|Why Surge Protection?
Until the introduction of solid state devices, most
AC-powered equipment was too insensitive to be upset by
"dirty" or surging power. However, electrical
power surges and the damage they can cause are
commonplace today. Our home and workplace are comprised
of solid state devices vulnerable to surges. We deal
daily with computers, office machines, data,
telecommunication equipment, major appliances, etc. All
of these depend on solid state devices which are
vulnerable to surge.
state devices depend on consistent,, good-quality power.
A single powerful surge literally melts, welds, pits, and
burns its way through solid state circuits and
Device failure is often the result
of many small surges and the cause is often not detected
by the repairing technician. In addition to the loss of
use, priceless stored data can be lost and meaningful
input or output information is turned into nonsense. The
driving force to shrink device geometries to increase
speed and storage capacity will continue to make solid
state devices even more sensitive to dirty power and
Many people think of surge damage
as being caused by a single, catastrophic event such as a
lightening strike. While lightning is one of the most
powerful and destructive surges, it's not always the
cause of most of the surge damage. In reality, surges
range from mighty to the minuscule.
Smaller surges occur several times
a day, or hundreds of times an hour. Almost continuous
surges can be produced by sources ranging from 250 to
over 1,000 volts. Typically, they are caused by the
operation of electric motors or other inductive loads
such as elevators, office machines. Microwave ovens,
vacuum cleaners, lame dimmers and countertop appliances
are some of the surge sources in the home.
Powerful, random surges result from
the switching of an inductive load such as an electric
motor starter, arc welder, furnace ignition, compressor,
etc. and these momentary surge sources range from 250 to
over 3, 000 volts.
Over or under
voltage power conditions 250 to 6,000 volts usually
accompanies a utility switching lines to meet changes in
demand, or when correcting a brownout or blackout.
While mother nature
provides the most visible and spectacular surges in the
form of lightning, the surge damage you suffer can be
generated by the power company, your own equipment, other
equipment in the building you occupy, or from a source
some distance from your facility. Surges travel on AC
lines, data lines, communication lines, coaxial cable,
metal fences, metal conduit, metal duct work, as well as
through the ground and air. Surges travel via any
conductor they can find.
Surge damage can be
classified into three categories:
» Latent failures
failures cause damage requiring repair or replacement of
electrical components. Glitches usually do not cause
permanent damage, just temporary damage or lost data.
failures result from continuous exposure to smaller,
non-catastrophic surges that erode equipment and its
performance. In the end, the equipment suffers hard
failure and the cause is unseen.
Noise is another
problem in power lines. Conducted noise is the most
destructive type. It is usually present in your AC power
source and you are surrounded by these radiated noises.
Noises can come from
the most simple device, such as an electric razor or
fluorescent lamp. Cars, TV's, cellular phones, electrical
transformers, lamp dimmers, office machines, etc. are
other examples. The list is endless. To solid state
devices, this is an invisible and lightning-fast
A high quality surge
suppression system is your first, best and only defense
against these potential threats to your equipment, data
No one can guarantee
to protect you from direct and catastrophic lightning
strike. Even the best lightning protection systems have
their limits. A properly designed and installed surge
suppression system can provide you the best defense
against all but the catastrophic direct lightning strike.
It is important that a surge suppression system be just
that - a system, not individual units of spot protection.
In designing the system, many
factors should be taken into consideration. Every
facility has some equipment that is critical to the
overall operation of the facility. That equipment will
probably require higher levels of protection than less
critical equipment. How susceptible is the equipment to a
surge? Equipment controlled by solid state devices is
more susceptible to surge damage. Each facility is
different and will require different levels of protection
for perhaps even similar equipment.
The Institute of
Electrical and Electronic Engineers (IEEE) has developed
a schematic showing the levels of surge severity relative
to location device or equipment. If surge sensitive
equipment is located on the same circuit as equipment
that generates surges, it must have protection. The only
way to properly design a system of protection is careful
evaluation of each and every facility.
suppression units offer varying levels of protection. All
have the same basic job, to prevent damaging voltage
spikes from reaching the device it is intended to
protect. More sophisticated suppression units also filter
Only a thorough
survey of your facility and its power supply, an
examination of electrical layout, circuit plans and
inventory of devices (present and future) connected to
all circuits can provide the information to form a
recommended plan of protection.
