Chris,
      Nice photos.

       You never know about the balancing, since generators of the same design, but different sizes, tend to load out evenly on a percentage basis.  Maybe even tying the fields together might not be necessary.  I think you'd have to try it first to be sure, unless you had really accurate impedance numbers for the generators, as well as the loads you intended on using.
      As far as the commercial AVR's go, apparently the CT is only for balancing the reactive power, I think they rely on the relative size of the generators to balance out the kW's themselves.  So I don't know if it's needed, but your idea for the logic circuit sounds neat.  As for synchronization, if you KNEW you wanted all that power on a semi permanent basis, link the two engines/gen heads together with ???chain/drive shaft coupling???  Just a thought.  Then you could also balance the power pulses out, and have one piston firing every 180 degrees.  If you set it up right, you might be able to do that during the electrical linking of the genheads.

Steve

Hi,
      Correct on 1 and 2.   

Let me address the breaker size first.  120V * 35A = 4200watts.  Well under the 5kW rating of the generator, so it's fine that way.

The other thing the breaker has to be sized for, believe it or not, is the engine. Simply put, there is no point in having a 35A breaker if your engine cant pump out enough power to make the 35+A required to trip that breaker.  In most commmerical generators, the engine is sized above that of the generator, that is you might have a 30kW engine on a 25kW generator end.  In the case of some (?most?) listeroid applications, we have a generator end thats sized larger than the engine.

The way I determine the breaker size for the engine
1) Engine at operating temperature, everything as it would be if you weren't there; genshed closed etc.
2) Slowly load the generator up
3) Watch the amp meter(s) as you load up the engine
4) Dont go over the generators rating (in this case 5kW or 41.666A @ 120V)

You will hit a point where you have either overloaded the engine (black smoke or belt slip or rack full open or overheating or a sense of "that's enough"), or the generator, and you need to size the breaker BELOW that point.  For exaple, if your engine holds 30A nicely, but is pumping out black soot at 35A, size the breaker at 30A.  Remeber that breakers dont drip exactly where they are rated.  Most  need a 25% overlaod to trip within 1 minute.  This all depends on exactly how much power you can get out of your engine, which we know can vary greatly.

As for the ground, you can improve it by using ground plates, same idea as a ground rod, only they are about the size of a dinner plate, and they get buried instead of driven in to the ground.  They have a large surface area, so they can get a better ground where you cant drive a rod deep enough. 

The point where you tie the neutral bus to ground is called the BONDING point, this has to be a good connection for the system to work properly.  I wont bother explaining all the things that can go wrong if it's not, so just make sure it's good.  Only do this at one point!  If you bond in the main panel, dont think you are improving things by bonding at the generator as well!  I'll skip the technical explanation on why this is so.

One thing to note here, only ground at ONE place.  If you ground everything at the genshed, dont put ground rods in at the panel that's 100ft away, instead tie everything back to the ground rods at the genshed.  It's ok to have mutiple plates/rods at one location, but they should all be tied in with one piece of wire.  Again, I'll skip the technical explanation.

OK, hypothetical situation; so you have grounded in 1 place, and bonded in 1 place. The connections are all good, but the earth is so dry that your ground is lousy.  Lets pretend we have a loose "hot" wire in a 3 prong metal case (grounded) drill.  Three possible things can happen.

1) Loose wire touches a neutral wire inside the drill, big spark, current flows back along netural wire, and the breaker trips.  This would not trip a GFCI.
2) Loose wire touches the metal case, big spark, current flows back on the ground wire, to the bonding point, then back on the neutral wire to the generator, and the breaker trips.  If you were on a GFCI, it would also trip (likely before the breaker), as this is a "ground fault".
3)You set the drill down on a 2 by 4, and the loose wire hangs out of the drill, and makes contact with the ground, but the drill stays off the ground.  Not much current flows, because of the high resistance of the bad ground, and the drills distance from it. So, maybe the breaker doesn't trip, because not enough current is flowing.  This is when you thank yourself for buying a GFCI outlet or breaker, as that has just tripped, because all it needs is something like 0.015A of ground current to trip.

The point of the story is that even with a bad ground, situation 1&2 take care of themselves, as no current ever went thru the ground rods.  Situation 3 might not take care of itself, even with a "good" ground, and that's why GFCIs are important, but even more so when you have a bad ground.

