Author Topic: HELP,I HAVE SOME QUESTIONS FOR THE FORUM GENERATOR GODS!  (Read 10274 times)

Bluecometk

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HELP,I HAVE SOME QUESTIONS FOR THE FORUM GENERATOR GODS!
« on: May 27, 2007, 01:06:21 AM »
I am building a back-up Generator using a 10HP @ 3600 RPM Yanmar diesel and a Chinese ST type 8 KW  @1800 RPM Gen head. I have a Gates PowerGrip GT 2 Sprocket drive belt and sprocket system which is roughly 2 to 1(Drive/Driven)
Drive size 2.206/Driven 4.411. I have been building it for about 3 months on the weekends. What's taking so long is #1 I'm slow at building stuff, #2 Roller frame, custom gen/belt screw adjuster, battery box, tank over Gen head   mount, noise/ weather enclosure and onboard electric panel/control panel, #3 interruptions from honey dew list!

I'm fabricating everything first and trying it out, then I will tear it apart and paint/powder coat it all. At that time, I will take the Gen head apart and perform all of the tips and modifications I have learned from the forum and order the Utterpower CD and rectifier kit.

Today was first start up day. Engine, Gen, drive system, frame, just to make sure my theory worked. Well, it didn't go as planned. According to the engine manufacturer the linkage is set for 3600 RPM @ the linkage W.O.T. position. I have no real way to tell if it attained that RPM yet. I was going to use the generator voltage output, but that was only going up to 236 volts and it was wavering at that rate. I then put a makeshift 4 position 120v receptacle on the side of the gen head and plugged in 4200 Watts and the voltage went down to 100v on that leg. The engine hardly even changed notes and the rack arm moved open about a 1/32 of an inch. I don't think the engine was even laboring at all.

Now to the questions.
  Do you think I need to spin the head faster?

  Do you think I made a valid test by only using 1 leg of the gen @ 120V and not both legs and spreading the 4220 Watt       
   load out on 2 separate recepticals/120V legs?

 With the feeble attempt at information I gave you, can you determine if I can lower my engine rpm (10hp@ 3600/9HP@3000RPM) while increasing my Gen head rpm if needed? Ratio/sprocket changes are not a problem just expensive.

1.899 to 1    gen rpm 1800   engine RPM  3402
                               1,900                      3,591

1.759  to 1    gen rpm 1,800     eng RPM   3,166
                                1,900                      3,342

1.691 to 1    Gen rpm 1,800     eng RPM   3,042
                                1,900                      3,211

With the info above, if I run the Gen head at a projected target speed of 1850 rpm to attain my loaded voltage, will I have enough horsepower to get the rated 8KW with the ratios I have given you?
The engineer at Gates thinks I should be able to run it at the 1.691 ratio and still have 1.5 to 2.0 HP in reserve. What do you think? He had never been asked this type of generator drive system question before and was only venturing a guess.
He also said that the sprocket system I have has an extremely low parasitic HP draw on the engine.

Thank you in advance for any assistance you may be able to give me, it will be much appreciated!!

Bluecometk
Bluecometk

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ronmar

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Re: HELP,I HAVE SOME QUESTIONS FOR THE FORUM GENERATOR GODS!
« Reply #1 on: May 27, 2007, 03:08:57 AM »
A single phase 8KW 240VAC is good for 8KW across the 240 connections or 4KW per 120VAC leg.  Throwing more than 4KW onto one leg was overloading that leg and would explain the voltage drop.  An 8KW 3 phase head would only be good for 2.66KW, or 1/3 total rated capacity, per 120VAC leg.

