Cherryland Electric
Cooperative brings you basic information on surge protection and how you can protect your
home or office from damaging power surges.
Why do We Have Power
Surges?
TRANSIENT VOLTAGE SURGES
Our power needs are fairly basic, lighting, heating, and power for
electric motors, that's why the founders of modern day electric utility companies and the
power distribution system decided to utilize alternating current instead of direct
current. They set the stage for a series of electrical and electronic phenomena called
TVS, Transient Voltage Surges. Our lighting requirements were satisfied through the use of
incandescent bulbs, and later fluorescent tubes. Electrical heating was supplied by the
use of resistive heat radiant devices, and motors were controlled by resistive devices.
Earlier generations of entertainment equipment ranging from crystal
radio sets, with vacuum tubes to transistor radios and television sets were more tolerant
of voltage fluctuations than today's equipment. Technology never stands still, every day
something new comes along that is better, smaller, and more energy efficient.
Technology, In the field of electronics, raced ahead of all other
fields. Beginning with the transistor we have developed, compacted, integrated, and
miniaturized to the point where a single integrated circuit chip can store a megabyte
(1,000,000 bytes) or more of information. For example, a few years ago
computer chips had only 2,000 transistors in about 3/8" square. Today's Pentium type
chips have over 10,000,000! Spaces between components are so compressed that damaging
arcing will occur above 5 to 10 volts. Damage can also result from lightning even miles
away. Even more sensitive chips are on the drawing boards.
The computer industry was one of the first to recognize the need for
"computer grade" power. Computer manufacturers have used the general disclaimer
"customer must supply appropriate power" for a long time. They recognized that
certain power fluctuations could affect the operation of their products. Unprotected
power can scramble your data, prematurely wear components, or destroy expensive chips.
Some symptoms are: unknown data errors, I/O retries, irregular performance, lost files,
high maintenance rates, intermittent system operations, mysterious bugs and unexplained
hardware problems.
Transient voltage and surge current (split-second electrical
disturbances), come and go sporadically; resulting in catastrophic failure of electronic
equipment, degradation of electronic components and software errors. These problems have
been documented by various studies and through the direct experience of users of *solid
state devices. By directing harmful power disturbances safely through a bypass path of
least resistance to ground, Transient Voltage Surge Suppressors (TVSS) have proven to
provide protection from these daily assaults.
The studies and standards defining transient voltage surges have
been available for many years. Yet today, many people view the existence of transients and
their harmful effect with skepticism. This is due to a lack of complete understanding of
the available information on the cause and effect of transient voltage surges and methods
to fully protect against them.
In reality, as much as 80% of today's electrical problems can be
traced to the activities of such harmless devices as elevators, air conditioners, vending
machines, copiers, and large computers. In fact, even something as simple as turning
lights on and off will cause surges of power and transient voltages.
*Solid State Device is any product or appliance that uses
microprocessor.
The utility distribution system interconnects many different types
of power loads that are difficult to control. In an effort to control the various
loads, the utility relies on load switching. Feeder and capacitor switching combined with
momentary short circuits and contact re-closures have become a hazard for *solid state
devices.
A frequent power disturbance seen in building wiring systems today
is transient voltage associated with inductive loads. These disturbances are a result of
turning inductive electrical equipment on and off in the vicinity of a sensitive device.
Such inductive electrical loads could be in the same facility as the affected device or in
another facility close by. The transient voltages generated by these switching operations,
from air conditioners to a electric motor, depends on the current supply and current draw
of the load. Example: an air conditioner generates a surge voltage as it changes state
(turning on/off). So does a 200 h.p. motor; however, the motor generates greater transient
voltage due to larger inductance. The resultant transient voltage surge can migrate
through the electrical system to solid state devices causing damage.
ELN is defined as electromagnetic energy present in a circuit, other
than the desired signal and it's harmonic components. Electrical Line Noise can cause
malfunctions in the solid state devices.
