David Roden wrote:
On 18 Dec 2006 at 9:33, Jim Coate wrote:The 120 volt AC output of the invertor connects to the Kill-a-watt meter. The Kill-a-watt plugs into a regular 120 VAC outlet.I don't mean to sound like a nervous nellie, but I hope you don't have any kids in your house. The thought of having a cable around with two male plugs on it concerns me. It could electrocute a curious (or careless) small child.
Unless he is using a motor-generator grid tie system (which would be really odd for solar and sad otherwise) he's using a grid-tie inverter. My guess with a 24 volt system is an OK4U-100 which is a 100 watt UL listed micro-tie inverter.
If it does not see the 120 volts, it shuts down instantly. Therefore you could unplug it, and stick the plug into your mouth with no problems.
What would be unsafe would be to have a DC motor attached to an AC motor that is plugged into the wall. The AC motor syncs to the grid instantly, however if the DC motor applies power to try and speed up the AC motor, it winds up feeding energy into the grid. Instant grid-tie inverter.
The issue there from what I remember is if you lose AC the AC motor should stop producing power since there is no grid to sync to. However (and this is a biggie) if there are capacitive loads on the AC motor that exceed the inductive loads it's possible it could self-excite and be a freewheeling generator. This is in the "any AC induction motor can be a generator if it has some running capacitance across the output to lead/lag the induction coils.
So never do that without some serious safeties to drop the AC (and the DC) if utility goes away. Doing that in a UL safe way is hard.
Chris
A 20 amp household circuit can produce about as much power as an ET drive motor. That's something to be treated with respect, IMO.David Roden - Akron, Ohio, USA= = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = Note: mail sent to the "etpost" address will not reach me. To send me a private message, please use the address shown at the bottomof this page : http://www.evdl.org/help/ = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = If voting changed anything, they'd make it illegal. -- Emma Goldman= = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =_______________________________________________ Elec-trak mailing list Elec-trak cosmos phy tufts edu https://cosmos.phy.tufts.edu/mailman/listinfo/elec-trak