Question

Calculate the De-rating factor if the string efficiency is 98%.

(a) .04

(b) .02

(c) .05

(d) .03

The question was posed to me in an interview for job.

My question is based upon Solid-State Switching Circuits topic in chapter Introduction to Solid-State Switching Circuits of Electric Drives

Answer 1

The correct option is (b) .02

To elaborate: De-rating factor is used to measure the reliability of a string. The value of the De-rating factor is 1-(string efficiency)=1-.98=.02.