The following sketch is of an old impedance bond in a track-circuit for a metro line operating on 800 VDC traction supply. In addition, there is a 75Hz 3 VAC voltage injected onto the rails for train detection. The 7 + 7 windings pose no resistance to the traction return current of 2000 A, however, the 75 Hz signal must see infinite impedance in the filter, i.e. not pass through the 14 windings. These windings are wound on a standard transformer laminate - secondary winding uf unknown number of turns is loaded with a 10micro Farad capasitor.
The question is: Disregarding the DC-current, what is the filter equation for this 75 Hz band-stop filter?
The second question: The 2x7 windings turn the same way, but with opposing currents, thus when carrying even currents, opposing fluxes will cancel each other under ideal conditions. If however the impedance bond is loaded unevenly, the iron core will saturate at some point from the DC current. What will happen to the filter characteristics?
Does anyone know a resource that discusses this particular filter. I am too old to have kept all my books from school
The question is: Disregarding the DC-current, what is the filter equation for this 75 Hz band-stop filter?
The second question: The 2x7 windings turn the same way, but with opposing currents, thus when carrying even currents, opposing fluxes will cancel each other under ideal conditions. If however the impedance bond is loaded unevenly, the iron core will saturate at some point from the DC current. What will happen to the filter characteristics?
Does anyone know a resource that discusses this particular filter. I am too old to have kept all my books from school
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