IRSE Exam Forum

My attempts for the fault tree questions on points and track circuits are very poor, they would struggle to achieve a pass!

Has anyone made an attempt or know where we can get example fault trees (rather than the analysis/method - which is in the yellow book and elsewhere on this forum).

Thanks,

Priyank

(29-09-2009, 01:06 PM)priyman Wrote: [ -> ]My attempts for the fault tree questions on points and track circuits are very poor, they would struggle to achieve a pass!

Has anyone made an attempt or know where we can get example fault trees (rather than the analysis/method - which is in the yellow book and elsewhere on this forum).

Thanks,

Priyank

I looked for stuff on fault tree analysis before I did mod five a couple of years ago. Unfortunately, the market seems to have been cornered by academics and software people who will only share their pearls of wisdom in return for money. I have not seen a serious attempt at one in my dealings with exam people so far.

If there is an FTA expert out there, please feel free to put us out of our misery!

(29-09-2009, 01:06 PM)priyman Wrote: [ -> ]My attempts for the fault tree questions on points and track circuits are very poor, they would struggle to achieve a pass!

Has anyone made an attempt or know where we can get example fault trees (rather than the analysis/method - which is in the yellow book and elsewhere on this forum).

Thanks,

Priyank

Have you
a) looked at Nigel Handley's article in IRSE News earlier this year; see http://www.irseexam.co.uk/showthread.php...fault+tree
b) typed "Fault Tree" in the Search field of this website; you'll find that one of the GM Rail module 5 questions at http://www.irseexam.co.uk/showthread.php...fault+tree gave an example for a signal head "lamp out"

If you want more detail that is freely available to download, try
http://www.nrc.gov/reading-rm/doc-collec...sr0492.pdf

yes, i did try those avenues!

the fault tree for 'signal lamp out' is attached. But again, i wanted the points and TC's.

(30-09-2009, 01:07 AM)priyman Wrote: [ -> ]yes, i did try those avenues!

the fault tree for 'signal lamp out' is attached. But again, i wanted the points and TC's.

I think you are missing the point a bit......
It is not a question of learning "the" fault tree for a particular bit of equipment; rather to undertand how to construct a fault tree from:
a) your knowledge of the format and how to depict
b) your knowledge of defects / faults / failures in general
c) your knowledge of the particular item of equipment
d) your understanding of the specific scenario described

You should be able to APPLY THE TECHNIQUES to produce an original answer for a particular question that you hadn't encountered before.

There is no value in being able to reproduce what someone else has already done (a photocopier does so far faster / cheaper / more accurately!). There is value in a person being able to build something bespoke from scratch to model a specific situation using "building blocks" gleaned from their previous experience and assembled in a novel way for that specifi purpose. The IRSE Exam is very much focussed on goving candidates the opportunity to do the latter.

If only we could have a photocopier in the exam, with a model answer, to use. ahh. lets wake up!

But It's more to the point that I don't know all the ways a T.C. can fail. No worries, I think its too late to learn!

good luck all!

(01-10-2009, 07:22 PM)priyman Wrote: [ -> ]If only we could have a photocopier in the exam, with a model answer, to use. ahh. lets wake up!

But It's more to the point that I don't know all the ways a T.C. can fail. No worries, I think its too late to learn!

good luck all!

Not too late to learn, but yes you have left it late for the exam this year!

Just think it through and you should get quite a long list; to start you off some ideas for a simple 867/939 dc track circuit:
a) loss of 650V power to location
b) open circuit feed fuse
c) burnt out bridge rectifier after lightening strike
d) loose link
e) wire pulled out of crimp
f) tail cable eaten by rodents
g) intermediate jumper cut by P-Way activities
h) faulty insulation under pandrol clip- low resistance
j) Insulated Rail Joint gone short circuit
k) relay coil burnt out
l) relay mechanically jammed
m) high resistance relay contact
n) track flooded- low ballast resistance
p) broken rail
q) missing galvanised bonds
r) ballast battery effect
s) difference in longitudinal volt drop in each rail due to traction return currents flowing

Think about which cause right side failures, which wrongside failures, which cause failures in isolation, which in combination with other factors ......

Draw upon all your relevant knowledge, such as that obtained from doing the module 5 track circuit calculation type questions