You folks have told me, and the opinion seems to be held by most of the rest of the electronics/generator world, as well that the ST generator head has a really awful waveform with lots of harmonics and other "noise" caused by feeding the field coils of off the Z winding in the generator, so . . .
What would happen if you threw away the Z winding, figuratively, and simply pulled the appropriate DC voltage, or really some voltage higher than what you really need, out of your battery string and ran that through some filter appratus/circuiit to get the charger noise out of the system and then through DC-DC converter and then through some dummy load, like a decade box, to chop it down to what is required to give you 120 Volt AC output from the generator?
Would this work, or am I missing something here?
Also, rcavictim has suggested that I use a three phase STC head to eliminate this problem, but 1) I can't find anything that tells me how clean this AC is, though it IS, apparently, cleaner than an ST head, but 2) wouldn't the above method also improve the output from an STC head, since, I think it also has a field fed off of a Z winding, and wouldn't it, too, have an improved/cleaner waveform if the above was used?
My thinking is that I'm going to have the DC Batteries there anyways, so if it improves the wave form of either head, why not use them?
It would, of course, be an exercise in "chopping the legs off of a table" to find exactly the right voltage for the supply., but I don't think that is an insoluble problem, just a matter of a little "fiddleing". <smile>
One thing that I am not sure about, however, is, is there a changing voltage requirement for the winding excitationn voltage to maintain the same flux density in differnet conditions of current draw, and hence a constant output voltage?
What did I overlook, this time? <grin>
Wayne Stayton
you can feed the field with a separate dc source but you will have to vary the field current depending on load.
that is where an avr would be handy
the issue surrounding the Z winding is with the transformer effect that the Z winding has when it is coupled to the stator output winding
it distorts the flux in the air gap and backfeeds some distortion.
(basics, the actual effect is probably much more complex)
the upside of the Z winding is it is additive, in that as the current rises in the stator winding the Z winding also gains current (back to the transformer effect) which feeds the field more current which stabilizes the generators output voltage ( to an adequate extent)
you can also take power off the stator , step it down and rectify it to dc, filter that well and feed it to the fields via an AVR, this will provide for good voltage stability over the full load range and also clean up most of the distortion because there is no Z winding interaction (provided you leave it disconnected).
bob g
Here is an o-scope capture showing the output waveform of my 24kW/30kVA 3-phase STC head under about 8 kW resistive load.
rcavictim:
Ok, I give up! <grin>
How come the STC waveform looks SOOOO clean and the ST waveform is so dirty if they're both fed off of the Z winding (They are both fed off of the Z winding, aren't they?)???
What's the differance? If I am just driving one set of coils to get a simple single phase or if I drive three coils to get three phase, aren't they both activated by the same thing? And if they are both fed by the same dirty source, how come one is clean on one is dirty?
BTW, shouldn't there be three wavesforms in the STC o'scope pic of the STC, displaced by 120 degrees from each other, or did you just show one of the three for clarity?
RCA
refresh my tired memory, does your stc head have an avr, or is it Z winding excited?
bob g
My STC head IS Z winding excited and it does have an AVR circuit module. I only showed one phase. I checked the others. They all look the same. Nice and clean. I don't have a 3 or 4 channel scope but I could have displayed two of the 3 phases in the photo. This waveform actually got cleaner under lower load. The peaks got smoother. Don't ask me how. I dunno and I'm not worried about finding out if I have to divert any of my precious time from more important ongoing projects to find out. Let someone else discover why and report back here. :)
mobile-bob;
I think (always dangerous!) that it is Z winding excited, inasmuch as rcavictim has been telling me that the waveform is dirty/terrible and his, as per his o'scope, is pretty and clean and, per him, AVR controlled. I also seem to remember from reading something from one of the head manufacturers in China, that the ST heads, at least from that manufacturer, were Z winding fed/controlled. Also, George Breckenridge has indicated that whatever brand of ST heads he was selling, at least in the sizes that he was advertising on his website, were Z winding controlled. I'm not sure if the manufacturer that I was communicating with was the same one that made the heads that George was/is(?) selling or not.
So can I just order an AVR from some company and plug (ok, not really "plug", more like solder!) it in and solve the problem, instead of reinventing the wheel? (Which I seem to be good at undertaking! <grin>)?
If so, who do you recommend as a source for AVR's?
i am not sure i am a big fan of avr's, at least most of those i have seen so far
tom osborne sells an avr if i recall correctly that seems to hold up and do its job
if i were to use an avr i would want some means to disable the field if there was an underspeed condition
such as what happens as you run out of fuel.
some of the st fields can be damaged by an avr that is fighting to keep the voltage up while the engine is spooling down
over several seconds to a couple minutes.
bob g
Here is Toms info, great guy!
Tom Osborne
Milledgeville Aviation, INC
Generator Division
216 Airport Rd NE
Milledgeville, GA 31061
478-453-9358
478-453-0642 fax
478-457-5524 cell
www.stores.ebay.com/georgia-generator
www.centralgagenerator.com
Email: info@centralgagenerator.com
"We appreciate you considering us as your Supplier!"
I sent Tom off an email last night - but in my typical style, I probably "buried" him in all my questions!! I am known for not being able to say "Hello" in less that 500 words!!! <grin>
My email is down/not-responding at the mement, so I can't tell if he has answered yet or not - sometimes cheap is its own reward!!! I suppose the answer is "What do expect for $5.50 a month?" <smile>
Oh, BTW I beg your indugence for my terrible typing - a stroke and couple of mini-strokes have left my finger co-ordination a little lacking - if it something where typing/spelling is critical (think email to your congressperson) I use a wordprocessor which nicely underlines all of my typing fubar's, but for everyday emails, I am lax enough to just type them direct and hope that the readers are understanding /discerning enough to read around them. If it REALLY bothers folks, let me know and I will revert to word processor and transfer.
On another side note, if you think my typing is bad, you should see my handwriting!!! The stroke/mini's have left that SO de/mis-formed that I can't even decipher it - The bank has told me it would be better if I paid everything possible electronicly, since each of my checks, when they come thru, get kicked out of the automation process for human intervention/examination to verify the amount and confirm that it was indeed properly drawn and not the random idle scibblings of some 1st grade child!
I'll let everybody know what Tom Osborn had to say when I hear (and get his permission to tell all!)
Regardz,
Wayne Stayton
I'd like to have an O-scope to read the wave patterns on my various generator heads, and those of my nearby friends, but I dont know very much about the type of scope I would need for such a basic operation. I went on line, did a little reading, I think an 8 bit analog handheld will do. I dont think I need more than 2 channels, etc. Does anyone have a suggestion? Like to spend no more $100 to $200 to accomplish this goal. Is this possible?
