letting the smoke out - inverter question?

[turf]

is that bad?


ok real question.....

im looking at inverters to power my existing 50a split phase power distribution panel.

i've come across an inverter that i think ties both sides of the panel together when inverting 120, and splits it apart again when 50a shore is detected and passed thru.

so what happens when 2 sides of a 240 load are fed from the same phase?
in my case, in particular.....

i have a 240v stove, 4 wires.
and i have an electric heater - 3 wires.

are either of those going to fry when applied the same 120 leg on both sides?

my guess is the clock on the stove works, but smoke comes out of the inverter when i turn on a burner?

or nothing?

idk .... what does the forum say?

[PorchDog]

If you feed two in phase signals to the same two pole breaker-- you get zero current flow and nothing happens. I have my backup generator for my house wired that way. I tie the normally separated 240 leads from my main breaker panel together and then feed 120 to them from my generator. This basically negates all the double pole 220Volt items in the panel-- they never power up.

Now-- they are tied together at the generator side of the connection, because when I go back to utility power-- if they were tied together it would create a dead short.

[turf]

thank you!!!

please explain that last bit though... you lost me.

tied together on the generator side?

are you just saying the same as what the inverter does.... join the 2 sides together when inverting. split when on shore power?

frankly this feature seems likely to fail. i hope its programable, as i dont really have to have power for anything on that side of the panel. its my 2nd AC, half of my 240 heat and stove, and a bank of outlets i dont need on inverter.

supplying the same leg of power to the other side doesnt help.

[PorchDog]

My assumption would be that your invertor does automatically what I do with a switch-- it ties the two legs together when operating on 30 Amp/120, and separates the legs when operating on 50 Amp 240. I have my two legs bonded together on the generator side of my two pole fused disconnect switch that feeds the main panel. I think your invertor handles this internally.

So-- your 240 stuff should not power up when the invertor is operating on 120.

Maybe some more folks will chime in on this....

[AlphaHare]

Some Victron inverters power only one circuit when on solar, and then two circuits when on shore power. Not to be confused with creating true 240, just two independent 120 legs in phase.

To create 240, you'll need two inverters, and again, some of the Victron ones will talk to each other and create 240 by putting the two legs of 120 exactly out of phase to each other.

Good view of a system idea here:

https://www.youtube.com/watch?v=-3vqdUws2Jk

[Rucker]

i have a 240v stove, 4 wires.
and i have an electric heater - 3 wires.

are either of those going to fry when applied the same 120 leg on both sides?

3 wires 220 VAC typically is: One leg or wire is hot; the other leg or wire is hot (but 180 degrees out of phase with the first), and one wire is common.

The current never exceeds one of the legs because they are only firing one leg at a time, 60 times a second.

4 wires: one is ground.

In old 3 wire installations any 120 volt application like a timer or a clock on a dryer would rely on one leg with power and a common; with no ground wire to drain off any stray voltage you could get a tingle touching any metal parts.

[nikitis]

Interesting.

I'm no electrician admittedly but doesn't most household circuit panels have two planes that intertwine so that every other breaker switches between each plane back and forth?

So when you add a 50 amp breaker, at least with GE style breaker boxes it takes up two breaker slots as one breaker touching both planes. Each plane is rated for around 110V, so if you have a breaker (50 amp) that touches both planes you are tapping into 220V. This is how you'd use a 220V welder or wire a plug to the breaker box via the 50 amp breaker. All that is pushing electricity towards your welder though.

Using the same principle you can send power in reverse the same way. If you hooked a generator into the 50 amp breaker, you'd feed juice to all the other outlet breakers and can power devices as long as they don't require more then 50 amps in total to run. People do this during power outages so they can have power but to make it legal you have to have a slide switch to prevent from back feeding past your house main and killing a linemen fixing the outage.

Now given those principles I would think you could use a 50 amp breaker because it would touch both planes and use your 240v cook top but only if it was on that one breaker spanning both planes.

But anyone feel free to correct me on that last thought.

[s2mikon]

I was told by a journeyman election that the loads for both side had to stay closely balanced to keep the transformer cool. Easy to do with 6 houses on a transformer more difficult with a inverter. I don't know for sure. I just went with 30 amp 120 and was fine.

[More2See]

Originally Posted by turf

is that bad?


ok real question.....

im looking at inverters to power my existing 50a split phase power distribution panel.

i've come across an inverter that i think ties both sides of the panel together when inverting 120, and splits it apart again when 50a shore is detected and passed thru.

so what happens when 2 sides of a 240 load are fed from the same phase?
in my case, in particular.....

i have a 240v stove, 4 wires.
and i have an electric heater - 3 wires.

are either of those going to fry when applied the same 120 leg on both sides?

my guess is the clock on the stove works, but smoke comes out of the inverter when i turn on a burner?

or nothing?

idk .... what does the forum say?

From a Victron Blog page.

The Multiplus-II 2x120v is intentionally designed to pass through split phase 120/240v power when connected to shore power or grid, and to provide the same 120V to L1 and L2 when inverting. No 240V appliances will work because L1 and L2 are the same (0 volts between them).

If it is just the well you need 240V for, maybe an autotransformer is the easiest way forward.

Victron example schematics show multiple ways to generate split-phase power with inverters.
Two standard Multiplus 120V or Multiplus-II 120V units can configured for split-phase using VE.Configure. The neutrals need to be combined.