Sorry for the lecture.

ST

Hi,
    I'll try and answer your questions; because someone will; but really, you may want to be consulting an electrician.  Please dont assume what you can learn here will be all encompasing, or be everything you need to know, or that we can "mind read" or guess everything about your installation particulars.  However, here are the answers to your questions:

1)  First of all, the neutral, hot and ground lines are all isolated from each other if everything is disassembled.  With a generator, whichever leg you tie to the ground (either in the panel, or at the generator), becomes the neutral.  As long as they are both fully isolated to start with, it doesn't really matter which one you tie to ground.  The "hot" wire only is "hot" with respect to ground.  It's instantaneous polarity doesn't matter, it can switch between +/-, and it will still be "hot" because the neutral is tied to the ground.  Since your generator is wired for only 120V, you will only have one "hot" wire, if it was wired for 240V, then you would have 2.

2) The lines from the generator should be isolated, so whichever line you tie to ground, will become the neutral, as explained above.

Any clarification needed, just ask.


ST

 

I'll send you a pic/video of my 6.7HP diesel snowblower if I get a chance before the snow disapears.  It looks ugly, as I haven't had much of a chance to clean it up.  Normally things are slow at work all Dec & Jan, but haven't been this year....  apparently the sales people at work haven't heard we are in a recession!

Steve

Well,  I'd get a fused disconnect or small breaker panel, and wire the outlets on the south side of that.  I'd mount the disconnect/outlet on a surface not subject to vibration, and run a piece of Teck/SJOOW/BX from a hole (with proper wire clamp for wire used) in the dog house of generator to the input of the disconnect switch.  Of course, I'd then have all of this properly inspected like the rest of my setup.    There are many variations on how to do this, but anything without circuit protection (fuse/breaker), disconnect means (switch/breaker), proper wire type (not regular house wire or orange extension cord), or proper wiring methods (wire not chaffing on side of steel box) is a bad idea. 

If your setup is wired for 240V, I'd use a piece of 4 conductor 12AWG wire and put in two 20A, 120V T-Slot receptacles, each wired on thier own leg of 120V.  That'd give you 4800w of 120V power available, with not much more hardware than needed to wire one 15A 120V circuit. 


Steve

Since most of us want our Listers to be prime movers for generators (except the odd one who likes to pump water) this may be of interest.

I had coffee with a bunch of old reprobates this morning and my buddy who still works for our hydro company asked me if my generator was up and working.  When I said not yet I'm not in a hurry, he answered that I'd better be.

It seems the town I live in has 2 "legs" both of which are operating waaaay over capacity.  I was told that the first branch that falls on a power line and shorts it out, there will be no switching capacity to the other leg, and as a matter of fact it may just crash as well because some of the switches will try to do their thing.  The result will be a long and prolonged outage.  He wouldn't elaborate citing "his a$$ would be in a sling" anyone found out he blabbed.

Is there anyone out there with some hydro experience that can tell me if this makes any sense?
STan

I will also be vauge about my specific involvment, and knowledge, but I will say this:  It makes sense.  Utilities make a lot of assumptions when wiring things, and often aren't sure what loads are on what lines/switches etc.  All of this is getting better with smart meters, GPS, real time remote monitoring, etc.  The thing that is not getting better, is that utilities push their equipment HARD.  It is not unheard of for a utility to run transfomers at 150% of thier nameplate rating, even on a hot summer day.  "Overloaded" wires/equipment dont build up much ice in an ice storm though, so there can be some trade-offs there.  In your senario, the automatic switching might put both feeders in the dark, but quick action (modern system and/or manual overrides) will get the non-damaged one back online pretty quick.  You also might be a little spooked if I gave you some realistic numbers about the chances of a breaker/fuse opening if there was a fallen line/short/etc, all I will say is to always treat any down line like it is live at 46kV.

Just for Info if anyone cares:

a 14.0L Detroit Diesel Series 60:

Bore: 5.24"
Stroke: 6.61"
Compression Ratio: 17:1

and the boost gauge regularly pins out at 30psi when accelerating, and is about 15psi lighly loaded.

Steve

Glad to hear you & yours are alright, and that the house is at least standing.

How many RPM are you running the engine @?   Any idea of the kind of current/wattage you are pulling?

Keep us posted!!

Steve