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craigie
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Join Date: Jul 2013
Posts: 4

Generator 200kva Cummins/Stamford Alternator

07/03/2013 10:29 AM

This generator runs fine with a small load of lighting and some small 3 phase motors up to 20 amps, when we load it with other equipment of not more than 30 to 50 amps, we encounter high revs and the generator cuts off on an alarm, over load. I have changed the Smartgen controller checked all electrics what I can. But revs up and cuts out on alarm
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PWSlack
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United Kingdom - Member - Indeterminate Engineering Fields - Control Engineering - New Member

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#1

Re: generator 200kva cummins/stamford alternator

07/03/2013 10:36 AM

Sounds like it's time to phone Cummins/Stamford and arrange for a Service Technician to call in.

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pnaban
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#2

Re: Generator 200kva Cummins/Stamford Alternator

07/03/2013 11:36 PM

200kVA set should not run at 20 A load.Consult manufacturers regarding recommended minimum load for it.

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SHOCKHISCAN
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Location: Eastern Arizona mountains on Route 666 about a mile from God's country
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#3

Re: Generator 200kva Cummins/Stamford Alternator

07/04/2013 10:39 AM

New machine or in service for awhile?

New problem or there from the beginning?

If it is a new problem on a machine that has been is service for awhile; Has there been any faults/failures or maintenance performed on the machine recently?

The generator engine should not be increasing the speed if the overload is real rather an overload would cause the engine to slow down due to the mechanical loading.

I would check the engine speed control as higher revs result in increased power frequency which will in turn will cause the Volts/Hertz ratio to be out of limit hence the generator protection circuitry will see an overload condition and trip.

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craigie
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Join Date: Jul 2013
Posts: 4
#4
In reply to #3

Re: Generator 200kva Cummins/Stamford Alternator

07/05/2013 1:53 AM

machine been in service for a while(190 run hours)

New problem, no others prior to this one

machine never been touched for maint or other faults, recently prior to fault.

Replaced the speed control and Smartgen control unit
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LAA_Lucke
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#5
In reply to #4

Re: Generator 200kva Cummins/Stamford Alternator

07/05/2013 3:47 AM

Speed control = Governor:

- What type: mechanical or Electronic?

It looks like the loop gain has gone wrong: When there is load demand, the fuel is increased by the governor to maintain the rpm constant as set. if the Gain is too high, the reaction will be too fast and too much for a small increase in load ( This is for both types). Check the Governor setting manual for any gain adjustment that might be available on the model. This needs some knowledge of the subject on servo mechanism and the particular governor.
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craigie
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#7
In reply to #5

Re: Generator 200kva Cummins/Stamford Alternator

07/30/2013 4:53 AM

managed to get another governor and replaced old one , sorted problem out, thanks for advise
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PWSlack
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United Kingdom - Member - Indeterminate Engineering Fields - Control Engineering - New Member

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#6
In reply to #4

Re: Generator 200kva Cummins/Stamford Alternator

07/30/2013 4:22 AM

Check also that the new unit is programmed the same way as the original. If it is set to reverse acting and the original is direct acting, for example, that feature alone would produce the behaviour indicated in the original post.

Find the manual and/or call the manufacturer for advice.

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craigie
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Posts: 4
#8
In reply to #6

Re: Generator 200kva Cummins/Stamford Alternator

07/30/2013 4:55 AM

settings set the same as old controller, changed the governor as an option and by doing so, this sorted out the problem. thanks
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Users who posted comments:

craigie (3); LAA_Lucke (1); pnaban (1); PWSlack (2); SHOCKHISCAN (1)

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