v8dave
Platinum Member
4-pole generator heads will spin at 1800 rpm to get 60 Hz AC power. A 2-pole generator head will spin at 3600 rpm for 60 Hz AC power. It's easier on engines to run them at 1,800 rpm which is why the 4-pole generators runing at 1800 rpm are more likely to be found in 24/7 application.
Not to say that 3,600 rpm generators won't last a while when running 3,600 rpm. Kubota offers several Diesel gensets that run at 3,600 rpm and they are touted as being able to run 24/7 service. Although, I doubt they would hold up for a year's service that way. For stand-by, worksite and occasional use they work just fine.
I don't remember who first posted this formula from here on TBN. But, the formula is: NP = (F * 120)/RPM
or
Number of Poles = Frequency times 120 and divided by RPM
A thing to look for in building a belt powered genset is to be sure your generator head is a two bearing unit. Single bearing generators are intended to be mounted on the engine's bell housing/flywheel and use the engine rear main bearing to support the front (input) shaft of the generator. Two bearing generators are built to handle the side load a pulley drive will present.
Not to say that 3,600 rpm generators won't last a while when running 3,600 rpm. Kubota offers several Diesel gensets that run at 3,600 rpm and they are touted as being able to run 24/7 service. Although, I doubt they would hold up for a year's service that way. For stand-by, worksite and occasional use they work just fine.
I don't remember who first posted this formula from here on TBN. But, the formula is: NP = (F * 120)/RPM
or
Number of Poles = Frequency times 120 and divided by RPM
A thing to look for in building a belt powered genset is to be sure your generator head is a two bearing unit. Single bearing generators are intended to be mounted on the engine's bell housing/flywheel and use the engine rear main bearing to support the front (input) shaft of the generator. Two bearing generators are built to handle the side load a pulley drive will present.