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Registered Member #1875
Joined: Sun Dec 21 2008, 06:36PM
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Posts: 635
It would be a much bigger project to build an inverter, but if you did, you could make an H-bridge, rewire the primary to take 12v in, and add a resonant capacitor to the primary to keep the current sinusoidal.
I say just wire the breakers in parallel and put fuses on every wire coming out of the wall. Monitor the current coming from each line, and if they're too unbalanced, compensate by adding extension cords to the one drawing more current until it evens out. Dirty, but it'll get the job done! Or at least, in theory it should.
Registered Member #2099
Joined: Wed Apr 29 2009, 12:22AM
Location: Los Altos, California
Posts: 1716
ScotchTapeLord wrote ... I say just wire the breakers in parallel and put fuses on every wire coming out of the wall. Monitor the current coming from each line, and if they're too unbalanced, compensate by adding extension cords to the one drawing more current until it evens out. Dirty, but it'll get the job done! Or at least, in theory it should.
It's much simpler to return to original concept: connect each MOT primary between hot and neutral of a separate circuit. Make no connection between the two circuits, except both grounding (green) wires are hardwired to both MOT cores, which is the common point of series-connected HV windings.
The two secondary currents will be equal, for any load connected between the two HV terminals. The two primary currents will be equal, to the extent that the MOT's are physically matched.
This is cleaner and safer than a hardwired parallel connection, but still can back-drive house wiring if one breaker is open AND there is a load between the HV terminals. So as STL said, plug nothing else into either circuit. Then (with this configuration) if one breaker trips, the associated MOT primary current will be zero (unless you have a capacitor across it). Then that MOT's secondary will present a huge magnetizing inductance, immediately and greatly reducing the current in, say, an arc.
Patrick wrote: >>for best safety i think you would need isolation transformers, that would solve at least your holding tripped circuits high. but for your wattage they would be big.
How would isolation transformers change the voltage back-driven onto a tripped circuit?
Registered Member #2431
Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639
Klugesmith wrote ...
Patrick wrote: >>for best safety i think you would need isolation transformers, that would solve at least your holding tripped circuits high. but for your wattage they would be big.
How would isolation transformers change the voltage back-driven onto a tripped circuit?
well, i was thinking its the arc that holds the wires at higher potential powering the 'should be' de-energized circuits. i was thinking too much maybe? any way maybe im wrong about that.
EDIT: Kludgesmith, your right, the isolation idea wont work, my bad.
But i have a better idea: use a double ganged breaker, with that pin that joins the two poles if one trips they both get thrown. At least you wont have an unbalanced current load causing immeadiate tripping of one and delayed tripping of the other. As, large current fuses are expensive.
also, this would be so much easier with a useful 240 socket / line, is there any possiblity of fixing that nail prroblem?
Registered Member #2463
Joined: Wed Nov 11 2009, 03:49AM
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Patric wrote: i was thinking its the arc that holds the wires at higher potential powering the 'should be' de-energized circuits.
It gets a little involved here: If you analyse the case of an arc being sustained when one of the breakers trips, and the arc holds up from the other transformer through the tripped one's secondary whose reflected reactance is through any other loads that may have been on that tripped branch circuit, you will see that at the moment it trips the now phanthom powered circuit experiences an instantaneous polarity reversal, and that circuit voltage fall after after the trip would be twice the rms value or 240 volts for one cycle.and there after reversed in phase what it was before. This because the primaries although intended to be paralleled, because of the mot's grounded high side on the secondary, have to be connected opposite in polarity to get twice the voltage at the outside winding terminal. If the hookup was on a split 120/240 volt pair of outlets then the tripped leg would be fed same phase as before, except through a very noisy source at the load end rather from the source end.
Registered Member #2431
Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639
radiotech wrote ...
It gets a little involved here...
as soon as i tried to simulate this situation, and i realized that reactance plays a significant role, i knew this was a lot more complicated then at first it would seem.
Registered Member #2463
Joined: Wed Nov 11 2009, 03:49AM
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That scenario happens in grids when lines get crossed in storms and here is a relay that can detect which way the "power" is flowing, which is not always clear in an AC circuits.
The advent of the MOT on the experimenter scene has changed the playing field in that fauilts of 1000 Joules at several thousand volts can be launched back in home wiring systems. This is not a problem in a new structures wired with up to date codes but in older marginal ones with loose connections (especially at outlets connected with quik-con terminals (the push-in type), sooner or later a fire might result.
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Seperate circuits
