SWP Power Grid & Ground-Based Infrastructure Impacts

Question 1

Geomagnetically induced currents (GICs) in power grids are caused by:

Accepted Answer

Rapid changes in Earth's magnetic field inducing electric fields that drive currents in long conductors

Answer

According to Faraday's law, time-varying geomagnetic fields induce geo-electric fields at Earth's surface that drive quasi-DC GICs through grounded transmission networks.

Question 2

The March 1989 geomagnetic storm famously caused:

Accepted Answer

Collapse of the Hydro-Québec power grid in approximately 92 seconds

Answer

GICs triggered protective relay operations in a cascading sequence that blacked out the entire Hydro-Québec network in under two minutes, leaving 6 million people without power for up to 9 hours.

Question 3

High-voltage power transformers are particularly vulnerable to GICs because:

Accepted Answer

Even small quasi-DC GICs can half-cycle saturate transformer cores, causing overheating and reactive power loss

Answer

GIC as low as a few amperes can saturate the ferromagnetic transformer core during one half-cycle of AC, generating harmonics, excessive VAR consumption, and potentially damaging the equipment.

Question 4

Which geographic characteristic makes a region's power grid most susceptible to GIC damage?

Accepted Answer

High latitude with resistive igneous bedrock and long transmission lines

Answer

High latitudes experience stronger geo-electric fields during storms, and resistive bedrock forces induced currents into metallic conductors; long transmission lines accumulate larger total GIC.

Question 5

The geoelectric field magnitude that drives GICs in surface conductors is most directly controlled by:

Accepted Answer

The rate of change of the horizontal geomagnetic field (dB/dt) and ground conductivity structure

Answer

The surface geoelectric field is proportional to dB/dt convolved with the local Earth conductivity structure; faster magnetic variations over resistive crust produce the largest fields.

SWP - Space Weather Professional Certification Exam Practice Test

SWP - Space Weather Professional Certification Exam Practice Test

SWP Power Grid & Ground-Based Infrastructure Impacts