On Monday, October 26, 2015 at 6:22:28 PM UTC-4, wrote:
On Mon, 26 Oct 2015 13:31:06 -0700 (PDT), westom
wrote:

On Monday, October 26, 2015 at 12:55:46 PM UTC-4, wrote:
When the power comes back on, particularly in those storm situations
where the power never really goes "out" but the lights blink - THAT is
when you get real "surges" - not to confused with the high amperage
high voltage "spikes" created by lightning. They can damage sensitive
electronics over time.

Surge is a subjective term used to describe low voltages, low currents, high voltages, radio frequency noise, and low voltages. The 'surge' discussed here is a current from a current source that will increase voltage on anything that might try to stop it. That is not the 'surge' you have described.

But that IS the surge most surge protectors protect against, quite
effectively. They are not DESIGNED to protect against lightning
strikes. They are designed to clean up the transients in the power .


Lost in the wilderness again. Do you even read any of the links?
Two guides to surge protection were provided here many times, from
the IEEE and NIST. Both talk extensively about using surge protectors
to protect against AC and communications line power surges from lightning.
In fact, they spend most of both guides talking about surges caused
by lightning. The main lightning discharge doesn't hit the PC or
even the house. It can hit utility wires a block down the street
and a nasty surge can still arrive at your PC. It's the most common
type of damaging surge encountered in homes.



That type surge is already made irrelevant by what is inside appliances. For example, computers has a safety lockout. This lockout must be cleared by disconnecting its power cord from the wall. No protector claims to or will even discuss this 'surge' that is irrelevant to the topic.

Pardon??? Computers have a safety lockout???

I think he's talking about disconnecting the power cord during
a lightning storm. You would also have to disconnect any cable,
phone etc too and of course the whole thing is impractical.



If a computer power
supply gets hit by enough transient spikes, the power supply WILL
fail, and it will fail without ever being "locked out". Particularly
with the industry standard and very common "ATX" power supply.

Yes, they have transient absorbers on them - designed to keep the
noise generated by the power supply itself from exiting into the AC
power system.

Wrong. They have surge protection, typically MOVs, just like all
other electronic appliances, to give some protection against AC
power line surges. Same thing on communication cards, eg modems,
the incoming comm lines are protected too.


It is also SOMEWHAT effective at keeping noise out of
the computer

Surge protection typically doesn't do much, if anything for noise.
It's there for surge protection.


- but not nearly as effective as an external surge
protector. What is in the power supply is called an "emi filter", not
surge protection.


You're confusing two different things, noise filtering and surge
protection.


As far as "appliances" most have NO transient or spike or surge
protection built in.


Every electronic one I've ever seen has it, eg TV, stereo, electronic
ovens, etc. An old toaster or stand mixer, they wouldn't because they
don't need it.




If inductive loads are creating surges on AC mains, then AC power switching off 120 times a second is also creating surges.
No, there is a resonance in a 60 hz power supply that tends to keep
the sine wave steady and clean. When a temorary short in the power
grid, say, from wires clashing together in a storm, which causes the
lights to flash, but does not blow fuses in the grid, there is aften
a very real and measurable surge or spike when the short opens and the
power comes back on. The dt/dv or instantaneous rate of change in the
voltage doesn't follow a nice clean sine wave in these conditions and
with inductance and capacitance in the circuit the voltage can lead or
lag the current

What happens when you turn on a switch? You have a similar effect,
power suddenly being applied. I can see power restoration possibly
causing a problem, but it sure doesn't seem to be the typical case.
When power goes out, 5,000 homes could be affected. In cases like
Sandy, it was millions. I heard of a lot of flood damage, wind damage,
but IDK of a single failure due to surges when power was restored.




You can say what you like - you sound suspiciously like an engineer. I
on the other hand live and work "in the real world" as a technician.

He doesn't sound like any engineer I've known. But interesting that
you eschew higher learning and think that engineers don't live in
the real world.