2004 Track Circuit Calculations

[Peter]

Hi,

I have attempted 2004 Track Circuit calculations question.

The last bit of the question relates to the advantages of additional Relay end resistance.

Feed End resistance is used to operate the track in various ballast conditions but am not sure why the additional relay resistance is used for.

Please help and provide your valuable feedback/suggestion.

Thanks in advance.

Regards,
JJ

I am not quite sure if there are some bits that you have carried over into these pages that you have calcualted elsewhere because I cannot see where you have got some of the numbers from. For instance, at the bottom of the first page, you say "rail to rail voltage = relay voltage + tail voltage" and go on to say "0.7 + 0 = 0.7". Where does the 0.7 come from. At pick up, relay voltage would be 0.04*9 = 0.36v and at DA, it would be 65% of this.

I don't have the question to hand to see if there is anything else given to help on this bit so if you can let me know, I'll be able to look into it a bit more for you.

Peter