What electronic comonents damaged in an EM Pulse

[kenimpzoom]

I was debating on another forum about EM Pulse (yes, I just watched War of the World ).

Anyway, does anyone know exactly what electrical components will be damaged by an EMP?

I know silicon chips would be dead, but what about capactors, diodes, resistors, etc.

Also, if a cars computer is shielded in a Faraday cage, would the unsheilded wires leading to the computer act as some type of antenna and still fry the computer?

Thanks, Ken

 

[ranger]

b) Passive elements. The passive elements most susceptible to
damage from HEMP-induced currents are those with very low voltage or power
ratings and precision components for which a small change is significant.
Resistor failures due to high-level pulsed currents are caused by energy-
induced thermal overstress and voltage breakdown. Resistor failure threshold
can be calculated from the resistor's parameters and the empirical relation
given in reference 2-9. Exposure of capacitors to transient currents sets up
a voltage across the capacitor that increases with time. For nonelectrolytic
capacitors, this voltage keeps rising until the capacitor's dielectric
breakdown level is reached. That point is typically 10 times the d.c. voltage
rating. For electrolytic capacitors, the voltage relationship holds until the
zener level of the dielectric is reached. After that, damage can occur. The
damage threshold for electrolytic capacitors in the positive direction is 3 to
10 times their d.c. voltage rating. For the negative direction it is one-half
their positive failure voltage (ref 2-10). Transformer and coil damage due to
HEMP-induced currents results from electric breakdown of the insulation. The
pulse-breakdown voltage is typically 5500 volts for power supply transformers
and 2750 volts for small signal transformers (ref 2-11).

http://jya.com/emp02.htm

It seems that most damage will be due to induced currents.

 

[kenimpzoom]

Sounds like everything would be toast.

I was debating on weather or not an old car with a "points" style ignition system would still work. The condensor would probably be fried, but I think it would still run without a condensor (just not very good).

If the car had a newer style voltage regulator, the diodes would fry, but the old style regulators would probably still work.

Thanks, Ken

 

[Cliff_J]

The wires inside the coil would likely be shot as well, so spark ignition might not be a good choice.

Near satellite observatories where they have clean zones for RFI/EMI they drive old mechanical injection diesel cars inside the zone to prevent adding any extra electrical interference. From that, the converse would seem logical that it would be simple to bypass any electrical fuel cutoff and replace with a mechanical valve to get an old diesel car running after an EMP event.

Strangely you'd likely no way to fill it up unless you find a farm with an overhead gravity feed diesel tank, look at even FL last year after the last hurricane cut power for 4-5 days and people thought it was the 18th century! And you'd have no headlights, and no radio - wait, why even bother driving...