UPS kinda switch

[windcruiser]

Haloo,

I am looking for a fast-switch circuit. Kind like the UPS uses to interchange wall AC supply and internal inverter. Anybody with an idea of how to use them fast swicthing Mosfets or a simple diagram.

Simon

[Victor]

When the switching is done internally by a SW or Outback  inverter, the inverter is in phase with the utility. If the inveter is running independent of the line they will be out of phase and switching within a few milliseconds may be a bad idea IMO. On resistive loads I don't see any problems but on inductive loads like your refrigerator it could cause large voltage spikes depending on the phase angle difference. A relay may be slow enough not to cause problems. CAVEAT EMPORE sp?

[windcruiser]

I was working from the direction of a single phase wind generator 240VAC and an inverter. The ideal situation is during the time the generator is runing supply goes direct to appliances 240VAC of cause through a voltage regulator feeding to this ideal switch and the inverter. And when wind slows down to low voltage levels the inverter is switched like how the UPS does.

I tried feeding my wind generator voltage through an UPS and it worked till i got tired of turning the machine with my hands. The UPS does not have the size of inverter I need.

Simon  

[RobD]

The trouble is you can't keep a wind turbine at 240 volts much less constant freq.

How do you plan to do that?

[Ungrounded Lightning Rod]

You seem to have a permanent grid connection and to be using your genny for opportunistic power, rather than as backup for grid failure or for pure off-grid operation.

In that case, why not use an inverter with a "sell" option, feed the genny's power to the grid when its available, and use net metering (which requires NO changes to the existing meter)?  That way you don't need a cutover, and you can use the grid to "store" your genny's power when it's making more than you need.

This is even legal and encouraged in most places in the US.  B-)

I think there's a federal mandate but I'm not sure.  But if your wind genny is under a couple kilowatts and your inverter is UL approved it may be just a matter of making a change to your power account records so they won't charge you for 99999 kilowatthours if you happen to make more than you use some month.  Ask your power company for details on how to do it right in your area.

In my area they won't pay ME if I make more than I use (without a separate deal), but they WILL go to annual rather than monthly billing so I can save it up in sunny/windy seasons to use when I nead more than mother nature is providing.

[Ungrounded Lightning Rod]

(Note that you DO need an approved inverter with a sell option.  That's so it will cut off if the external power line is down, so you don't electrocute the lineman that comes out to fix it.)

[windcruiser]

Keeping the genny at constant 240 and frequency 50Hz is a problem I agree. This baby juices over 380 volts without load. I would have to design a sort of circuit which watches the voltage (some thyristors with many tapps on the coil which will ensure I get a constant 240). The Voltage regulator really helps -- issue is it has a maximum voltage too. I have watched my TV while turning this genny, lights in the house etc (of cause after switching off grid power).

Truelly where I come from you do not sell power to the government. They sell it to you! I would prefer a selector switch from National Grid to own power as I please. That is why I built the 240VAC genny -- the trouble is automating the whole setup. Wind is very much available no doubt. I recently designed a friberglass blade six time lighter than the pine blades, does not need any kind of mould to make. I will post the drawings once I figure out how to get them to my area on the board. I once tried and failed to upload a single picture.

[tecker]

   Looking for a transfer switch ? These are pricy but with net control options

http://www.apcc.com/products/family/index.cfm?id=14

    man that sell option is the way to though .

[ghurd]

Can also be a pain finding someone that understands grid tie enough to approve it. I think it is legal everywhere too.

I've heard 1st hand horror stories that boil down to "Ya'll aint hookin' that thang up in MY wires!"

[Nando]

Simon:

What you want is a UPS connection and that requires a precise phasing of the AC and the Inverter ( has to be sine wave ). -- the Inverter frequency needs to be locked all the time to the incoming AC frequency and ready to start switching when the AC goes.

Some even have brownout capabilities to add power for stabilization of the energy.

It is complicated and, as well, the circuit needs to make sure that when the AC returns the circuit does not contend for certain time until the Inverter frequency matches the AC incoming to be able to transfer at zero crossing and polarity.

Regards

Nando