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Author Topic: 10Kw gen on lister 6/1  (Read 11733 times)

RhodesRoundtable

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Re: 10Kw gen on lister 6/1
« Reply #15 on: December 08, 2008, 01:32:36 AM »
matt,
not to be argumentative, but after consideration I concluded my question and input were pertinent to the thread. 1958steve is dealing with availability of a gen-head (specifically 10Kw). Therefore, it seems not at all like a change of topic. I would, however, like to adhere to forum etiquette and not step on the toes of veterans. Any agree it was not closely enough related, please let me know.

In any event, thanks for the link though matt.   
« Last Edit: December 08, 2008, 01:34:12 AM by obfuscation »
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matt

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Re: 10Kw gen on lister 6/1
« Reply #16 on: December 08, 2008, 12:40:37 PM »
Hi Obfuscation,

I didn't mean to come across authoratative. Sorry if I was.

I suggested a new thread because the Chicago Gen Head you mentioned is an interesting alternative to the ST, and if it had its own thread it would attract more attention and then the responces would be collated in the thread. This facilitates easier later recall when all the info is together.

I have seen this generator many times on the net under many different brand names, and I am curious as to what these are like in comparison to our beloved ST Gen Heads.

How much were they asking for it?

regards,
Matt

Tom

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Re: 10Kw gen on lister 6/1
« Reply #17 on: December 08, 2008, 05:19:05 PM »
The harbor freight head, being a 2 pole 3600 rpm unit, would require a 4" pulley that might not have sufficient to surface area to handle the load. And due to the much higher ratio needed to get the necessary rpm's needed is much more likely to flicker worse than a 4 pole head. That said some vendors are selling similar lash ups, but I don't believe we have had any comments from an actual user.
Tom
2004 Ashwamegh 6/1 #217 - ST5 just over 3k hours.

RhodesRoundtable

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Re: 10Kw gen on lister 6/1
« Reply #18 on: December 08, 2008, 08:23:47 PM »
Fair enough matt, thanks for the communication.
The current price is $320 in store no shipping (I guess STs are about $400)
http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=45416
They specify peak performance at 20HP.
HF and Northern Tool have been carrying these units for years and are probably the source for many net offers. I have seen them for around $289 last year. Also, they just sent me a 25% off coupon (usually 10%) that I let got to waste ($80 off that item for instance). If you are not familiar with harbor freight, they have very inexpensive tools, but they are cheap. China made really cheap stuff. One Note: There are 2 HF web sites http://www.harborfreight.com/
http://www.harborfreightusa.com/ (check the "see our current add on the left") They are, I'm told, independent and the former will almost always have higher prices. Below is an expansion on Tom's point about the 4" pulley and transmission loss problems that may be useful (accurate?). HF generator rpm requirements and drive ratio:
"A couple things to think about, 20hp @3600 rpm is the requirement to run it at full power (7200w). As for your setup, ie. 7 to one or 3 to 1, the hp requirements will change. Because you are stepping up, with 7 to 1 you need something like 140hp PTO hp to produce 7200w (60hp at 3 to 1). Likewise I would figure 20hp stepped up 7-1 would only produce something like 1000w before the tractor stalls. 20hp/7=3hp at gen, (6hp @ 3-1 ratio) figuring (7200w/20hp=360w per hp) You would be looken at 1080w and 2100w respectively. I am sure these are not exact figures and it does not mean it won't work. But if you are want 7200w you need the hp to get it (ie.. PTO hp x step up or an gen that will work at lower rpms). Regulation is another story and as stated in previous post, could be a real problem if your gov is not up to snuff. A miller 225 welder fit my needs just right at 7500w. But it has its own 20 hp twine cyl engine and internal reg. Good luck."

Best
Regards,
obfu
« Last Edit: December 08, 2008, 08:25:58 PM by obfuscation »
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SteveU.

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Re: 10Kw gen on lister 6/1
« Reply #19 on: December 08, 2008, 09:17:07 PM »
Sorry, your quoted source for the ratio change requiring higher HP to produce the same WATTS doesn't make sense. I'll leave that convincing up to others.

15-1800 versus 3600RPM has been debated many times.
Basicly you WILL never get more than you are willing to pay for. Two pole is almost always nonservicable throw-a-away. Four pole is servicable; give to your grand children. Your choice.
One factor I've never seen discussed:  noise.

My gen head was availabe as both 2 pole/3600 and 4pole/15-1800RPM.
The four pole in a full 15db quieter.  That is huge.
My set up will be open mounted in my shop as a power and space heat source. With a slow soothing proven quietable Lister/iod driving. Life in the slow low lane.
I have too many 3600-13000RPM  fast lane screamers already.

All my own opinions
SteveU.
« Last Edit: December 08, 2008, 09:20:20 PM by SteveU. »
Use it up. Wear it out. Make Do, or Do Without.
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rcavictim

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Re: 10Kw gen on lister 6/1
« Reply #20 on: December 08, 2008, 09:32:19 PM »
Sorry, your quoted source for the ratio change requiring higher HP to produce the same WATTS doesn't make sense. I'll leave that convincing up to others.

