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Marine Generator Stator - Average lifespan? Rewind? Rotor too?


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  #1  
Old 04-15-2011, 07:13:05 AM
antinucci antinucci is offline
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Default A Voltage Regulator Fuse continuously blows - Kohler 18.5 CCOZ Genset

I have a Kohler 18.5CCOZ Genset. I have been having intermittent problems with the genset that has now escalated to issues seemingly associated with the circuit board and/or voltage regulator. The part numbers are H-239563 and A-344342.

The initial problem was that the 8A "Voltage Regulator Fuse" repeatedly and intermittently would blow... sometimes immediatley after start, sometimes after a few minutes, sometimes after hours of genset operation. This fuse is connected to the voltage regulator's power supply lead, labeled "5" of the connection block on the right hand side of the voltage regulator.

The problem has escalated to the point where the 8A fuse immediately blows and the circuit board's operational sequence of LED/relays indicates the circuit board needs replaced. The engine starts, LED1, LED2, and LED3 and all light up, then LED4 light flashes and the engine cuts off. LED5 never lights up. The fault tree in my Kohler TP-5630 Service Manual indicates the circuit board needs replaced.

I sent the rectifier, circuit board and voltage regulator board to Colburn Electron Controls in IL for analysis/refurbishment/restoration yesterday. They might have some info on what is wrong or what went wrong.

My fear is that something internal to the generator, such as the stator, rotor, or exciter windings are shorted and it will just go a blow my repaired boards.

Thoughts?

Last edited by BTPost; 04-15-2011 at 12:24:38 PM. Reason: One Thread, in One forum is sufficient....
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  #2  
Old 04-15-2011, 12:16:39 PM
Isaac-1 Isaac-1 is offline
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Default Re: 8A Voltage Regulator Fuse continuously blows - Kohler 18.5 CCOZ Genset

Have you checked the wiring from the fuse to the voltage regulator and from the voltage regulator to the generator end to make sure nothing is shorting out?

Ike
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  #3  
Old 04-15-2011, 05:51:44 PM
Lloyd H Lloyd H is offline
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Default Re: 8A Voltage Regulator Fuse continuously blows - Kohler 18.5 CCOZ Genset

Try a temporary 5 Amp fuse between regulator and the brushes, maybe isolate the problem
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Old 04-16-2011, 08:34:18 AM
Daverepair Daverepair is offline
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Default Re: 8A Voltage Regulator Fuse continuously blows - Kohler 18.5 CCOZ Genset

I have the manaul for that unit in PDF. It has good info on trouble shooting. Email if interested daverepair@gmail.com
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Old 04-16-2011, 11:01:33 AM
antinucci antinucci is offline
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Default Re: 8A Voltage Regulator Fuse continuously blows - Kohler 18.5 CCOZ Genset

Quote:
Originally Posted by Daverepair View Post
I have the manaul for that unit in PDF. It has good info on trouble shooting. Email if interested daverepair@gmail.com
I have the manuals, thank you however! I found them online and have read them all, front to back:
http://marinegenerators.us/kohler/lit/TP5630.PDF
http://www.atlantismarine.co.uk/Imag...ile/TP5593.PDF
http://marinegenerators.us/kohler/lit/TP5592.PDF

I still have not received the full report from Colburn on the three boards I sent them, but I did do further investigation with my ohmmeter and after about 10 minutes of probing, my heart sank. I found that the V1/V4 leads (wires 33 and 44) to one of the stator windings are shorted to ground. The output 240 hot/netural also have continuity to ground as well. So, it looks like I am in route to having my stator and rotor rewound. From the manuals, this is a non-trivial effort.

From a recommendation, I have contacted Broward Armature in FLA to see if they do the rewind or an exchange.

Now the fun of taking the genset apart - this is akin to the level of effort of a car transmission replacement, in my opinion! Egads.
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Old 04-16-2011, 11:07:06 AM
antinucci antinucci is offline
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Default Marine Generator Stator - Average lifespan? Rewind? Rotor too?

I have a Kohler 18.5 CCOZ Genset and it looks like the V1/V4 leads of the stator are shorted to ground. The output 240V hot/neutral also have continuity to ground.

I have three questions:

1. what is the normal lifespan for marine generator stator? This genset is only 10 years old with 600 hours on it. It is clean and well maintained. I was surprised when this happened.

2. I have engaged a company to do the rewind and/or exchange (Broward Armature in FLA). Does anyone have any other good experiences doing a stator rewind, and if so, who did you use?

