An electromagnetic pulse, or EMP, is a form of fast-moving electromagnetic energy. It is capable of damaging and destroying electronic components as well as equipment, and it can also result in voltage challenges and transformer damage. EMP has triggered many concerns among everyone from policy experts and technical journals to preparedness websites and the media.
What are some of these major concerns?
One of the biggest concerns is that the high burst of energy resulting from the rapid acceleration of charged particles, such as solar heat or a nuclear bomb, could damage the electric grid, as well as key telecommunication and emergency infrastructures. Moreover, the devastating damages could have severe impediments to recovery.
An EMP is a short burst of electromagnetic energy. The origin of an EMP may be a natural occurrence or a man-made one. Depending on the source, the pulse can occur as an electric, radiated or magnetic field, or as a conducted electric current.
Not All EMPs Are Equal!
Firstly, it’s important to understand that not all EMPs are the same. The most significant EMP effects are caused by E1 and E3 fields. These two types of principal EMPs are generated by nuclear burst detonations at altitudes above 24.86 miles, and they do threaten to debilitate critical infrastructure systems over large regions of the earth.
A “fast-pulse” EMP field, also referred to as E1, is created by gamma-ray interaction with stratospheric air molecules. The resulting electric field peaks at tens of kilovolts per meter in a few nanoseconds, and lasts a few hundred nanoseconds. Induced currents ranging into the thousands of amperes, on exposed systems makes them become upset or permanently damaged.
The “slow-pulse” phenomenon, or E3, is caused by the distortion of earth’s magnetic field lines due to the expanding nuclear fireball and the rising of heated, ionized layers of the ionosphere. The change of the magnetic field at the earth’s surface induces a field in the tens of volts per kilometer, which, in turn, induces low-frequency currents of hundreds to thousands of amperes in long conducting lines only (a few kilometers or longer) that damage components of long-line systems, including the electric power grid and critical communication and data networks.
The Risks and Consequences of Misconception
While an EMP is highly unlikely, the electric industry must clearly understand the seriousness of EMP effects and secure cost-effective mitigation measures that don’t result in drastic consequences and impacts.
Without understanding and emphasizing realistic consequences of transient electromagnetic disturbances or EMP, policymakers run the risk of delaying action or dismissing important arguments altogether. That said, there are 6 key and harmful misconceptions about EMPs that must be ironed out: type of EMPs; exposed electronic systems; critical infrastructure systems; nuclear weapons; the cost of protection; and fiber-optic networks. So, let’s get into them.
Top 6 EMP Misconceptions
1. EMP Will Cause Every Exposed Electronic System to Cease Functioning
Not every electronic system will be affected equally by an EMP event. Small, self-contained systems, such as motor vehicles, hand-held radios, and unconnected portable generators, tend not to be affected by EMP events and often experience temporary disturbance rather than component burnout. However, systems connected to power lines are highly vulnerable to component damage and require repair or replacement. The more EMP energy that is coupled into the system, the higher the probability of damage. As a result, the electric power-grid network and landline communication systems, are almost certain to experience permanent component damage when exposed to an EMP event and include cascading effects on most dependent infrastructure systems.
2. EMP Effects Will Have Limited, Easily Recoverable, “Nuisance” Effects on Critical Infrastructure Systems
Because affected and unaffected systems are interdependent upon one another, widespread failure of a significant electrical and electronic systems will create a large-scale cascading failure event to critical infrastructure networks. For example, a single component failure, where the average links are set as two per node, will affect approximately half of the remaining “untouched” network nodes. For many systems, especially unmanned systems, loss of control is tantamount to permanent damage, and in some cases causes machinery to self-destruct.
3. Nuclear Weapons Are Required to Cause Serious EMP Effects
The effects can depend on various factors. During a limiting atmospheric saturation effect in the EMP-generation process, low-yield weapons can produce a peak E1 field similar in magnitude to high-yield weapons if they are detonated at altitudes of 31.1 ~ 49.7miles above the Earth. When nuclear weapons with yields ranging from 3 kilotons to 3 megatons, are detonated at their optimum burst altitudes, they exhibit a range of peak E1 fields. In the case of an E3 EMP field, a 30KT nuclear weapon above 62.14 miles above the Earth, would cause geomagnetic disturbances as large as solar superstorms.
4. Protecting the Critical National Infrastructure Would Be Cost Prohibitive
Out of the14 critical infrastructure sectors at EMP risk, the highest is for electric power grids and telecommunication grids, which are essential for sustaining population “life-support” services. However, some major grid components could take months, or years, to replace if many components are damaged. Protection of critical large transformers will reduce the time required to restore the grid plus restore the necessary services it enables. While protection costs for heavy-duty grid components are in the $10 billion range, the cost is a small fraction of the value of losses should they fail during or after an event. Giving attention to the Electromagnetic event hardening of these infrastructure grids alone will provide significant benefits to national resilience.
5. Only E3 Will Damage Electric Power-Grid Transformers
Oak Ridge National Laboratory’s January 2010 report on its E1 tests of 7.2KV distribution transformers, produced permanent damage to the transformer windings in seven out of the 20 of the units tested. The failures were due to transformer winding damage caused by electrical breakdown across internal wire insulation. As an important side note, transformers with direct-mounted lightning surge arrestors were not damaged during the testing.
6. Fiber-Optic Networks Are Not Susceptible to EMP (FALSE)
In general, fiber-optic networks are less susceptible than metallic line networks. However, fiber-optic multipoint line driver and receiver boxes, which are supposed to be designed to protect against ground currents, will fail in EMP environments. In addition, telecommunication and regional Internet fiber-optic repeater amplifiers’ power supplies are particularly vulnerable to EMP environments, as are undersea cable repeater amplifiers. Undersea cable repeater amplifiers are connected to a coaxial metallic power conductor that runs the length of the line. Because of its low-frequency content, E3 penetrates to great ocean depths, which subjects undersea power amplifiers to high risk of burnout.
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