Quote from: Horsepoor on March 26, 2011, 02:58:54 AM
I'd like to have an O-scope to read the wave patterns on my various generator heads, and those of my nearby friends, but I dont know very much about the type of scope I would need for such a basic operation. I went on line, did a little reading, I think an 8 bit analog handheld will do. I dont think I need more than 2 channels, etc. Does anyone have a suggestion? Like to spend no more $100 to $200 to accomplish this goal. Is this possible?
I've seen some of those inexpensive pocket o-scopes on ebay and the problem with all of them is the lack of adequate input range scaling to safely deal with the kinds of voltages you will be looking at in measuring power circuits. These things often use a miniature headphone jack as the probe input. That is just a junky toy. IME all these miniature jacks seem to be plated with some sort of metal this is non conductive in order for them to stay shiny. That causes nothing but grief when trying to measure voltages. They are sort of OK I guess for looking at logic levels and audio signals, etc. while you are in an airplane washroom at 30,000 feet or somewhere else where it would be just as inconvenient to have a real oscilloscope in front of you, but beyond the novelty factor what's the point? Not all pocket scopes are junk however. If you can find a used Fluke ScopeMeter that would be ideal for you.
Search your local craigslist or allofcraigs.com or your local pawn shops. There are some good deals out there, you just need to do the legwork. Epay if all else fails. You don't need anything more than your basic 2ch 20Mhz scope like B&K, LG or an older Tek. Stay away from the vintage stuff unless U just have to have it. Yea, they look cool but are very touchy.
I searched allof craigs this morning and found a nice EZ here in Houston for $200. Too bad I'm not in the market. THere was also a nice 460 somewhere out there. Digitals have there advantages and disadvantages but 4 what you want to do anything will work.
If you do get one be careful not to blow it. I was using a 6.5V xformer but it was pointed out here that I was altering my signal with that and sure enough I was. I built a resistor voltage divider to measure true signal. The Xformer cleaned it up a bit whereas I am seeing the real signal across the resistor now.
Quote from: Horsepoor on March 26, 2011, 02:58:54 AM
I'd like to have an O-scope to read the wave patterns on my various generator heads, and those of my nearby friends, but I dont know very much about the type of scope I would need for such a basic operation. I went on line, did a little reading, I think an 8 bit analog handheld will do. I dont think I need more than 2 channels, etc. Does anyone have a suggestion? Like to spend no more $100 to $200 to accomplish this goal. Is this possible?
If you get one it will drive you crazy! LOL
It did me!
IF you're handy with electronics you can use the sound card in your computer and some software for a cheap oscilloscope. Search for "sound card oscilloscope" for some ideas. You should be able to easily get 2 channels that will cover the frequencies involved for line power plus harmonics.
If you don't already know the dangers of line voltages, then don't attempt this. You could blow up your computer, start a fire, or worse, electrocute someone. You'll need the resistor voltage divider that BigGreen discussed above - DON'T ATTEMPT TO PUT LINE VOLTAGE STRAIGHT INTO THE COMPUTER!
Ok, I heard back from Tom Osborne, along with his permission to display the message or parts thereof, here.
First, what I asked, having chopped off all the description of what I am planning, since you already know that:
>1) First, I am concerned about the wave form on the output of the ST Generator
> Head, as delivered, no chages to the internal regulator. From your experience,
> just how dirty is the output and would it likely interfere in normal household
> loads like a computer or a tv w/ a satellite receiver, microwave, etc.
>
> 2) If the output is, indeed, unsuitable or even marginal for these type uses,
> how is the output if the AVR-type regulator that you also sell? Would it then
> be acceptable for the uses described above.
>
> I have seen an o'scope trace of the output of one of the other member's of
> Microcogen with your AVR on an ST head as delived from your shop and that
> apeared to be very clean, though that was a three phase head, so I'm not sure
> that I should automatically expect the same result on a single phase head.
>
> 3) Also, besides the wave form, how is the voltage vs load with the AVR
> regulator vs the straight Z winding fed output withouot the AVR unit?
>
> 4) Are the bearings in the two bearing head as delivered from China, generally
> lower quality than would be available here? I am inclinded to change them
> right "out of the box" if they come from China, but I am interested in hearing
> your opinion of them.
>
> 5) No matter how the head is equipped, with regard to the circuit feeding the
> windings, I figure that in an emergency, I could always feed straight DC from
> my battery bank to the brushes of the field coils of the generator to get
> electricity if all else fails, What is your opinion of this emergency-only
> procedure. Obviously I would "fish" around to determin what DC voltage gave me
> an acceptable output voltage, starting with 36 volts and increasing by 2 volt
> steps (one cell's worth) until I got something that I could live with - I would
> think that such a fishing expedition shouldbe conducted in advance so I woulod
> know what voltage to use if it was needed and could just hook it up if
> necessary
> and required.
>
> 6) How many hours do you feel tha one should plan on getting out of one set of
> brushes for this 24 kW generator-head.
>
>
> 7) Are their any spare parts that you would recommend, in addition to an extra
> set of brushes?
>
> 8) Do you see any problem using the Lovejoy type coupling that you sell to hook
> the generator to the output of my automotive transmission? I had thought that
> it might be nice to try and figure out where the peak loads were coming from
> the generator (4 per revolution) and then set it up so so that they didn't
> coincide with the torque peak from the engine, but I have no idea of how to
> identify where the peaks from the generator occur! <grin>
>
To these questions, Mr. Osborne replied as follows:
>The ST generators is a good generator for backup or prime power >as long as you understand a few things about generators.
>This unit does have a little trash on the sine wave that come from >running brushes.
>There is also brush maintenance that must be done. They will last >from 900 hours to 3700 depending on how you keep the aligned >on the slip ring. The ST is inexpensive so it makes them popular >with the DIY people.
>The best quality, if you do not want to do any maintenance, is >the Stamford brushless type. The waveform is very clean and >stable
>It has a SX460 or AS440 AVR that comes with this unit.
>Will try and answer your questions in the order you asked them.
>1) On the engine, make sure you use a good governor, mechanical >or electronic. Will need to maintain the gen head at 1800 rpm + - >60 rpm. This is 62hz to 58hz
>2)Would recommend an AVR for all your electronics even though i >have used them for all my electronics without an AVR( George at >Utterpower does not recommend the AVR) www.utterpower.com >I just like the steady voltage. Remember, a steady voltage will >not make up for a varying rpm (frequency) Rpm must be regulated >(governed ) first
>3) Some people like doing away with the harmonic winding, do not >know exactly the reason.
