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Generators & Electric Motors General Discussion Antique Generators and Old Electric Motors: Questions and answers about restoring and showing old power generation systems.

Generators & Electric Motors General Discussion

Stuart and Stevenson Generator Help?


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  #1  
Old 07-11-2018, 04:04:39 PM
Arkie Arkie is offline
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Default Stuart and Stevenson Generator Help?

Guy called and has a Stuart and Stevenson Gen, model 6GD-100, 3 phase 100 kw 320 amp, 1800 rpm.
I have not seen the unit and I suspect these are the gen head model numbers and maybe not the complete rig model number.

Says bought the rig and it will only generate 180v and can run rpm and fre up and down from 58-63hz and the voltage adjustments don't change the voltage and voltage remains at 180 volts constant.

Anyone got any idea where I can find some service or owners manuals for the unit?

Or anyone care to take a guess at the electrical issue or know anything about these rigs?

I see they are still in business out of Houston, Tx, tried a phone call and had to leave a voice mail with the power generator guy and he has not returned my call.
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Old 07-11-2018, 07:05:06 PM
Vanman Vanman is offline
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Default Re: Stuart and Stevenson Generator help?

What voltage is it supposed to be? 320 amps and 100 kw works out to ~180 volts at unity power factor, or ~225 volts at the typical rating of 80% pf.

75% pf works out to ~240 volts. That would be odd! But I have seen 90% and 70%, so...
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Old 07-11-2018, 07:48:03 PM
Arkie Arkie is offline
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Default Re: Stuart and Stevenson Generator help?

Quote:
Originally Posted by Vanman View Post
What voltage is it supposed to be? 320 amps and 100 kw works out to ~180 volts at unity power factor, or ~225 volts at the typical rating of 80% pf.

75% pf works out to ~240 volts. That would be odd! But I have seen 90% and 70%, so...
You know that is strange that they gave me a amperage and no voltage from a name tag.

Their main point being it's hung at 180 volts and the voltage controls will not change the voltage at all.
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Old 07-12-2018, 06:38:38 PM
Arkie Arkie is offline
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Default Re: Stuart and Stevenson Generator help?

Quote:
Originally Posted by Vanman View Post
What voltage is it supposed to be? 320 amps and 100 kw works out to ~180 volts at unity power factor, or ~225 volts at the typical rating of 80% pf.

75% pf works out to ~240 volts. That would be odd! But I have seen 90% and 70%, so...
They emailed me a pic of the tag

220volts at 80% pf.

It stays at 180 with no load and won't move up or down with regulator adjustments.

Trying to communicate with (the horses mouth) Stuart and Stevenson in Houston, Tx. Not going great.
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Old 07-12-2018, 10:07:45 PM
Wayne 440 Wayne 440 is online now
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Default Re: Stuart and Stevenson Generator help?

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Originally Posted by Arkie View Post
...Trying to communicate with (the horses mouth) Stuart and Stevenson in Houston, Tx. Not going great.
I'm not surprised. About 20 years ago I called them and they tried to help me, but the eventual conclusion was (this may not be a 100% accurate quote, memory fades) "I have no idea, back then we made many different models, for many different buyers, and once they were out of warranty we didn't worry too much about keeping that stuff...".
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Old 07-12-2018, 11:10:08 PM
Vanman Vanman is offline
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Default Re: Stuart and Stevenson Generator help?

I wonder if the generator has a manual voltage control rheostat for use when the AVR fails, and he is manipulating that control instead of the voltage adjustment on the AVR itself?
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Old 07-13-2018, 12:19:46 AM
Steve Dawkins Steve Dawkins is online now
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Default Re: Stuart and Stevenson Generator help?

Maybe the AVR board has a coarse adjustment potentiometer, and he is adjusting the fine adjustment trimmer pot on the face of the control panel. I used to set the trimmer pot to mid-position, and then adjust the coarse pot for the desired voltage. Then the trimmer could be used to fine tune the output voltage one way or the other, if necessary.
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Old 07-13-2018, 06:34:23 AM
Arkie Arkie is offline
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Default Re: Stuart and Stevenson Generator help?

Quote:
Originally Posted by Wayne 440 View Post
I'm not surprised. About 20 years ago I called them and they tried to help me, but the eventual conclusion was (this may not be a 100% accurate quote, memory fades) "I have no idea, back then we made many different models, for many different buyers, and once they were out of warranty we didn't worry too much about keeping that stuff...".
This is what I'm beginning to suspect also.

Seems to be the norm last few years, they want to sell new or get a service contract.

The ease of availability of real good Onan generator electrical Service manuals can sure spoil a guy.

The S&S vintage gen is about 60 miles away from me, 100 F heat, it's a new old purchase, 3 electrical guys have already told them they don't know why. I'm wondering why they did not test the unit BEFORE buying?
I'm not interested in going and wasting time with no service data or even knowing if parts can be obtained.

I have enough contact info that I can hiss the owner of the gen onto them.
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Old 07-13-2018, 07:40:04 AM
pegasuspinto pegasuspinto is offline
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Default Re: Stuart and Stevenson Generator help?

I wouldn't waste my time with S&S on this old set. I also wouldn't waste time looking up any service manual. This thing is probably a straight connected simple AVR likely with 6 wires. 2 to the panel knob, two for the field, 2 for sensing. Step 1, does the generator have equal voltage on all 3 phases? Yes-go on, no, generator end may be bad. Step 2, check the rotating rectifier and ohm out the exciter stator and rotor and the main field. Step 3, replace the VR. You can go with the new version of whatever is on there, or I would just probably put in a power tronics.
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Old 07-13-2018, 01:59:16 PM
Arkie Arkie is offline
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Default Re: Stuart and Stevenson Generator help?

Quote:
Originally Posted by pegasuspinto View Post
I wouldn't waste my time with S&S on this old set. I also wouldn't waste time looking up any service manual. This thing is probably a straight connected simple AVR likely with 6 wires. 2 to the panel knob, two for the field, 2 for sensing. Step 1, does the generator have equal voltage on all 3 phases? Yes-go on, no, generator end may be bad. Step 2, check the rotating rectifier and ohm out the exciter stator and rotor and the main field. Step 3, replace the VR. You can go with the new version of whatever is on there, or I would just probably put in a power tronics.
Would you want to take a shot at working on it?
(or know anyone that would)

It's in NE Oklahoma, around Grove area I think.
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