2000 question- AC track circuit attempt

[DarrenW]

I have attempted the calculations for the a.c. track circuit question from the 2000 Module 5 paper. Would somebody in the know be able to have a look over it for me please? I'm certain that I'm on the right lines, but have done it from memory without digging the old uni folders out.

[Peter]

DarrenW Wrote:I have attempted the calculations for the a.c. track circuit question from the 2000 Module 5 paper. Would somebody in the know be able to have a look over it for me please? I'm certain that I'm on the right lines, but have done it from memory without digging the old uni folders out.

I'm not an ac tracks expert, but your approach is exactly what I would have done. Your electrical analysis is sound and your calculations good and it is presented quite clearly.

There is one point that I think you might like to look at. You have calculated 8.77uF which you note needs to be rounded to 8 or 9. Having selected 8, what does that do to the voltage?

Based on your the first part, see what you make of the next part calculating the value of the train shunt with the capacitor.

Peter

[DarrenW]

Peter Wrote:I'm not an ac tracks expert, but your approach is exactly what I would have done. Your electrical analysis is sound and your calculations good and it is presented quite clearly.

There is one point that I think you might like to look at. You have calculated 8.77uF which you note needs to be rounded to 8 or 9. Having selected 8, what does that do to the voltage?

Based on your the first part, see what you make of the next part calculating the value of the train shunt with the capacitor.

Peter

Thanks for your response Peter.

I see what you are getting at with your second point - an increase in capacitance results in a decrease of the capacitors reactance and thus an increase in rail voltage. So an answer of 9uF would have been more accurate to give the 1V rail voltage calculated (would give approx 1.02V).

I shall have a look at the train shunt next.

Darren

[Peter]

DarrenW Wrote:Thanks for your response Peter.

I see what you are getting at with your second point - an increase in capacitance results in a decrease of the capacitors reactance and thus an increase in rail voltage. So an answer of 9uF would have been more accurate to give the 1V rail voltage calculated (would give approx 1.02V).

I shall have a look at the train shunt next.

Darren

More importantly, you need at least a volt to pick the relay, so don't look for the closest voltage, look for the one that will do what you need.

[jenni.joseph9]

Hi,

Does any one have AC Track Circuit calculations Question which was asked in the year 2000?

I am not sure about the pattern of the question that was being asked.

Please help.

Thanks & Regards

[Peter]

(23-09-2010 08:07 AM)jenni.joseph9 Wrote:  Hi,

Does any one have AC Track Circuit calculations Question which was asked in the year 2000?

I am not sure about the pattern of the question that was being asked.

Please help.

Thanks & Regards