>4) The bearings are sealed on the units we have. They will last >10,000 hours so would not be concerned about bearing at this >time.
>Use them until you hear a noise then change.
>5) The loveJoy coupling will be fine, just make sure the engine >and gen are mounted solid to the same frame, (no rubber shock >mounts) and then shock mount the frame if you like.
>6) Do not know how to figure peak loads coming from the gen >head. Do know you need to check carefully the harmonic >vibrations
>Do a good search on the harmonic vibrations in diesel generator >sets http://www.deicon.com/technote/>diesel_gen_tuned_vib_abs.pdf
>Small units like this is not as much a problem as larger units.
Read it and tell me what you think!
Regardz,
Wayne Stayton
Quote from: Horsepoor on March 26, 2011, 02:58:54 AM
I think an 8 bit analog handheld .
There is digital, where bit count= resolution, and there is Analog. Anyone trying to sell you 8 bit analog, I'd be wary of .
Quote from: mike90045 on March 27, 2011, 08:21:53 PM
Quote from: Horsepoor on March 26, 2011, 02:58:54 AM
I think an 8 bit analog handheld .
There is digital, where bit count= resolution, and there is Analog. Anyone trying to sell you 8 bit analog, I'd be wary of .
Could be the price. two bits = 25 cents. 8 bits = a dollar.
8 bit resolution refers to binary numbers (digital is only ones and zeros) meaning the scale is divided into 256 discrete steps. That is not very good resolution.
I had the same concern when I'm on generator, how safe are the power on the sensible equipment. The best idea is to have all those equipment on a UPS.
Or run all gen head output through charge controller first. Then the only thing that gets to the house is perfect sine wave from the inverter.
My ST-5 output is not that bad. I have compared it to generators I work with using an O-scope, and it is comparable with perhaps a little brush noise, and some slot noise as the ST rotors are not skewed. I am also not running mine at maximun output(not enough engine:() so the Z winding effects may not be as pronounced at those lower loads. Good simple backup power, I am happy with
Most electronics should not have a problem, as they are taking the AC line voltage and converting it to DC via a switching power supply anyway. That power supply has a very large input voltage range, and can take in some real crap and make DC out of it:)
Completely in agreement w/ Ronmar. The only problem I ever had w/ the ST head was flickering fluorescent light bulbs, probably because of the pulsed output from the slow speed engine's power strokes. Anything that ultimately uses DC shouldn't care. Are there any specific devices, Wayne (original poster), that you are worried about?
After living for 3 years with our ST5 the only item in the house that has an issue with the output is our dishwasher. It seems to be very sensitive to over voltage at around 126 volts. It works fine while bulk charging, but as we reach the end of the absorption cycle it tends to shut it's self down. We have all the other common household stuff and as a software developer I'm on the computer a lot of the time while it's running and no problems. Fortunately we've had no appliance failures either. :) Our ST5 is a straight Z winding non-AVR unit.
My dishwasher works just fine on ST power, well at least as fine as she does on commercial power. She being a teenager can be a little difficult to get to do her chores regardless of the power feeding the house:)
Actually I don't try and run my electric dishwasher on the generator. My power study showed It's internal water heating elements are a rather large single leg/120V load...
to mbryner:
I'm most worried about a desk computer (no name - built by me with a basket-full of cheap parts) and television via satellite receiver.
However, I my have made a mountain out of a mole hill, here, since I'm planning on running the generator only about 6 hours a day twice a week for 20 weeks out of the year and then 6 hours a day once a week for ten weeks out of the year - this would be only for supplemental power when the solar panels wouldn't keep up due to length of day, cloudy weather limitations.
Maybe I'm doing a truck load of worring about a small-basket sized problem?
Current plan, FWIW is to use a 24 kW ST head with the AVR controller plugged by Tom Osborne, though I didn't feel that his response to my query really answered some (most?) of my questions - I may go back for a second dip on a couple of them! <grin>
We've got satellite internet and TV, no issues there either. Even with infamous Listeroid flicker. :o
I reckon I have run just everything possible that can consume electric on my ST5 without any AVR. I have not experienced any issues other than the microwave appears to be noisier. I have also not noticed any flickering lights either (incandescent or fluorescent). Perhaps using a resilient engine mount provides sufficient damping of the 5.4 power stroke to keep a significant portion from getting to ST.
Bob B.
Bob B, Without an AVR, I don't see how you could possibly not notice the flicker. All single cylinder gensets have it. The most resilient engine mount in the world will do absolutely nothing for the crankshaft/rotor deceleration on the compression stroke, and the acceleration on the power stroke... I use mostly CFL's, so don't hardly see it when on generator power, but the incandescents and a few of my shop florescents show it... Since the harmonically excited ST heads output voltage is RPM dependent, these accelerations and decelerations make the voltage change that really make the flicker "Pop". An AVR really takes the edge off of the flicker by stabelizing the voltage during these accelerations and decelerations...
Like Tom, I run sat receiver, flat panel TV and computers without any issues. All these modern devices have switching power supplies with a very wide tollerance. In fact, most modern equipment is built for the world market, with one power supply able to handle UK/European 220 power at 50HZ all the way down to 120V US domestic at 60HZ, with only a plug change, or use of an adapter plug at the receptical... The only thing that really effects them are extreme low voltages(brownout), where they basically herniate themselves trying to hold up their end of the log and deliver their rated output from the greatly diminished input.
I have UPS's on these systems to mainly protect from brownout conditions, but they are small switching type UPS's so if the input is acceptable(between 107 and 127V), they are passing it right thru to the output, or they are online, draining battery and beeping every minute:) When I loose power on an evening, I can be up on generator power, without the wife or kids ever stopping the watching of the tv show that is on:) The UPS fills in the 10 minutes or so of power gap...
I would certainly agree that one can feed PCs practically pure noise and they will digest it perfectly fine given that they are DC devices with robust power supplies. I think I have in excess of 15 homebuilt PCs operation at our place for various purposes (and some are used for high end gaming, high end engineering analysis, and home automation) and we have never experienced a single hiccup while on ST power. The only device I have any concern running on ST power has been our microwave, which actually sounds different when being feed ST power...but nevertheless works well and hasn't had a problem either.
I would agree that if the infamous Lister/ST flicker is purely due to the piston velocity change during the power stroke, in theory this should be unaffected by the method of engine mounting as the piston is indeed hard linked to the flywheel, which is also essentially hard linked to ST (if one assumes a serpentine belt provides hard linkage). However, the forces that create piston velocity also react (equal and opposite) with the engine crankcase and hence the engine mount, which can then ultimately react with the piston (both fundamentally and via harmonic structural bending modes).
