Generator/Inverter Interlock

norcal

Senior Member
If it won't work with a single pole breaker, is there any reason not to use a 2 pole breaker & leave 1 leg unused?
 

synchro

Senior Member
Location
Chicago, IL
Occupation
EE
What would get rid of the problem is installing a 120->240/120 transformer. 120v from the generators and 120/240 into the panel interlock. I dont know if the little honda inverter generators would be able to magnetize the transformer before tripping on overload.
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Connecting the transformer as an auto transformer would allow one bus to be directly connected to the paralleled generators, with the autotransformer supplying the other bus. That would allow it to handle larger loads and current surges from motors, etc. on the directly connected bus.

If the magnetization current trips the inverter generators, then perhaps a balast resistor load could be placed in series to limit the current. And then the resistor would be shunted by a contactor after a short interval.
 

Jon456

Senior Member
Location
Colorado
Honda EU2000i generators are awesome little generators for their designed purpose. Their main selling points are portability and quietness; they are ideal for remote power (e.g., camping). Their drawback is that they don't produce very much power: a single EU2000i is only rated for 15A (max 18.3A). Two EU2000i generators in parallel are only rated for 26.7A (33.3 Max). So feeding half a house panel is really beyond the capabilities of these generators. Feeding both buses would be nuts. Practically, you would only use these for covering the bare minimums needed in a blackout: your refrigerator, a gas furnace, room lights (preferably LED), garage door opener, a microwave (if most other loads are off at the time), etc.

Typically, you plug your loads directly into the generators which would naturally limit you from overloading them. But I can see the advantage of having a hard-wired set-up, particularly in areas with frequent blackouts (I'm looking at you, California). But this will dramatically increase the odds of users running too many devices simultaneously and overloading the generators. Note this warning from Honda:
Substantial overloading that continuously lights the overload alarm (red) may damage the generator(s). Marginal overloading that temporarily lights the overload alarm (red) may shorten the service life of the generator(s).
If I were installing this, I would definitely go with a dedicated subpanel for the critical loads, with a manual transfer switch between the subpanel and the main. It makes it clear which loads are on the generator, helps limit the loads, guarantees no potentially-lethal backfeed, and helps prevent someone monkeying with the set-up in the future and doing something dangerous.
 
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