17th edition ( equations and formulas)

[martinh89]

I'm not sure if this topic has been covered before but I cant seem to find anything. What equations are likely to appear on the 17th edition test ? so far im ok with zs , adiabatic equaution including finding the fault current , cable calc and volt drop. My question is are there any others that ive missed ? Plus any hints and tips people would like to share would be very much appreciated Thanks .

 

[chrish_1977]

Isn't it an open book test? All you have to do is know how to use the glossary and the index

 

[Johnuk]

yea open book

 

[neon]

I'm not sure if this topic has been covered before but I cant seem to find anything. What equations are likely to appear on the 17th edition test ? so far im ok with zs , adiabatic equaution including finding the fault current , cable calc and volt drop. My question is are there any others that ive missed ? Plus any hints and tips people would like to share would be very much appreciated Thanks .

There are no equations to do so wont need a calculator either.
Just run through a few practise papers and you will be fine. The answers are all in front of you in the book!

 

[martinh89]

Y es it is an open book test but id like to understand fully how to use the equations before I get asked about them

 

[martinh89]

Our tutor at the test centre has told us there will be the odd working out ie volt drop ect

 

[telectrix]

it's a good idea to flag any question that may take a bit longer and leave till last.

 

[Pete999]

I've just finished mine, past OK there were three equations in my exam, Volt drop, adiabatic and Ze, Zs etc. One piece of advice learn how to transpose the volt drop equation, yes it' an open book, try not to rely on the index concentrate on the contents page at the front of the book. Good luck
Pete999

 

[snowhead]

Our tutor at the test centre has told us there will be the odd working out ie volt drop ect

In my 17th earlier this year, there was a question that needed you to identify the correct formula (found in the regs) for a given problem, then a couple of questions later use that formula to prove which of the 4 answers was correct.

If you start messing around thinking about doing calculations you won't get thro the 60 questions.

Tips;

Don't leave any question unanswered, Put an answer to every question, at worst it's a 1 in 4 guess, prior knowledge and judgement should reduce those odds.

Use your own watch, don't trust the onscreen time reminder.

If you can't find or don't know the correct answer within 1 minute, guess, flag it and move on and go back to the flagged ones at the end.

In a 1 in 4 assessment your first guess is more likey to be right, if you change it only do so if you are absolutely certain of the correct answer.
You're more likely to change it for a wrong one.

 

[martinh89]

Cheers guys for the feed back, pete999 what do you mean by transpose the volt drop equation? To be honest ive found the contents pages much more helpful than the index

 

[telectrix]

transpose means to find a value from the other side of the equation. e.g. V=IR, transpose to find R--- R=V/I.

 

[telectrix]

so like with VD eqauation, the formula is VD = mV/A/m x L x A, trranspose to find L for a given VD.

 

[martinh89]

so like with VD eqauation, the formula is VD = mV/A/m x L x A, trranspose to find L for a given VD.

Ahh i see, thanks if its certain thinga including ohms law i should be fine, im sorry if this sounds like a daft question but how would i just find the length in a vd calculation? All the examples ive done, the lenght has always been included in the information

 

[Pete999]

answered by telectrix exactly, dont worry about move on only 2 mins per question. The question was you were given 4 values of vd, if you can't transpose, you wont be the only one, try this trick use the formula
VD=LENGTH X AMPS X mv DROP do it 4 times until the answer matches the right one in the answers given in the question.
Pete999

- - - Updated - - -

Sorry my last and divide by 1000
Pete999

 

[Richard Burns]

These are the only equations likely to come up even tangentially and complex calculations would not be required.
View attachment Equations for Installations.pdf

 

[Guitarist]

Make sure you read the questions carefully. I misread a few and ended up with only 92.something percent. Was gutted at the time.
Very simple really as long as you've digested your 7671. Oh, and a few marker tabs at table pages helps too.

 

[snowhead]

Make sure you read the questions carefully. I misread a few and ended up with only 92.something percent. Was gutted at the time.

It's ones like which IS the correct or which is NOT the correct, except they don't print is and not in bold

 

[telectrix]

Ahh i see, thanks if its certain thinga including ohms law i should be fine, im sorry if this sounds like a daft question but how would i just find the length in a vd calculation? All the examples ive done, the lenght has always been included in the information

easy. transpose. 1000 x VD = mV x A x L, so L = (VD x 1000)/( mV x A )

 

[Geordie Spark]

Make sure you read the questions carefully. I misread a few and ended up with only 92.something percent. Was gutted at the time.
Very simple really as long as you've digested your 7671. Oh, and a few marker tabs at table pages helps too.

A few marker tabs??


I used those coloured Post It notes - so many in fact, my book looked like a grass skirt.

 

[martinh89]

Cheers for all the advice its very much appreciated, ive been studying all afternoon and adding post it notes throughout the book, ive got my test on Thursday so ill let you know how i do