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Author Topic: 7-10kw gen head U.S.  (Read 759 times)

Tanman

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7-10kw gen head U.S.
« on: February 28, 2019, 09:42:49 PM »
Looking for a single phase gen head for my Chinese 1115 build.
« Last Edit: February 28, 2019, 10:06:37 PM by Tanman »
Yanmar L100-5KW set
Chinese 1115-8KW stamford
96 Suburban 6.5 turbo

ajaffa1

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Re: 7-10kw gen head U.S.
« Reply #1 on: February 28, 2019, 11:22:25 PM »
Harbor Freight are selling a 10,000 watt  belt driven generator head for under $300. It`s probably capacitor governed rather than having an AVR, so the output might be a bit dirty.

You could look at a Chinese ST10 head. If you swap out the cheap bearings and clean up the slip rings, they are a very reliable unit which can easily be adapted to Automatic Voltage Regulation.

Bob

BruceM

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Re: 7-10kw gen head U.S.
« Reply #2 on: February 28, 2019, 11:58:28 PM »
I have a fair amount of experience with the US imported ST heads, both my neighbor and I use an ST-3.  I think the idea that the only thing wrong with ST heads are bearings and bridge diode is pure marketing fantasy.  The QC just isn't there for any aspect of the design, and one day I had 3 ST-3 stators on my bench, and no two were the same.  The last ones I had my hands a couple years ago  were all being sold with AVRs because the harmonic windings were done wrong, with wildly excessive harmonic output.  My neighbor's is that way, so he keeps an extra AVR on hand (the $50 China ones typically last a couple years- sad that they are so poorly designed). He had one ST-3 rotor fail- ends up some are made with aluminum windings.  I regret recommending the ST head for him. 

The Stamford clone heads have a good reputation and I have not seen anything but positives about them.  They do cost substantially more than an ST head.

A few guys have used the HF 10K head at well below rated output and have not reported any problems, so I don't think it's a bad choice for a bargain head.

For Christmas, or in your will, don't forget to leave me a Marathon 4 pole head. That's what I'd really like, but didn't have the budget for.



« Last Edit: March 01, 2019, 12:00:37 AM by BruceM »

glort

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Re: 7-10kw gen head U.S.
« Reply #3 on: March 01, 2019, 12:39:11 AM »

A few guys have used the HF 10K head at well below rated output and have not reported any problems, so I don't think it's a bad choice for a bargain head.


Believe it or not, I found one of the have a fright 10/ 7K heads for sale here.
They seem to have the 10K max, 7K intermittent rating.  Would you think these would be a better choice than the  China 3 phase heads Bruce?

Do you know if the HF heads are OK at 7kw or are they more suited to 5kilo or lower?
The one I'm looking at is only a 2 Pole head but having an output shaft I can gear it so the engine is not screaming so that's a plus if not perfect soloution.
It does 120 and 220 so should be easy enough to wire for my 220 needs. It is a capacitor type  so I am reliably told it might only need the value of the cap brought up a bit to increase the voltage at the lower revs I'd want to drive it to get the frequency right.

I notice some big gennys have a frequency ( or is it voltage) adjustment so when the load is connected the output can be tweaked to be spot on. I imagine this would allow for other effects such as air temp, elevation etc that may effect the generators absolute speed.
Would it be possible to hook something like a DC PWM controller to the cap and then over rate it so the capacitance and therefore voltage could be fine tuned or would there be another way of doing it?

Might have to look at Alli and see what a stamford head would cost? Probably be able to buy  4 Chinese ready to run petrol machines for the same price.

BruceM

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Re: 7-10kw gen head U.S.
« Reply #4 on: March 01, 2019, 12:53:38 AM »
I don't have personal experience with the HF 2 pole, 10KW head.  If it's rated 7K intermittent, 10K peak, then I'd believe those figures as "marketing" figures for a cool day and would want to knock at least 25% off that. 

I'm not familiar with capacitor regulation on generator heads.  Simple enough to replace with a cheap AVR if need be. 






32 coupe

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Re: 7-10kw gen head U.S.
« Reply #5 on: March 01, 2019, 01:52:35 AM »
I have 3 st heads and 1 stamford clone.

The first 2 st heads have been reliable units with the standard
windings that are stable under any load. They were purchased years
ago. They will handle an unbalance load without problem.

