Discuss tonights 2391 exam....(10th march 2011) in the Electrician Courses : Electrical Quals area at ElectriciansForums.net
I took this to mean electrical installation certificate for new circuit, periodic inspection report for installation testing, am I on the wrong lines cos I did have to read it a few times!
functional testQ. What test would you do on the rcd? (8 marks) I think it said to include time, mA
what size rcd? if 30mA then
did it ask for tester used etc better if you get a copy as the C&G speak needs to be read fully to understand there geeky language lol
A. Residual current device testing
test at 1/2X 15mA at both half cycles no disconnection
then test at 1 x 30mA at both half cycles disconnection in 300ms
then test at 5x 150 mA at both half cycles disconnection in 40ms
Q. What other test would you carry out on the rcd (2 marks)
functional test
press the test button on the the protective device (RCD) to check correct operation of the mechanical parts are working correctly
With the ir test isn't it best to just quote the test as in gn3? I.e. Make reference to removing any voltage sensitive equipment or link out where applicable and not leave out steps based on the fact your just testing the swa?
Q.a) In the shower unit, what visual inspections can you do to the c/u (4 marks)
B) explain answear to "a" (4 marks)
Whats the two things you can ONLY find out from the DNO?
Q26. What 2 types of Inspection & Test for confirm for voltage drop?
Went for PSCC and PEFC, dont know if this was right carnt seem to find it in GN3 to confirm?
Q26. What 2 types of Inspection & Test for confirm for voltage drop?
Went for PSCC and PEFC, dont know if this was right carnt seem to find it in GN3 to confirm?
Got me thinking this one, had a stab at external earth loop impedance Ze and type of earthing supply TNC-S/TT/TN-S
How about measurement and calculation?
You can physically measure the voltage drop or calculate it from cable length/size/load
If it said 'only from the DNO' then it's something you can't measure or visibly confirm so it has to be from the characteristics of the sealed supply fuse eg. BS, type, rated current and short circuit capacity.
I suppose you could get away with supply frequency.
Q.a) In the shower unit, what visual inspections can you do to the c/u (4 marks)
Unless I misinterpreted the question I believe it was a visual without taking the front panel off so I put i) damage, ii) labels, iii) correct size rcd, iv) correct size mcb. These are the things that we do naturaly without thinking, like tying your shoes laces but try and describe in writing how to do it?
There was a question at the start, what 3 tests would be carried out first on a three phase supply to (can't remember what it was but I had never heard of it)?
a kiln is basically an oven, usually used for firing pottery. so asfaik, just heatingA 3-Phase Kiln (Iv'e never heard of it before either) so just played it safe with the Continuity of Protective conductors/Insulation resistance/Ze tests
a kiln is basically an oven, usually used for firing pottery. so asfaik, just heating
I put:
continuity of protective conductors
ir
polarity
Spot on.
Im sure everyone who sat this exam would agree that it was a bit of a nightmare! I think i did quite well bar a few things. q26 : 30ma for additional protection. half test full test both cycles and functional didnt put 5 times. 5 times needed for functional? head was battered by that point!
q2 anyone know the statutory document the dno have to abide by? surely that cant be a 2391 requirement!!
earth electrode resistance question. i answered with an earth loop tester rather that earth electrode. i think both answers would get marks but ive noticed a bit of confusion on this question, no where in the scenario does it mention there is rcd protection. the first mention is in q26. we know there will be but what are we getting marked on, something we know would be there or the scenario they have laid out?? i went through this with my tutor after the exam and he seems to think both answers would pick up marks.
After studying years of past papers i would deffo say this is the hardest exam out of them all!
i was hoping for a 15 mark question on rule of thumb values or insulation resistance!
noticed this is the first exam to have 2 questions that required description and diagrams of 2 test procedures! my hands still in cramp!
im quite confident but i dont this this exam was an easy one to pass!
Im sure everyone who sat this exam would agree that it was a bit of a nightmare! I think i did quite well bar a few things. q26 : 30ma for additional protection. half test full test both cycles and functional didnt put 5 times. 5 times needed for functional? head was battered by that point!
q2 anyone know the statutory document the dno have to abide by? surely that cant be a 2391 requirement!!
earth electrode resistance question. i answered with an earth loop tester rather that earth electrode. i think both answers would get marks but ive noticed a bit of confusion on this question, no where in the scenario does it mention there is rcd protection. the first mention is in q26. we know there will be but what are we getting marked on, something we know would be there or the scenario they have laid out?? i went through this with my tutor after the exam and he seems to think both answers would pick up marks.
After studying years of past papers i would deffo say this is the hardest exam out of them all!
i was hoping for a 15 mark question on rule of thumb values or insulation resistance!
noticed this is the first exam to have 2 questions that required description and diagrams of 2 test procedures! my hands still in cramp!
im quite confident but i dont this this exam was an easy one to pass!
You must perform the 5X I delta n test on a 30mA RCD/RCBO.
The DNO document is ESQCR 2002
Traditionally, the EFLI tester was used on TT earth electrodes and the earth electrode resistance tester on earth electrodes for generators .
thats why i went efli because the only knowledge ive got of the electrode tester is on generators. plus i dont know enough detail of that test procedure to pick up full marks!
i hope everyone labeled the general mass of earth on their diagrams!
hmm Even though Polarity is the next test after IR i've seen Ze being an acceptable answer too on past paper and the Exam success book. so hopefully I still get the 3 marks as you can also confirm Polarity via the EFLI test.
Reply to tonights 2391 exam....(10th march 2011) in the Electrician Courses : Electrical Quals area at ElectriciansForums.net
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