Lightning has the capability to generate extremely large surge
currents and surge voltage. At the point of discharge of a lightning stroke, 600 million
volts and 300-500 thousand amps can be generated. A direct lightning strike is not
necessary to cause system damage. Through magnetic induction a lightning discharge two
miles from exposed overhead electrical lines can produce a 20 KV surge resulting in
potential catastrophic failure of electronic equipment.
*Solid State Device is any product or appliance that uses
microchips.
400 vs 330 Volt Clamping. Most cheap devices will not offer
specifications better than UL's 400 volt clamp rating. This means spikes will rise to 400
volt levels before they are contained. If this is from the bottom of the sine wave, the
un contained spike may actually rise to nearly 570 volts! Your equipment will be damaged
every time the photocopier fires off a copy; or transients jolt from air conditioners,
elevators or large switching motors, etc.
Sine Wave Tracking. Cheap devices do not have sine wave
tracking. Its is a high- tech capability that clamps spikes tightly against the sine wave.
This prevents spikes from rising too high. High rising spikes are killers.
Response Time. Cheap devices have a 5 nanosecond
response time, sometimes even slower. Too slow to be effective. Response time less than 1
nanosecond ( a billionth of a second) is much more acceptable.
Safety Diagnostics. Devices with two LED diagnostic lights
warn you of four critical safety features: (1) the power is on; (2) the protection is
present (It's working even if the power is turned off); (3) the wiring configuration
inside the receptacle is correct (with the conducting hot wire on the correct side,
otherwise you could get a severe shock by touching two appliances at the same time); (4)
sufficient ground path to which damaging spikes can be directed (cheap devices may never
tell you until a fatal moment. No ground path, no protection.)
Warranties. Most hardware store devices have NO
warranty or only one year warranty. If they have an equipment damage coverage, are you
going to get any satisfaction from Korea, Taiwan or somewhere in China? A quality device
provides you a lifetime warranty with coverage of any damage from $2,500 to $25,000!
Let-Through Voltage. This is rarely mentioned in cheap
devices but is very important. For example, a quality protector under conditions of 6,000
volts 200 amps only allows 10 volts through. Lesser devices don't even come close to
offering this level of protection.
Joule Rating. This is a measure of how much damaging energy
suppressors can handle. The higher the better. Many don't mention this, or they range from
50 to 200 joule level. These low ratings mean that their devices are not made to handle
serious power disturbances like lightning. (But, they look nice!)
Peak Amps. A similar energy absorbing rating is called
"peak surge current," measured in amps, the force behind the voltage (more
accurate than joule ratings).
Telephone Line Protection. If you are attached by a modem to
the outside world, on the internet for example, you need this feature. Telephone lines are
antenna systems that direct powerful surges right into the heart of your computer, and to
anyone attached to yours, even if the lightning activity is miles away.
Noise Attenuation. Electro-Magnetic Interference (EMI) and
Radio Frequency Interference (RFI) are disruptions on the smooth AC power line sine wave.
This noise on the power line can be caused by lightning, generators, radio transmitters or
even household appliances. This noise shows up as glitches or errors on computer systems,
or "snow" on a TV.
Thermal Fuses. Few cheap devices have "thermal
fuses" in them. They omit them because it increases the cost. (This is a quality
feature.) These fuses are safety devices that are activated in the event that there is an
extended over voltage (which can happen). They will automatically take the device off the
power line, eliminating the possibility of a burned protector or damaged equipment.
A A surge
occurs when the power line voltage goes higher than nominal, and stays there longer than
10 milliseconds.
Q What causes
power surges?
A
Thunderstorms and lightning are the most dramatic and destructive causes of power line
problems. Only 35% of the problem is generated outside the home or office by events
such as lightning, utility grid switching, line slapping, miswriting, etc. 65% of all
electrical surges or transient voltage activity is generated within the home or business.