The third st is a different story. It came with the AVR and digital
output meter. It will run a 120 OR 240 load but will not tolerate an
unbalanced load at all. It will scream  like a banshee and voltage will
fall off quickly with an unbalanced load.

I tried removing the AVR with results as Bruce mentioned, voltage in the
375 range or better.

I would NOT recommend the st head....I would if I could see it in action
with a meter and load in hand, in person.

The stamford clone is a very good, stable out of the box, unit that
I would recommend. Just hook it up and put it to work. No bearings
to repack or replace. No brushes to setup/adjust/clean. No worry about it
being anything more than a boat anchor like my last st.

I am looking at buying another head in the near future. There is no
 other choice at the moment but the stamford clone.


Another item I have with my 1115 setup is a direct coupling from engine
to gen head. It was purchased years ago and I haven't seen one like it
for 8 or 10 years.
If I were to build another 1115 with direct coupling I would use a Lovejoy
coupler and a shop built engine stub. I did this on my last build and am
pleased with the results.

Using belts will work, and I have several belt driven units, but the direct coupling
method for the 1115 series engines is a far superior choice in my opinion.





« Last Edit: March 01, 2019, 01:59:32 AM by 32 coupe »
Metro 6/1 turning a ST 7.5 KW gen head
Changfa 1115 turning a ST 15 KW gen head
Ashwamegh 2/25
John Deere 110 TBL
New Holland TC 30

"I was sitting here reading this thinking what an idiot you are until I realized it was one of my earlier posts !"

Tanman

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Re: 7-10kw gen head U.S.
« Reply #6 on: March 04, 2019, 04:51:38 AM »
Other than fleabay, where is a good place to source a stamford clone?
Yanmar L100-5KW set
Chinese 1115-8KW stamford
96 Suburban 6.5 turbo

38ac

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Re: 7-10kw gen head U.S.
« Reply #7 on: March 04, 2019, 04:55:15 PM »
 I recommend Diesel Electric Service,  Gary is a contributor here and will stand behind what he sells which is a huge plus over dealing on EBay. 
I bought two ST heads from Tom Osborne back when they were selling a lot of them and both have been trouble free in stand by service other than one bridge diode. Voltage is perfect running on the harmonic and the AVRs are still in the box. Unused. With the big fall off in sales it isn't hard to believe that quality control went south.  Personally I would not consider the current crop of ST heads unless they were known to be copper wound and will produce correct voltage operating on the harmonic as designed.
Collector and horder of about anything diesel

BruceM

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Re: 7-10kw gen head U.S.
« Reply #8 on: March 04, 2019, 07:22:30 PM »
+1 for DES recommendation, outstanding technical support of what he sells, truly exceptional. 

John (Boston)

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Re: 7-10kw gen head U.S.
« Reply #9 on: March 18, 2019, 06:01:50 PM »
Not sure if I mentioned this before or not...  I have two different ST-5 type heads.

One head I got about eight years ago, maybe.  It's a steel cased unit.  Good and bad with this design.  Good, in that the main housing can't crack like an iron one.  But, not so good in the fit and finish department.  The welds don't look so great and it goes down hill from there.

The case is made up of pieces of welded steel and then machined "true".  During the machining for the stator seats (those ribs that the stator is pressed into) they cut all the way through in a couple places.  The stator seems to be tight but it looks like pretty sloppy work.  Remarkably, the pole gap looks pretty uniform.  The mounting base is made out of the same thin sheet metal and is actually a bit flexible if you yank on the end of the head.

This "tin can" head does seem to have copper windings and it does have iron ends.  The harmonic winding is "weak" and the unit can't hold voltage at much of a load.  I intended to play with capacitors on the harmonic to see if I could get the voltage up a bit but I haven't had the time to play with it.  It came with a "western style" bridge rectifier - which I need to change out (didn't know those were suspect when I first bought the head).

Next, about a year ago, I bought an iron ST-5.  The castings are a lot thinner than I'd like but do seem to be pretty good quality, maybe better than the Listeroid castings.  The machining seems OK - bearings fit properly (not jammed tight but not sloppy).  The mounting base is very solid and obviously has no detectable flex.  The main housing has me a bit worried because it is clear there is some stress in it (trying to make it expand) due to the press fit of the stator.  The bell-end at the pulley side seems to be very fragile.  There is not much iron left where they have all the cooling slots on the bottom.

