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Old 12-11-2019, 12:38 AM
El Oso El Oso is offline
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Default 30kw Generator Wiring

I'm new at this so please bear with me.

I recently aquired a diesel (White/Hercules D2300) powerd 30kw (Lima Electric) standby unit. This unit hasn't been used in years and for some unknown reason, ALL the control and output wires were cut. I have been successful in getting the engine to run but am at a loss for wiring or testing the generator. I have also been unsuccessful in finding a schematic for this unit. Any information provided would be a huge help.

Thanks,
El Oso
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Old 12-11-2019, 09:55 AM
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You might check over on Smokstak.com. They have a section on generators and the folks there are very helpful. There may be someone here that has had experience with that particular set up, but if not, some of those folks are really into generators.
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Old 12-11-2019, 09:57 AM
El Oso El Oso is offline
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Thanks Norm
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Old 12-11-2019, 10:06 AM
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Welcome to the forum El Oso. That looks like a fun project, and should be darn useful once you get it all figured out!
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Old 12-11-2019, 11:17 AM
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I'm can't be much help, but I'd like to see some up close pics of the unit any tags visible.
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Old 12-16-2019, 11:34 AM
bunkclimber bunkclimber is offline
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Default 30kw generator stator leads..3phase?

12wire low voltage 3ph= leads#1+7 together=PhaseA, leads#2+8 together=Phase B, leads#3+9 together=Phase C. Connect #4,5,6,10,11,12 all together that's the neutral..get back to me with model # and number of leads in generator box and we can make it up. that's for low wye 208-240v.There's also 2 wires for the field that go to a regulator..easily substituted with a modern module if its missing..about $75
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Old 12-22-2019, 05:20 PM
El Oso El Oso is offline
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Sorry it has taken so long, but here is what I have
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Old 12-30-2019, 08:45 AM
bunkclimber bunkclimber is offline
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Default 30kw

the voltage regulator is easily replaced(I would)by a Marathon SE350 or its compatible clone.there are two(2)wires that are your field leads,they are polarized,one is + and one is -,follow them from the F+ and F- terminals on the present regulator you have now and identify and mark them.The generator is single phase,probably a 4-wire not a 12-wire like I recommended connections for earlier.When you take it apart further take plenty of pics and make drawings as to what is connected.Hopefully there are lead wire tags(small aluminum numbered tags)or poly ID tags on the leads-don't lose or allow them to come off. Lima was acquired by Marathon in WI back in the 80's and continues to manufacture some of the Lima design generators.As far as any factory support I doubt Marathon has any of the old prints of this alternator.Let's take it apart piece by piece and see what we can determine from what lead wires are present.Get plenty of pics as you go.The only leads you need are the field+/- and the stator output leads(bigger black wires)..you can junk the round CTS and all the white wires going to the regulator if you are going to update it.Some of the white leads are probably sensing leads from the power lead combinations back to the regulator.You'll only need two hots for a SE350,the CT's are unnecessary.
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Last edited by bunkclimber; 12-30-2019 at 09:00 AM.
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Old 12-30-2019, 01:53 PM
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Before spending any money on the electrical side find out if the generator has internal issues.

To do this mark , disconnect and isolate all output wires but make them available for metering.

Using an ohm meter check for grounded windings any grounds and the windings are in trouble and need a rewind shop

If all is fine start the engine and run it up to rated RPM (1800)
use a separate 12 volt battery to connect to f+ and F_ .

If the motor loads up and starts working Test is over because the generator has issues and needs a rewind shop.

If the motor runs fine leave the field connected and check output leads carefully because you should have very close to rated voltage on the winding pairs.
if you do you have near rated voltage on each pair you have a winner if not shut the motor off and disconnect the field.

At this point your problem will be one of three things all on the rotating assembly.

To troubleshoot further you need to remove the rear end bell to get at the rotating parts. Disconnect the battery first

The rotating parts are
A rotating generator at the rear that amplifies the magnetic field from F+ and F- and converts it into 3 Ph.

Next a three phase rotating rectifier converts that to DC and feeds it into the main rotor to generate the powerful magnetic field that converts the input power into electricity.

There will be an MOV (Metal Oxide Varistor) on the rotating rectifier assembly as well. it usually looks like a disk capacitor. It's purpose is to clamp the voltage spikes caused by load changes thus protecting the rotating diodes. When it fails the diodes die and the generator quits.

There are some tests you can do.

First disconnect and mark all leads.

inspect the MOV for damage and check with an ohm meter it should read open circuit.
Next check each winding for grounds they should be open circuit to your meter. There are tools that can test this further but on a generator faults are usually very obvious.

Next check each diode in the rotating bridge there should be three forward diodes and three reverse diodes. They will be about 20 amp 600 volt or higher rated parts that are stud mounted and coated with a conformal epoxy to protect against rotating and vibrating forces.

if everything seems fine to this point we get to my favorite test.

The angle GRINDER test.

You need a big old 7 or 9 inch grinder an extension cord with the black lead exposed and cut with a means to connect it for test purposes.

First test with the main rotor winding isolated from the diode bridge
connect it in series with the grinder by connecting the black leads to it.
so power will come in from the plug go through the main rotor and out to the grinder then back through the white wire. This is a live line test so be careful.

Plug in to 120 VAC nothing should happen yet.
Hold the grinder as if you are grinding and turn on the grinder
if all is well the grinder will growl and turn slowly.

If there is a shorted turn in the rotor the grinder will run normally.

The final test is to disconnect the plug from the wall take one wire off the rotating field and ground it to the main rotor.

Plug in and try the grinder it should do nothing if it growls or spins there is an insulation issue in the rotor.

If the generator passes all these tests it has no electrical faults.

There is still one possible issue which is damp windings.
The tests for this are called Hi Pot tests and involve putting an increasing voltage between the windings and the body through a sensitive current meter and a current limiting resistor.
A dry winding will show a small but linear increasing current as the voltage is raised to about 1000 volts. If the rate changes stop the test as this is the limit for the windings now.

Wet windings will show a much steeper change.

This test is very "interpretive" the larger the machine the steeper the curve.

The only cure for wet windings is to put the stator in an oven and heat it slowly to about 200F for about 12 hours to dry it out. After it cools retest and go from there.

The hidden issue with wet windings is rust forming in the laminations.
Rust occupies more space than the steel it is made from so it can stress the winding insulation leading to failure in the near future.

There you are now qualified to troubleshoot an unknown generator with no risk of further damage to it.
It takes longer to read this than to do the tests once you understand them.
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  #10  
Old 01-02-2020, 10:12 AM
bunkclimber bunkclimber is offline
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Default 30kw

Terry pretty much called it out with the stator winding test suggestions.No use going further until you can prove if it's any good.Sometimes tho we just fire em up after a simple checkout and see,bigger units can get catastrophic if there's something amiss. I've had a lot of old units come thru our shop that were good electrically but suffered from corroded connections,typical frayed lead wires,cracked and broken mountings..on and on. I'm trying to look closer at your photos and from what I can see it looks as tho this might be a 360 frame 12 lead generator,if its 12 lead you can make it up 3phase or single phase zig zag at 2/3rds output KW.You didn't state what you are using it for.If its for intermittent occasional use you might be OK but if you're gonna put big hours on it you might want to look into replacing the end bearing. Get back to us again,maybe we can help you.
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