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Forum Index : Windmills : F&P goodies
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| dazz Regular Member  Joined: 15/04/2008 Location: Posts: 78 |
Hi All, I got around to pulling the control boards off an F&P machine to see if there was anything useful.There is some good stuff in there. What looks like a complete switchmode regulator, 12V solenoid valves(normally they are 240V), various nice components and a braking resistor. This was the most interesting part. It is about 30cm long and housed in a water cooled aluminium heatsink. The incomming cold water to the machine first flows through this heat sink which is designed so the water flows to the end and back. This heat sink is also used to cool the MOSFETS as they are pressed against the sides of the heatsink. So question. The braking resistor weighed in at around 25ohm, is this low enough to be an effective dump load for a F&P windmill? If so, then the whole unit is just ripe to use wasted dumpload heat to heat water. The unit can be mounted on the pcb and so water can be brought right to the board for heating. Additionally, power components in the windmill regulator could also be attached to this heatsink in the same way F&P do it, to keep them cool and pour even more wasted heat back where it's useful. Thoughts? Cheers, Daryl |
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Gill Senior Member  Joined: 11/11/2006 Location: AustraliaPosts: 669 |
G'day dazz, The breaking resistor came up in this thread on dump load resistors a while ago. Basically the resistance is wrong for our voltages/power. It would need to be shortened to such an extent that it would not be expected to be effective as a water heater dump load. At least that's how I remember it.  was working fine... til the smoke got out. Cheers Gill _Cairns, FNQ |
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Bryan1 Guru  Joined: 22/02/2006 Location: AustraliaPosts: 1458 |
Hiya Dazz, I pulled off some of the fets on the f&p board and asked in another forum for a datasheet on the part numbers but the answer I got was ' it is common for big manufacturers to name their own part numbers on chips' and after extensive searching I couldn't find a datasheet. It really is a shame but if some other member can provide info on the fet's they could prove usefull in a dumpload if the current rating is high enough. Cheers Bryan  |
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Gizmo Admin Group  Joined: 05/06/2004 Location: AustraliaPosts: 5116 |
On a F&P control board I have its using IRF840 Mosfets, Google found these to be 8A, 500V, 0.850 Ohm, N-Channel types. Tuff little buggers. But I know there are several models of these things, some even have surface mounted MOSFETS, good luck finding the datasheet for those. Glenn The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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GWatPE Senior Member Joined: 01/09/2006 Location: AustraliaPosts: 2127 |
Hi All, Electronic devices that have been used on rectified mains voltages are probably unsuitable for DIY systems at typically 24V. The Mosfets I use, have an ON resistance of around 15mOhms. You would need at least 50 of the IRF840 devices for the same resistance. This is important to remember in a switching power supply, but not too important if you only intend to switch on a diversion load and mount the devices on a heatsink. The 25ohm resistor on a 24V system would make about a 31W diversion load. You would probably need at least 9 of these resistors in parallel as a diversion load in a 24V system with a single stator F&P mill. The aluminium heatsink is fine to preheat the water in a washing machine, but I am unsure of the suitability to heat water that may be used for drinking. .. Gordon. become more energy aware |
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| carl1 Regular Member Joined: 16/04/2007 Location: AustraliaPosts: 79 |
Hi Dazz for info on electronic components go to: http://www.datasheetcatalog.com/ regards Harald  |
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| grub Senior Member Joined: 27/11/2007 Location: AustraliaPosts: 169 |
When the washing machine is spinning and you lift the lid, the motor acts as a generator and on the earlier water cooled modules the MOSFETS were (are) prone to blowing if you did this (lift the lid while the bowl was spinning)once too often. The water tube was to dissenpate the build up of heat created by the MOSFETS and while the machine was washing the cold water soliniod dribbled water to remove said heat, that is why the cold soliniod cost twice as much as the hot soliniod. On the later air cooled modules the generated power was directed to the pump (240v) and if the pump shorted or open circuited you "blew" the board. The inlet soliniods are 12v, the motor 300v, and the pump 240v. Just a bit of trivia on the F&P machines to help you understand how they operate. |
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| dazz Regular Member Joined: 15/04/2008 Location: Posts: 78 |
Hi People, Thanks for all the tips and interesting info :) I had a look at the other thread on the topic of dumploads and did some more thinking. As far as i can tell, there are two times you need a dumpload. when the batteries are charged and when you want to brake the mill in strong winds. So the best dumpload would be one that adheres to the maximum power theorem? So something less than an ohm for an F&P single stator? I contemplated that a while then realised that even with the best wiring from the mill, the wiring would exceed the dumpload in resistance by quite a bit. So Gordon, is that why you use a dumpload of around 3ohm instead of much lower? Also, would the best dumpload design be one where the dumpload is at the mill where it could more closely match the impedence of the stator without added resistance from long wires? Cheers, Daryl |
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| GWatPE Senior Member Joined: 01/09/2006 Location: AustraliaPosts: 2127 |
Hi Dazz, I don't know where I have said I have a dump load. The grid is what I use for a diversion load when the battery is full. The power gets to be consumed by the base load of my house. I have no idea of what this resistance would be. If the grid is unavailable[ie OFF], and the battery is full, then my mill just shuts down electronically. The rotor slows to around 20RPM. Even in a gale the mill responds the same way. I had used a mosfet to short the windings, but this was a bit sudden. I now use an IGBT. The electrical braking is only a secondary protection. My mill is set up to be dynamically furled at about 25 knots. This results in a max of about 600RPM on the rotor. The Lakota carbon fibre blades were originally designed for a hub where each blade touched the others around the shaft. I adapted the blades to my alternator and this resulted in the blade being 50mm further from the shaft. The inner portion of the blade now acts like a paddle and seems to act like a brake at higher RPM. This seems to stall the blades at high wind speeds. Even with my mill turned OFF, the blades still furl in high winds. I do not care if there is power wasted in these conditions. My mill #1, not a F&P has produced 455W. I now restrict this to around 400W, so the effective diversion load at this maximum power would be 2 ohms. Once the maximum power output is known, by recording the maximum battery current and the voltage, then the effective resistance to create that load can easily be calculated. If the power output is not known, then a staged load can be used to increase the load at preset increments of voltage. This is a system that Bryan1 has described on another thread. ... .. Gordon. become more energy aware |
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| dazz Regular Member Joined: 15/04/2008 Location: Posts: 78 |
Thanks Gordon. My mistake, I just assumed a standard setup had a dump load. Hence I included your system in my assumption. I hadn't considered a grid tie system. Some more of the pieces are comming together. Gordon, why is using an IGBT less sudden for shorting the windings? These days they are both very fast aren't they? Or is it that you have more control with the IGBT to turn it on slowly? Daryl |
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| GWatPE Senior Member Joined: 01/09/2006 Location: AustraliaPosts: 2127 |
Hi Dazz, The switching speed of the device is not really relevant. If you peruse some device specifications it is pretty easy to see how the devices differ in operation. Basically the IGBT shorts to a voltage and the mosfet shorts to a resistance. {this is sort of what happens} The mosfet reduces the RPM to around 2RPM and the IGBT to about 20RPM. This may only have relevance to my mill. I have yet to see if the same principles will work with a F&P mill. Gordon. become more energy aware |
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| BjBlaster Regular Member Joined: 04/04/2008 Location: AustraliaPosts: 55 |
The IRF840 is really a G4RC10S but the G4 is surface mounted. I found the data sheet here RS Site Had to fix our 1998 F&P 5KG washer this morning after the lighting killed it. One of these blew plus the opto that feeds his gate... Check out my projects here in: Bj's Shed |
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