If the base apparent power Sbase is doubled while the voltage base remains the same and Zactual unchanged, how does Zpu change?

Prepare for the LADWP Electric Station Operator Test focusing on Circuit Breakers, Disconnects, and Transformers. Study with tailored questions and detailed explanations to enhance your knowledge and boost confidence. Ace your exam!

Multiple Choice

If the base apparent power Sbase is doubled while the voltage base remains the same and Zactual unchanged, how does Zpu change?

Explanation:
The main idea is how per-unit impedance changes when the base power changes while the voltage base stays the same. In per-unit terms, Zpu = Zactual / Zbase, and Zbase = Vbase^2 / Sbase. With the voltage base fixed and the actual impedance unchanged, doubling the base apparent power makes Zbase drop by half (since Zbase is inversely proportional to Sbase). If Zbase halves and Zactual stays the same, then Zpu doubles. So the per-unit impedance increases by a factor of two.

The main idea is how per-unit impedance changes when the base power changes while the voltage base stays the same. In per-unit terms, Zpu = Zactual / Zbase, and Zbase = Vbase^2 / Sbase. With the voltage base fixed and the actual impedance unchanged, doubling the base apparent power makes Zbase drop by half (since Zbase is inversely proportional to Sbase). If Zbase halves and Zactual stays the same, then Zpu doubles. So the per-unit impedance increases by a factor of two.

Subscribe

Get the latest from Examzify

You can unsubscribe at any time. Read our privacy policy