Ability to perceive light flicker does vary significantly for different people too. I think the generally accepted average threshold of perceiving light flicker is about 50 Hz (i.e., if a light goes ON and OFF less than 50 times per second, it becomes perceptible to the average population). For our US 60 Hz power, an incandescent light flickers at 120 Hz (i.e., the light goes ON and OFF 120 times per second). The older florescent lights with magnetic ballasts flicker at 120 Hz as well. The newer florescent lights that have electronic ballasts flicker in excess of 20,000 Hz. No one in my family has noticed any flicker on our old tube fluorescents, new compact fluorescents, or incandescent lights. The only thing visibly noticeable is the brief transient when toggling from live grid to live generator via the transfer switch.
Bob B.
I should also mention that my ST is wired for 120VAC, so my electrical loads are ALWAYS balanced and my ST doesn't exhibit any "growling" or other associated unsteady ST dynamics issues. Our house power requirements range from about 1500 to 2500 watts, so well below 6/1 and ST5 limits. I also use George's engine throttle linkage mod to minimize the RPM variation resulting from our relatively small electrical load variations. Per Kilowatt monitor, my maximum voltage variation is less than plus/minus 3 VAC from my nominal 122 VAC. Frequency variation is within plus/minus 1 HZ from my nominal 60 HZ. If I had a light flicker issue, I think I would consider designing/constructing a low bandpass filter with a cutoff frequency around 25 Hz in lieu of using an AVR.
Bob B.
So, I guess what you guys are telling me is that, in asmuchas will be using a four cylinder engine runing at 1800 or, maybe, 2560, rpm, and will be ordering my ST-24 with an AVR controller, I shouldn't have a problem!
I will also, per Bob. make sure that I have a fuse of appropriate rating, in the output of the AVR, so that it won't have a fit trying to maintain voltage on shutdown. I'm assuming that this will still be neccessary, even if I don't shut the ST down under load so as to avoid needing "field flash" upon restart? And, does this mean that I will require 1 fuse per shutdown, because the AVR will try to maintain voltage as it is going away? Or should I rig a switch in the AVR feed and shut that down after shutting down the load on the ST-head, but before stopping the engine, and thus avoid the "1 fuse per shut down issue"?
It's nice to hear, for a change, that what I'm planning is not completely stupid! <grin>
Thanks for all the input, guys!
Regardz,
Wayne Stayton
I don't think you would ever want to have a shutdown with loads still on your ST because of adverse brownout effect. You might want to build something to ensure that this will never happen. See "Engine Speed and Voltage Protection System" in below link for what I did:
http://listerenginegallery.com/main.php?g2_itemId=351
I defer to other's expertise regarding AVR issues as I don't use one and I am not really a fan of using one for this application...too much complexity for too little value IMHO.
Bob B.
If you're feeding into the xantrex inverter discussed, it will disconnect from the generator at around 108 volts and/or frequency out of spec. So there should be no need to disconnect before shutdown. It also has a delayed connection to the generator to allow the engine to warm up.
Simply locate a 3-pole breaker at the STC head and open it when you shut down the diesel engine. That way you can start the engine without a load and let it warm/stabilize for a bit before applying load as well.
My selection and purchase of the 24kW/30 kVA STC head was a deliberate ~2X oversize based on the thinking that I would not hurt it by operating under load at much slower shaft RPM than 1800. This was essential in my wind turbine app. I have one in operation on a Changfa 1115 engine and have operated it loaded at as low as 1200 RPM without anything getting warm or failing. So far so good. I also have shut mine down with as much as 9 kW resistive load from rated 1800 RPM and never needed to flash the field yet.
I think starting up one of these heads or any head is a bad idea under anything approaching a real load and may in itself be the cause of needing a re-flash of the field rather than any loss of magnetism during a loaded shutdown.
I don't think i will have a problem on normal shutdown or start-up, since I plan on having a disconnect for the output from the generator-head, along with it own 200 amp circuit breaker across the output, but I won't be using the circuit breaker as a shutdown (except in an emergency!) becuase my uncle, the electrician, told me that shutting off circuit breakers under load causes excessive wear such that they start tripping under lower current. Not sure if that is true, or not, but it is cheap insurance to operate as though it was/is.
Where I would wnticipate having a problem is if the engine shut down without supervision such as from a plugged fuel filter or, God forbid, loss of oil pressure! If that were the case, there would be nothing to shed the load upon shut down, so, I am hoping that this is where the fuse in the AVR feed would come in!
Also, I'm not sure if the automatic shut down of the inverter occurs before the AVR draws excessive current, since I think that it will continue to increase the voltage until it reached the limit of it's supply voltage. Anyhow, the fuse on line to the AVR makes that a moot point - I would rather buy a $0.25 fuse than a $100.00 AVR any day of the week!
Also, I will have 120/240 loads other than the inverter - things that I don't, or can't, run off of the inverter because of lack of capacity will run off of the generator - really, I envision shifting the whole AC distribution panel over to the generatro when that was running, so the only load on the inverter would be its battery charger function - admittedly, a big load, but a singular one, nonetheless.
Thanx for the input!
Regardz,
Wayne Stayton
Quote from: WStayton on April 01, 2011, 11:11:55 AM
I don't think i will have a problem on normal shutdown or start-up, since I plan on having a disconnect for the output from the generator-head, along with it own 200 amp circuit breaker across the output, but I won't be using the circuit breaker as a shutdown (except in an emergency!) Regardz,
Wayne Stayton
I do hope you don't intend to place a 200 amp breaker across the output of the gen head as a shorting switch to bring the thing to a screeching halt. :o It might be cheaper to jam a crowbar into the engine crankshaft to effect the same result since crowbars are cheaper than 3-phase 200 amp breakers.
rcavictim:
Bad choice of words on my part!!! <grin>
You're supposed to read what I mean, not what I say!!! <smile>
Actually what I meant was that the 24 kW ST generator-head will have its own 200 amp, total, 100 amps per leg, in line with the output so that there is no way that I can try to draw more than 24 kW out of it. I THINK that I need this because the generator-head will feed the charge function of the inverter and the main 200 amp panel for the whole place, this way I could be drawing 50 amp for the charger function of the inverter and still have a rogue(sp?) load of everything trying to start at once and drawing more than the 150 amps still available.
BTW, I am assuming that the 100 amps that is available form the inverter for battery charging is as 48V DC, yes? Which means that I need, in round numbers, with charger losses and everything, 50 amps of 120 V AC, yes?
