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Author Topic: Why the monster ST? Why not a brushless? (Newbie)  (Read 10092 times)

DirtMerchant

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Why the monster ST? Why not a brushless? (Newbie)
« on: April 14, 2013, 11:38:00 AM »

 So I am getting ready to bite the bullet, trying to order a Powerline 6/1 electric start from Justliveoffgrid.com (Jim is a bit slow to respond to emails). I want to set this up to provide off grid power, I have solar, wind, batteries and inverters, I am thinking the smart way to go is with a 220vac 60hz gen head and let a charger recharge the batteries. I like the idea that if the batteries or inverters crap out I can still use the Listeroid to provide power to the property.

I am wondering why everyone seems to build Listeroid gensets with ST brushed gen heads? Forgive me but wouldn't it make more sense to go with a brushless more modern design ?

Thob

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Re: Why the monster ST? Why not a brushless? (Newbie)
« Reply #1 on: April 14, 2013, 01:37:22 PM »
The ST brush design has no electronic parts, so nothing to go wrong in case of a severe event such as EMP.  The brushless designs have diodes that are installed on the armature, some consider that a weak spot.  Also most modern generators will have a voltage regulator, which is more electonics to fail when you need it most.

I have my ST set up with a voltage regulator, but I can switch a couple of wires and I'm back to "old style".  I bought a spare set of brushes and bearings when I bought the generator.

Another aspect is price, the ST head is much cheaper.

Another aspect is the DIY angle.  Why buy a gen head that's ready to use when I can buy a gen head that I need to open up, check the bearings, align the brushes, replace the "dog house", and add a varmint screen?  After you do all that, you know your generator inside and out!
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mike90045

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Re: Why the monster ST? Why not a brushless? (Newbie)
« Reply #2 on: April 14, 2013, 02:12:12 PM »
On my unit, I had to replace both end bearings.  There is a redundant pair of brushes (2 brushes per slip ring) and I use it wired for 240V, to run the integral .9PF charger in my inverter.   The voltage has been quite steady (except for the listeroid "flicker")

Beware, not all AC chargers have good Power Factor, the lower the PF, the less efficient your charger will be, and you waste alternator capacity.

I have a AVR (new, still in box) and a spare diode bridge, neither which I have used.  And a kit of spare brushes and slip-rings.

DirtMerchant

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Re: Why the monster ST? Why not a brushless? (Newbie)
« Reply #3 on: April 14, 2013, 02:19:13 PM »

 Ok , apparently I need to do more research, I am all about reliability and being able to repair things myself, rather than throw away a head because the internal regulator smoked on the made in china brushless....had not considered that.

On the ST heads, I am confused, I would assume you would want an AVR to power a shop or home? If you don't run an AVR you can get consistent 240vac 60Hz power another way from the head?

 So pretty much any imported ST head requires taking it apart and going through it to make sure it will not self destruct?


BruceM

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Re: Why the monster ST? Why not a brushless? (Newbie)
« Reply #4 on: April 14, 2013, 04:32:57 PM »
The ST's are popular because of the price.  There are better quality generator heads out there, which will be reliable without the every 200-400 hr brush/slip ring maintenance. But at many times the price.  The ST single phase output varies between units, but doesn't look anything like a voluptuous sine wave. Some units have some nasty spikes and "ratcheting" as the windings on these units aren't skewed, as they are in all better quality generator heads.  These distortions don't cause problems for most equipment, but they do for some.  

Some of the ST heads require replacement of the stock diodes, bearings and the "dog house" within less than 100 hrs of operation.  This is true for my ST-3.

The harmonic winding regulation system is not precise, and causes distortion of the AC waveform, but the guys with the ST-5 or ST-7 heads on 6/1 Listeroids can get by with them if the load range isn't too big and the driven equipment isn't too fussy.  The timer in my Kenmore upright washer would audibly growl and get hot on harmonic regulation of my ST-3. I designed and built my own AVR powered via transformer from my 240v output. No more growling appliances, and much less "Listerflicker".

