RK05 spindle pulleys - trade 50Hz vs 60Hz?

Jon Elson elson at pico-systems.com
Thu Jul 26 11:02:20 CDT 2018

On 07/26/2018 09:54 AM, Anders Nelson via cctalk wrote:
> To get that power, did they have to use a rotary convertor from 60Hz
> 3-phase to get 400Hz?
IBM mainframes in the late 1950's early 1960's (707x and 
709x series) used motor generators to generate 400 Hz 
3-phase power, which was distributed to all the major 

For the 360, they came up with a solid state version, it ran 
the CPU, memory and such on 2500 Hz single-phase power, 
using a "converter-inverter".  It rectified and filtered the 
3-phase 50- or 60-Hz input to DC, and then used ultra-fast 
SCRs to invert it.  But, the energy stored in the filter 
caps in that was way smaller than the rotational energy in a 
motor generator set.  So, the 360 was susceptible to power 
glitches and dips.  For the 370, they went back to a 
motor-generator set actually INSIDE the CPU cabinet to 
produce 415 Hz 3-phase power.  Larger systems often had a 
UPS with electronic inverters in them.


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