> Norm; > If, as they claim, there are protective devices in the generator, I imagine > they either open the load or short the output. Since shorting the output > would increase the heating of the coils I doubt that's what they do. Ken; Yet this is exactly the approach that is used in a motorcycle regulator and other PM alternators, and as we will see here (keep reading or scroll down), it is also what the KISS does.
Norm; I can only imagine they open the output to stop overheating the coils. If this > is the case, as it appears to be, then the increased no-load voltage does > not damage the units since they are still working after a 82 mph squall. Ken; Most diodes made for auto alternators, as yours are said to be (and the Hotwire website verified for me), will not withstand more than 40-60 volts reverse depending on how hot they get (which is why you are not supposed to run an alternator with no load on the output). The amount of voltage created by an opened PM alt in such circumstances would be as much as 200 volts, from experience. Not only that, but opening the load would allow the blades to 'run-away'. You would get an instant and very significant increase in blade speed that would accelerate until the blade speed stabilized from air turbulence, bearing friction, and other forces, which could mean an unacceptably high speed, esp. in a sustained high wind event such as a hurricane. In fact, the folks who sell the KISS DO sell such a load, they call in a "divert load". From their web site at http://www.svhotwire.com/divert_loads.html ; "Divert Loads From Hotwire Enterprises Divert loads are typically needed with a wind generator to reduce the possibility of voltage spikes which could damage the charge controller. They also maintain an electrical load on the wind generator when the batteries are fully charged. This prevents the blades from "freewheeling", thus reducing noise and vibration as well as wear on the wind generator." Hotwire Enterprises offers three options for divert loads:" And from "http://www.fieldlines.com/story/2007/12/14/0349/8059";; "The Kiss is a three phase permanent magnet alternator. The three phases are brought down the mast and there is a switch (to short the phases and stop the turbine) and a rectifier in a box inside the boat. Kiss actually recommend using the wind generator without a regulator, but they assume a battery bank of around 500Ah (not uncommon on sailboats these days) which would be able to take the average output of the turbine as a maintenance charge without problems. However, the boat only has a battery bank of 220Ah and has no room for more batteries without a serious redesign, so we installed a LVM 12V / 40A dump load regulator. (Normally sold with the Aerogen 6 wind generator.)" They go into more detail on their FAQ pages. And from: " http://www.cruisersforum.com/forums/f14/windbugger-852.html " "I just experienced a failure of my KISS wind generator of a nature that I've been worried about for quite some time. The KISS generator has a thermal breaker on each of the 3 outputs of the generator. These open when the generator is getting too hot by generating too much power. This sounds OK in principle, but the problem is that when the breakers open, the blades freewheel at a very high rate of speed. The power curves that KISS supplies shows the generator producing 18 A at 20 Kts and 25 A at 25 Kts. However, there's nothing in their literature which shows the maximum sustainable power output. A switch, located between the generator wiring and the connections to the battery provides a method of feathering the generator by shorting the outputs to ground or each other. In winds of less than 25 kts this typically causes the blades to spin at a very slow rate of speed. However, once the thermal breakers have tripped, this switch does nothing. To me this is a serious design flaw. The system should feather itself instead of letting the blades freewheel. I first noticed this on the trip from FL to Guatemala last summer. I had just installed it and was quite surprised when it wouldn't feather in a squall that blew through. I contacted the US KISS distributor about this, and their response was that I should take a boat hook and use it to pull the generator sideways into the wind via a string that goes from the tail of the generator to the support pole. Yeah, that's a great concept until you're at sea with the boat pitching all over the place and probably a lot of other things going wrong at the same time." It seems that the 'protective devices' are only to protect the wind generator from overheating its windings, and when they begin to get too hot then the load is disconnected by a thermal breaker and the unit may then run-away. As far as damage to the diodes when the breakers cool and re-connect the windings to the load through them, I would say that if it does not happen often it could be lived with as such devices can absorb a certain amount of such transient high voltage spikes, but it would not be a good thing if it happened a lot. From http://www.kissenergy.com/PracticalSailor.html ; *"Electrical Protection* In winds of up to about 30 knots, an electrical brake slows the unit’s rotation to a crawl if you want to stop free-wheeling when not producing electricity. Above that point, the unit should be turned off and allowed to free-wheel. If the alternator is left on in high winds and overheats, a thermal switch shuts down the alternator and allows the blades to spin. Although Billings says at least one machine has survived hurricane-force winds, we would lock the blades in place with a shock cord retainer when bad conditions are forecast." The 'electrical brake' they mention is the shorted output...this would be WITHOUT a 'divert load''. In high sustained winds, it seems there is danger of run-way if the blades are not tied down so they cannot spin (actually removing