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2014 Q1 Principles & Functional Testing
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02-03-2016, 12:35 PM
Hi,
I am part of a study group and we are currently working through the 2014 exam paper. We would be grateful if you could review, critique and give feedback on our model answer (attached). Regards, Fran 
18-03-2016, 11:44 PM
(02-03-2016, 12:35 PM)FBaker Wrote: Hi, Part a) for 4 marks, you had 6 bullets- 1. Broadly true, but not directly relevant to what you were asked, background only. 2,3 & 4. True and relevant, but better if more immediately juxtaposed with the contrasting description pertinent to Functional testing 5 & 6. Worded more to include all verification testing (so including things like inspection,, wirecount and continuity) rather than just the functional testing (i.e. power up, check that voltages are present / absent in accordance with conditions as dictated from looking at the circuit design or data design) which checks the behaviour implemented is what the design specified. So not bad but it would have been more clearly (and economically in terms of time) presented as a table with a couple of columns for the different categories and a row in which you could have stated the ROLE / PURPOSE and another row in which you could have described the PERFORMANCE of the test. Indeed you could perhaps have extended the table to more rows to tackle part b) of the question. You wrote more than you needed to, yet your presentation didn't show the distinction obviously (although by the end it became evident that you understood the distinction, the difference had to be inferred than very in-your-face). Part b. You did give two sets of three bullets clearly which was great; however it looks very minimalist for 6 marks and therefore I deduce that the examiners must have wanted more detail. The ii) was worse than i), because all you have really done is give a name and to give the example of "functional testing" as "function testing" really does not help! For the 6 marks I think you ought to have written a sentence or two for each bullet to explain rather than just name the activity. e.g. Proving that it is not possible to set the route-under-test whilst there is any opposite train movement still underway which requires the same infrastructure, but that route can set once the opposing movement has got behind the signal concerned (or if only an overlap opposed, been timed to a stand at its exit signal). Whereas I might agree that correspondence testing sometimes contains an element of Principles testing whilst being largely a functional test, by including it in part ii) but with the enigmatic comment that it could be argued to be better in i) you rather weakened your argument initially about the distinction between the two categories. However had you EXPLAINED WHY you said this, instead of detracting it could have enhanced your answer. I think you'd have been better to have chosen the example of Through Testing for this third bullet and then you could potentially have thrown in your example Correspondence of trackside functions to the control centre display as a bonus extra 7th built which was really a combination of end-to-end through test with a little Principles (check of signaller's view against Signalling Plan and site reality) thrown in to the activity- this could have been the "icing on the cake" as an addition to the basic answer requested since it displays more experience in that it is often pragmatic to undertake a combo-activity. For the first bullet in b) ii) I think that I would have talked about the electrical testing of points, such as measuring the normal running current and the clutch slip current and checking the throw time of the switches. Similarly I would have explain that a Strap &Function test ensures that a voltage is only fed to the end function when each of the circuit elements are in the state as required by the circuit design details and this is achieved by operating the relevant function until the contact breaks therefore losing the output, before then bridging that contact with a strap to regain the volts.
