MHD-EMP protection guidelines
A nuclear detonation at altitudes several hundred kilometers above the earth will severely distort the earth`s magnetic field and result in a strong magnetohyrodynamic electromagnetic pulse (MHD-EMP). The geomagnetic disturbance interacts with the soil to induce current and horizontal electric gradients. The geomagnetic disturbance interacts with the soil to induced current and horizontal electric gradients in the earth. MHD-EMP, also called E3 since it is the third component of the high-altitude EMP (HEMP), lasts over 100 s after the exoatmospheric burst. MHD-EMP is similar to solar geomagnetic storms in it`s global and low frequency (less than 1 Hz) nature except that E3 can be much more intense with a far shorter duration. When the MHD-EMP gradients are integrated over great distances by power lines, communication cables, or other long conductors, the induced voltages are significant. (The horizontal gradients in the soil are too small to induce major responses by local interactions with facilities.) The long pulse waveform for MHD-EMP-induced currents on long lines has a peak current of 200 A and a time-to-half-peak of 100 s. If this current flows through transformer windings, it can saturate the magnetic circuit and cause 60 Hz harmonic production. To mitigate the effects of MHD-EMP on a facility, long conductors must be isolated from the building and the commercial power harmonics and voltage swings must be addressed. The transfer switch would be expected to respond to the voltage fluctuations as long as the harmonics have not interfered with the switch control circuitry. The major sources of MHD-EMP induced currents are the commercial power lines and neutral; neutral current indirect coupling to the facility power or ground system via the metal fence, powered gate, parking lights, etc; metal water pipes; phone lines; and other long conductors that enter or come near the facility. The major source of harmonics is the commercial power system.
- Research Organization:
- Oak Ridge National Lab., TN (United States)
- Sponsoring Organization:
- Department of Defense, Washington, DC (United States)
- DOE Contract Number:
- AC05-84OR21400
- OSTI ID:
- 10127646
- Report Number(s):
- CONF-920223-4; ON: DE92008898
- Resource Relation:
- Conference: 1992 hardened electronics and radiation technology (HEART) conference,Albuquerque, NM (United States),24-28 Feb 1992; Other Information: PBD: [1992]
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
45 MILITARY TECHNOLOGY, WEAPONRY, AND NATIONAL DEFENSE
ELECTROMAGNETIC PULSES
POWER SYSTEMS
BLAST EFFECTS
HYDROMAGNETIC WAVES
NUCLEAR EXPLOSIONS
VULNERABILITY
HARMONICS
ELECTRIC CONDUCTORS
POWER TRANSMISSION LINES
EQUIPMENT PROTECTION DEVICES
RECOMMENDATIONS
240100
450200
NUCLEAR EXPLOSIONS AND EXPLOSIVES