Re: Brown out protection.

Brownouts do not cause electronics damage. That was an industry
standard even long before the IBM PC. Low voltage must not harm
electronics. Many even forget what happens when powering off
electronics. Electronics suffer a brownout - then eventually a
blackout - and without damage. Many will say otherwise based only
upon assumptions, observations, or popular urban myth. For example,
they saw the brownout but failed to see a reason for that brownout -
such as a preceding overvoltage. Many of your replies are based on
speculations. They assume; therefore it is a fact?

A UPS is to maintain power during blackouts and extreme brownouts.
Electronics must remain operational for a short time as that UPS
disconnects from AC mains and connects to the battery. Why is that
switchover time significant? Because the destructive surge could
repeat 100 times before that switchover occurs - the switchover takes
that long and surges are that short. A UPS connects electronics
directly to AC mains when not in battery backup mode. A UPS cannot
disconnect from a surge fast enough. The typical UPS does not even
claim to protect from typically destructive surges. It simply switches
to battery when AC voltage gets too low.

Usual way of protecting that Cisco is the same and simple solution
found in the telephone CO (central office). Any destructive surge is
earthed before it can enter the building. Do same with one properly
earthed 'whole house' protector. Such devices are not sold under
brand names of lesser companies such as Belkin, Tripplite, or APC.
Effective protectors are sold under responsible brand names such as
Siemens, Intermatic, Leviton, Square D, Cutler-Hammer, and GE.

Review spec numbers for that UPS. Chances are its joules are even
inferior to a paltry circuit found in power strips. That is near zero
protection. Those who recommend a UPS for surge protection often do
not even know how the UPS works and did not even first consult spec
sheets. They know only from half truths promoted on color glossy
sales brochures.

All electronics contain internal protection. Computers tend to have
protection numbers well in excess of other appliances. A surge that
might harm some appliances may also be irrelevant due to protection
inside a computer.

Protection inside any electronics can be overwhelmed. So we install
one 'whole house' protector to earth the rare and so destructive
surge. If properly earthed, that rare surge will not overwhelm
protection inside maybe 100 household appliances.

How many electronics fortunately were not damaged this time? Did
you lose furnace controls, dishwasher, smoke detectors, bathroom
GFCIs, or dimmer switches? Some of those electronics devices are more
critical to your safety. All have internal protection. Internal
protection that may be overwhelmed should the rare and destructive
surge not be properly earthed. We earth any incoming surge so that
even internal protection in every appliance (includeing that Cisco
power brick) is not damaged.

Brownouts only harm electronics where someone saw a brownout,
assumed no surge preceded it, and proclaimed their assumption as
fact. This 'cherry picked' reasoning also proved Saddam had WMDs.
Even 35 years ago, industry standards required electronics not be
damaged by brownouts. Chances are the brownout was preceded by a
surge. A surge sufficient to damage only some items and not
sufficient to overwhelm protection in others.

Phil Allison makes an important point. Such failures are unusual
and only a post mortem can provide further definitive facts.
Potentially destructive surges average maybe once every seven years -
and can vary significantly even without same town.

All electronics must either work just fine even when lights are
dimmed to 40% intensity, or shutdown without damage if that voltage
drops farther. It is an industry standard so old ... and yet how many
posted in denial of well known industry standards? Any power supply
damaged by a brownout was defective when designed. Brownouts do not
damage electronics.

On Oct 3, 2:29 pm, Control Freq <n...@xxxxxxxxxxxxxxxxxxxxxxxx> wrote:
Hi,
Recently, I experienced a Cisco firewall device break during an
electricity power failure. The power went off, came back up briefly,
then suffered a brown out then went off again.

Inspection of the device showed that the power supply transformer
device had broke, not the firewall iteself. We got a new firewall
device (and transformer) to get our systems up and running again.

Anyway, I was wondering how a brown out could have caused this
problem. The device is connected to a surge supressed mains outlet!

So, what is the usual way of protecting sensitive equipment to this
sort of failure?

All of our computers are connected to UPS, and they don't (yet) suffer
from problems with power failures, but all of our network hubs/
switches are not on UPS, only surge supressors.

Can someone fill in the blanks in my knowledge.

Thanks in advance.


On Oct 3, 2:29 pm, Control Freq <n...@xxxxxxxxxxxxxxxxxxxxxxxx> wrote:
Hi,
Recently, I experienced a Cisco firewall device break during an
electricity power failure. The power went off, came back up briefly,
then suffered a brown out then went off again.

Inspection of the device showed that the power supply transformer
device had broke, not the firewall iteself. We got a new firewall
device (and transformer) to get our systems up and running again.

Anyway, I was wondering how a brown out could have caused this
problem. The device is connected to a surge supressed mains outlet!

So, what is the usual way of protecting sensitive equipment to this
sort of failure?

All of our computers are connected to UPS, and they don't (yet) suffer
from problems with power failures, but all of our network hubs/
switches are not on UPS, only surge supressors.

Can someone fill in the blanks in my knowledge.

Thanks in advance.


.

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