Surge Info
Surge Info
WHY SURGE PROTECTION
Brown-outs - Over-volts - Lightning - Dirty Power
Electric utilities (your local, lovable Power Company) may occasionally reduce line voltage to Brown-out levels in an effort to adequately manage power generation and distribution during periods of heavy usage. Very hot days, when most air conditioning and refrigeration equipment would be operating almost continuously, is an example of such a situation.
Even without utility intervention, extreme overloads caused by most air conditioning and refrigeration equipment operation could tax the electrical distribution system to the point where a permanent brown-out state could exist over much of the power company distribution network.
Locations at ends of long electric distribution lines may experience chronic Brown-out conditions due to line loss. Intermittent heavy loads on this trunk circuit may cause the Brown-out effect to fluctuate with the load.
Installations using ship-board or temporary power sources are especially prone to operation in a Brown-out mode. Usually of limited capacity, it is quite easy to overload the power source, giving rise to permanent Brown-out. (Permanent Black-out, if users are not careful)
What are some common effects of Brown-outs? Brown-outs are the mother of all sorts of Bad Stuff.
Power supplies in some electronic equipment may fall out of regulation. Errors, due to erratic power supply performance, may creep into computer operations.Other electronic equipment may function poorly - or not function at all.
Marginally performing devices (electronic or electric) will probably cease operation entirely.
Motors will overheat. Some motor types will slow down.
Electrical interference will greatly increase. Increased interference may affect computer and communication operations.
Off-line UPS units (the vast majority of lower cost units) continuously cycle between power line and internal battery operation. UPS batteries (generally sized to provide only 5 - 10 minutes back-up) will soon be discharged, unable to generate additional Back Up power. You are out of business. If system has not been shut-down, the entire system (UPS & computer) may snap back to life when power rises slightly, only to again shut down when the power line voltage falls back into the Brown-out zone. Such "ON-OFF" operational cycling is unhealthy for UPS, batteries and connected electronics. For Brown-out correction see our Voltage Regulator Page.
Spikes generated by electrical machinery also greatly increase. Air conditioners, refrigerators and other motorized devices generate local spikes. Industrial machinery (often miles away) create additional spikes which may find their way unto the electrical distribution system, and into your sensitive, valuable equipment.
Surge suppressors limit the voltage potential by "turning on" when a preset voltage is reached and then absorbing part of the energy of the surge and eventually diverting all surge energy to ground. Once the surge has been dissipated, the suppressor "resets" and waits for the next surge. Crucial in the design of a suppressor is its ability to turn on rapidly and absorb or divert all the energy present in the surge and clamping or holding the "let through" overvoltage down to a level safe for exposed circuitry. Transient voltages have proven to be the leading cause of semiconductor-based equipment failure and have cost the American industry more than 10 billion dollars in equipment damage alone. At least 75% of all reported failures have been attributed to electrical overstress. Almost everyone in today’s world has been affected by electronic equipment failure. These failures encompass all aspects of electronic devices and applications.
Listed below are just a few
Home: (air conditioning, security systems, appliances, televisions, audio systems, etc.)
Medical: (diagnostics, monitors, x-ray machines, electronic filing, data transmission, etc.)
Industrial: (CNC machines, injection molding, meters, computers, printers, etc.)
Heavy Industrial: (DP transmitters, measurement & control systems, power equipment, electrical safty equipment, instrumentation, etc.)
Banking: (communications lines, computers, printers, fax, modems, ATM’s, etc.)
Manufacturing: (Electrical Tools, pick and place equipment, programmable logic controllers, etc.)
Without adequate protection, all electronic based equipment is at risk. Usually the failures are not seen right away. Repeated stress from normal electrical transients weaken components and lead to shortened life with every surge it takes. Since there are no "wear out" phenomena inherent in solid state components (semiconductors) the life of such equipment should be indefinite.
A lightning strike "cloud to ground" or "cloud to cloud" produces electromagnetic fields that can induce voltages on the conductors (wires) of AC circuits as well as data communication lines, phone lines, or transmission cable. Lightning ground current flow results when a strike that discharges to the earth couples into common ground impedance paths, causing voltage differential across the ground grid and between ground-neutral or ground-line circuits. In short, the reference ground (supposedly zero voltage) is elevated a few milliseconds, therefore creating a large voltage difference between ground and the incoming power and/or data lines. Direct lightning strikes, to high voltage primary circuits, inject high current into service transformers and produce voltages either by flowing through ground impedance or flowing through the surge impedance path of the primary conductors. Direct lightning strikes to secondary circuits may exceed the withstand capability of equipment and conventional surge protection devices rated for secondary circuit use.
Lightning causes utility company primary gap type arrestors to fire, limiting the primary voltage but coupling transients through the capacitance of mains, transformers, and injecting surge voltages in addition to those coupled by normal transformer action.
Power company protective devices limit life-threatening overvoltage; however, they create a number of damaging transients in the process that may damage electronic equipment. Lightning does not have to be close to create high voltages in any line (power, neutral ground, or communications). The effects of nature’s electricity induce voltages into all lines for miles around. These voltages near the lightning strike can be catastrophic, the induced voltages a mile away can cause high voltage that can create electronic system failures, and a few miles away can stress electronic equipment causing delayed (latent) failures.
Utility main power system switching disturbances are created by capacitor bank switching, grid switching and switching on or off backup generators. Electrical utilities correct a fault by sending a power surge to clear a short in a service line, transformer, or other load grid short circuit. Multiple re-ignitions or re-strikes frequently occur in power factor corrector capacitor banks and can exceed three times normal system voltage. In addition, when power fails causing a "blackout" and then is restored, voltages exceeding several times primary power levels are typically generated. Short circuits and arcing faults or other system faults, which cause current limiting fuses to clear or circuit breakers to trip, generate high voltages when the trapped inductive energy is released upon collapse of the electrical field.
These lightning and switching surge threats to electronic equipment have been well defined by regulatory agencies such as ANSI/IEEE, IEC and Underwriters Laboratory (UL)
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Switching transients can be associated with both normal and abnormal conditions. Minor switching transients occur when appliances, air conditioners, compressors, etc., cycle or through the normal turn off of other electrical loads. Other periodic transients (100ms range) occur during each cycle of the commutation of motors, generators and other power converter type equipment.
Multiple re-strikes occur from air contractors or mercury switches that generate surges several times in amplitude larger than system voltage. Therefore even equipment commonly present in the home or business generates damaging transient overvoltage.