You really need a frequency meter to set up the proper running RPM of the set.  60HZ measured on the voltage output will be 1800 generator RPM.  If using the panel meter that came with the ST head, you could see significant error in the indicated voltage as they are pretty low quality.  At any rate, you always want to set the engine RPM by frequency.  A Kill-A-Watt works great for this at a reasonable cost, or a digital voltmeter with a HZ setting.  Since the ST is non regulated and harmonically excited, they will experience significant voltage droop.  You actually want to set the output frequency/RPM a little high at 61-62 HZ.  This will give you a slightly higher output voltage around 125VAC per leg.  If everything is setup well, at 1/2 load, 2KW per leg, you should be right around 120VAC per leg.  At full load you will see perhaps 115VAC.  I would expect the engine RPM to droop a little as the load increases so this usually works out well.  there is a lot of excellent information about the St heads at www.utterpower.com.

With a 10HP engine and a 8KW head, you are only allowing 1.25HP per KW at full generator output.  That figure seems low from my experience.  It is usually a much higher 1.75-2.0 HP/KW for engine longevity.  Your highest ratio shown in your post only shows 3400Engine RPM with the generator at 60HZ/1800RPM so you are not even delivering the full rated HP from the engine.  Available HP decreases with altitude above sea level so if you are at any appreciable altitude then your generation capacity will also decrease.  I don't think you will achieve the full 8KW out of the head without overloading the engine.  I think 5-6KW is a more realistic figure for 10HP.  Any more and you will most likly experience cooling and engine reliability issues.  I am running a ST-5 with a 6/1 listeroid.  The flywheels give it a good surge capacity for starting motors, but it is only good for around 3KW continous output a that HP. 

Post some pictures of your setup.

Good Luck     

Ron 
« Last Edit: May 27, 2007, 03:39:16 AM by ronmar »
PS 6/1 - ST-5.

Doug

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Re: HELP,I HAVE SOME QUESTIONS FOR THE FORUM GENERATOR GODS!
« Reply #2 on: May 27, 2007, 04:00:29 AM »
Personaly I think buying the Utterpower CD is a waste of time ( and the kit for that matter ).....

136 v no load is a bit low but not by much, personaly I would expect inthe 145 range NL....

Check to see your head has the proper connections.
Test your rectifier bridge.

I'll provide you with part number for a bridge rectifier I use industrial switch gear that has proven itself reliable if you like ( need double check with my stock code for the number ).

All syncronous machines have a high output impeadence, the whole point behind the harmonic winding ( if you look closely you will see there are infact two sets of coils ) is to provide a base excitation and load compensation. Now if something is wrong with your rectifire or connections that might explain a lot
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mobile_bob

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Re: HELP,I HAVE SOME QUESTIONS FOR THE FORUM GENERATOR GODS!
« Reply #3 on: May 27, 2007, 10:11:47 AM »
i will side with ronmar on this one and part company with doug

1. the utterpower cd is of significant value to just about anyone on various levels and at various levels of experience
    think what you like of George but he has put alot of effort in collecting the info contained on that cd and for the
    money it is well worth the expense. unless you are very well experienced in all that is lister, changfa, and st head.
    Even then my bet is there is at least one thing on that cd that you will learn, and that one thing is worth the price of
    admission.

2. George's kit is fairly priced for what one has to do to produce and sell one, sure you can build one yourself if you are so
    inclined, if not then there is one available to purchase. i am unaware of any other dealers supplying this and other parts
    to the diy guy.

    i figure why not support those that actively try to support the cause?
    its ok to be a cheap, tightass old bastard,, we can all be that way, but why deny someone from trying to cover expenses?
    if George makes a buck it gets reinvested in development of other stuff folks need or want.


as for you genhead, you are certainly overloading it at 4200 watt on one leg, the harmonic winding probably cannot compensate for
this much load,, with your setup at 3600rpm i would be surprised if it will carry much more than 2500 watts per leg reliably, and that is at sea
level, derate 3% per thousand feet above sea level is a good rule of thumb.

so i guess i would start there, figure out how much below 2500 watts per leg you can realistically pull, and apply that load and see how it does
i would expect ~130 volts no load and as ronmar has said somthing around 110-115 at full load

if you tried to pull 4200 off one leg, then going down to ~100 volts on that leg would be expected and normal operation, albeit out of range
because of overloading,,,

i doubt you have any issues with the rectifier at this time, but they are noted as being somewhat weak so i would get a suitable replacement
either from George or wherever you like.