This iron head seems to have copper windings (the connections are welded, by the looks of them).  It came with an AVR and a digital meter.  The meter seemed to work OK so I kept it (though I moved it off the head).  The AVR worries me (I bought two spares) BUT I assume its presence means that the harmonic winding is "hot" and could be adjusted with a resistor.  I just hope it fails open and doesn't run away and fry my equipment.

I swapped out the rectifier on this head (it was similar to the other head).  I used a nice quality one and put snubber caps across each diode.  I put fuses on the output (though I don't think the Listeroid is capable of blowing up the generator).

I will say that the AVR is pretty stable and keeps the voltage nice and tight - even with good size load fluctuations.  I have not put a scope on the output - someday...  But first I need to fix the scope - or get one of those new ones.  My scopes are all so old they have tubes (and I don't mean the CRT).

Strangely, the armatures of these two vastly different heads seem to be nearly the same.  They both seem to have copper windings.  They have the same plastic bobbins (which have a few cracked and broken ears) and they both have what look like cast aluminum fans.  Both heads came with noisy (but sealed) bearings.  The brush rigging is identical between the two.

Overall, I like the simplicity of these heads - you can take them apart in minutes - I just wish they had a little more quality.  I gave the windings (stator and armature) in the iron head a good coating of Glyptal 1201.  Also coated all the unpainted raw iron (basically the entire inside and the bottom).  It hadn't rusted at all so I thought it was a good time.  I need to do the other "tin can" head as well but it was partially rusted (inside) when I got it so not sure how good that will turn out.

-John (Boston)
Metro 6/1 (genset)
Cummins 6BT (89 Dodge truck, bought it new)
Cummins 4BT (91 Oshkosh bread truck)
Kubota D1005 (B2320 tractor)

ajaffa1

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Re: 7-10kw gen head U.S.
« Reply #10 on: March 19, 2019, 10:26:15 AM »
Hi John, the quality of these ST heads varies enormously, the things to concentrate on are firstly that you have copper windings, secondly that the two bearings are of reasonable quality and not filled with yakfat and casting sand, thirdly it is vital to check that the slip rings are concentric with the shaft if they are not you will get through a lot of carbon brushes in a very short time.

I find it very disappointing that these simple and reliable heads are made to such poor standards, I would happily pay a little more for a slightly better assembled head which I had confidence in.

Bob

John (Boston)

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Re: 7-10kw gen head U.S.
« Reply #11 on: March 19, 2019, 03:16:09 PM »
Yup, forgot to mention...  Slip rings on the newest (iron) gen head are NOT quite concentric and are also a little crooked (side to side).  So I assume the brushes will wear a bit fast on this one.  I have two new slip ring assemblies (don't know how true they are) and I may try to change the wobbly one.  I no longer have a lathe but the brass rings might be thick enough to take a light cut and make it better - don't know.

Not sure what holds the assy onto the shaft.  It almost seems like it's epoxied in place.  There seems to be too much space in the gap for a press fit and I have a feeling that if I mess with it too much it's going to crumble (one reason I bought a couple spares).  I'll probably have an other try at it when I do the bearings (which are noisy, especially in the cold).

The older "tin can" head seems to have straighter slip rings.

"nice" weather coming soon - time to get working on the Listeroid project again - and do a lot of hiking...

-John (Boston)
Metro 6/1 (genset)
Cummins 6BT (89 Dodge truck, bought it new)
Cummins 4BT (91 Oshkosh bread truck)
Kubota D1005 (B2320 tractor)

BruceM

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Re: 7-10kw gen head U.S.
« Reply #12 on: March 19, 2019, 11:19:25 PM »
By removing the brush holders and spinning the head via motor to 1800 rpm, you can do a fair job of truing the slip rings by hand if you are careful.  A file braced to the housing will do the rough work, self stick sandpaper on  hardwood can do the finish work.

A felt tipped marker braced to the housing will allow you to check the trueness of the slip rings as you proceed.

It is a crying shame that QC on the ST type heads is so poor.  The best one's, with replaced bearings and bridge diodes are quite reliable.