3. Should I go ahead and rewind the rotor too?

Last edited by BTPost; 04-16-2011 at 12:51:25 PM. Reason: Please try and keep to a single thread per unit.....
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Old 04-16-2011, 05:53:14 PM
pegasuspinto pegasuspinto is offline
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Default Re: Marine Generator Stator - Average lifespan? Rewind? Rotor too?

Rotors and stators have no expiration date, as such. They can go a million hours if kept clean and dry and not abused, and will be ruined in about 0.1 second if there is an object let loose in the generator end. I'd look close for damage and the answer might be plain when you find it.

Robert
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Old 04-16-2011, 06:03:32 PM
kg5388 kg5388 is offline
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Default Re: Marine Generator Stator - Average lifespan? Rewind? Rotor too?

did you disconnect the stator windings before you tested them? and isolate each set of windings from each other?
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Old 04-17-2011, 10:13:22 AM
Jack Hottel Jack Hottel is offline
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Default Re: Marine Generator Stator - Average lifespan? Rewind? Rotor too?

I agree, make sure that ALL stator leads are isolated before testing for grounds.
Jack Hottel
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Old 04-17-2011, 11:19:47 AM
armandh armandh is offline
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Default Re: Marine Generator Stator - Average lifespan? Rewind? Rotor too?

the other question is if the short is not in the stator
are you looking at the bonding point or some other ground fault.
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Old 04-18-2011, 08:27:08 AM
antinucci antinucci is offline
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Default Re: Marine Generator Stator - Average lifespan? Rewind? Rotor too?

THANK YOU ALL!!!

Wow! what difference that makes... no where in the manual does it say to do that... now that I am thinking about though, I am like "duh!!!!"....

Anyway, by disassembling the generator, I finally can see how this thing is wired... My manual has so many different output voltage configurations and schematics that it was impossible to see which one my set was configured for... It turns out that the output configuration brings one side of two of the windings to ground in the controller box! That is why I thought I had two of my windings shorted! The stator has four big black wires labeled 1, 2, 3 and 4:

Wires 1 and 2 are one winding
Wires 3 and 4 are another winding

Wires 2 and 3 are connected together and bolted to ground in the controller box - I think these are "neutral" according to the diagram - should these really be bolted to ground??? That is a rhetorical question, because I know the should be because the genset worked perfectly for 600 hours in that configuration, I just don't understand it.

Wire 1 and 2 are connected to a double circuit breaker, each to their own circuit breaker switch. The output configured is a "120/240V 3 wire"... I just don't understand how this thing creates output current with so much continuity to ground! Wires 1, 2, 3 and 4 are all showing continuity to ground in this configuration! Again, I know it is right, but don't understand it.

While a feel a bit better, I still need to figure out why my 8A fuse keeps blowing that is attached to input of the VR... I should get the full report of the three circuit boards I sent out sometime today... stay tuned for that.

The manual says I should use a "500V Megohmmeter" to fully test the stator thing out... Looking online, these things are $500+!! I have cheap multimeter that ranges up to 2MegaOhms, but I suspect that is not good enough? Thoughts?
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Old 04-18-2011, 10:51:40 AM
kg5388 kg5388 is offline
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Default Re: Marine Generator Stator - Average lifespan? Rewind? Rotor too?

I think your going in the wrong direction by looking at the stator. I'm not that experienced with the Kohlers but you state this is the input fuse from the stator to the regulator.

Let's look at how a fuse works. Source-->>--fuse-->>--load the fuse protects the source from a problem in the wires or the load.

If it is the input from the stator and it checks ok then you need to check the voltage regulator and the other side of the voltage regulator.

I could be dirty slip rings to a flying short in the rotor or if it is brushless it could a problem with the exciter stator, exciter rotor, rectifiers or the main rotor.

If you follow the print what does this 8 amp fuse supply power to?
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Old 04-18-2011, 02:02:54 PM
antinucci antinucci is offline
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Default Re: Marine Generator Stator - Average lifespan? Rewind? Rotor too?

I just got the report back on the three boards, all boards checked out ok (circuit board, rectifier, voltage regulator) with 100% confidence.

Colburn indicates I need to test the exiter stator and exiter rotor as well. He also does not think it is the main stator either.

So, when the boards arrive tomorrow morning, I plan to separate the exciter field using a 12V battery iinstead of the VR (once I get everything hooked back up.) That is after I double check all the continuity and resistance of the exiter components.