also derating the rpm of the engine will likely only make the problem worse, you will have less hp available and thus less to turn the genhead.

and yes you will need a meter to set the rpm to the proper hz, or a killawatt unit which will be useful for other stuff later.
alternatively you can plug in an electric clock and compare its timeing of the second hand to that of your wrist watch
at proper speed 60hz they will be in sync,, if the wrist watch is faster your genhead is rotating too slow and visa versa

you can time it over 5 minutes to increase your resolution if you like, in any event i would target as ronmar has stated ~61-62hz no load
and expect it to be ~59 hz at full load or somewhere close, the govenor quality will have a significant impact on how well it regulates the hz.

so for instance set it up to go to 62 seconds on the electric clock for 60 seconds on your wrist watch at no load.

good luck

bob g
otherpower.com, microcogen.info, practicalmachinist.com
(useful forums), utterpower.com for all sorts of diy info

Bluecometk

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Re: HELP,I HAVE SOME QUESTIONS FOR THE FORUM GENERATOR GODS!
« Reply #4 on: May 27, 2007, 04:53:31 PM »
Thank you all for your advise and insight.

 I feel like a fool.

#1 I have a Kill-A-WATT and didn't think to use it.
Its hooked to another appliance collecting data. (DAA)

#2 I feel stupid for not realizing that I was over loading the leg at 4200W when the Gen head is only 8000W max   (DAA #2)

I also noticed that the comutator ring is sort of eccentric and wobbles in its rotation.

Question # 1 Could this be the cause of the voltage variation (up/down)?

I will be performing another test today with both legs loaded to the values you all suggested for each leg and with the KILL-A-WATT in place. When I get back to my shop after the Holiday I will use an inferred laser Pyrometer on the exhaust port/manifold to get an idea of the engines load also.
As I said in the initial post the engine hardly even changed tone or speed when the load was applied

Question # 2    Am correct in thinking that the 2 to 1 (Eng 2.206 to 4.411Gen) ratio the engine has over the Gen has potentially doubled my horsepower as the Gen sees it?

Once again sorry for the remedial questions but I am just starting out. If this all works out I will post pictures when I learn how. If the project  doesn't work out it will Go to the DUM IDEAS THAT DIDN'T WORK PILE!

Thank you again for your assistance
Bluecometk.
Bluecometk

Yanmar 10 hp LA-100 DIY genset
2 MTU 2000 V12's
12 KW 4cyl Kolor Genset
35 KW  4cyl  Cumins Genset
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Onan DJB 6.0 genset
Waiting for a proven Redstone

ronmar

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Re: HELP,I HAVE SOME QUESTIONS FOR THE FORUM GENERATOR GODS!
« Reply #5 on: May 27, 2007, 06:29:39 PM »
Thank you all for your advise and insight.

Question # 2    Am correct in thinking that the 2 to 1 (Eng 2.206 to 4.411Gen) ratio the engine has over the Gen has potentially doubled my horsepower as the Gen sees it?

As jens stated, gear ratios don't multiply HP, they multiply torque.

Torque:  The measurment of rotational force IE 1 pound of force at 1FT from the center of rotation = 1 FT/LB of torque.

HP:  The measurement of work over time. Developed by James Watt to gauge his steam engines performance to the common mode of propulsion of the day, the horse. He established that a horse could pull a 550lb weight up from a coal mine at a rate of one foot every second, for an eight hour shift.  1HP=550FT/LB/SEC  A machine that could perform the same work provided 1 HP.