About the 200 amp breaker across the generator for a dead short: I may be dumb, but I don't think I am stupid! <grin>
Though, I guess, it is better to say something and make SURE that I'm not stupid, so thanx for keeping me honest! <smile>
Regardz,
Wayne Stayton
Your plan sounds OK, 100A per leg = 12KW per leg @ 120V... I have circuit breakers on my generator output. They are open for startup, and again open for shutdown to remove the load from the generator/engine...
In the case of a non AVR ST head, a simple shutdown could be rigged from a simple voltage sensing circuit. Since voltage output is RPM dependent in the plain ST head, a droop in RPM caused by a missfire or runing out of fuel, would cause a voltage droop, and the sense circuit could open a large electrical contactor on the output once a low voltage was detected. Clean electrical break, no brownout. the same circuit could then also shutoff the fuel and secure the engine. It then becomes a simple matter to add thermal sensors to provide the sam function in an overtemp/cooling malfunction...
The AVR makes this a little more difficult, as it maintains the voltage till it absolutely cannot do it anymore, and a lot of current may trade places while it is blindly trying to do it's job during a spooldown. The one thing that is predictable about an AVR is that it will maintain voltage by increasing field current. as you increase load, line voltage wants to drop. The AVR senses this and increses field current to maintain line volatge output. So for a given electrical load on the generator, the AVR will be providing a fairly predictable field current. This is where that fuse comes in. if you measure how much field current you are providing at your maximum load and add a fuse to the field circuit just slightly higher than that max normal field current, you will protect the AVR from feeding any perceived load greater than that, such as during a brownout spooldown...
If you are putting together your own generator, don't be afraid of the reflash process, it is really quite simple... In fact, I would say add labeled field reflash terminals to your generator doghouse, and write up a procedure to reflash the field using a car/starting battery... Be a shame to run the engine out of fuel, then be dead in the water because you do not know how to reflash the field...
I suppose this should be a new question, but its getting late and I'm getting tired so . . . I'll just stick it here! <grin>
I've heard/read that the "doghouses" on ST generator-heads are really just a problem looking for a place to happen in that they break and fall off due to fatigue from vibration.
My intention is to relocate everthing in the doghouse in a new/different/bigger electrical box at/in the control position for the generator which will be about 3 feet from the generator. It is my intention to run everything to and from the generator in conduit and I plan on a separate run of 3/4 inch conduit to carry the wires from the generator to the stuff that was previously mounted on top of the generator. I guess this would also include the AVR box.
Is this acceptable? I realize that the shorter the wires between the control "stuff" and the generator-head proper, the better, but is three feet within what is acceptable?
My plan is for the control bench to contain everything to operate the engine and the generator-head, with switches/selectors to turn on the engine operating circuit(s) and to operate the starter and shutdown. There will also be a 200 amp breaker and a disconnect for the output from the generator. For instrumentation I plan on having a tachometer, an oil pressure gauge, a coolant temperature gauge, a pyrometer with selector to read fuel pre-injector-pump temperature and fuel post-injector-pump temperature, a 12 V DC amp-meter, a 12 V DC voltmeter, two 120 V AC voltmeters to read each leg voltage, and two 120 V ampmeters to read the current on each leg. I guess I should also have a DC voltage gauge to read the AVR output voltage. There will also have to be a selector that has two positions 1) engine-generator and 2) inverter, to switch the whole load to one or the other. I think that the inverter functions are fixed on/in the inverter and there is no provision for manual remote actuation but if there are remote actuators for the inverter they would be mounted on/in the panel also. I guess the inverter itself could be mounted on/near the control panel, also, to keep all the lines as short as possible. The battery bank will be immediately at the end of the bench. I envision a space just wide enough to walk down between the control-bench/battery-bank and the engine-generator. The four water tanks to hold the cooling/heating water will be another aisle width down the space and yet another aisle space away will be the wood burning boiler. This whole assembly of pieces/parts takes a space about 22 feet long and 12 feet wide, maximum, which will have to fit in a space 20 ft x 30 ft, so there should be enough room for a tier of fire-wood on the furnace end of everything and still have a reasonable aisle way on the other side, where the space connects with the house.
Anybody see anything I have left out?
Input is hereby solicited! <grin>
Regardz,
Wayne Stayton
Put your batteries in a separate enclosure, preferably built outside... Charging batteries and open flame/sources of spark(genset brushes) are a bad combination. Batteries also containe an incredible ammount of instant energy. Something going wrong in the charging scheme, or wiring, and you have a potential home/structure wrecking installation. Plan your safety disconnect fuses VERY carefully, as they may save your life or your home!
You know, I have a hard time believing that an AVR doesn't have frequency sensing in it.
Quote from: Tom on April 03, 2011, 09:37:52 PM
You know, I have a hard time believing that an AVR doesn't have frequency sensing in it.
I need to do some testing and find out because
if it does that is gonna screw up how I was hoping the STC head would operate in my wind turbine.
Anyone have or seen a schematic of these AVR's from China? Since mine are potted that would be enormously helpful.
My 20/2 Listeroid powered ST-15 setup provides (at times) near useless power. Truth be told, it will run the basic electric motors such as window AC units, well pump and the fridge. However, so many things have trouble with the power that I'm not sure what to do, other than to run down the list of "fixes". Running "off grid" is an exercise in beeping UPS', grumbling electrical components, flickering lights and unsteady power.
Things that won't run, no matter what I do:
1) microwave
2) air conditioner (central)
3) TV
4) Direct TV sat receiver
5) half of my UPS'
My Robin/Subaru/Homelite generator runs everything without problems.
Part of the problem is the unsteady power of the listeroid, along with very poor governing, allowing the frequency to vary. The other part of the problem is the poor waveform. The combo is unsatisfactory electrical power.
I put a SX460 clone AVR on my ST10. Works great, stable voltage, under speed roll off, and no Z winding. I have not had a chance to scope it but no problems yet. The SX460 is designed for brush-lesses generators though. I do not know if it will be harder on the brushes being a SCR regulator. With the higher impeadance of the ST field the inrush current will be reduced somewhat. I believe you must power it from both legs (220v) to get enough voltage for the field, I am.
The only anomaly that I have noticed is that the stability control has little or no effect. Even at maximum gain the generator output is stable. Probably has something to do with the high impedance of the ST head. The clone 4609s are available on Epay for around $70 bucks. Worth a try, worked for me!
Greg
I have a 1ph 12KW ST direct driven by a ISUZU C-201 (4 Cylinder). It runs everything I have.... I have never had any problems with any electrical equipment ever. Mine has no AVR. I have never had a scope on it to see the sine wave (or lack there of!)