I'd gladly replace my ST-3 with a Marathon generator head.  You will never see an ST head  being advertized with an oscilloscope screen shot of the output. Marathon has oscilloscope screen shots of their AC output that make me drool.  I just didn't have the budget for it.

FYI- All the Listeroids must be considered a "kit" of parts in my opinion, as the build and parts quality is just not there in Rajkot.  A complete tear down is the only way to go if you need reliable off grid power.  They are often full of casting sand, sometimes intentionally hidden in gobs of grease that are not visible, like under the top of the piston.  You should not rely on an assembled visual inspection alone. Some seller's seem wildly optimistic, and some have spent a great deal of time, money and effort trying to get Rajkot to improve their quality, but the parts all come from the same small shops and the standards are 3rd world.  

Best Wishes,
Bruce
Off grid homestead with custom designed 120VDC power system, Listeroid 6/1-ST-3 for intermittent AC power and backup charging.


« Last Edit: April 14, 2013, 07:16:40 PM by BruceM »

dieselgman

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Re: Why the monster ST? Why not a brushless? (Newbie)
« Reply #5 on: April 14, 2013, 04:49:38 PM »
Very well stated Bruce, there are good and bad ST heads and also good and bad Listeroids. On the ST heads, some (few) fail or have problems early on, and most others are just fine without any difficulties. On the Listeroids, we have seen and heard horror stories (few) about most all of the commonly available brands. Everything in terms of parts from the same sources - cottage industry, and a business model that leaves off accountability - all lend themselves to erratic quality or inconsistent resulting equipment. Branding has almost no correlation to quality as one would expect from a Western viewpoint and business model.

These are "kits" any way you slice it, and they CAN be made to conform to Western standards with the appropriate elbow grease and finesse.

dieselgman
« Last Edit: April 14, 2013, 04:54:04 PM by dieselgman »
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BruceM

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Re: Why the monster ST? Why not a brushless? (Newbie)
« Reply #6 on: April 14, 2013, 07:10:16 PM »
Good points, dieselgman.  Some of the better ST suppliers are now insisting on better bearings and diode bridge as supplied from China.  I'm sure that would include those sold by dieselgman.

 If I was buying another Listeroid "kit" or a generator head myself, I'd be looking at dieselgman's business.  He impressed us all with his  handling of a not brand new listeroid with a broken crank. (A VERY rare occurrence.) There is a fair chance that on tear down of a Listeroid, you'll find a defective part or two. You really want to buy from a dealer that stocks parts and provides good support.
« Last Edit: April 14, 2013, 07:14:28 PM by BruceM »

selmawp

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Re: Why the monster ST? Why not a brushless? (Newbie)
« Reply #7 on: April 15, 2013, 03:23:56 AM »
http://listerengine.com/smf/index.php?topic=6790.0.  Hi, before you spend your hard earned dollar ;D check this video.

ronmar

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Re: Why the monster ST? Why not a brushless? (Newbie)
« Reply #8 on: April 15, 2013, 04:46:09 AM »
One of the cool things about a CS clone is the open wheels allow you to easilly belt a wide range of generators to the wheels.  SO you will be able to run a large alternator and charge controller for direct efficiency.  Another reason to run the ST is that they are already configured for and easy to setup to be belt driven.
As stated some ST heads are better than others.  The ST heads harmonic excitation/regulation is typically adequate to provide residential power.  A little filtration of the crude excitation signal generated by the harmonic windings, making it closer to a DC signal, goes a long way toward cleaning up the output waveform.  Initially I had difficulty getting UPS's to respond to my ST's output, but after filtration of the excitation current with electrolytic capacitors, all my UPS's accept the AC power output by my ST. 

This is the raw output from the bridge rectifyer to the field windings on a stock ST.  Dosn't look very much like DC does it?


