Brownouts, shorts, explosions and the unix pc.

[Mark C. Otto]

In article <1991Jan7.124138.19055 at ims.alaska.edu> floyd at ims.alaska.edu (Floyd Davidson) writes:
>
[ ... lots of good stuff deleted ... ]
>If you do want to do something along these lines, wrap a couple
>turns through a high Q toriodal core.  ...

Yes!  I have seen coils used effectively with MOV's (per Gil's mention
earlier) to provide reasonable amounts of protection at low cost.
If you want to see how things can go awry, read Jerry Pournelle's
"Chaos Manor" column in Byte Magazine ... uh ... oops! I forgot the
issue ... uh, suffice it to say a lightning strike took out a high
voltage line and put it squarely in contact with the 220V feed to
his neighborhood.  He details the types of protection he had and what
types of stuff survived and what didn't.  In general MOV/coil circuits
handle lightning strikes if they are several miles away or on the other
side of a step-down transformer.  More serious stuff - like what 
happened to Mr. Pournelle - can only be dealt with properly via an
UPS, preferably with an isolation transformer and a good over-voltage
trip circuit.  I feel good power protection is like buying insurance
for your computer - you can go without it, but the downside risk
can have devastating potential.



-- 
Mark C. Otto   EMail: mco at slimer, {teemc | hpftc}!slimer!mco
Voice: 1-313-441-4264    USnail: 5133 Heather #208, Dearborn, MI. 48126
Quote: "Yeah. Right. Kermit my a*s." - Mark C. Otto, '90