I do have a similar list of equipment (and more)
1) microwave
2) air conditioner (central)
3) TV
4) cable box
5) half of my UPS'
6) cable modem
7) WiFi router
8) Vonage phone router
Just reference info for everyones consideration.
Rob
Quote from: cujet on May 01, 2011, 06:47:09 AM
My 20/2 Listeroid powered ST-15 setup provides near useless power. Sure, it will run the basic electric motors and the fridge. However, so many things have trouble with the power that I'm not sure what to do. Running "off grid" is an exercise in beeping UPS', grumbling electrical components, flickering lights and unsteady power.
Things that won't run, no matter what I do:
1) microwave
2) air conditioner (central)
3) TV
4) Direct TV sat receiver
5) half of my UPS'
My Robin/Subaru/Homelite generator runs everything without problems.
Part of the problem is the unsteady power of the listeroid, along with very poor governing, allowing the frequency to vary. The other part of the problem is the poor waveform. The combo is unsatisfactory electrical power.
Cujet, one issue with the ST series is the rectified harmonic energy is fed right to the field raw. It is a real ugly waveform. The addition of some filtration to this rectified signal greatly improves the output waveform. My ST-5 initially would not feed a UPS. With the addition of some filter caps to the output of the bridge rectifyer which basically turns the waveform from pulses into DC, it now runs all the UPS's in my house, and I have no other issues with any other device in my home running off the output including all the ones you mention. The flicker is mainly a function of single cylinder engines, and the 2 cylinder roids don't fire directly in opposition, their power output curve is similar to a single. The voltage output of the harmonically excited generator being RPM dependant dosn't help matters any. An AVR takes a lot of the edge off of the perceived flicker in incandescent lights. Most of my lights are CFL's and they don't show it as bad(hardly notice it) as the incandescents do . I just posted some old waveform pics showing the output waveform of my ST-5 with different field inputs for Veggie in this thread.
http://www.microcogen.info/index.php?topic=1938.0
Quote from: gregger2k on May 01, 2011, 09:03:30 AM
I put a SX460 clone AVR on my ST10. Works great, stable voltage, under speed roll off, and no Z winding. I have not had a chance to scope it but no problems yet. The SX460 is designed for brush-lesses generators though. I do not know if it will be harder on the brushes being a SCR regulator. With the higher impeadance of the ST field the inrush current will be reduced somewhat. I believe you must power it from both legs (220v) to get enough voltage for the field, I am.
The only anomaly that I have noticed is that the stability control has little or no effect. Even at maximum gain the generator output is stable. Probably has something to do with the high impedance of the ST head. The clone 4609s are available on Epay for around $70 bucks. Worth a try, worked for me!
Greg
Question: Is the ST head still self exciting without the Z winding in the circuit? It looks like a great idea and I'd be very willing to try it.
One of the issues I have is that my ST-15 head does not produce enough voltage. Under a 6000 watt load, the voltage sags to 106-109. That's a bit low for comfort.
Using an AVR in this manner"might" solve that problem and a few others. My ST-15 head did come with an el-cheapo AVR, but it's been removed as it lowered voltage further still.
Couple that AVR with extra gen head flywheel mass to smooth out the power pulses (the reason the microwave does not work) and I "might" be on my way to use-able power.
Thanks!
Chris
Chris
I've observed my neighbor (Cujet - Chris) struggling with his generator head for several years. Interestingly, I have an almost identical Listeroid setup as follows:
20/2 GTC down rated to 850 rpm with extra heavy flywheels. (As I recall Chris is his running at 750 rpm)
I have an ST 15 generator head, 11 in pulley which equals a 70 lb chunk of metal spinning at 1800 rpm.
I replaced my AVR very soon after installing my gen head. I don't recall if it burned out or just rattled apart. (As I recall Chris had a malfunctioning AVR and ended up removing it). I ended up spending $49 to replace the AVR from Tom Osborne (Central Georgia Generator = CGG).
I replaced the misaligned brush holder in my ST 15 head and the brushes. Had to fabricate a few small parts to get the brushes to lineup properly on the slip rings but now I have a good and flush contact surface.
In fairness to Chris, I bought my ST 15 generator head in 2006 from a shop down in Miami, which is now out of business, and Chris bought his from another vendor up in Orlando, as I recall back in 2007. There is a difference in quality, perhaps I just got lucky or I just had a different set of defective parts.
In 2008, I ended up replacing both generator head bearings with Timken (I know this is like putting lipstick on a pig but I don't ever want to have wrestle those heavy ST head components around again, and to do so with damage was a real effort). While I was inside the gen head, I placed a coat of Glyptal onto the windings and replaced the 1960s Chinese vintage diode bridge with a (CGG) 40 AMP large heat sink version: This is also over kill but I do not want to be messing around with trouble shooting a generator failure during hurricane recovery operations.
I am currently in the process of mounting the solid-state diode bridge rectifier, and the AVR on to a power meter panel / board away from the Listeroid to isolate it from vibration. I hope to finish this process this week.
The results of what I have been accomplished thus far include:
1. Virtually eliminated light flicker, even in florescent lights, I believe this was primarily accomplished by engaging lots of heavy spinning metal flywheels and pulleys. Perhaps my 850-rpm prime mover speed, as opposed to 750-rpm, is just enough to smooth out the power pulses where the flicker cannot be seen. Perhaps placing a little more spinning metal on Chris's generator head could push the pulse flicker into the not noticeable category.
2. My existing UPS, microwave, TV, computer, and everything else have no problem digesting the power output from my ST. I have invited my other neighbor (Ray Carlson) to stop by with his O scope because I really want to see what the wave form looks like. While we are at it, I am going to check my Metro 6/1 800 rpm ST 7.5 gen head which is setup the same as my ST 15. And then the $99 Harbor Freight two stoke.
3. This week I load tested my 20/2 GTC with ST 15 head on a hard 5 hour run on six year old treated waste jet fuel. The generator was loaded continuously to 9 & 10 kW for most of the time with occasional loads up to 11,200 watts (52A @ 215 V). The 11,200 W load is an absolute maximum, as the frequency started dropping (58 Hz) while the Listeroid struggled to maintain rated speed. I held the 11 kW load for 20 minutes just to test the over temperature shutdown system. I am extremely pleased with the unit, now that I have been able to fix all the original defects.
Chris has an impressively designed and setup 20/2 GTC, ST 15 all on a steel wheeled cart. His cooling system and compact setup are very nice. It is a real chick magnet. I know his job really prevents him from doing all the tinkering I have done, but as hurricane season approaches, we both need to ensure operational effectiveness of these power units.
Chris - I've got a spare AVR and a spare 20 A solid state diode bridge if you want to test them out.
