Andrew Lawless| Feb 01, 2013

Geomagnetic Disturbances and their Impacts on Power Transformers

Siemens GIC Final-011513 Cover

On January 15, I presented a webcast on Energy Central titled “Geomagnetic Disturbances and their Impacts on Power Transformers”. You can view the presentation here.

This webcast presented a simple overview of the phenomena that has received so much recent attention. After attending meetings and conferences with a diverse range of attendees, including engineering professionals, utility managers, insurance professionals, government officials, politicians, NGO’s, and policy makers, I wanted to offer a layman’s overview to talk through some basic details about GMD and the impacts on power transformers, especially given the many misconceived notions of impending doom from GMD which has been seized upon by popular media outlets.

I hope this blog can dispel any unfounded misconceptions about natural occurring GMD and help channel the many recommendations and ideas into practical solutions.  

I received more than 100 questions during and after the webcast, and although it will take a while to answer them all, I hope to do that here and engage with you in dialog that will be informative and engaging.

Take a look at the webcast, and post your questions and comments here.

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D. Chaply| 1330 days ago

Great and timely webcast. Two clarifications requested:
1 - is the current at ground level induced in the soil and then selectively jumps onto the transmission line (because it is a lower resistance path) or is it induced in the long transmission line and then finds a return path in the soil (somehere)?

2 - what theoratically happens to the current flow over large bodies of water / lake / ocean? And what happens, as the earth turns, as the induced current transitions from predominently water to predominantly land?


Andrew Lawless| 1305 days ago

Thank you for your questions! Below is an answer to each of your questions

Answer 1: GMD causes a current (electro-jet) to be generated in the upper atmosphere which causes disturbances in the Earth’s geomagnetic inducing an electric field at the Earth’s surface. This electric field causes currents to flow in any loop made between the ground and any man made structures, such as transmission lines, pipeline or railways because of their relatively lower resistance. In the case of transmission lines, the current will enter into the transmission lines through transformer neutral connections to ground.

Answer 2: We are not aware of any studies that consider dc potential induced into water as a significant issue. "Ground resistivity" of the water is relatively low, so any induced dc potential would be dispersed deeply and widely throughout large bodies of water. It is not anticipated that such uniformly distributed water charges can noticeably transfer into dc flow in solid ground, since land's earth resistivity is considerably higher.

I hope this helps clarify some of this for you.

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