With a 2:1 ratio you are doubling your torque output from the engine, but you are also doubling the ammount of time(halving the RPM) over which it is applied.  The net result is the same HP at the generator, minus the losses of the gearing mechanism.  Conversely my 6/1 at around 640RPM uses around a 1:3 gear ratio to spin the generator head at 1800RPM.  I have divided the torque output of the engine by 3, but I have also shortened the time in which it is applied to the generator by a factor of 3 (tripled the RPM) so the net HP applied to the generator is the same 6HP I started with, again minus the losses of the drive system.

I am sure yours will work as this type gearing is employed in many generators, but I think it will only sustain a 5-6KW output.  This is OK though as the 8KW head will not be overloaded and should run at a comfortable temperature with a little reserve.  The added mass of the spinning drive pullies and that heavy ST rotor will help with a more constant regulation of speed and provide the grunt to start larger loads, just as the listeroid flywheels do.  

The commutator rings not running true will probably cause you problems and added wear to the brushes and holders. I have never personally turned comutators in place, but I believe it can be done.

Ron
« Last Edit: May 27, 2007, 06:57:54 PM by ronmar »
PS 6/1 - ST-5.

Doug

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Re: HELP,I HAVE SOME QUESTIONS FOR THE FORUM GENERATOR GODS!
« Reply #6 on: May 28, 2007, 01:19:03 AM »
After re reading this and Bob's and Ronmar's posts I see I'm wrong, I thought I saw 200 volts and 236 NL and I'm not even on the same page as everyone else.

136 on one leg is a little high ( but not grosely and I wouldn't tinker with it until you can get it working and be sure its running at correct speed ), and there is a way to reduce the voltage by putting a pot between the rectifier output and rotor.

Did you check the rectifier?

And a good multimeter like the fluke I use has a frequency setting you can use to check that you are around 60hz.

The clock thing is also a good idea, but it has to be old style with a reluctance type motor not a digtal all clock.

Sorry for any confusion Bluecometk I skimmed your post and fired off a reply too fast...
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Bluecometk

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Re: HELP,I HAVE SOME QUESTIONS FOR THE FORUM GENERATOR GODS!
« Reply #7 on: May 29, 2007, 04:11:44 AM »
Thank you all again for your answers and info.

 Doug, I did not check the rectifier because me testing it would be like a first grader doing calculus. Engines are my thing not complicated stuff like that. I was going to buy the Utter CD to help guide me through it.
 
 Well, I performed another test today and the findings are below.

 Control:
              Temp:          92F
          Humidity:           88%
           Altitude:           12'
               Fuel:            (yellow) fuel oil

W. O. T.  on the linkage:
 
 No load  123V ,    62.5 Hertz    both legs
 1500W   115V,    60.4 Hertz     both legs  total  3000W
 3000W   106.6,    56.6 Hertz     both legs  total  6000W   no smoke    notable load no RPM loss
 4500W   106.4,    55.5 Hertz     one leg     total  7500W   some smoke  notable load  no rpm loss
 3250W   106.5,    55.8 Hertz     one leg    total 7750W   moderate smoke. heavy load no rpm loss

Question How do the numbers look on this test?
 
 The gen voltage seems to be getting more stable with run time.

At 7500W I put a contact pyrometer on the head fins and recorded a 218F temp after 5 minutes of running at this load. I will try this test again with a laser pyrometer on the exhaust/manifold next week.

 With the 7500W load on it I manually increased the rack to bring the hertz up and the RPMs increased but with Heavy smoke.  At that point I thought the air cleaner was restricting the engine/intake but there was no reduction of smoke when I removed it. I think the engine is turning above 3600RPM. I also think it is just running out of cam at this point.
W.O.T. LINKAGE NO LOAD I tried to increase the RPMs and the engine smoked immediately upon rack increase. I think that I will order the lower ratio pullies.I think if I can slow the engine down and get it back up higher on its torque curve it will carry more load at the desired Gen head RPM. I also think that once the engine breaks in it may do better, but at this point it only has 2 hours of no load run time.

CAN YOU SAY TURBO CHARGED!
I work three jobs, one full time and two fun part time jobs. The reason I'm mentioning it is the fact that I work on a professional NHRA drag team and we are always trying to get another tenth or MPH out of the car, hence my need to not leave well enough alone.   
 