Forum – I really would like to know more about ST DC filtering via capacitors. I do not have a deep electronics knowledge, so if someone would break it down in simple terms I would really appreciate your help. I need to know what size capacitor works well and exactly where to insert the C in series with what. I have traced and labeled all wires on my ST heads so I can now interpret any instructions / advice.
Quote from: Horsepoor on May 04, 2011, 02:35:08 AM
Forum – I really would like to know more about ST DC filtering via capacitors. I do not have a deep electronics knowledge, so if someone would break it down in simple terms I would really appreciate your help. I need to know what size capacitor works well and exactly where to insert the C in series with what. I have traced and labeled all wires on my ST heads so I can now interpret any instructions / advice.
The filtration cap acts like a battery. The pulsed output of the bridge rectifyer charges with this energy, and basically turns a pulsed output to a flat(or nearly so) DC voltage. You use electrolytic capacitors, with a voltage rating higher than the peak voltage. The capacitance is installed across the output of the bridge rectifyer where the energy is fed down to the brushes. Rule of thumb for filtration is around 2000 Microfarads(represented an "uF") per amp of power supply current draw. Too much filtration, however will delay the voltage response, as it takes a little time for the caps to charge and discharge with input changes such as when you load and unload the generator. In this case you would want to use the minimum ammount of capacitance to get the AC output waveform cleaned up. Another side effect is the output voltage of the generator increases with the capacitance being added. This is due to the interaction of the capacitance with the windings, and the more stable power being applied to the field(field is more stable, and not radically expanding/collapsing with the unstable input). I am at work now, I can post some pics and O-scope shots of the before and after field excitation waveforms later this evening.
EDIT: Here are some images to show you what the signals look like.
The first is the raw output of the Z winding.
(http://i270.photobucket.com/albums/jj85/rmarlett/th_zwindingoutput.jpg) (http://s270.photobucket.com/albums/jj85/rmarlett/?action=view¤t=zwindingoutput.jpg)
The next is what it looks like after it is rectified. This is what is fed to the brushes and field on a stock ST.
(http://i270.photobucket.com/albums/jj85/rmarlett/th_rectoutput.jpg) (http://s270.photobucket.com/albums/jj85/rmarlett/?action=view¤t=rectoutput.jpg)
Here is what it looks like with some filter capacitance installed(basically DC):
(http://i270.photobucket.com/albums/jj85/rmarlett/th_filtered.jpg) (http://s270.photobucket.com/albums/jj85/rmarlett/?action=view¤t=filtered.jpg)
Thank you, this just the type and scope of information I was looking for. So, to save me some time, what size capicator would you or someone else recommend for an ST 7.5 producing 4,000 watts ? And what starting recommemdation would you have for an ST 15 producing 10,000 watts? I figure I dont need to reinvent the wheel because their must be sevral forum members who have refined the selection to a narrow band of choices. Thank you again for the pics and post reply.
Quote from: Horsepoor on May 04, 2011, 05:57:31 PM
Thank you, this just the type and scope of information I was looking for. So, to save me some time, what size capicator would you or someone else recommend for an ST 7.5 producing 4,000 watts ? And what starting recommemdation would you have for an ST 15 producing 10,000 watts? I figure I dont need to reinvent the wheel because their must be sevral forum members who have refined the selection to a narrow band of choices. Thank you again for the pics and post reply.
You need to put an amp meter in circuit with your field, and measure the AC amps being fed to your field winding with the respective generator under load. If I recall correctly, I think my ST-5 pulls about 2.5A of field current with 3000W of electric load. I am currently running Four 1300uF 50VDC electrolytic caps(each about the size of a D battery) in parallel(caps in parallel are additive) for a total of 5200uF, connected right across the bridge rectifyer output. Electrolytics, like batteries, are polarity sensitive, so be carefull how you hook them up. Once you measure your field current with an amp meter, I would say start at 1000uF per amp and work up from there till you get the minimum ammount of capacitance in circuit that achieves your output waveform goal. Too much is bad, as like a battery, once charged, the cap acts like a UPS feeding the field to carry the load across a slump in the input, which is how it transforms the ragged input into nearly flat DC. If you are running a lot of capacitance, and are running the generator at a very high load(lots of Z winding input), and suddenly remove a large load, the output voltage WILL spike. Under heavy gen load the caps are being fed at their highest rate from the Z winding. When the load(and z winding input) goes away, the caps still have a lot of energy feeding the field, but the output load has dissappeared, so that field energy turns into an output voltage increase untill the energy in the caps bleeds down to the level that the Z winding is feeding under the reduced generator load... Same is true with sudden load increases, it takes a little time for the caps to charge with increased input, so there is a little output voltage drop untill they catch up. The more capacitance you run, the worse the voltage excursions are with major load changes, so use only what is absolutely necessary.
Good luck
Ronmar:
So would I be correct in assuming that a cheap-o AVR is just an elegant collection of capacitors and some mechanism to provide an appropriate voiltage for the field?
Conceptually, a very smart mouse with a voltage meter and a variac who ALWAYS watches to output voltage?
Yea, I know, it couldn't POSSIBLY be that simple! <grin>
Regardz,
Wayne Stayton
Yep, only the cheep-o ones still use mice:)
You are correct, the AVR monitors the output voltage and inveresly regulates the current flow into the field to maintain the output voltage. A typical AVR dosn't use many caps, it is more chips and transistors...
The use of caps on the ST head dosn't do anything for voltage stability, in fact, it probably adds lag/overshoot to it if too much is added as I described above. the Z winding relationship to the field is where that type gets it's relatively stable voltage. The caps only help clean up the waveform. there are capacitive regulated generators, but they are wired much different, and can use a change in capacitance to change the output voltage. There are quite a few ways to skin this cat...
The harmonic or Z winding in the generator does the same thing naturally, as it's output is based on the current flow thru the secondary winding. More current with increased generator load = more z winding output being fed to the field to maintain output voltage under the increased load. It is however a tricky process to determine exactly how many windings are needed in the Z winding to give the desired slope to the output to maintain voltage under load... unfiltered, it makes for a distorted and unstable field waveform, which translates to a distorted AC output waveform. Also since you are robbing from the generator field to produce this field energy it also probably adds to the output waveform distortion.
Quote from: Horsepoor on May 04, 2011, 02:35:08 AM
1. Virtually eliminated light flicker, even in florescent lights, I believe this was primarily accomplished by engaging lots of heavy spinning metal flywheels and pulleys. Perhaps my 850-rpm prime mover speed, as opposed to 750-rpm, is just enough to smooth out the power pulses where the flicker cannot be seen. Perhaps placing a little more spinning metal on Chris's generator head could push the pulse flicker into the not noticeable category.
