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Forum Index : Windmills : Three phase power
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| Ray.e. Newbie  Joined: 14/07/2014 Location: AustraliaPosts: 5 |
Hi fulfrog, I have a very basic understanding of single electrics, I know that a power supply requires both live and neutral connections, all the information I have seen on the F&P smart drive rewiring in three phase show three outputs, which I understand are the three live feeds (red white and blue). Where is the neutral?. I would be grateful if you could solve this for me, I have most of the gear to get started on my project but I want to get the basics sorted. I have an energy source which is giving me up to 1,000 rpm so I am looking at using a full 220-250v a/c. I just can't work out where to get a neutral link! Regards, Ray. |
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Gizmo Admin Group  Joined: 05/06/2004 Location: AustraliaPosts: 5078 |
Hi Ray Not possible to use a F&P to supply single phase 250VAC 50Hz power without a lot of other stuff. The 3 phase power needs to go into a 3 phase rectifier, where its converted to DC. Then it needs to be regulated to a reasonably constant DC supply, using batteries is the easiest way. You can then use this DC to supply a inverter, to provide 250VAC. Single phase power uses 2 wires, and a single sine wave voltage that swings from positive to negative many times a second. In a domestic situation, one of these wires is earthed, and becomes the neutral. The other is called the active. Plus we have a earth wire, for safety. 3 phase uses 3 wires, with 3 out of phase sine waves. Using a single one of these phases is possible, but not practical, and I wont go into how the commercial power grid does it. Besides the F&P output frequency is all wrong. Sorry Ray but its not going to be that easy. The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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| Ray.e. Newbie Joined: 14/07/2014 Location: AustraliaPosts: 5 |
Gizmo, thanks for the rapid reply, the rectifier would not be a problem, could you tell me if there is a product available other than batteries to regulate the D.C. currant before it is put through an inverter?. |
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| Gizmo Admin Group Joined: 05/06/2004 Location: AustraliaPosts: 5078 |
A fella called Bob Mann did some work with the F&P and a power point tracker, which I think he fed directly into a grid feed inverter. He got some good figures, dont know where it all ended up. Search the forum for posts by Bob Mann, you should find something. What are you trying to build Ray? Sounds like a gen-set for supplying 240VAC. If so, then using a F&P is not the best approach, the project will become expensive, unreliable and dangerous. You would be much better off either using a generator head from a gen-set with a deceased motor, or building a F&P battery charger, and use a inverted to get your 240VAC. Also, a F&P at 1000RPM will generate lethal voltages, over 240VAC. Even hand spinning a F&P can produce enough volts to kill a person. Be careful. The way we usually use a F&P is to reconfigure the windings for a lower voltage, and charge a battery bank ( 12/24 or 48v ), which is fairly safe. Glenn The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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| Ray.e. Newbie Joined: 14/07/2014 Location: AustraliaPosts: 5 |
Glenn, the idea was borne out of the wind generator using an F&P motor but building the thing from scratch using those basic principals of a permanent magnet motor to supply 240VAC. There is a reliable external energy source the speed of which can be varied, 1,000 rpm was arrived at because that is high spin speed of the F&P washer. As the coils can be configured to produce 12/24 volts etc, for use as a wind turbine. Using what is possibly misguided logic, the coils should be able to be reconfigured to produce 220-250VAC. That was the start and I wanted to know how to make the three phase output usable as a nominal 240v supply. Ray. |
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| Gizmo Admin Group Joined: 05/06/2004 Location: AustraliaPosts: 5078 |
Hi Ray That makes sense. Unfortunately its not workable. Even if you did manage to get one phase of the F&P to sit at 240VAC, it would change with load. So if you plugged in a 50watt light bulb, the voltage might drop to 100 volts. If you adjusted it to produce 240v at 50 watts, then unplugged said bulb, the output could swing over 400v. Plug in a 25watt bulb and it would blow. There's no regulation, making it a dangerous beast. Thats why we use the F&P to charge batteries, and use a inverter to manage the output voltage. Inverters sense output load and make adjustments to keep the output voltage regulated. Glenn The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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| Ray.e. Newbie Joined: 14/07/2014 Location: AustraliaPosts: 5 |
Good morning Glenn, I hope you don't loose patience with me. Just a little background on me, I have been installing split system A/C units for the past 12years working with an electrician and I am fully aware of the dangers and precautions relating to electricity, although I am now fast approaching 69 years of age my brain cells are more active and they won't rest until I have sorted this thing out, after that! who knows?. I have been looking at the seven phase conversion on the site. I am looking at making the fixed stator up with plain coils on a flat disk and spinning the magnetic field on both sides. Using the seven phase system and the bridge rectifier, could this be fed directly into an inverter without going through a battery system if the speed of the generator is controlled?. Ray. |
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| Gizmo Admin Group Joined: 05/06/2004 Location: AustraliaPosts: 5078 |
Hi Ray No. The 7 phase system is a way to decog the F&P. Normally you would not use it. If you want to make your own alternator, you could design one to produce single phase, but you still have the problems I've said above, of poor regulation. What you are trying to do is just not possible, which is why we use the windmill to charge batteries, and connect a inverter to the batteries to provide our 240VAC with regulation. There really is no other simpler system. The windmill output swings from 0 to 300 watts, give or take, depending on wind. The batteries absorb these fluctuations. The inverter then supplies 240VAC, and can provide regulation under various loads. Throw in a regulator to keep the batteries charged correctly, and you have a safe foolproof system. You need batteries. Glenn The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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| Ray.e. Newbie Joined: 14/07/2014 Location: AustraliaPosts: 5 |
Thanks for all your help Glenn. Ray. |
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