2391 Past Exam Paper

[Spazz]

so where does this cable factor come into it?

 

[Spazz]

I was thinking because we have the cable factor do I:

0.83 x 1.2 = 0.996
1.07 Max = Acceptable

 

[trev]

I'll have to go and dig my 2391 notes out

 

[Spazz]

Here is the whole question - might make more sense

 

[trev]

Ok I'll put my hands up here, I'm drawing a complete blank on this cable factor. It can't be a derating factor as they are considered at the design stage and an up rating factor makes no sense

 

[Spazz]

Bloody C&G they like to make problems for us dont they!

 

[spark 68]

They are divisors, ie. divide by 1.2:95:

 

[trev]

They are fond of their red herrings yes

 

[Spazz]

still lost!

 

[IQ Electrical]

View attachment 12666

Here is the whole question - might make more sense

Check Guidance Note 3 2012 Appendix B1 and all will be revealed

 

[trev]

So what is to be divided by the 1.2 Spark68?
I'm having a major brain fart here

 

[Spazz]

I only have the older version of GN3 - not the new 2012 version

 

[spark 68]

I was too slow, Lol

I was looking in GN3 to show Nicholas, as I wanted to give him the text book answer for the 2391, but IQ has posted it,

edit: and Nicholas

 

[trev]

So it's a slightly amended way of showing the ambient temperature adjustment

Zs measured = < 1/1.2 X Zs max tabulated

 

[trev]

I was beginning to think I had forgotten something vital there but as 1/1.2 = 0.83 recurring I think I'll stick with the old 0.8 rule of thumb