Well, I am glad that I am not the only one who doesn't notice light flicker WITHOUT using a AVR. :)
I suspect (but can't prove) that just maintaining a good steady nominal voltage (I run 122 +/- 3 VAC) and frequency (I run 60 +/- 1 HZ) by always keeping electrical loads balanced, not pushing your engine or ST near their limits, and minimizing undesirable low frequency engine/ST dynamic effects (with resilient mounting, increased flywheel weight, etc.) goes a long way to reducing perceptable light flicker. It sounds like Cujet's problems may have much to do with simple voltage sag than anything else.
Bob B.
Using capacitors to filter the excitation current is just 1/2 of an LC circuit. You could use an inductor such as 1/2 of a transformer instead, or calc the LC circuit. No?
Quote from: mbryner on May 07, 2011, 01:19:18 PM
Using capacitors to filter the excitation current is just 1/2 of an LC circuit. You could use an inductor such as 1/2 of a transformer instead, or calc the LC circuit. No?
Any L you place in series with the exciter circuit is going to make the excitation voltage drop like a stone. It will also slow the response to load shift as was mentioned that too big a C will do.
the rotor field winding already is the "L" in the tank circuit
i suppose that and the Z winding comprise the "L" component
no need for more inductance?
bob g
Finally got some time to take measurements, and add some photographs concerning my ST 15 Gen head. Built a meter panel with a no voltage emergency shut down system for about $15. I wanted something that would trip if a belt breaks, rectifier blows, etc. Here as some measurements off the top of the ST 15.
At 230 Volts with 35 amp load I read the following (No AVR in the circuit for these measurements):
55 VDC coming out of the diode bridge at 3.75 A
74 VAC coming off the Z winding. (Used a clamp meter here to get a questionable reading of 0.45 A)
These 11 pin Potter & Brumfield relays are cheap and allow several trip circuits to be created in one relay trip event. I step up a combination of 12 VDC and 110 VAC switches based upon this relay.
Next we attached an O-Scope to examine what happens to the wave form when the new AVR is removed. As cited elsewhere on the forum, the wave form is slightly better with the AVR in the circuit. In the attached O-Scope photo, I illustrate the worse wave form we could create by intentionally lightly loading the ST 15 at about 1,000 to 2,000 watts. This wave form is still not bad, and when heavily loaded it is close to perfect. But who wants to see perfect. Next step is to explore adding just enough large capactors to raise the voltage a little.
Here is an unresolved problem: With the AVR engaged, I get the following reads at the generator head: 110 VAC line #1, 115 VAC line #2, 226 VAC across both lines, and this holds pretty constant across all load ranges 3 KW to 10 KW. Problem is up at the main house 250 feet way via the gound calbes (4 AGW) I get 105 VAC on some house outlets. A little low, but serviceable. I just wonder why one identical line off the ST 15 always has a voltage 5 or 6 volts lower than the other leg. The AVR measures the 226 VAC line. ? Any ideas?
My ST5 will do that depending on which leg is loaded heavier.
Tom,
Even when very lightly loaded? For example 1,500 watt load on a ST 15 head. Very interesting, learning all the time. Still, I love this stuff because I can repair, fix, and understand just about all of the componets.
Bruce
Well on an ST5 1500 watts is a pretty good percentage of the 2500 watt per leg output. I've seen as much as a 20 volt difference between legs. I've got a load balancing transformer sitting in the engine shed, guess I should try hooking it up some time and see how well it works.
We just tried 2000mF on the rectifier output on a friends ST-5 6/1 setup. The pocket O-scope (fleabay special) clearly shows a nasty rectifier output. 1000mF was sufficient to smooth the ripple out to DC, so we installed 2ea. 1000mF caps in parallel.
The bottom line: The ST-5 output sine wave form is nasty. It cleans up by some small amount under a 3000 watt resistive load. The caps "might" help the 115V output wave form some, but it is not significant. I'm fairly sure that there was some sort of difference between the caps "not connected" and "connected". But it was so small compared to the wave form distortion, I'm not sure it matters.
I am the "other friend Chris has" and I just finished experimenting on my ST 15 gen head loaded at 40 amp and 230 VAC. Ended up with 8000 uF which raised my output ST voltage to 238 VAC and a better overall wave form. I am pleased with the results for what it is.
Another benefit is an increase in voltage. My ST VAC was always a little low. Now the AVR has something to regulate and I can, if desired, adjust it down some. Here are some crude photos using my $5 volt meter and $75 pocket O-Scope, nothing but the best for my ST & listeroid. Also, ignor the units on the O-Scope, I am still learning how to use the device but the wave form is valid.
Hey Horsepoor,
I only have 2 friends! ;D
Is the pic above before or after? And, do you have before/after pics?
Also, what was the load?
Chris
Chris,
Only two friends who will admit they know you ... The before O-Scope pictures were posted last week forum, look in recent posts fo the full sized O-Scope green sceen back ground with a very light load, on the ST at about 1500 warrs. I posted the worst O-Scope image we could get at that time "without" and filtering circult.
Back to current events, I didnt want to experiment on my ST system, so I talked Rocketboy into testing all this stuff on his unit with your assistance. Sorry, but I deleted the photos after posting on the forum. Overall, I dont think my wave form changed that much primarily because it wasnt that bad to begin with. I am extremely pleased with the VAC increase so that my AVR now has something to regulate. One leg of my ST 15 had a low voltage reading (109 VAC) under load up at the main house 200+ feet away which has now been corrected - happy days are here.
I realize 8,000 uF is a rather large amount of capacitance which will lag behind resulting in higher voltage after a large load has been disengaged, and a slower rise in voltage when a large load is added, but this is the way I figure it at on my ST 15 @ 230 VAC. Going from 45 Amp to 35 Amp as one air conditioner kicks off is no big deal, likewise going from 30A to 45A as the electic hot water heat kicks in should be no big deal due to relative high loads normally on the system. I hope I am correct.
Bruce
I just installed a whole house electrical remote monitor. I highly recommend you buy one of these.
http://www.energymonitors.com/product.php?product=175282 (http://www.energymonitors.com/product.php?product=175282)
Took every bit of 60 seconds to clamp the sensors onto the current lines, it really works well and has great range. Sitting here watching the whole house load change in real time with appliances engaging and tuning off, really cool.
Check eBay, just saw a new one for $89 plus shipping. I paid $144 but it was worth it. I can now easily monitor load from 100+ feet away. Oh, it has an adjustable alarm for load too. What a neat item.
Bruce