15-1800 versus 3600RPM has been debated many times.
Basicly you WILL never get more than you are willing to pay for. Two pole is almost always nonservicable throw-a-away. Four pole is servicable; give to your grand children. Your choice.
One factor I've never seen discussed:  noise.

My gen head was availabe as both 2 pole/3600 and 4pole/15-1800RPM.
The four pole in a full 15db quieter.  That is huge.
My set up will be open mounted in my shop as a power and space heat source. With a slow soothing proven quietable Lister/iod driving. Life in the slow low lane.
I have too many 3600-13000RPM  fast lane screamers already.

All my own opinions
SteveU.

Steve makes some good points about the RPM, longevity, serviceability, etc.  3600 RPM is good for intermittent use, throw away kitchen blenders.
-DIY 1.5L NA VW diesel genset - 9 kW 3-phase. Co-gen, dual  fuel
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oliver90owner

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Re: 10Kw gen on lister 6/1
« Reply #21 on: December 08, 2008, 11:05:34 PM »
Being as this has not really been addressed in this thread:

A couple things to think about, 20hp @3600 rpm is the requirement to run it at full power (7200w). As for your setup, ie. 7 to one or 3 to 1, the hp requirements will change. Because you are stepping up, with 7 to 1 you need something like 140hp PTO hp to produce 7200w (60hp at 3 to 1).

Put straight.  Pure and utter poppycock!  Sorry but you need to go back to the text books and basic mechanics. :)

Hp is a rate of doing work (about 750Watts or 750 Joules of energy per second). 7 times the energy would mean that 6 times the original work done would be lost in the process?  As heat?  I think not.  In any instance.

The torque would certainly change , which is a function of speed and power, but the rate of work will not change.  The losses will be in transferring the energy from a low speed shaft to a higher speed shaft - there will always be friction losses.

Losses in tight arcs with belts are well documented - that is why they use cut-away belts (to reduce the compressive forces as the belt is turned in a tight arc).  You may notice that a belt will run hot warm due to the friction in the sheave and the flexing of the material.  This is the main loss in transmission power for these systems.  It does not really make a lot of difference whether the small pulley is driving or driven.

The general rule of thumb we use is 2 horse power per 1 kW electrical output.  This works for the normal run-of-the-mill set-ups we find in most places. 

This one recommends 20HP for 7.2kW or near 2.8Hp per kW. ! >:( That would seem to indicate a poor efficiency performance of the generator and probably reflects high copper losses (heat lost in the windings due to I2R and Ohms Law - due to skimping on the winding wire (cross sectional area).  More heat losses then means more cooling required and so leads to a larger fan and consequent power losses along with increased noise levels.  Also increases the likliehood of a burn out. It also reduces any transient overload ability that is useful for starting motor loads.

SteveU is about right re the quality and longevity.

Certainly for anyone running any appreciable hours, a 35% increase in fuel costs is a convincing argument for paying extra and recouping that extra capital cost while still having a serviceable unit at the end of the period, or the then continuing lower running costs.  A balance of short term gains over long term losses.  That unit appears to be little better than automotive alternator generators which are around 50% efficient (and efficiency falls as they get hotter)

Please imagine a step-up gearbox.  It would not use seven times the power to achieve its rated output.  It would soon glow red hot!!  Many tractor driven generators use a 3:1 increase in speed and some use 6:1.

Hope this does not deter you from posting but you do need to understand the difference between torque, power, energy, etc.

Regards, RAB

RhodesRoundtable

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Re: 10Kw gen on lister 6/1
« Reply #22 on: December 09, 2008, 02:49:57 AM »
Well, I guess that sets that straight!
Thanks Oliver
Evidently I didn't give enough credit to where I took this from, hence the peren (accurate?)
It sounded off, that is one reason I put it out there. I figured there could be something in tractor PTO's that I was clueless about. I See it failed your guys test. "poppycock! "  ;D
I did put it in quotes but I should have tagged the link
Post by Errin OH
http://www.ytmag.com/cgi-bin/viewit.cgi?bd=ttalk&th=326232

I appreciate straight talk even when the straight/crooked talkin is completely wrong, at least it is honest. Apparently no one was there to set this guy right, as I'm lucky enough to have here.
I know very little about this kind of stuff comparatively, and less about text books and basic mechanics. A somewhat light green, if you will. Most everything I know about this sort of thing is self taught, so I appreciate the expertise I have especially noted on this forum.
cheers

When people who are honestly mistaken learn the truth, they will either cease being mistaken, or cease being honest! – Anonymous

lowspeedlife

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Re: 10Kw gen on lister 6/1
« Reply #23 on: December 30, 2008, 01:14:13 AM »
I followed that link & it appears that someone did inform errin of his computational errors way back in febuary 2003, our very own RAB !! although he didn't use the word poppycock !!

     scott r.

Scott R.

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