Here is what it looks like after some filter caps are installed.


And if I recall my scope images correctly, this is the output waveform under stock excitation and 1.5KW of load.


And this is the waveform under filtered excitation and the same 1.5KW of load.
PS 6/1 - ST-5.

BruceM

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Re: Why the monster ST? Why not a brushless? (Newbie)
« Reply #9 on: April 15, 2013, 05:54:18 AM »
Ron, I believe the change in the waveform is not due to the capacitive "filtering", but rather that it has shifted the harmonic current pulse timing on your ST-5's scope shots to earlier, making for a smaller but more abrupt distortion.  The timing of the single phase harmonic winding current pulse is the problem, as the 3 phase units have much less distortion. The rotor has massive inductance, and will smooth out the current pulses sent to it without capacitance. Thus AVR's can do low frequency squarewave banging.  Your large capacitor will look like a dead short to the harmonic, which has pulses as high as 400v on a measly ST-3.  Apparently  by time shifing that pulse to earlier, it cleans up your unit's hump.  I didn't get the same effect on my ST-3.




DirtMerchant

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Re: Why the monster ST? Why not a brushless? (Newbie)
« Reply #10 on: April 15, 2013, 09:47:13 AM »
 Jim at JustLiveOffGrid.com got a hold of me, turns out while I was battling snow over the last couple days, he was battling an ice storm and lost internet for a few days. My order is in now, and I will do a tear down inspection of the Listeroid "compressor"  when it arrives. I wanted his electric start as I like the positive engagement of the ring gear and starter. I am wondering if I could put on high torque starter that could start it without decompression, if that is the case, with a fuel solenoid, I could setup a remote start for it?

I did order a 5kw 120/240 4 pole/4 wire ST head with the engine, but the stories here make me a bit nervous, the plan is to feed 240 to the two legs of my mains which my Prosine inverter charger is on one 120 circuit to charge the battery bank when I get too many cloudy days or over tax the system, but now I am a bit concerned that the power will not be clean enough for it?

What can I do specifically to the head or outboard to the ST to clean it up? The caps make sense to smooth it out, what size caps and what configuration? Parallel ? Series?

The ST comes with an AVR doghouse, are these typically junk? Can a Marathon doghouse be a direct replacement?



« Last Edit: April 15, 2013, 09:52:11 AM by DirtMMerchant »

ronmar

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Re: Why the monster ST? Why not a brushless? (Newbie)
« Reply #11 on: April 15, 2013, 03:23:29 PM »
Bruce
  I should put up a pic of the stock ST unloaded.  In those, you can actually see the spikes from the harmonic input on the output AC.  Just like I can when I use a brushless AVR on the field input as it also delivers a single pulse per cycle. It isn't an issue on a brushless as the coupling windings in the brushless configuration act like the filter caps and absorb that massive pulse before it gets to the rectifyers on the rotor...  On mine, both waveforms have the hump visible on the leading edge of the positive going and negative going half cycles.  I think that is actually a factor of how my head is wound.  I firmly believe that it is less evident with the filtered field input because of the more DC like field created by the filter caps(field not in constant alteration between charge/collapse).  I can still see the hump when I fed a pure DC excitation current and completely unloaded the harmonic winding.

As for modifications.  I am using about 1500Uf of electrolytic capacitors placed across the output of the bridge rectifyer, similar to what you would find used as filtration on a traditional DC power supply. These basically charge using the ragged pulses of the raw field signal and provide a more stable signal to the field.  this is the same thing the field does with the ragged pulses, but in absorbing that pulse, it can transfer some of that transition over to the output.  That is about as much capacitance as I would reccomend, as too much capacitance can cause slow response to load changes as the capacitors have a time constant and take time to both charge and discharge...    The stock doghouse is pretty crummy.  I use a plain electrical enclosure on top of mine.  Way more robust and makes a great way to attach conduit of clamp in power cables.
« Last Edit: April 15, 2013, 03:33:18 PM by ronmar »
PS 6/1 - ST-5.

