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Old 23-05-2015, 11:20   #1
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generator problem

We have a new 5kw generator with a 2 cylinder Yanmar diesel engine, 2TNB70-HGE that supposedly runs at 1800 rpm. The following are the running load statistics:
1920 rpm at 0 amp load
1914 rpm at 1 amp load
1884 rpm at 10 amp load
1877 rpm at 20 amp load
1843 rpm at 30 amp load
Are these normal? Or, should there be some sort of a governor to keep the rpms steady? As soon as the generator starts, the incandescent and fluorescent ac lights flicker and get progressively worse as the load increases.
Any thoughts?
Thanks.
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Old 23-05-2015, 11:29   #2
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Re: generator problem

Do you have a freq meter? I'd be surprised to see a 5kw driven by a 2cylinder at 1800 rpm.
If it is in fact an 1800 rpm 60hz unit, the speed difference loaded and unloaded seems to be about as good as you're going to get with a small engine.


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Old 23-05-2015, 11:31   #3
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Re: generator problem

Generators usually run a little bit faster under no-load, giving a bit higher frequency. But they generally hit their design frequency and rpm when under load, and can dip a bit below that when fully loaded to max.

What output frequency are you measuring at no-load and 20A load? Is this unit capacitor or AVR regulated?

Lights flickering sounds like a frequency issue, which would be rpm related.

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Old 23-05-2015, 11:36   #4
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Re: generator problem

Wrong thread?

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Old 23-05-2015, 11:48   #5
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Re: generator problem

Quote:
Originally Posted by pbaran View Post
We have a new 5kw generator with a 2 cylinder Yanmar diesel engine, 2TNB70-HGE that supposedly runs at 1800 rpm.
How are you measuring RPM? According to this web site:

YANMAR | 2TNV70-HGE

That engine is rated for full power at 3,600RPM. If it is really turning at 1,800 RPM then you have a serious problem I think.
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Old 23-05-2015, 12:23   #6
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Re: generator problem

In answer to your questions we determined the rpm with a digital rpm meter on the timing pulley. The specs on the motor are 5.96kw at 2000rpm, ranging up to 10.3kw at 3600 rpm. Frequency at no load was 64hz and at 20 amps it was 62hz and at 40 amps it was 60hz. It has a 25uF, Qn 2.3Kvar, Un 550V-50Hz, -25+70C capacitor.
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Old 23-05-2015, 13:40   #7
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Re: generator problem

Sounds to me like it's working just fine then. It may be that the generator end produces "dirty" sine waves causing your lights to flicker.

To clarify my earlier post, on an engine of this size, if you try to regulate too closely the engine speed it will hunt. It's about as accurate as it can be.


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Old 23-05-2015, 14:48   #8
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Re: generator problem

It's not too bad. What are you running to load it?
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