 Thank you all again for your help and expertise in answering my remedial questions.

Bluecometk.
« Last Edit: May 29, 2007, 04:25:38 AM by Bluecometk »
Bluecometk

Yanmar 10 hp LA-100 DIY genset
2 MTU 2000 V12's
12 KW 4cyl Kolor Genset
35 KW  4cyl  Cumins Genset
3 cyl  Volvo  bow thruster
Onan DJB 6.0 genset
Waiting for a proven Redstone

Tugger

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Re: HELP,I HAVE SOME QUESTIONS FOR THE FORUM GENERATOR GODS!
« Reply #8 on: May 29, 2007, 04:25:57 AM »
looks like your rpm is dropping under load ...
one leg?
both legs?
it doesnt matter how many legs you stand on...
« Last Edit: May 29, 2007, 04:27:36 AM by Tugger »

Doug

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Re: HELP,I HAVE SOME QUESTIONS FOR THE FORUM GENERATOR GODS!
« Reply #9 on: May 30, 2007, 12:42:23 AM »
Yup you have some voltage drop there as well as frequency loss.

Both seem proportional so thats in my opinion expected and accpetable without a regulator of some sort. If you could adjust your govener so we know what the voltage drop is when you increase your speed back to about 60 hz that would be nice.

I don't know what the % regualtion is suposed to be but its hard to judge with speed drop. Is there a sensitivity adjustment on your govener?

My feelings on voltage drop are if you can keep the droop under 10% your OK. I set the taps on transformers to come in a little high and at full load not more than %10 and this has worked out fairly well over the years. No one notices if they have 610 volts ( lightly loaded system ) to there machines but let it drop bellow 550 and things shut down and overloads trip.
I'm trying to think back to MG room where we had sets to make DC and convert 60 to 25 hz. Frequency drift wasn't realy an issue because everything was designed hold a very steady speed. That much said everything had to produce about 10 volts per hertz on a 600 system in order to keep things operating at or near its designed magnetic sweet spot. Computers and electronics won't like a lot of drift but if the bulk of your voltage change is proportional to the speed is going to be a fact of life.

The harmonic winding will react better with a ballanced load than single leg.
Inductive loads will cause big drops than unity ones so add capacitors where needs for motors ect.

Looks like your rectifier is working just fine. If you had a blown open diode the voltage drop would be alot worse than what your seeing.

115 at 60 hz 1500 watt load sounds alright. But me personaly would like to be able to raise that another 10 volts, others may disagree. I assume to loose 5-10 %  in line losses ( again other may disagree and this is too much but I'd rather be higher than lower and assume worse case ) so I'd like the NL to be higher and this isn't adjustable in this case.

Doug
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ronmar

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Re: HELP,I HAVE SOME QUESTIONS FOR THE FORUM GENERATOR GODS!
« Reply #10 on: May 30, 2007, 05:24:36 AM »
Your voltage does seem a little low.  I would have expected a little more at no load with 62.5HZ, at least 125 per leg if not a bit more.  The 115 at 3KW load and just over 60HZ is considerably lower than I would expect.  You did have 1500 watts on each leg(legs equally loaded) for that 3KW total right?  What are you using for a load?   That is not even 1/2 load for the genhead at rated RPM.  I think the voltage under those conditions should be higher.  This is a new generator though and the brushes probably are not bedded yet.  Any brush hop or partial contact could be limiting your field current to the windings and causing the lower output and excessive droop.  One quick check you can do is remove the genhead drive belt and disconnect the leads going from the rectifyer output to the brushes/field winding on the rotor.  While you are in there, go thru and solder all the cheap chinese crimp on connections so you have a good electrical circuit that can feed the necessary current to the field windings.  Connect a volt/ohm meter and measure the resistance of the field winding in the rotor thru the brushes.  With this hooked up, rotate the generator rotor by hand and watch for variances in the resistance readings.  This will show you any serious changes in the brush contact resistance as they are drug around the rings.  You mentioned that your rings were not true, this could also cause you problems, but since the ST's have 2 sets of brushes at 90 degree angles from each other, the odds of effecting both brushes at the same are lower.  As you get more time on the genhead, your output voltage may come up a bit.