PJW
(02-03-2016, 12:35 PM)FBaker Wrote: Hi, Note that it was not until I read as far as the top of the second side that I realised that the context of this answer was London Underground (I had briefly wondered earlier, but decided it must be NR although I admit that on the Forum I do have the advantage that I could have checked your bio which does make it clear). However as nan exam tip: I think a candidate is wise to state their context initially or else there is the risk that the examiner may be labouring under a false assumption when reading.....I didn't go back and amend my earlier comments but I may have made them slightly differently if I knew then what I do now. Part a) for 4 marks, you had 6 bullets- 1. Broadly true, but not directly relevant to what you were asked, background only. 2,3 & 4. True and relevant, but better if more immediately juxtaposed with the contrasting description pertinent to Functional testing 5 & 6. Worded more to include all verification testing (so including things like inspection,, wirecount and continuity) rather than just the functional testing (i.e. power up, check that voltages are present / absent in accordance with conditions as dictated from looking at the circuit design or data design) which checks the behaviour implemented is what the design specified. So not bad but it would have been more clearly (and economically in terms of time) presented as a table with a couple of columns for the different categories and a row in which you could have stated the ROLE / PURPOSE and another row in which you could have described the PERFORMANCE of the test. Indeed you could perhaps have extended the table to more rows to tackle parts b) and c) of the question. I think I would have answered on an A3 blank sheet and put the answer to everything apart from d) in one table drawn on it. You wrote more than you needed to, yet your presentation didn't show the distinction obviously (although by the end it became evident that you understood the distinction, the difference had to be inferred than very in-your-face). Part b. You did give two sets of three bullets clearly which was great; however it looks very minimalist for 6 marks and therefore I deduce that the examiners must have wanted more detail. The ii) was worse than i), because all you have really done is give a name and to give the example of "functional testing" as "function testing" really does not help! For the 6 marks I think you ought to have written a sentence or two for each bullet to explain rather than just name the activity. e.g. Proving that it is not possible to set the route-under-test whilst there is any opposite train movement still underway which requires the same infrastructure, but that route can set once the opposing movement has got behind the signal concerned (or if only an overlap opposed, been timed to a stand at its exit signal). Whereas I might agree that correspondence testing sometimes contains an element of Principles testing whilst being largely a functional test, by including it in part ii) but with the enigmatic comment that it could be argued to be better in i) you rather weakened your argument initially about the distinction between the two categories. However had you EXPLAINED WHY you said this, instead of detracting it could have enhanced your answer. I think you'd have been better to have chosen the example of Through Testing for this third bullet and then you could potentially have thrown in your example Correspondence of trackside functions to the control centre display as a bonus extra 7th built which was really a combination of end-to-end through test with a little Principles (check of signaller's view against Signalling Plan and site reality) thrown in to the activity- this could have been the "icing on the cake" as an addition to the basic answer requested since it displays more experience in that it is often pragmatic to undertake a combo-activity. For the first bullet in b) ii) I think that I would have talked about the electrical testing of points, such as measuring the normal running current and the clutch slip current and checking the throw time of the switches. Similarly I would have explain that a Strap &Function test ensures that a voltage is only fed to the end function when each of the circuit elements are in the state as required by the circuit design details and this is achieved by operating the relevant function until the contact breaks therefore losing the output, before then bridging that contact with a strap to regain the volts. Part c) I think the amount you wrote for these bullets was about right and indeed I think the examiner having given you low marks for part b) would go back to revise the score when they found the missing detail had actually been covered later (e.g. strap and function description). bullets 1-3: Generally good, but you haven't really justified why these are Principles test rather than functional which is my reading of the question. However I must admit that the answer would really be much the same for each of the three activities, so don't really see what they wanted. Your explanations are good, it is clear you know what you are talking about and therefore, despite the fact that you have really answered ""the safety risks that the ACTIVITY mitigates", I am tempted to say I would score this section highly (because I can't think how to answer any better). bullets 4-6: Similar. Clear that what you call Function testing is what I would call Circuit Function; given that the first sentence rally belongs in part b) then bullet 4 is short. However you make up for this in the detail and good explanation given for S&F. Conversely my approach would have been to have focussed 4 on some external equipment in order to make more different from the scenario of bullet 5. Part d) For 6 marks this section was brief. I initially struggled to reconcile your examples with "design process" as certainly you seem to have interpreted as "design approach" but I really don't see what else the question could mean; the PROCESS by which the design is undertaken shouldn't really affect the tester, except inherently (e.g. if it impacted upon the date the design was available, or legible etc.). The examples in themselves were good but another sentence on each was needed; for example you could have added to the last one by emphasising that the rapid changeover facilitated by plate racks enables elements of work to be undertaken in the very limited engineering hours midweek nights that would otherwise just not be possible without a weekend closure and thus can fundamentally change how alteration work could be implemented. In summary this was a good answer and would probably be a Credit; it certainly would have been if you had taken a little more cognisance of the mark allocation. Therefore this is the standard to aim to achieve by yourself in exam conditions in 6 months time.
PJW
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