3 phase generator

trimguy · October 21, 2021, 10:13:38 AM

Leroy Somer
Type LSA410L4
Model 40978/2

Is anyone familiar with this ? I just acquired one and was checking some things out. My voltage seems high, I checked it with 2 different testers, 1 said 252 volts, the other said 257 volts. All three legs read the same with each tester. Is this voltage to high ? I also believe I have a governor problem, but more on that later. Any help would be great.

Southside · October 21, 2021, 10:17:30 AM

How old of a unit is it? I had one years back that you had to dial in the voltage each time you fired it up, just a slight tweak on a knob with a needle that you could read.

trimguy · October 21, 2021, 10:35:08 AM

Year 1992 . I don't recall seeing a knob . I will look tonight when I get home.

trimguy · October 21, 2021, 10:37:07 AM

sawguy21 · October 21, 2021, 11:35:51 AM

It sounds like your engine speed is too high,, dial it back to 1850rpm no load and check the voltage.

trimguy · October 21, 2021, 11:58:35 AM

What would be the best way to check the RPM's ? It doesn't have a tachometer on it.

Magicman · October 21, 2021, 01:13:52 PM

Is either end of the engine or generator shaft accessible? If so there are many options available for direct contact tachometers: LINK

There are also other options such as optical/photo or wired.

beenthere · October 21, 2021, 05:30:54 PM

Think I've heard of an rpm app for a smart phone. Giri comes to mind, but have not tried it.

trimguy · October 21, 2021, 08:23:07 PM

A couple of pictures.

The round thing is not a knob, it's a transistor, or resistor, or something. I ordered the tachometer and the link from above, thanks @Magicman. Does anything look familiar @Southside, or anyone else?

Ljohnsaw · October 21, 2021, 08:51:15 PM

Quote from: trimguy on October 21, 2021, 08:23:07 PMThe round thing is not a knob, it's a transistor, or resistor, or something.

Capacitor

Southside · October 21, 2021, 09:04:13 PM

On mine the adjustment knob was on the motor side. Thinking about it the adjustment was to dial in the Hz, but it changed the motor RPM. What are you showing for Hz at that voltage?

scsmith42 · October 21, 2021, 09:05:46 PM

If it were me, I'd check the voltage and hertz under a load. If both are high, decrease the governor linkage a turn or so until it within spec.

sawguy21 · October 21, 2021, 09:08:49 PM

Is it gas or diesel drive? If gas a wireless tachometer held near a spark plug wire would give you engine speed. There are cheap ones that are reasonably accurate that use a wire wrapped around a spark plug lead creating an induction coil. I am not that familiar with diesels. Scott's method is more accurate if you have the proper tools.

trimguy · October 21, 2021, 09:16:34 PM

It's diesel. Can you check Hz with a voltage meter ? I have never had to check that before. I have never worked on a generator before, either . I will have to look at mine.

scsmith42 · October 21, 2021, 09:22:40 PM

Quote from: trimguy on October 21, 2021, 09:16:34 PM
It's diesel. Can you check Hz with a voltage meter ? I have never had to check that before. I have never worked on a generator before, either . I will have to look at mine.

My Fluke will measure hertz, but my Ideal won't so it depends on the multi meter.
My 400hp Kohler has an adjustable voltage regulator. You dial in the engine rpm to achieve the correct hertz, and then adjust the VR as needed.

trimguy · October 21, 2021, 09:32:21 PM

I just walked out to the shop and looked at my voltage meter, it will not do Hz. I will see if I can find one I have to work tomorrow. I was thinking this was going to be a plug and play situation, once again I was wrong. Thank you everyone for the help so far.

Southside · October 21, 2021, 09:38:03 PM

It may be that the previous owner ran it full load or even over a lot so they kicked her up a bit to be over voltage with no load. I am presuming you want 240V? Should not be hard to address.

Edit: I guess I take that back, looked at your tag, it says 208. Have you checked the taps to be sure someone didn't cross a couple of lines?

trimguy · October 22, 2021, 07:08:56 AM

As in taps, I guess you mean the wires coming out of the generator that are numbered, one, two, three,...... this was originally set up for 110 V when The previous owner bought it. He had someone change some of the wire number connections to make it three phase Output.He didn't know what had been done . Just hired a electrician switched it over and hook it up to make his saw work.

moodnacreek · October 22, 2021, 08:13:41 AM

My 208V side is around 217V and that is fine for motors. As mentioned you could be running a little fast.

scsmith42 · October 22, 2021, 11:26:09 AM

Quote from: trimguy on October 22, 2021, 07:08:56 AM
As in taps, I guess you mean the wires coming out of the generator that are numbered, one, two, three,...... this was originally set up for 110 V when The previous owner bought it. He had someone change some of the wire number connections to make it three phase Output.He didn't know what had been done . Just hired a electrician switched it over and hook it up to make his saw work.

If you have a 12 wire alternator you should be able to rewire it into 240 or 480 3 phase. Sometimes 240 single phase too.
The 12 wires should be labeled and the voltage output will depend upon the sequence in which they are combined.

trimguy · October 23, 2021, 08:26:52 AM

I bought a new voltage meter that will do Hz. Running with no load is 258 V, 62.5 Hz. Under load, the tablesaw read the same. Under load the planer drops to 116 V 33 Hz. The engine dropped way down on RPMs, tells me the governor is not kicking in. This is a Duetz F2L912. The tachometer that I ordered to check the RPMs won't be in till end of next week so I don't know exactly what they are. This is a 12 wire alternator. There is what appears to be a factory tie wire on the throttle setting, for whatever that's worth, I know parts wear. My questions are, Is a 62 Hz fine or is that to high ? Does anyone know about the governor on these? Where its at? I'm assuming by the fly wheel, but if anybody has any information before I start tearing apart would be great. I don't know anything about this set up.

sawguy21 · October 23, 2021, 12:21:03 PM

It seems you have two problems. First the voltage is way too high, either the engine is overspeeding or the voltage regulator has gone awol. Secondly that rpm and voltage drop trying to run the planer tells me the engine is not up to snuff and somebody tried to jerry rig it. I suggest having a qualified mechanic look at it before you get in over your head, it will be money well spent.

trimguy · October 23, 2021, 05:08:34 PM

Thanks sawguy, but I do hope your wrong. My son knew somebody That had a tachometer, At idol is 1862 RPMs, with the planer on 968 RPM's. The tag all the engine says 1800 RPM. Shouldn't there be a governing system On this to kick the RPMs back up when a draw is put on it??

moodnacreek · October 23, 2021, 09:46:16 PM

This voltage output is confusing. If it is a 208 as tagged I think 1 lead would read 110V. If it has been reconnected for 480V, one lead to neutral should read 277V. 257V is right in between and I don't think the rpm is far enough off to do that but it's not dead so there has to be a fix.