# New NCEES POWER PROBLEM 537



## jcreit (Mar 30, 2009)

Can someone please explain this to me:

1. A transmissioin line open at the end is equivalent to an increase in the radius of the conductor (rc).

2. I know from the formula for C, that increase in denominator (rc) will increase capacitance c. Then Xc will decrease;from

Xc= 1/(2 x 3.14 x f x c). With lesser Xc we get more current. However, the solution explains it otherwire. What am I missing?


----------



## niurou (Mar 30, 2009)

jcreit said:


> Can someone please explain this to me:
> 1. A transmissioin line open at the end is equivalent to an increase in the radius of the conductor (rc).
> 
> 2. I know from the formula for C, that increase in denominator (rc) will increase capacitance c. Then Xc will decrease;from
> ...



Yes, I think you are right, the increase in rc will increase the C, and increase the current. the solution is wrong.

but the answer is correct, because current is not proportional to rc, they are not linear. say if the rc increase by 50%, current will not increase the same amount.


----------



## KEG (Mar 31, 2009)

There is a correction on the ncees website for this explanation.

http://ncees.org/exams/study_materials/power_errata.pdf


----------



## niurou (Mar 31, 2009)

thanks man!!



KEG said:


> There is a correction on the ncees website for this explanation.
> http://ncees.org/exams/study_materials/power_errata.pdf


arty-smiley-048:


----------

