Hi
We have an office with a spur, single-phase 240v 30A that feeds several
computers etc.
Rather than buy an individual Belkin or similar surge protector trailing
socket for each item of equipment, I'd ideally like to put a single surge
protector / voltage regulator in line to protect the lot. But, I'm confused
about what is the best option to go for on the UK market. Various products
can be found by Googling, but I'm concerned that they may not provide the
right protection.
Any help would be much appreciated.
Cheers
Brian Abbott
If your really worried about protecting them then your going to need 2 areas
of protection. One at the panel and one at the unit itself. That is what
the IEEE recommends for protection. I realize that you have slightly
different standards but not that much different.
OR
Bite the bullet and put in a big UPS that has voltage regulation and surge
protection.
Remember if you have Ethernet going out from where these machines are and
going to a machine fed from another panel/source, you can get a difference
in ground voltages. If you have this condition please consult a
professional. It will be worth the money and time.
Sorry I do not know of a simple/cheap solution
Plug-in UPS does not even claim to protect from the type of
transient that damages computers. Any protection provided by
that UPS is already inside a computer power supply.
Furthermore, the plug-in UPS connects computer directly to AC
mains when not in battery backup mode.
Do not assume a surge protector is going to stop, block,
filter, or absorb a surge. Simply the urban myth used to
promote ineffective protection such as the plug-in UPS.
Concepts that will become obvious in newsgroup discussions
cited below.
Computer already includes sufficient protection - without
any UPS or power strip protector. But that internal
protection assumes a destructive surge is earthed before
entering a building. It's called 'whole house' protector.
Every incoming wire must connect to earth ground - either by
hardwire connection or via a 'whole house' protector - at the
service entrance. Effective protector costs about £1 per
protected appliance. Some examples:
formatting link
Same is also required for other incoming utilities such as
phone line:
formatting link
formatting link
Fundamentals are explained in the newsgroup
alt.certification.a-plus entitled "Opinions on Surge
Protectors?" on 7 Jul 2003 or at
formatting link
Critical to effective protection is single point earth
ground located when those utilities enter building. Further
technical information provided in discussions at:
formatting link
,
formatting link
, and
formatting link
Bottom line - no earth ground (such as that recommend
plug-in UPS) means no effective protection - which is why that
UPS (and those who recommend it) does not discuss earthing and
avoids mentioning the different types of transients. A surge
protector is only as effective as its earth ground - which is
why those above discussions should be read starting with
"Opinions on Surge Protectors?".
Brian Abbott wrote:
What I believe you are talking about is a spark gap device I believe.
But let me clue people to one thing.
We hear about using a common ground.
But that is really wrong when designing electronic equipment.
First each circuit, particularly input and output circuits should have their
own wire to the common ground.
Second in swithching power supplies and other devices that switch. the
return wire should be to the switching device and then that loop should be
returned to the common ground point with out carrying any other ground
currents, so switching current generated voltages are not impressed on other
circuitry.
This is often a source of ripple and oscillations.
I went through this when I had to teach a class at Kennedy space center on
how to make measurements between points above ground.
In fact I suggested the use of Battery operated scopes as differntial scopes
often did not have enough common mode rejection.
Thanks for that w_toml. Very interesting.
Around where we are lightning strikes are pretty rare, but we can count on a
blackout 1 or 2 x per year. I've always unlpugged anything like a PC in
these circumstances to avoid the surge when power is reconnected. How much
of a concern is the reconnection surge? Does the same rule about effective
earthing apply?
Power restoration is a surge of current; not a voltage
surge. With so many things taking full power simultaneously,
load is just too large to create excessive voltage.
Furthermore, appliances must withstand in excess of 600 volts
transients. Computer power supplies typically withstand on
the order of 1000 volts differential and 2000 volts common
mode transients; without damage. If suffering voltages that
large when power is restored, then every GFCI, electronic
timer switch, clock radio, etc also requires replacement.
Have not observed it, but another possible source of serious
common mode transients is said to occur when a utility main
breaker trips. Therefore it would not be power restoration
that was the problem; but a common mode transient during power
loss.
Brian Abbott wrote:
PolyTech Forum website is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.