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cases, the protective circuits designed to protect devices and power-distribution systems from
lightning damage may well be adequate, but in those cases where the rapid E1 effects have
damaged the device's lightning-protection elements, the E2 effects falling immediately on the
heels of the E1 effects will cause the destruction of those devices.
The late-time EMP effects are categorized as E3 effects, and may last for a minute or more.
E3 pulses are quite similar to the geomagnetic-induced currents from solar storms. E3 effects
are known to induce huge currents and voltages on long runs of electrical wires and conductors.
Geomagnetic storms, such as the one that fried the major HydroQuebec grid transformer, are
known to cause major damage to electrical-system components at much lower levels than
might reasonably be experienced during an E3 EMP event.
Based upon E3-type effects observed during previous geomagnetic storms, in combination
with EMP simulation testing on electrical components and systems, and data gathered from
Soviet and American aboveground nuclear testing prior to the partial test ban treaty in 1962,
the following are some anticipated effects from a nuclear-device-generated EMP:
• Extended grid collapse due to failed major-grid power transformers as well as critical
SCADA and PLC systems. Owing to cascading effects, the grid failure is likely to
extend far beyond the region directly affected by the EMP. For example, on August
10, 1996, during a triple-digit heat wave, sagging power lines in Oregon shorted
against insufficiently trimmed tree limbs, causing a cascading blackout that cut
power to 7 western states, parts of Baja, Mexico, and parts of two Canadian
provinces. The grid had been operating near peak capacity because of massive loads
from air-conditioning units operating during the heat wave, and the shorted lines
threw it over the edge into short-term collapse, affecting millions of customers.
• Cellular telephone systems are particularly susceptible to EMP and will likely fail
immediately owing to direct E1 and E3 effects.
• Landline telecommunication systems that were not damaged by the initial E1 and E3
effects, will likely fail within four to seventy-two hours as battery backup supplies
run down, and generator backup power for central telephone substations run out of
fuel reserves. In many locations, landlines with corded handsets that do not need
110-VAC connections will still work from between a few hours to three days, after
which all local telephone services, including 911 emergency services, will cease to
operate within the affected area, which is exactly what happened across a wide area
devastated by Hurricane Katrina.
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