EMP surge protection

Re: Making a PV system survivable in EMP/CME conditions?

We have a few threads here about CME and EMP:

Solar Flares/Sun spots
EMP
EMP
HAM with some EMP

From my post in the Ham Radio thread:

This guy wrote something that I pretty much agree with (with my limited education):

To answer the specific question of the OP, it depends upon the application. Military electronic hardware, save for acceptable commercial-off-the-shelf (COTS) components, area built to specific interface standards like MIL-STD-464 (Electromagnetic Effects Requirements for Systems), MIL-STD-461 (Requirements for the Control of Electromagnetic Interference Characteristics of Subsystems and Equipment), and MIL-STD-2169 (Classified) (High Altitude Electromagnetic Pulse Environment). The latter is probably most pertinent to the question, and for obvious reasons unavailable to the public at large. However, the ugly truth about high altitude EMP is that no amount of shielding, save being buried deep under hundreds of feet of rock or dirt, is really adequate to protect sensitive microelectronics. By their nature, the electronics are delicate and sensitive to small levels of excess voltage, and it is nearly impossible to make a practicable sensor, communication system, or avionics control that has to interface with the outside world and yet is adequately isolated against large pulses.

High altitude EMP (HEMP) devices produce three distinct regimes of pulse, referred to as E1, E2, and E3. Microelectronics are most sensitive to E1, which is due to interaction of x-ray and gamma ray radiation with the rarified upper atmosphere and the geomagnetic field resulting an a nearly coherent, widely distributed pulse, sort of like a very large free electron maser. In more dense atmosphere where the the rays are rapidly absorbed and don't have much length to deflect, this pulse is serious attenuated, and the amount of damage done but the physical effects of the blast (shock and thermal wave) would likely make E1 effects moot. E2 is more like static electricity, and can typically be shielded by using a protected ground or faraday cage type shielding. E3 is energy that is stored in the Earth's magnetic field (similar to that which comes from coronal discharges and solar flares) and will cause longer term disruption and very high voltage spikes in large arrays like power grids; again, not much of a threat to microelectronics.

So, from my point of view, the solar flares produced relatively low frequency changes in magnetic fields... Probably would take structures on the size of miles or 10's of miles to capture the energy (1/4 wave length or larger?).

Here is a wiki entry for geomagnetic storms:

Electric grid When magnetic fields move about in the vicinity of a conductor such as a wire, a geomagnetically induced current is produced in the conductor. This happens on a grand scale during geomagnetic storms (the same mechanism also influences telephone and telegraph lines, see above) on all long transmission lines. Power companies which operate long transmission lines (many kilometers in length) are thus subject to damage by this effect. Notably, this chiefly includes operators in China, North America, and Australia; the European grid consists mainly of shorter transmission cables, which are less vulnerable to damage.

The (nearly direct) currents induced in these lines from geomagnetic storms are harmful to electrical transmission equipment, especially generators and transformers— induces core saturation, constraining their performance (as well as tripping various safety devices), and causes coils and cores to heat up. This heat can disable or destroy them, even inducing a chain reaction that can blow transformers throughout a system. This is precisely what happened on March 13, 1989: in Québec, as well as across parts of the northeastern U.S., the electrical supply was cut off to over 6 million people for 9 hours due to a huge geomagnetic storm. Some areas of Sweden were similarly affected.
According to a study by Metatech corporation, a storm with a strength comparative to that of 1921, 130 million people would be left without power and 350 transformers would be broken, with a cost totaling 2 trillion dollars.

By receiving geomagnetic storm alerts and warnings (e.g. by the Space Weather prediction Center; via Space Weather satellites as SOHO or ACE), power companies can (and often do) minimize damage to power transmission equipment, by momentarily disconnecting transformers or by inducing temporary blackouts. Preventative measures also exist, including digging transmission cables into the soil, placing lightning rods on transmission wires, reducing the operating voltages of transformers, and using cables that are shorter than 10 km.

I do not believe that an off-grid solar array, backup generators, inverter, etc., would be susceptible to a solar flare event.

For grid tied systems--there may be a risk of damage from surges on power company transmission lines entering the home electrical system (guess on my part).

An easier way to search our forum... Use Google and the "site:http://forum.solar-electric.com/" tag to limit searches to our forum (or type in the web address of other sites you are interested in). For example:

• EMP site:http://forum.solar-electric.com/ (updated to new forum address)
  

Short search terms here work much better with Google than the forum search tool.

-Bill

I am more worried about the stability of our governments/world populations than EMP/CME... If an EMP/CME does take down a regional grid--Local Electricity will not be our only concern.

-Bill