1800 rpm 60hz / 1500rpm 50hz given a four pole alternator. One of the reasons old stationary engines (in Europe) in the pre-governator time ran at a fixed spee

1800 rpm 60hz / 1500rpm 50hz given a four pole alternator. One of the reasons old stationary engines (in Europe) in the pre-governator time ran at a fixed speed of 1500 RPMs