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Generators / Single phase generator alternator
« on: October 05, 2007, 04:17:40 PM »
I have an Onan welder/generator model CW251-C, 220V 10KW generator, 350 amp 78VDC welder that was manufactured in 1956. I originally thought it was a Koehler, but I was mistaken. Runs like a top, 2 cylinder, air-cooled, gasoline powered, 30+PSI oil pressure, 90PSI compression.
I inquired some time back about my concerns over the starting circuit being Positive Ground, but have since put that part out of my mind. The starting circuit is not even needed - the engine uses a magneto and has a 6 volt starter.
My questions now are about the generator and alternator.
The alternator is close coupled to the engine and when the gen/weld selector switch is in "power" mode the engine runs at 1800 RPM. Voltage and frequency are a product of RPM and are not regulated otherwise on this unit. 4 pole with 2 slip rings.
The generator is on the same shaft (one piece shaft) and when in "weld" mode, increases the throttle (governor) setting to 2300 RPM giving a rated output of 350 DC Amps with an open circuit max of 78 volts.
It has a fairly small bridge rectifier, a fairly large transformer and 3 coils that are maybe one inch in diameter - 6-8 inches long with one connection on each end. The weld/power switch closes two contacts that go to or from the welding control reostat.
My biggest question is - since the unit welds AND will generate 110+ and/or 220+ volts AC (simultanously), without the battery installed, one of the rotating devices must be magnetically excited? Should I be able to tell if one of the components attract steel (magnetic)?
Does any one know or willing to venture a guess as to whether welding at 1800 RPM (rather than 2300 RPM) will result in a lower than otherwise expected voltage, amperage, or both? Or is it more likely that the 2300 RPM is required only for the increased power output from the engine?
I fully intend to convert to an 1800 RPM diesel when I get a chance if the above questions can be resolved.
I think I can send pictures of the unit and of the individual components if that would help answer the question.
Thanks in advance,
Rosie
I inquired some time back about my concerns over the starting circuit being Positive Ground, but have since put that part out of my mind. The starting circuit is not even needed - the engine uses a magneto and has a 6 volt starter.
My questions now are about the generator and alternator.
The alternator is close coupled to the engine and when the gen/weld selector switch is in "power" mode the engine runs at 1800 RPM. Voltage and frequency are a product of RPM and are not regulated otherwise on this unit. 4 pole with 2 slip rings.
The generator is on the same shaft (one piece shaft) and when in "weld" mode, increases the throttle (governor) setting to 2300 RPM giving a rated output of 350 DC Amps with an open circuit max of 78 volts.
It has a fairly small bridge rectifier, a fairly large transformer and 3 coils that are maybe one inch in diameter - 6-8 inches long with one connection on each end. The weld/power switch closes two contacts that go to or from the welding control reostat.
My biggest question is - since the unit welds AND will generate 110+ and/or 220+ volts AC (simultanously), without the battery installed, one of the rotating devices must be magnetically excited? Should I be able to tell if one of the components attract steel (magnetic)?
Does any one know or willing to venture a guess as to whether welding at 1800 RPM (rather than 2300 RPM) will result in a lower than otherwise expected voltage, amperage, or both? Or is it more likely that the 2300 RPM is required only for the increased power output from the engine?
I fully intend to convert to an 1800 RPM diesel when I get a chance if the above questions can be resolved.
I think I can send pictures of the unit and of the individual components if that would help answer the question.
Thanks in advance,
Rosie