2004 Track Circuit Calculations

[Peter]

Purpose of adding adding Relay end Resistance:
-Ability to detect on poor rail surface & Reduce significance of interference voltage is it correct?

Those are the two reasons that I know about.

[jenni.joseph9]

Hi,

i found the same 2 reasons while I was referring the NR standard 11755(DC Track circuit) last week.

Am attaching the copy of the solved part with out considering the additional relay Resistance. Drop shunt resistance is 0.3 V more when compared with the earlier calculations(i.e with additional relay end resistance).

Please look in to the calculations and do let me know the mistake if any.

suggestions/corrections are highly appreciated.

Thanks in advance.

Regards,
Jenni.

[Peter]

Hi,

i found the same 2 reasons while I was referring the NR standard 11755(DC Track circuit) last week.

Am attaching the copy of the solved part with out considering the additional relay Resistance. Drop shunt resistance is 0.3 V more when compared with the earlier calculations(i.e with additional relay end resistance).

Please look in to the calculations and do let me know the mistake if any.

suggestions/corrections are highly appreciated.

Thanks in advance.

Regards,
Jenni.

Your steps were correct but you made a slip with the numbers.

When you calculated Vf right near the beginning, you (correctly) attempted to take the rail voltage from the battery voltage to work out the voltage across the feed resistor but instead of using 0.36 (rail voltage) you slipped in 0.126 which was the value of feed current that you had just calculated. This error was then carried on meaning that you got 38.68 vice 36.825 for the feed resistor leading to you value for DS of 5.81 vice 4.98. While this is only a small discrepancy, given the exercise you were trying to do here, it was sadly the wrong way (the value in the original calcs was 5.42), hence you concluded that the provision of the relay end resistor had the opposite effect on DS to what it actually does.

Peter

[dorothy.pipet]

FYI