38ac

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Re: Why the monster ST? Why not a brushless? (Newbie)
« Reply #12 on: April 16, 2013, 03:32:43 PM »
Dont know what your plans are for the power but we have two STs that provide very well for our emergency power needs just as they came to us. By that I mean the quality of the power produced. Does this mean the next one shipped would be the same for me? Nope! It only means that at least two were sent out that produce satisfactory power without fooling with them.  I would try the head as is prior to modifying it electrically personally. The box and connection board is a different matter. All of them need to be deep sixed and changed out for domestic units and mount anything off the head than can be easily moved. There are several good articles here and on George's site for that. Also check that engine out thoroughly prior to putting it in service. Problems with part quality, assembly and sand are not infrequent and cross all names cast into the crankcase doors. Personally I would remove the head and jug at the minimum and then power wash the insides prior to picking and poking around in the various nooks and crannies for sand and slag. Be sure to quickly force dry and spray something like WD-40 on the various moving parts if you power wash. The only parts I would trust as shipped  is the MICO pump and injector.
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cujet

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Re: Why the monster ST? Why not a brushless? (Newbie)
« Reply #13 on: April 16, 2013, 03:35:16 PM »
I need to chime in here!

Disclaimer: By nature, I prefer quality equipment of all sorts. And, this generator head is no exception.

I power my ST-15 with a 20HP Listeroid twin. The power produced has been problematic. My house has modern appliances and some won't accept the listeroid-ST power at all.

Here are the issues, none of which are major.

First, the ST, as delivered, has low voltage under load. About 6KW load results in 109V each leg. So, Tom from GA GEN set me up with a voltage regulator that eliminates the Z winding, and uses 120V from one of the legs to excite the field. Much better idea.

Second, the (now eliminated Z winding) excitation power is, as depicted in the post above, nasty.

Third, After very little use, my bearings are howling.

Fourth, The doghouse box is utter-junk. Made of steel so strong you can bend it in your fingertips.

Fifth, the overall quality and wiring, and insulation rating is poor. Requiring some effort to "fix" flaws.

Now, the question on everybody's mind..... Would I do it again? Yes, if powered by the listeroid, as the ST is a good companion. The Listeroid has power/combustion-event pulses that affect the AC output, and so the AC output won't ever be 100% clean. Even with very heavy flywheels on both the engine and generator head.
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DirtMerchant

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Re: Why the monster ST? Why not a brushless? (Newbie)
« Reply #14 on: April 17, 2013, 09:31:40 AM »
I need to chime in here!

Disclaimer: By nature, I prefer quality equipment of all sorts. And, this generator head is no exception.

I power my ST-15 with a 20HP Listeroid twin. The power produced has been problematic. My house has modern appliances and some won't accept the listeroid-ST power at all.

Here are the issues, none of which are major.

First, the ST, as delivered, has low voltage under load. About 6KW load results in 109V each leg. So, Tom from GA GEN set me up with a voltage regulator that eliminates the Z winding, and uses 120V from one of the legs to excite the field. Much better idea.

Second, the (now eliminated Z winding) excitation power is, as depicted in the post above, nasty.

Third, After very little use, my bearings are howling.

Fourth, The doghouse box is utter-junk. Made of steel so strong you can bend it in your fingertips.

Fifth, the overall quality and wiring, and insulation rating is poor. Requiring some effort to "fix" flaws.

Now, the question on everybody's mind..... Would I do it again? Yes, if powered by the listeroid, as the ST is a good companion. The Listeroid has power/combustion-event pulses that affect the AC output, and so the AC output won't ever be 100% clean. Even with very heavy flywheels on both the engine and generator head.

Wow, not exactly instilling  confidence in me for the new head I just ordered. I am not very savvy when it comes to electrical, just enough to be dangerous, sounds like I need to find somebody to help me get it patched together when I receive it.