the blades is recommended by KISS, and that is an easy thing to do with the KISS) . Norm; KISS dismisses the use of regulators with their wind generators by saying that occasional overcharging of the battery bank is a good thing (equalizing charge) so no regulator is needed in most cases (with a large enough battery bank). Of course, I don't see why a shunt type regulator could not be added if desired. Ken; Here is what the folks at Hotwire Enterprises (not KISS) have to say about regulators; http://www.svhotwire.com/kiss_faqs.html "8. What regulator do I have to have? Aboard s/v HOTWIRE, we don't use a charge controller. We use a digital e-meter to monitor the state of our batteries. On those windy days when our batteries are fully charged, we'll plug in the watermaker, transmit on the SSB/ham, make popcorn and watch a video, whatever uses the power as it's being made. (If we can't keep up, we've been known to feather the unit at an angle to the wind, reducing the blade speed and the charging rate.) If all this sounds too complicated to you, we have charge controllers and divert loads (for excess power) to make your system fully automated and prevent overcharging, especially important if you're using AGM or gel cell batteries." So they say either monitor the charge rate and divert the load when needed, or get an auto controller and divert load. This is IF you have a big battery bank (they had a 500 AH bank I think)! If you don't you will likely be constantly re-routing your power to a dump load or turning on things to use it up. This is a sort of 'manual' shunt load. The automatic type is their charge controller and divert load. For a short primer on the tech used in typical voltage regulators associated with Perm Mag generators such as the one the KISS uses, see; http://faq.f650.com/FAQS/VoltageRectifierFAQ.htm#So%20What%20(Simply%20Explained)%20does%20The%20Voltage%20Rectifier%20do There you will find that regulation of this type of device typically involves shorting the output to ground when too much power is put into the load, as it seems is the one of or the default method the KISS still uses. This site goes into most of these issues in great detail; http://64.233.169.104/custom?q=cache:tDHy03mAvVwJ:www.smallwindindustry.org/fileadmin/ewea_documents/documents/projects/swiis/technology/050525RegulationTechnology.pdf+%22PM+generator%22%2B%22magnets%22%2B%22overheat%22&hl=en&ct=clnk&cd=5&gl=us&client=pub-8503897397197043This So it seems other folks are aware of the issues I mentioned, and the unit is in fact designed to be shorted when the batteries are full if there is no 'divert' or dump load, and the KISS also uses a thermal breaker in the phase windings to limit heat build up when the unit is shorted and disconnected from the load (to prevent overspeeding and too high a voltage in the windings) when the batteries are fully charged and there is no divert load. Apparently in such circumstances the KISS is disconnected manually by the operator (default install mode) or automatically by a charge controller BEFORE the rectifier/regulator so that if the thermal breakers open the diodes are not then endangered, a good idea. So yes, it seems at least some folks do in fact install and set it up with a "dump load" for the reasons I mentioned. It is obvious that the KISS still does NOT use an internal 'dump load' as I thought they did not. Don't get the wrong idea, I like the KISS wind generator, the main reason I do not use on is it is to much weight for its power for my small boat. But it IS a simple easy to repair design. My point in all this is NOT to be critical and point out supposed 'design flaws', as each design possess its own strengths and weakness (not necessarily "flaws"), the Air Marine as well as the KISS, but rather to point out deign approaches and limitations, both in commonalties and differences. To do this it is necessary to know all the data. I hope this goes some ways to underscoring some of the differences in the approach the KISS has taken. It is a reasonable approach, but the end user should be familiar with the issues to achieve an appropriate installation. The fact you have had no trouble with your installation does not mean it could not be improved. You may wish to consider for instance, an auto divert load if you ever wish to leave the boat un-attended for an extended time in a windy location with the wind generators operational. For boats with less battery capacity and less electrical load then yours (like my boat), such a consideration would be much more important, in fact it would be even critical. I myself would not wish to use it on my small boat without a divert load and controller for extended un-attended periods. Norm; Maximum Power Point Tracker PV panel regulators have been around for a while, I have one. They work best in cold climates. They work by adjusting the load on the panels so as to produce the most power into the batteries, much like a controllable pitch airplane propeller does to allow the engine to run at peak performance rpm while varying the power produced. Ken; Good analogy. Yes, and it is maybe good to note also that they loose almost no power in doing this. This "switch mode" design used in this solar panel tech regulator/controller/charger is very similar to the way the Air Marine wind genny achieves its power regulation. -Ken > _______________________________________________ Liveaboard mailing list [email protected] To adjust your membership settings over the web http://www.liveaboardnow.org/mailman/listinfo/liveaboard To subscribe send an email to [EMAIL PROTECTED] To unsubscribe send an email to [EMAIL PROTECTED] The archives are at http://www.liveaboardnow.org/pipermail/liveaboard/ To search the archives http://www.mail-archive.com/[email protected] The Mailman Users Guide can be found here http://www.gnu.org/software/mailman/mailman-member/index.html
