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150 cycle supply

Kelly Marie Angel

My first job was as a test technician in a transformer factory I remember we had a 400 cycle supply from a motor generator big old noisy thing it was. Also a 150 cycle supply derived from 3 transformers this gave a max if 500 volts out  i never figured out how it worked  how do you get that from normal 3 phase 50 cycle mains??

  • 0

    probably a cycloconvertor based on SCR switches, assuming 1970 or so.

     Still used for some countries railway traction power at 16.6Hz (50Hz/3) to 50Hz conversion. Waveform quality is not great without extra L-C filtering, probably not an issue for a transformer maker to rustle up some extra coils !!

    thyristors fire off to make the outgoing waveform by slicing up the incoming one into 3rds, or is it 9ths ..

     

    7010754c97000f75b72199fc33539670-original-cycloconvertor.jpg
    I'm not sure this text book image is quite right. Or at least the single line diagrams hide some swapping of phases.
  • 0

    A supply at three times the input frequency can be produced by a special type of transformer, so designed as to produce significant third harmonics, with multiple windings  connected so as remove the 50 cycle waveform from the output.

    This was used in VERY early radio transmitters. A special high frequency alternator was used, and the frequency then tripled with a transformer.

    AFAIK one such transmitter remains in working order and is still used to a very limited extent, for historical interest.

     

    Frequency tripling transformers are still made.

    https://m.bossgoo.com/company-info/173389/other-electronic-instruments/sbf-frequency-tripling-test-transformer-17055496.html

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