[AMPS] 50hz? 25Hz???

[Johan Nordin]

> 
> Does anybody know why 25Hz, anyway? 60 Hz you can sort of see from 60 seconds to
> the minute. 50Hz gives some convenient motor speeds like 3000, 1500, and 750.
> (2, 4 and 8 pole machines)
> 
> The 16-2/3Hz  that Johan mentions is also used on Belgian railways, (possibly
> others, too) although at 3300volts. I suspect there could be some sort of
> relationship to the Ganz 3 phase system of railway electrification (2 overhead
> wires and track return). It also provides a lower motor speed, requiring lower
> gear ratios. 

I donīt think it had something to do with lower motor speeds
Thoose old trains I was talking about ran DC motors directly at 16-2/3 Hz
without rectifying!! Maybe thats why they needed the low frequency :-)

73īs de Johan


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