They are generally caused by motors and other electrical appliances turning on and off However, as much as 80% of power problems can be tied to local
environment. Surges are caused by elevators, air conditioners, vending machines, copiers,
large computers,even lights turning on and off will cause rushes of power and transient
voltages back up the line.
Q Can these
surges cause damage?
A Yes.
Today's computerized appliances and electronics can be damaged or destroyed by
over-voltage surges or spikes. This includes computer equipment and peripherals;
electronic equipment such as stereos, TVs, and VCR's; household appliances including
washers, dryers, refrigerators, dishwashers, microwave ovens, food processors, blenders,
can openers; and other electronic devices such as fax machines, telephones, and answering
machines. Large appliances like air conditioners or refrigerators are
less susceptible, but can be damaged as well.
Q Can a surge
harm my equipment if I am not using it?
A Yes.
Many electrical devices have electronic timers, clocks, or remote controls (TV, VCR) which
remain in operation even when it is not in use. Also, some appliances cycle off and on at
random like air conditioners, water heaters, pumps, or refrigerators and they could be on
during a surge.
Q Why do I
need surge protection?
A
There are several reasons why power quality has become such an important issue:
Today's computer chips are far more dense than they were even a few years ago, and
subsequently, much more sensitive to even slight surges.
Clock speeds, or operating frequencies, have increased and reached the frequency range
of high-voltage transients. Slower processors ignored them, but high-speed processors may
actually interpret a transient as a command sequence.
Most homes and offices are using more pieces of equipment that draw electricity than
ever before. Each time an electric device is turned on, transient voltages may be
generated.
More microprocessor technology is being used than ever before. Microprocessors are
showing up in TVs, stereos, VCR's, refrigerators, washers, dryers, dishwashers, etc.
Q Won't my
circuit breakers protect my equipment?
A
No. Circuit breakers are only designed to protect against over current, not a voltage
spike or drop.
Q What is a
Surge Suppressor?
A
A surge suppressor is a piece of equipment designed to protect sensitive equipment from
voltages that are above nominal on the power line. They provide an alternative pathway for
excessive voltage.
Q Why do I
need one?
A
The problems caused by disturbances in the power line may not surface immediately. They
can cause the gradual breakdown of electronic circuitry. They are often unexplainable
problems that show up on the repair bill as "No Trouble Found". Many times such
problems are no more than surge induced damage. Any piece of electronic equipment that
behaves in a erratic fashion may need a surge protector. However, new piece of equipment
should be protected when installed.
Q Do these
suppressors handle all voltage problems?
A
Maybe, though they do handle the most frequent and destructive ones. More sophisticated
technologies, i.e. hybrid power conditioners and uninterruptible power systems, are
available to handle complex power problems.
Q What is the
purpose of the phone jacks on surge suppressors?
A
Some of the surge suppressors incorporate protection circuitry for telephone equipment.
There are two sockets on these products. By plugging a phone line through the sockets, you
can minimize the effects of a surge coming into your equipment through the phone line.
Facsimile machines, cordless phones and answering machines are especially sensitive, and
computers with internal modems can be completely destroyed by spikes on the phone line.
Q What is the
difference between a surge suppressor and a surge arrester?
A
Suppressors are usually devices that plug into the wall outlet and can handle surges up to
6,000 volts. Arresters are usually devices that are installed at the service entrance
(meter or electrical panel) and can handle surges up to 20,000 volts. Arresters divert
excess energy to the ground, reducing voltage surges to a level that can be handled by
your electrical system and surge suppressors located downstream from the electrical panel.
Q Is the UL label an indication of a quality product?
A No! Many manufacturers misrepresent their products. Some
claim a UL listing for their products if they use a single UL listed component such a the
power cord. Other products have never been tested as anything more than a Temporary
Power Tap, UL's term for an extension cord. Many claim that they meet standards or
that it has passed UL standards, when in fact, they have never been tested by UL.
Q How
much should I spend on surge protection?
A
Ten percent of the purchase price of a solid state system is a good value to use for
insurance against power disturbances.