There is an RPM-voltage output ralationship that you need to have from the start.  You should have a solid 120 VAC at 60HZ.  If the voltage is too high, you can add resistance to the rectifyer output to lower the generator output voltage.  But if it is too low?  Well one thing I have discovered in cleaning up the output of my ST-5(mine will now happily feed a trip-lite UPS) is that in adding capacitance to the rectifyer output to clean up the excitation signall from the harmonic winding(it looks terrible on a scope) I raised the generator output voltage.  The electrolytic filter caps I added did cut out the funky peak pulses(and the AC ripple) that were making their way onto the generator output.  I also believe filtering the rectifyer output raised the average current to the field winding raising the generator output voltage.  I have had to add a limiting resistor to the rectifyer output to get the output voltage back where I wanted it.  If yours is low, a filter cap on the rectifyer output may boost it back where it needs to be.

That is quite a large span from 62.5 to 55.5 HZ.  I bet it would be around 58HZ at 5KW?  Again, I think that 10HP is going to limit your reliable production to around the 5KW mark for this set.

Good Luck

Ron
PS 6/1 - ST-5.

rpg52

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Re: HELP,I HAVE SOME QUESTIONS FOR THE FORUM GENERATOR GODS!
« Reply #11 on: June 05, 2007, 11:28:02 PM »
Hey - mobile_bob, ronmar, Doug,

Thanks, all of you guys, for all the info on generators, electronics, etc.  Unfortunately, my only educational background in this stuff was several physics classes - long ago and far away.  I now wish that I had had some vocational education in the practical application of this stuff.  You are talking over my head, but it makes sense - I'm going to have to print this stuff out and ponder it a while, before I can use it on my little 5 Kw head and wiring situation.  Thanks again  :)
Ray
PS Listeroid 6/1, 5 kW ST, Detroit Diesel 3-71, Belsaw sawmill, 12 kW ST head, '71 GMC 3/4 T, '79 GMC 1T, '59 IH T-340

okiezeke

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Re: HELP,I HAVE SOME QUESTIONS FOR THE FORUM GENERATOR GODS!
« Reply #12 on: June 06, 2007, 01:46:37 AM »
Ron,
I dont have a scope, any idea what size filter cap would work on a ST15?  Thanks,
Zeke
Changfa type 25hp with 15kw ST head
Lovson 20-2 in blueprinting/rebuild
International TD-15 B  1962 dozer
Changfa 8 hp., 280 A battery charger

Doug

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Re: HELP,I HAVE SOME QUESTIONS FOR THE FORUM GENERATOR GODS!
« Reply #13 on: June 06, 2007, 05:27:40 AM »
Thats seven pages of math Zeke.......

Others prefer trial and error.

Ron I think ( purely a hunch based on some foggy vector digrams in myhead form college ) the caps are adding a little reactive power as well so yes that will raise the voltage a touch. Yes you can have a lagging power factor reflected back to the line threw a rectifier, this is why we add free wheeling diodes across armatures in DC machines fed by electronicaly rectifed ac systems.......

This also brings up an experiment, would a free wheelinf diode help make better power in a ST head ( I dont know )
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okiezeke

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Re: HELP,I HAVE SOME QUESTIONS FOR THE FORUM GENERATOR GODS!
« Reply #14 on: June 06, 2007, 05:34:54 AM »
Doug,
I'm always up for some trial and error.  Where would I start, and go which direction.
Zeke
Changfa type 25hp with 15kw ST head
Lovson 20-2 in blueprinting/rebuild
International TD-15 B  1962 dozer
Changfa 8 hp., 280 A battery charger