey Fergies. Learned to drive on one of those at age 13. Could write reams about what I did with it. And the MF65 that replaced it. Happy times in what seems now to be a different life. Memories!!!

Regards to all,

Peter G. Shaw

Edited to add note about Fergies.

Edited By Peter G. Shaw on 19/09/2017 21:11:37

[Steve PaveyParticipant @stevepavey65865]

But we're still no closer to finding out exactly what this machine actually does. Can you find out for us?

[not done it yetParticipant @notdoneityet]

Tractors don't drive machinery with old 6 splined pto at 540 rpm when the power transmitted gets to around a 100HP. They then use 1000rpm with about 20 splines. I'm not even sure what they use on the really high power tractors.

I think the OP is perhaps a bit overawed at the farm machinery he has seen. I think silage choppers are now about 800HP, perhaps even 1000HP. My brother hedge cuts with around 150HP – and that has a reach of about 8 metres, I think

[MeunierParticipant @meunier]

Almost on thread for once, the harvester has just left the field opposite after cutting the sunflower crop. Wasn't sure whether to post in here or the motorcycle thread as it was a big red Laverda – that's a blast from the past.. I stopped the contractor on his big tractor one day out of curiosity and asked him what HP it was – 300HP he said – not surprised as he ploughs six furrows abreast with it in clay-ish soil going uphill.
DaveD

[Neil WyattModerator @neilwyatt]

Strike me that efficiency and expense are unlikely to be significant considerations, if it frees up a man and a tractor. Mind you my recommendation would be to work out the minimum required HP and buy and old hack that's one step from being relegated to cleaning out silage clamps as at least it will be able to move itself.

The trouble is, if you ask this lot for advice, they will debate several alternative purposes for the equipment, none of which is right, but decide the proposed solution isn't suitable and recommend a portable steam engine as the best solution

[Nick_GParticipant @nick_g]

Posted by Neil Wyatt on 20/09/2017 22:20:54:

and recommend a portable steam engine as the best solution

.

But then, and only then, if said steam engine had been made on a myfud.

Nick

[FarmboyParticipant @farmboy]

"efficiency and expense are unlikely to be significant considerations" . . .

Have you ever tried extracting money from a farmer? If 200KVA is really needed he could be parting with £20k at least for a motor & diesel generator setup, judging by what's available at online auction sites.

"… spends a lot of time doing nothing while the machine works away by itself"

Probably true, but leaving it alone for a while can prove expensive. A 200HP machine can do a lot of damage when something goes wrong!

PS My crusher and hammermill were both driven by flat belt from a 40HP Field Marshall tractor . . . not at the same time

Edited By Farmboy on 21/09/2017 00:11:41

[Antony PowellParticipant @antonypowell28169]

Can't you get a grant of the EU to pay for it ??

[Clive HartlandParticipant @clivehartland94829]

By hiring a suitable generator you do not have to worry about maintenance, Here in Medway there is a local Genny hire firm who supply Hospitals with standby genniies.

Also supply to the local shopping center.

Or, buy surplus and couple them up to get the power you want.

Clive

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