Old Continental/GE Generator History?

[MChalkley]

Here's a little mystery for you old equipment detectives out there (and one you'll hopefully find a little interesting - it's been fascinating so far, to me):

After hurricane Isabel, our power was out for 10 days and the little 6500-watt generator I had was unable to cope, so I decided to work on getting a real generator. I really wanted a diesel-powered one in the 20kw or so range, but didn't have $8k to drop on one, so I started scrounging. I found an old GE 25kw generator at a local junkyard, and bought it for the generator head, assured only that the it should be salvageable - the dealer told me he was pretty sure the engine was beyond hope and the voltage regulator definitely was. I was planning to put a used 37-hp Isuzu diesel on it, anyway, so the engine was going to be discarded. Then when I got to looking at the engine, it intrigued me, so I started doing some checking and found it was made in February, 1956, a Continental FA244. It had been converted to natural gas (no carburetor), had a stuck valve, a blown head gasket, no oil filter, etc.

I won't attempt to describe the many many hours I put into this thing, but the good news is that the engine runs almost perfectly. I still need to find a distributor cap for it, replace the points, and make up some plug wires, etc., but it runs beautifully, considering. There's a dozen other things that need to be done to it, choke and throttle cables, and the like, but all in all, it's amazing that it's doing as well as it is. The original voltage regulator was toast, so I had to buy a new solid state one, and the generator had to be re-wired for single phase instead of three phase, but all that's working, too. I actually put a 97-amp 240-volt load on it (10kw from a generator test unit and all four burners and the oven from an electric range) and ran it for almost an hour - nothing smoked and the generator never got too warm to hold your hand on it, voltage only varied 5 volts or so, and frequency only varied a couple hertz, so I sure can't complain about the output capability of the unit.

Anyway, here's the mystery: I can't find any info on the generator itself. Based on what little I know about 50's electrical devices, I don't think it's that old, but I'd like to find out. The generator is directly coupled to the flywheel of the engine, and the whole works is mounted on a cast base that must weigh 1000 pounds, so it sure looks like it's a unit built like that and not jury-rigged, but I can't help feeling the generator is newer than the engine, maybe late 60's or early 70's. Here's most of the info from the data plate on the generator: General Electric, Model 5SJ432A21Y10, Type SJ, Frame 324U, Serial #275277420, 1800 rpm, 25kw, 31.25 kva, PF .8, Encl DP, 3 phase, 240/480 volts. Does any of this info mean anything to anybody here? There's also some info on "temp rise" that I don't have recorded, but I can get it if there's anybody here that could translate it for me.

This thing is my pet project right now, so if anybody has any other info on the generator or engine, I'd sure appreciate it. Does anybody have any idea how many gph this thing will suck under, say, half load? Does anybody here have any experience with this particular engine? (I know, for example, that Ferguson, Massey Harris, and some Case tractors, as well as a whole slew of forklifts, etc. used Continental/Red Seal engines, but that's about all.) I did find a shop manual for the engine online, so that was a big bonus. (I'll tell you one thing: This engine is sure put together - I've never seen 33 head bolts on a straight six engine before... /forums/images/graemlins/ooo.gif)

 

[JerryG]

Mark,
Here is a place that has manuals for Continental engines. They do have a F244 but don't list a FA244. You might check with them. Continental Manuals

 

[JerryG]

Mark,
Continental changed owners a time or two in the past. I thought a company in Memphis owned the tractor, industrial engine part of the company now but have not been able to find them as such. Here is another place that has a lot of part as well as manuals.Continental Parts etc

 

[chim]

</font><font color="blue" class="small">( and the generator had to be re-wired for single phase instead of three phase, )</font>

How did you go about this?..........................chim

 

[MChalkley]

It's not hard, as long as the generator has 12 wires, not counting the 2 field wires. There's a dozen or so different ways to wire a 12-wire generator for different voltages and phases. The two most common 240v/single phase methods are called zigzag and double delta. For some reason, zigzag wouldn't work on mine, so I used double delta. There's several sites on the Internet that show these wiring methods, and most industrial generators come with the diagrams. If you need a source, holler.

 

[chim]

Yes, I'd be interested in a source. I understand the different voltages, it's the 3-phase to single-phase that has me scratching my bald head. I suspected the generator would have three sets of windings at 120 electrical degrees apart.

Some info from the codes you gave:

Frame 324U = physical size/characteristics of the generator

25KW, 31.25 KVA and PF 80 are all related = The generator will carry a load of 25,000 watts at 240 volts and a 0.8 Power Factor (PF), assuming a 3-phase connection. That would require it to push a tad over 75 amps, and would generally represent a load of motors or other inductive components. KVA represents the Voltage X Amperage X 1.73 X 1,000 for three-phase. 75.265 Amps X 240 Volts X 1.73 = 31,250 KVA. KW represents Voltage X Amperage X 1,000 X PF. That is 75.265 Amps X 240 Volts X 1.73 X 1,000 X 0.8 = 25,000 Watts. If it supplied power to electric heat or non-inductive loads, the output could be 31,250 Watts because the PF would be 1.0 in lieu of 0.8.

Encl DP = Dripproof enclosure.

Going three-phase to single-phase still escapes me....................chim

 

[MChalkley]

Thanks for the info - the electrical stuff I knew, but the mechanical stuff I wasn't aware of. I'm still trying to find out when the generator was built. I actually talked to somebody at GE who told me he'd have to do some research - he callled me back a few days later and said he couldn't find any indication that they'd ever made any generators that small. So I don't know if I've got a real rarity on my hands, or if I just talked to somebody who didn't know anything and only pretended to try to find out.

The best source of generator wiring diagrams I've found is at Marathon Electric's Generator support page. It looks kinda confusing, but it's all pretty generic stuff. Look at the columns for phase, voltage and number of leads from the generator (not counting field exciter leads), and pick the one you want.

 

[chim]

Thanks for the reference. Interesting. I've never been involved in an installation that required those connections. (Been a long time since school too.) Installations we've done were nearly all 3-phase wye, and some delta center-tapped for 120/240 with a high leg.

How about a little help with Windings 101? I could use some. When looking at the generator you have in the original 480V 3-phase 31.25KVA connection, tha FLA would be 37.6A per leg. In a 480V hookup, with the windings in series, each winding would be subjected to the 37.6A, which I imagine is the design max current. If this is the case, would the output of the generator be just over 18KW at 240V at full load when connected for single-phase? In the zig-zag connection, you'd end up with current flowing through parallel windings, each of which could do 37.6A, or 75.2A per leg, and you'd lose the 1.73 multiplier. Thanks..................chim

 

[MChalkley]

Interesting question. I've asked three different guys, all with over 20 years experience in working with generators, and all with EE backgrounds, and gotten three different answers. One said he didn't know, another said you had to de-rate to 50% when going from 3 phases to 1, and the third said you had to de-rate to 50% if you used the low-voltage zigzap method, but to only 80% if you use the double delta method.

I'm not an EE, but it seems logical to me that double-delta would only de-rate the generator to 80%. As I said earlier, that's the method I used and I actually tested the generator at more than 80% for an hour without damaging anything that I could see (or smell). Other than that, I'm hoping somebody else here will chime in with some facts.

 

[chim]

Well, you have me using parts of my memory bank that haven't been visited for a long time. It's fun...............chim

(certainly no EE, haven't even slept at a Holiday Inn Express, just an old "sparky" that has been spending more time on General Construction and Mechanical projects than Electrical in recent years)