Re: brown-out

From: Walter Roberson (roberson_at_ibd.nrc-cnrc.gc.ca)
Date: 11/20/05


Date: Sun, 20 Nov 2005 18:01:03 +0000 (UTC)

In article <4380416F.5F1EC764@hotmail.com>, w_tom <w_tom1@hotmail.com> wrote:
: The quote is backwards. Should read, "I've never seen any
:device fried by a brownout, but I have had a few devices fried
:by a surge." Brownouts: lights (voltage) dim so low as to
:appear brownish. Surges: excessive voltages that damage
:electronics.

As the author of what was quoted, I assure you that the original
was correct: *I* have never seen equipment fried by a surge, but
I have seen several pieces of equipment fried by brownouts.

: A UPS is not for hardware protection. A UPS protects data
:from extreme brownouts and blackouts.

I can't agree. Data does not exist in isolation. Data is just
information, and information is not affected by brownouts or
blackouts or any other physical phenomena (except *maybe*
black holes, and there are big arguments about that.)

What is being protected is not the data, but rather the carrier
of the data -- the hardware.

:The UPS does not even
:claim to protect from a typically destructive transient.

The last UPS I bought certainly claimed to.

: For hardware protection, a destructive transient must be
:connected to earth before entering the building.

Oh? Does the grounding equipment lose its effectiveness if I put
a tarp over it? A roof over it? If I drape some curtains over the
side to hide it? How does the electricity know whether the cable
is in a shed or in a manhole or free and clear and exposed to the
birdies?

Obviously, -at most- the issue is connecting to earth before the
transient reaches the equipment to be protected. And they've been doing
some interesting transient eliminations with MOSFETs for 40 years.

:That means
:an earthing connection for every incoming utility wire -
:telephone, cable, and AC electric. This connection, when
:using a protector, is called a 'whole house' protector.
:Effective protectors have serious manufacturer names such as
:Square D, Leviton, and Siemens. The Intermatic version is
:sold in Home Depot. GE and Cutler Hammer sold in Lowes. No
:accident that APC, Tripplite, and Belkin are not mentioned.

Did APC stop making their Symmetra series since their last website
update?

: Others may mention that a power strip surge protector should
:never be plugged into the UPS output. Why? Voltage and
:spikes can be so large from a computer grade UPS as to damage
:a power strip protector or the UPS. Notice those spikes are
:not destructive to computers. Computers are so robust as to
:already contain protection.

I would rather think that would depend upon the computer.
And there is other connected equipment such as network data switches.

:Protection that can be
:overwhelmed if a destructive type of transient is not earthed
:before entering the building. Internal protection that makes
:a spikey UPS (in battery backup mode) safe for that computer.
:You don't require fancy voltage regulation and noise
:suppression inside expensive UPSes. A computer power supply
:makes all that irrelevant. The cheapest UPSes (computer grade)
:will provide data protection.

You are presuming a lot about what kind of equipment is being
connected, and you are presuming that "the cheapest UPSes" are
being used. I wouldn't buy "the cheapest UPSes".. except perhaps
for the somewhat uncommon situation of a fickle but otherwise
clean power supply to equipment that was inexpensive, non-critical,
and easy to replace, but was a nuisance to have go down.

:For hardware protection, start
:with THE most essential component of a surge protection
:'system' - single point earth ground - for all incoming
:utilities.

I know a couple of people who have had some unprotected home
equipment damaged by nearby lightning. I certainly don't deny that
it happens sometimes. In some parts of the midwest USA it might
be a common problem. But where I am, which is -not- especially
prone to big thunderstorms, in our high-tech lab with several hundred
computers and other interesting and delicate equipment, in a dozen years
I have not heard of even -one- piece of our equipment fried by
an electrical surge. We -have- had equipment damaged by brownouts,
including PCs and data switches.

A few years ago, a brownout did serious damage to our expensive
clustered email system with big power supplies and power distribution
rack and everything; they ended up having to effectively scrap the
system because they could not fix it in a cost effective timeframe.
I am quite sure that it was a brownout, because I happened to be in
the building working the night it happened; and the underlying
electrical failure event made the news and was -specifically- described
by Hydro as including an extended brownout.

-- 
   Okay, buzzwords only. Two syllables, tops.  -- Laurie Anderson