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Arthur Newbie Joined: 05/03/2009 Location: United KingdomPosts: 28
Posted: 11:35am 10 Mar 2009
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I wonder if anyone has experience of this generator? It's not mine but a chap asked for help. It's a 12volt version. I have read how wonderful it is and a new phase in generators with a new brake system that makes everything else stone age. However this chap saw it charging at 17volts one evening at 65Amps. :( He does have a large capacity. Next day the super quiet wings had taken off in bits. It appears that this thing is computerised control
I guess his has not been set up propeery? Or it's an expensive braKING SYSTEM:). can anyone help with how this thing has to be set up please or does he throw the box away and go for a conventional system of charging/offloading? thanks Arthur
GWatPE Senior Member Joined: 01/09/2006 Location: AustraliaPosts: 2127
Posted: 01:52pm 10 Mar 2009
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It would not matter what capacity, 17V on a 12V battery is not good. Seems like there is a problem with the controller. 15V would be an upper max.
BTW computerised control could be analogue, ala PWM chip, or digital, ala Pic micro. computer control sounds like a sales thing.
The new chinese controllers give electro magnetic braking and mine was given to me. It is a complete potted unit, with preset voltage limits. Mine was for a 24V, 200W mill, and limits at 29.5V.
Those ARI units seem to have no mechanical furling, and rely on this electro mechanical brake. The ratings seem to be at high windspeeds. Not hard to get high numbers with a machine that does not furl. If the blades desintegrate, then this does suggest some design problems.
The electro mechanical braking is normally used on downwind mills. If the mill has a tail, then why not put it to good use.
This braking system sounds like an expensive broken one. I don't know what offloading you are talking about. Do you mean diversion loading?
Sounds like more than one problem here.
Gordon.become more energy aware
Arthur Newbie Joined: 05/03/2009 Location: United KingdomPosts: 28
Posted: 02:07pm 10 Mar 2009
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Thanks Gordon, they make a big thing of their braking system making for reduced mechanical problems. I guess KISS is always the best rather than go to thss kind of control which apparently did not work, seems they keep the blades to the wqind regardless of its speed. I have traced a website in |Hungary that sells these; the controller is extra theere but it does show a picture of the controller with a diveersion load by it's side I'm not really sure if this chap has the load. I guess that the brake takes power off the battery to operate then? Arthur
oztules Guru Joined: 26/07/2007 Location: AustraliaPosts: 1686
Posted: 09:04pm 10 Mar 2009
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Generally electronic braking means shorting out the stator. I use it to stop the mill, never to control it. Any mill over 4' without some form of furling/pitch control/wing flaps, is an accident waiting to happen.
Their cunning braking is probably a pwm short circuit across the windings. The heat has to go somewhere, and will probably be fine in normal conditions where the heat can get away, and the power is not great anyway.
If you chose Fets with a high Rds on, then your heat sink will dissipate a lot of the heat and the rest in the mill, a low Rds on will mean the mill cops it all.
One suspects his fets are shot to bits, and have failed open... probably with physical signs of distress, Failing open is not their first choice. According to their schpeel, there is an overload fuse as well.....unless this is sensibly chosen (100A plus) it may have blown before the fets... or after the fets shorted, and the mill ran away??
If the stator has a very low impedance, then a brake switch is the best he can hope for in a big blow with no furling, and hope the prop never breaks out of hard stall.
If the stator has higher impedance and iron in it, then interesting things happen when you try braking them hard in a good blow. The higher ampere turn induced by the short circuit, seems to create a high armature reactance, and instead of braking when you short it, it runs on and even away if the furling does not protect it. In this event, just proportionally overloading the prop (pwm short circuit) will probably do a much better job of stopping it... or a lowish resistance load will bring it slowly to a stop.
Without furling, there is no safe way to load it, and know it will stop. There are lots of KW in strong winds, and the strong winds (gale force etc) will bring this electronic braking undone... one way or the other. With 45 mph winds my mill would have to deal with 20000 watts if it could not furl out of the way... As you can guess, would take a lot of silicon to try and handle that.
His 1.8m unit would see some 5000w at about 50 mph... thats a lot to off load somewhere.
So electronic braking only works for reasonable winds, unreasonable winds need to be tempered into reasonable winds mechanically. Their system is asking for destruction. Placing your faith in silicon chips between mother nature and an unfurlable mill is akin to suicide... however..it is "reassuring" to know that when all else fails.... their blades disintegrate
.........oztules
Village idiot...or... just another hack out of his depth
Arthur Newbie Joined: 05/03/2009 Location: United KingdomPosts: 28
Posted: 04:05am 11 Mar 2009
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|Tha, may see bits of fets all over the place hi.nk you for your reply most interesting and along the line i was thinking. I'm now wating for some closeup pictures of the control unit Will post here what I can gather from the photos if anything. \\\\\\\\arthur
Arthur Newbie Joined: 05/03/2009 Location: United KingdomPosts: 28
Posted: 07:32am 15 Mar 2009
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I beleive after reading the manual on line and taking a few days to think about what I read that these people say that the charging is controlled in steps. From that I gather that they pulse the charging by pulsing a dump load across the battery lengthening the pulse as the battery gets near full, when full the dump load is put across the battery, unfortunatly from this systen I can see the generator freewheeling and off go it's blades. T|his is an american (addresses) company but I'm wondering if they are made in China.Unfortunatly thap that bought id has spent a lot of money on a 12volt invverter and is off grid so cannot afford to dump it, it has 3 wires coming from the generator, my humble advice was to build another charger controller and to short the 3 alternator wires with a relay to stop it from turning?
Any offers, thanks Arthur
GWatPE Senior Member Joined: 01/09/2006 Location: AustraliaPosts: 2127
Posted: 01:12pm 15 Mar 2009
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The diversion load and controller would be better placed on a separate rectifier system with battery voltage sensing control. This would eliminate any relay switching and prevent the diversion load from discharging the battery directly.
Gordon.become more energy aware
Arthur Newbie Joined: 05/03/2009 Location: United KingdomPosts: 28
Posted: 01:29pm 15 Mar 2009
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Thanks Gordon, very difficult to know what has gone wrong. I am just trying to assist someone about 900 miles away off grid and not electrically minded; I can only guess this USA compaNY HAVE MADE A DRASTIC STEP 'FORWARD' in this
design and that blades will fly off until the generator is replaced. Arthur
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