posted by Austin on .
Large geomagnetic storms can cause surges of electric current here on Earth. What is the MOST LIKELY result of a large surge in electric current?
F. power outages
G.better TV reception
H. cheaper electric power
I. Local Group galaxy
What is the answer???
I believe its F, but don't take it from me, I'm only 12.
Power outages due to damaged transformers. The question is then how can even a modestly large induced current cause such a damage? The answer is that the energy that does the damage really comes from the powerplant.
Due tothe geomagnetic storm you'll get an induced current in powerlines which is almost a direct current because it oscillates on very long time scales. This will cause the cores of the transformers to get a permanent magnetization. What then happens is that the power transmission from the powerplant via the transformer becomes far less efficient.
Normally, when the oscillating current in the primary coil of the transformer coil is maximal the core has a magnetization in one direction and when the current is in the other direction, the magnetization is is exactly in the other direction. But the response of the core is not perfectly linear. If you add a current in the secondary coil, you shift the magnetization by some amount but not ina uniform way; you shift the zero point upward by some amount, but the peak magnetization is shifted upward by less due to saturation effects.
This then means that the power that is transmitted via transformer becomes significantly less, which in turn means that a lot of energy from the power plant will be dissipated in the transformer core via Joule heating.
Since we are dealing with powerplants that produces many hundreds of megawats of power, only a tiny fraction of this power dissipated in the transformer core is enough to melt it.