4. Power Systems and Grids
Distribution — Quiz
Test your understanding of distribution with 5 practice questions.
Practice Questions
Question 1
What is the recommended time grading margin between downstream and upstream overcurrent relays for proper coordination in distribution systems?
Question 2
A distribution transformer has a nominal voltage of 10 kV and an on-load tap changer providing ±10 % adjustment in 16 equal steps. If the receiving end voltage is measured at 9.5 kV and the target is 10 kV, how many tap steps upward are required?
Question 3
Which protection scheme uses directional overcurrent elements to handle reverse power flows caused by distributed energy resources?
Question 4
Which device, also known as an arc suppression coil, is used in ungrounded distribution systems to limit ground-fault currents?
Question 5
A single-phase distribution feeder is 10 km long with per-unit-length impedance $Z'=0.08 + j0.04\,\Omega/\mathrm{km}$ and carries 120 A at 0.8 lagging power factor. What is the magnitude of the voltage drop $|\Delta V|$ and its percentage on an 11 kV system?