portable genset question

[SQLit]

Simple answer is no

The controls to keep the voltage and frequency are not there. I guess you could buy the controls. You would probably spend more than the cost of getting a bigger home generator.

[barry]

After the connection is made, they will be at same voltage and freq. Other factors will determine direction & magnitude of energy flow.

The BIG problem is in parallelling them before making the connection. If not done, there can be one serious electrical/mechanical jolt on making the connection. You need to get phase-angle to zero, and one traditional way of sensing this is with light bulb connected across phase leads before connecting the leads.

HTH, J

[kevin]

Does this sound loony to anyone else? There is nothing in most generators to keep the voltages or frequency the same. Well, okay, sure, once you put the two wires together, yes, there is now only one voltage in the system, running at some frequency (or, rather, some combination of fequencies). The question here is: are the voltage and frequency the one you want (120V, 60HZ), or are they something unusable (varying voltage, pulsing frequency)?

The important part here is the _phase_. If the frequencies are even slightly off, you can never get them to stay in phase, resulting in a pulsing combined signal. Totally useless. If you could get the frequencies to be perfectly matched, and stay that way (a physical impossibility*, btw), you would have to then get the phases lined up. Here you might be able to get away with the light bulb trick, since it probably wouldn't matter for most devices if you got a perfect match.

• why is it impossible? Same reason that you can never tune a piano wire to a precise frequency, or even match exactly to a reference frequency. To get ever more precision, you have to wait ever longer to hear the beats in the output signal. The only way around this is to use some kind of active system, like the honda DC generator system. If I remember correctly, they have electronics in the two inverters talk to each other continuously, to keep them pretty much in sync. It is not just a matter of getting in sync then letting go, instead they are constantly readjusting the outputs to keep them from drifting away from near synchrony.

[RB]

Are randomly selected portable home generator sets close enough in frequency and voltage to be used in parallel feed situations?

All references point out that the gensets to be parallelled must match frequency and voltage.

There's a ton of stuff through Google on parallelling generators. Most of it, though, is for big plants, and multi-phase.

I'm just wondering if the portable gensets bought out of Home Depot, Walmart, Lowes, etc, can be parallelled without problems? What I'm hoping is to hear from someone who's done it, and that it works.

[toller]

You have got to be kidding. Even if they were off by 0.001% they would wildly fluctuate between being in synch and 180 out of synch. Think about it.

[calhoun]

I don't know what gens HD.Lowes etc sell. I know Honda makes a genset that can be hooked to another. It is a DC generator that provides AC though an inverter. This allows it to be parallel with another gen. I really don't see the purpose. Unless you need 2 generators at 2 different places but also need one large. It would be better just to buy the size you need and not mess around with hooking 2 together.

[Ulysses]

A lot of RVers have opted for two small Honda inverter generators (eu2000 mainly) because it's easy to pick up one of those and not very easy to pick up, say, an eu3000. This way they can have portability and excellent fuel economy or they can connect two together if they want to run their AC etc.

[RB]

Thanks for the info. Looks like it's not doable. Just thought I'd toss it out to see.

[Ulysses]

What is it that you are trying to accomplish? You can buy an inverter that will tie to the grid and synchronize. Perhaps use a generator to charge batteries which feed the inverter?