High quality surge
suppression units, when properly applied in surge
suppression systems, are one of the best investments you
can make. Considering the small cost, it will be hard to
find a higher return on any investment.
Surge Protection Devices
1. Are all building electrical and systems
grounds common and bonded together? Is neutral bonded
properly to ground at the service entrance?
2. Do you have a low resistance grounding system? Has it
ever been checked or measured? Is there any bonding of
the AC neutral and ground at electrical sub panels? Are
all your electrical outlets equipped with life safety
3. Are metallic plumbing and sewer pipes entering your
building(s) bonded to ground? Is the steel reinforcement
and framing of your building(s) bonded to your common
4. Are all metal fences attached to your building bonded
to your grounding system? Are parking lot or exterior
pole lights grounded properly?
5. Is your main electrical service equipped with a panel
protector on the load side of the main breaker? Are your
sub panels equipped with panel protectors? Do you have an
isolated ground electrical panel with panel protectors
for your sensitive loads such as computers?
6. Are terminals and CPU in different buildings? If so,
surge suppressors should be installed at both ends of the
wire that connect them.
7. If all terminals and CPU are in the same building,
make sure there is only one meter (electrical service)
providing power to the building. IF there is more than
one meter, the grounds must be electrically bonded. If
the electrical services are not bonded, a difference in
the ground potential will exist. Problems associated with
this condition will show up as I/O port problems on
8. Are telecommunication lines running between buildings
from your computer network, PBX, key telephone system,
security system, video security system, fire alarm
system, PA system, or environmental control system? Any
metallic lines must be surge protected at both ends of
the wire entering or leaving the building. (Remember they
must share a common ground reference.)
9. Are long runs of low voltage cable surge protected?
Are these lines in conduit, underground or just lying on
the ceiling system? Are they within 12 inches of
fluorescent light fixtures?
10. Are roof top electrical/mechanical systems surge
protected? Do you have a bonded lightning protection
system on your building? Are satellite earth stations,
coaxial cable, and power or control lines surge
Main and sub-panel surge suppressors usually
come in two general types, series protectors and parallel
protectors. Series protectors are load bearing devices
and have no conform to the current the power company
delivers to the main and sub-panel. Parallel protectors
are non-load bearing devices and therefore can be used
regardless of current delivered to the main or sub-panel.
Series protectors are usually very expensive and require
breaking the incoming line to install. Parallel
protectors are usually installed on the load side of the
main breaker and are quite efficient. Underwriters
Laboratories (UL) under 1449, has chosen to rate surge
suppressors in pass-through voltage categories. There is
one serious fault in their testing. Some manufactures of
parallel type surge suppressors utilize plug-in modules,
which allow for the replacement of damaged modules. The
ratings are obtained at the module itself without
consideration for the length of wire required for the
installation. A module rated at 400 volt pass voltage
with an additional two feet of wire added for the
installation actually becomes a 1000 volt pass voltage.
When placed in a 24" x 24" box, two feet of
wire would be minimal for the installation, therefore
ratings of this modular type panel protector can be
Surge suppressors are designed to protect the electrical
and electronic equipment to which they are connected. In
rare cases, when extremely large surges occur, the surge
suppressor will be sacrificed to save the protected
equipment. This is the purpose of a surge suppressor.
Some surge suppressors claim to have a rating of 100,000
amps or more. The ANSI/IEEE 587 and UL ratings have a
maximum test of 10,000 amps. This is more than adequate
for the main service electrical entries.
