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Kohler Generators

Kohler 12 RES Installation


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  #41  
Old 12-02-2018, 10:51:13 PM
zaphod zaphod is online now
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Default Re: Kohler 12 RES Installation

5-15 ohms? OK, I'll check it out.
Thanks,
Zaphod
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  #42  
Old 12-02-2018, 11:38:22 PM
Zephyr7 Zephyr7 is offline
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Default Re: Kohler 12 RES Installation

Make sure the brushes are not too worn, that they can move in the holders, and that the slip rings aren’t corroded/burned/damaged. You might need to clean the slip rings and/or replace the brushes.

Bill
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  #43  
Old 12-06-2018, 02:14:09 PM
zaphod zaphod is online now
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Default Re: Kohler 12 RES Installation

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Originally Posted by Zephyr7 View Post
Make sure the brushes are not too worn, that they can move in the holders, and that the slip rings aren’t corroded/burned/damaged. You might need to clean the slip rings and/or replace the brushes.

Bill
Brushes are fine, clean, mobile, plenty of meat left, no dust. Contact screws are clean. Slip rings were a little dirty, cleaned them off with contact cleaner and water dispersant. Checked continuity between slip rings and ground - none Continuity between slip rings is o. Don't have a megaohm meter. Going to try the new SCR ($110) then call in the troops. Still only produces 52-55 volts. Ideas?

Cheers,
Zaphod
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  #44  
Old 12-06-2018, 02:50:42 PM
Zephyr7 Zephyr7 is offline
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Default Re: Kohler 12 RES Installation

Zero ohms as measured across the field winding? That’s either too low, or your meter is unable to measured in the ten ohm or so range. Field resistance should be In the 5-15 ohm range or so as previously mentioned.

If it really does show zero ohms, then you probaby have a short somewhere. Check if you can measure resistance across the slip rings only (brushes isolated), although I doubt the brushes would have shorted to each other. It’s possible the field winding is bad, but that would be unusual. I’d suspect conductive debris somewhere around the slip rings or brushes first. Possibly a burned wire somewhere in the harness?

You are taking these field resistance measurement with the SCR pack disconnected, correct?

Bill
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  #45  
Old 12-06-2018, 07:28:32 PM
zaphod zaphod is online now
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Default Re: Kohler 12 RES Installation

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Originally Posted by Zephyr7 View Post
Zero ohms as measured across the field winding? That’s either too low, or your meter is unable to measured in the ten ohm or so range. Field resistance should be In the 5-15 ohm range or so as previously mentioned.

If it really does show zero ohms, then you probaby have a short somewhere. Check if you can measure resistance across the slip rings only (brushes isolated), although I doubt the brushes would have shorted to each other. It’s possible the field winding is bad, but that would be unusual. I’d suspect conductive debris somewhere around the slip rings or brushes first. Possibly a burned wire somewhere in the harness?

You are taking these field resistance measurement with the SCR pack disconnected, correct?

Bill
No. Forgot about that. Back to the drawing board.
Thanks.
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  #46  
Old 12-06-2018, 09:31:54 PM
Birken Vogt Birken Vogt is offline
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Default Re: Kohler 12 RES Installation

Quote:
Originally Posted by zaphod View Post
Brushes are fine, clean, mobile, plenty of meat left, no dust. Contact screws are clean. Slip rings were a little dirty, cleaned them off with contact cleaner and water dispersant. Checked continuity between slip rings and ground - none Continuity between slip rings is o. Don't have a megaohm meter. Going to try the new SCR ($110) then call in the troops. Still only produces 52-55 volts. Ideas?

Cheers,
Zaphod
What about the 300 ohms? Across the brush terminal screws and the rotor rings - 300 ohms, 5 ohms, zero ohms?
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  #47  
Old 12-07-2018, 10:57:53 AM
zaphod zaphod is online now
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Default Re: Kohler 12 RES Installation

The zero was recorded across the slip rings with nothing attached, ohmmeter set on 2000
Brush resistance is about 5 ohms. Zero ohms from either brush pole to ground or slip ring to ground. I don't think the rotor or stator are pooched, no heat scarring, or burned wires. I really think it's either a controller board or scr issue.
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  #48  
Old 12-07-2018, 11:33:32 AM
Birken Vogt Birken Vogt is offline
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Default Re: Kohler 12 RES Installation

From one slip ring to the other should be 5-15 ohms as well. Definitely not zero. That would indicate a shorted rotor although that happens infrequently, I am questioning your meter.

One way to confirm this finding is to apply 12V to FP and FN while running the unit (or not running it for that matter)

Measure the current, do the math and find if the resistance is the same as the meter indicates.
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  #49  
Old 12-07-2018, 12:56:20 PM
Zephyr7 Zephyr7 is offline
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Default Re: Kohler 12 RES Installation

With everything disconnected, you should not be showing zero ohms to ground on either brush terminal. Zero ohms to ground indicates something is shorted to ground.

Is “brush resistance” the resistance as measured from one brush lead to the other, so the current path is meter->brush1->slipring1->fieldwinding->slipring2->brush2->meter ? That total path should be in the 5-15 ohms range, and measuring from brush1 to ground or brush2 to ground should show open circuit, not zero ohms. Anything else indicates a problem.

It is very important while testing to isolate each component you are trying to test. If you have other things in the circuit that you don’t know about, or don’t tell us about, your readings won’t make sense or we’ll think something is wrong when it’s not. Service work is all about being methodical and doing things step by step to isolate each part, gradually working towards locating the one part that is the source of the problem.

Bill
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  #50  
Old 12-08-2018, 08:27:55 AM
zaphod zaphod is online now
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Default Re: Kohler 12 RES Installation

Quote:
Originally Posted by Zephyr7 View Post
With everything disconnected, you should not be showing zero ohms to ground on either brush terminal. Zero ohms to ground indicates something is shorted to ground.

Is “brush resistance” the resistance as measured from one brush lead to the other, so the current path is meter->brush1->slipring1->fieldwinding->slipring2->brush2->meter ? That total path should be in the 5-15 ohms range, and measuring from brush1 to ground or brush2 to ground should show open circuit, not zero ohms. Anything else indicates a problem.

It is very important while testing to isolate each component you are trying to test. If you have other things in the circuit that you don’t know about, or don’t tell us about, your readings won’t make sense or we’ll think something is wrong when it’s not. Service work is all about being methodical and doing things step by step to isolate each part, gradually working towards locating the one part that is the source of the problem.

Bill
The problem is English is an acquired language for me. When I said “zero ohm” I
meant no circuit or “open circuit” nothing is shorted to ground, no continuity between the slip rings and the chassis. All components are isolated. 5 ohms is between brush contact and slip ring. No broken wires. 300 ohms was probably a bad meter which I have since changed.
Cheers,
Zaphod.
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