Re: LF: 33 Hz QRM

[David Hine <evad_hine@yahoo.co.uk>]

Hi,

16 2/3 Hz was used as it enables the older brush motors to have much less losses than if they were run at 50 Hz -they would behave much more as if DC was applied (easier to handle). However 50 Hz is used on modern systems with electronic controllers on the trains to feed the AC motors. The UK (southern Region) 3 rail DC is a 'throwback' from the past (when DC was easy to generate and use) and  here also modern stock uses electronic motor controllers to convert the track DC to suitable output for the modern AC motors. Eventually 16 Hz will disappear and it will all be overhead HV 50 Hz except for a few DC metros because of confined tunnels -even these now have electronic AC on train motor control. So there are always many sources of 'stray' signals near to railways. Hope this is of some help, Dave. 

 

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From: Andy Talbot <andy.g4jnt@gmail.com>
To: rsgb_lf_group@blacksheep.org
Sent: Thursday, 17 March 2016, 14:18
Subject: Re: LF: 33 Hz QRM

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