Thanks for the input!
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Old 04-18-2011, 02:15:01 PM
kg5388 kg5388 is offline
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Default Re: Marine Generator Stator - Average lifespan? Rewind? Rotor too?

when you flash the field with 12vdc make sure the voltage is equal and stable on both legs. if you check one leg there may be a problem with the other.
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Old 04-18-2011, 04:52:10 PM
antinucci antinucci is offline
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Default Re: Marine Generator Stator - Average lifespan? Rewind? Rotor too?

Any thoughts on this question I had:

"The manual says I should use a "500V Megohmmeter" to fully test the stator thing out... Looking online, these things are $500+!! I have cheap multimeter that ranges up to 2MegaOhms, but I suspect that is not good enough? Thoughts?"
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Old 04-18-2011, 06:41:21 PM
Fred M. Fred M. is offline
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Default Re: Marine Generator Stator - Average lifespan? Rewind? Rotor too?

Antinucci-

Your meter may use a 9 Volt battery for its power. If the stator fails your 2 Megohm meter test, it would certainly fail a 500 Volt test. If it passes, you still don't know if the insulation can withstand the higher voltage.

Fred
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Old 04-18-2011, 11:19:52 PM
Kimbra Dean Kimbra Dean is offline
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Default Re: Marine Generator Stator - Average lifespan? Rewind? Rotor too?

I really don't know anything specific about your generator but it does sound like it could very well be a problem in the exciter stator ( that's assuming you have a brushless generator). You might also want to carefully check the wiring from the voltage regulatror to the exciter stator. I would check it first with a multimeter. If it checks bad with a multimeter then you don't need to meg it.

If you do decide to buy a megger here are a few to choose from:
http://www.newark.com/jsp/search/bro...atchallpartial

As far as the ground on your stator just think about it. You have two 120 volt windings. Connecting 2 to 3 puts the two windings in series for 240 volts from 1 to 4. You will have 120 volts from 1 to the connection of 2 and 3, or from 4 to the connection of 2 and 3. So, the connection between 2 and 3 is the netual which is grounded. The stator windings must have a very low resistance otherwise there would be too much voltage drop in the stator when there is a heavy load on the generator. So when 2 and 3 are grounded you will read through the stator winding resistance at 1 and 4, which is very low, to ground.
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Old 04-19-2011, 06:13:25 AM
armandh armandh is offline
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Default Re: Marine Generator Stator - Average lifespan? Rewind? Rotor too?

the reason a seperatly derived source of power is bonded [bolted] to earth [or the hull] is to be sure that the electrical system does not rise above the output voltage in relationship to ground. this could happen through static electricity generation or down stream equipment ground fault.

there should be only one such connection between ground and neutral
otherwise a neutral failure can result in electrically hot equipment.
there can be many case to ground connections but
the ground leads do not carry current except in a short lived fault situation.

current should return to the source only through the neutral wire.
[or in the case of a 240V load on split 240, the other hot wire]

Last edited by armandh; 04-19-2011 at 06:22:49 AM.
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Old 04-20-2011, 10:37:46 PM
antinucci antinucci is offline
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Default Re: Marine Generator Stator - Average lifespan? Rewind? Rotor too?

OK, all I triple-checked stator, exciter and armature and all wires to/from the control box. I visually inspected all cables as well. I tested the stator/exciter/armature in different positions by hand-turning the shaft. Everything tested ok (without using a 500V megger). I also got all the boards back from the ABSOLUTE BEST Chris Colburn from Colburn Electronic Controls in IL and they all checked out 100%. So everything is perfect, all except for the 8A fuse that blows - reminder: that fuse connects one of the stator windings to the voltage regulator.

SO, I just reassembled everything, carefully reorganizing the wiring in the control box; carefully and meticulously installed everything else - rectifier, exciter field, and armature... shop-vac'ed everything... installed a new 8A fuse... and guess what???

The genset works and the 8A fuse did not blow.

I ran it with my boat's stove on and it was drawing 35 AMPs at 254 volts and 63 Hz. As the coils of the stove periodically turned on and off, the generated adjusted accordingly.

I don't understand it, but I am not complaining.

I noticed in my emergency genset repair kit, they give you five (5), yes! five spare 8A fuses... Maybe these dumb things just blow all the time!

I fully expect to be posting to this forum again when the genset acts up again... intermittant failures stink!!!
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Old 04-20-2011, 10:54:31 PM
kg5388 kg5388 is offline
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Default Re: Marine Generator Stator - Average lifespan? Rewind? Rotor too?

Volts and HZ is high. it is reaching the high point of the scale for no load.It shouldn't have been that high with load.

What was it without load???
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