2394/2395 Question

[Mike Blair]

Question is :

- The insulation resistance of two circuits is of 40M? an 36? respectively. When tested together what is the total insulation resistance:

answer is 19 ohms but how? can some one explain

 

[Leesparkykent]

Question is :

- The insulation resistance of two circuits is of 40M? an 36? respectively. When tested together what is the total insulation resistance:

answer is 19 ohms but how? can some one explain

In parallel use 1/Rt = 1/R1 + 1/R2 or you could use Rt = (R1 x R2)/ (R1 + R2)

 

[Leesparkykent]

I should point out that Rt = (R1 x R2)/ (R1 + R2) can obviously only be used with two resistances in parallel which you have in your question. With three or more resistances in parallel then use the method below.

 

[Mike Blair]

i got you looking back through my college work n found it confused my self with series revising for my 2394/5 stressful! haha i remember in college you could use (R1 x R2)/ (R1 + R2) for only 2 the other method for more

 

[Leesparkykent]

i got you looking back through my college work n found it confused my self with series revising for my 2394/5 stressful! haha i remember in college you could use (R1 x R2)/ (R1 + R2) for only 2 the other method for more

Thats it. In series they are just added together.

 

[Leesparkykent]

i got you looking back through my college work n found it confused my self with series revising for my 2394/5 stressful! haha i remember in college you could use (R1 x R2)/ (R1 + R2) for only 2 the other method for more

Get your head stuck in to guidance note 3, read old chief examiners reports for previous runs and the exam success book is worth getting. Remember that terminology is key.

 

[telectrix]

and just as an aside. for capacitors in parallel, just add the values. in series, use the reciprocal formula. opposite to resistors.

 

[Mike Blair]

i got it now guys remembering things from college XD thanks guys!!

 

[Mike Blair]

written exam in 2 weeks scary!! after the 3 day course i remember almost everything so im not worried about the science or math the terminology is making me crap

 

[Leesparkykent]

written exam in 2 weeks scary!! after the 3 day course i remember almost everything so im not worried about the science or math the terminology is making me crap

Mike, if you PM me your address I can send you a copy of the 2394/2395 exam success book if you want it?