Question

a battery system is being installed with conductors having an ampacity of 100 a. the correction factors for conditions of use are 0.8 and the derating factors are 0.9. what should be the rating of the overcurrent protection device in amperes?

Explanation:

Step1: Calculate the adjusted ampacity

The formula for adjusted ampacity is \(I = I_{original}\times correction\ factor\times derating\ factor\).
Given \(I_{original} = 100\ A\), \(correction\ factor = 0.8\), \(derating\ factor=0.9\).
So \(I = 100\times0.8\times0.9\).
First, calculate \(100\times0.8=\$80\).
Then, calculate \(80\times0.9 = 72\).

Step2: Determine the over - current protection device rating

The over - current protection device rating should be equal to or greater than the adjusted ampacity.
Since the adjusted ampacity is \(72\ A\), and standard device ratings are considered (in practice, we look for the next standard size if the calculated value is not a standard one. But if we assume no standard - size consideration for a basic calculation), the rating of the overcurrent protection device is based on the adjusted ampacity.

Answer:

\(72\ A\)