Re: LF: 33 Hz QRM

[PA7EY <pa7ey@amsat.org>]

I suppose 16 2/3 is correct (16 1/3 x 3 = 49), according to my information, they actually use 16.7 in some places these days.

73 Ulrich PA7EY

2016-03-17 15:59 GMT+01:00 <phl@netikka.fi>:

Hello John, Johan, LF

16 2/3 Hz should probably be 16 1/3 Hz, one third of 50 Hz as John pointed out.


Here in OH-land we use 50 Hz for the railways but during my EE studies, the SM-land railway QRG was also mentioned for two reasons (hope I remember this right now, it was about 25 years ago...):

- A lower frequency was selected to minimize the voltage drop caused by the series inductance formed by the long overhead lines supplying the locomotive.

- Initially 16 1/3 Hz was generated in rotary converters, for example a 6-pole 50 Hz motor would drive a two pole generator which gives the required step-down. Rotary converters need maintenance and so this system was later replaced by non-mechanical devices such as cyclo-converters or other early ways of electronic frequency converters that supposedly require less maintenance. In fact,  I think this was the main reason for bringing up this subject in school.


BR

Paul-Henrik, OH1LSQ



Quoting Andy Talbot <andy.g4jnt@gmail.com>:

Is that to minimise skin loss in steel track ?

UK Third rail is, of course, DC, and I once spent an idle moment
calculating the loss if 50Hz AC were to be used with magnetic iron
conductors.  I think I came to the conclusion a 1MW train could probably
travel a few hundred metres before it lost its power supply.

andy  G4JNT

On 17 March 2016 at 13:21, Johan Bodin <jhbodin@tele2.se> wrote:

Railway QRG is 16 2/3 Hz in Sweden too.

73 de Johan SM6LKM

John Rabson wrote:

I seem to recall that some railway systems use at about 16 2/3 Hz (one
third of 50 Hz) for traction.

...

Can someone say whether my recollections are correct, please?

73 John F5VLF