The measurement of a surge suppressor's performance is
the pass voltage (actual voltage) your equipment sees
after a suppressor does its job. High current ratings do
not mean low pass voltage. PSI surge suppressors have a
lifetime warranty and have been protecting customer
facilities and equipment for 10 years. During this time,
PSI's customers have experienced no equipment losses.
|A. Outlets and Long
- All outlets at more than 10m (30ft) from Category B
with wires #4 - 10
-All outlets at more than 20m (60ft) from Category C with
wires #14 - 10
feeders and short Branch Circuits
- Distribution panel devices
- Bus and feeder systems in industrial plants
- Heavy appliance outlets with short connections to the
- Lightning system in commercial buildings
C. Outside and service entrance
- Service drop from to building entrance
- Run between meter and distribution panel
- Overhead line detached buildings
- Underground lines to well pumps
Transient Voltage Surge
The unit of measure for current flow. One ampere
equals 1 coulomb of electrons passing a point in a
circuit in one second.
American National Standards Institute
A device that can store an electrical charge.
An automatic protective device that will allow current to
flow under normal conditions, but will open the circuit
under abnormal conditions to prevent damage from
A component whose action is triggered by a predetermined
voltage. A clamping device will activate (turn on) and
deactivate (turn off) at specific predetermined voltages.
The flow of electrons through a conductor. Current is
measured in amperes.
The interference in a signal transmission or reception
resulting from the radiation of undesirable electrical or
magnetic and electrical fields.
A surge suppression component that is made up of two or
three electrodes in a sealed envelope that contains a
rarefied gas. A gas tube is a crowbar device.
A voltage reference point which may be connected to earth
The conductor used to connect electrical equipment to
a grounding electrode, i.e., ground rod.
A conductor or a group of conductors (usually a rod,
pipe, or plate) in direct contact with the earth,
providing a connection to the earth.
Institute of Electrical and Electronic Engineers.
A unit of measure, expressed in Ohms, of the total
opposition (resistance, capacitance and inductance)
offered to the flow of alternating current.
The ability of a coil to store energy and oppose changes
in current flowing through it.
A number of turns of wire wrapped around a core used to
provide inductance in a circuit. Also called a coil.
The unit of measure of energy equal to one watt second.
3,600,000 joules equal one kilowatt hour.
Metric prefix meaning thousand or 103. The
abbreviation is k.
A device that receives electrical energy from a source,
draws current and/or provides opposition to current,
requires voltage, or dissipates power. Resistors, light
bulbs and electronic motors are examples or loads.
Metal Oxide Varistor
A solid state surge suppression component that can handle
large amounts of current and reacts in the low nanosecond
Metric prefix meaning one millionth or 10-6.
The abbreviation is the Greek letter mu (a lower case u
can be used).
Metric prefix meaning one thousandth or 10-3.
The abbreviation is m.
National Electrical Manufactures Association.
Metric prefix meaning one billionth or 10-9.
The abbreviation is n.
The unit of measure of resistance equal to the resistance
in a conductor in which one volt of potential produces a
current flow of one ampere.
Term used to describe the hot line or lines in AC power.
Metric prefix meaning one trillionth or 10-12.
The abbreviation is p.
A measure of force produced between charged object that
moves electrons. See Volt.
The rate at which work is performed or heat is generated.
Power is measured in watts. The abbreviation is P.
The ability of a component to dispense power, usually in
the form of heat energy. The rating of a component's
ability to dissipate power.
Applied to an AC sine wave, the RMS value is also known
as the effective voltage and is .707 times the peak
Silicon Avalanche Diode
A solid state surge suppression component that is
extremely fast, but lacks the ability to handle heavy
A short-term voltage increase that exceed the established
upper limits for less than 2.5 seconds.
The process by which transient voltage surges are
prevented from reaching electrical or electronic
An abrupt change in voltage of short duration, which
may cause signal impairments, loss of memory or physical
damage to electrical and electronic equipment.
The unit of measure of potential or electromotive force.
One volt is the force required to cause one amp to flow
through a conductor with a resistance of one ohm. The
abbreviation is V.
Potential energy difference (electrical pressure).
Base unit of apparent power; 120 electrical degrees.
The unit of measure of power equivalent of one joule per
second. A watt is equal to the power in a circuit in
which a current of one amp flows at a potential of one
volt. The abbreviation is W.
The graphic depiction of a progressive disturbance
propagated from point to point.