Knowledge Base

  • ABCs Of Power Conditioning +


    It seems like almost every power protection device that’s sold today claims to be a power conditioner. But what really makes a power conditioner? The answer to that question depends largely on determining the power quality needs of the electronic load.

    A system with a linear type power supply will frequently already have an isolation transformer but may be sensitive to voltage fluctuations. These systems will probably need some type of surge diverter and maybe a voltage regulator, too.

    Most modern electronic systems, however, have switched mode power supplies (SMPS). This type of power supply technology is largely immune to changes in power line voltage but in the process of making the power supply smaller, more efficient, and cheaper, the isolation transformer has been eliminated from the design. Systems with a switched mode power supply will require, at a minimum, a surge diverter, a noise filter, and an isolation transformer.

    Meanwhile, any system in which data is held, edited, or manipulated in some way in volatile memory may need the protection of a battery backup system or UPS to ensure that data can be saved and the system properly shutdown in the event of a power outage.

  • Power Facts +


    POWER FACTS

    FACT #1: Power quality is critical to the smooth operation of computer systems!
    Each computer system is composed of tiny micro-circuits that operate on very low voltages. These circuits do their computing wizardry by comparing very small changes in these operating voltages. Power problems interfere with these voltage comparisons. As long ago as 1986, the semiconductor industry at their fifth annual conference published their criteria for the type of environment where their products can operate as they were designed. In addition to setting standards for such factors as static discharge, the industry also published standards for the protection of their devices from spikes, normal mode noise and common-mode voltage. These three disturbances are the ones that are most prevalent in almost any electrical system.

    FACT #2: Power quality standards have been established by the semiconductor industry.

    The industry established that power disturbances must be limited to less than 10 volts in the normal mode (phase to neutral) and less than .5 volts (1/2 of one volt) in the common mode (typically neutral to ground). In addition, the industry established that these criteria must be met even though power disturbance might be as large as 6000 volts as defined by the IEEE (Institute of Electrical and Electronic Engineers) in their guideline labeled IEEE C62.41.

    FACT #3: Systems are susceptible to more than power outages.

    It’s true that without power, your system can’t operate. But power outages are infrequent compared to disturbances such as noise, spikes, and common-mode voltage. We’ve been conditioned to be worried about outages because they are a visible manifestation of power problems. Spikes, noise, and common-mode voltage are invisible but present to some degree all the time. For that reason, your computer needs to be protected from them constantly, not just when the lights go out.

    FACT #4: A UPS (uninterruptible power supply) does not always condition power.

    Many uninterruptible power supplies (UPS) claim to condition power, too. The fact is that most are simply a surge protector with a battery system for providing power in the event of an outage. It takes specific electrical components to provide the level of protection needed by modern electronic systems.

    FACT #5: Power conditioning requires three important elements.

    First a surge diverter. Surge diverters take high voltage transients and divert them safely away from your electronic system. Second, a low impedance isolation transformer. Transformers eliminate common-mode voltage and ensure that the logic ground (or decision making reference) for the computer is not disturbed. Third, noise filters are important to protect the system from high frequency normal mode noise. These three elements are the foundation for all effective power protection solutions. Battery systems can be added to this foundation, but a UPS without all three of these important elements cannot be a comprehensive power quality device.

    FACT #6: One power conditioning elements is commonly left out of most UPS products.

    The low impedance isolation transformer. Again, the 1986 semiconductor industry conference states on page 9 of its proceedings that low impedance transformers are required for maximum compatibility with switching power supplies.

    FACT #7: POWERVAR power conditioners provide excellent protection for your system.

    Every POWERVAR power conditioner contains the three essential building blocks of an effective power quality solution—1) A Surge Diverter, 2) a Low Impedance Isolation Transformer and 3) a highly effective Normal Mode Noise Filter. These three elements are designed to work as a system so that your computer can be protected from all three electrical failure modes.

    FACT #8: There are three modes of system failure.

    Your computer can be damaged by power disturbances in three different ways. We call these “the 3 Ds.” They stand for Destruction, Degradation and Disruption. Destruction is the most visible of failure modes because it is usually accompanied by burned or charred components and immediate and catastrophic system failure. Lower magnitude power disturbances do not cause outright failure. Instead they degrade system components—weakening them a little at a time much like rust attacks metal. Usually the damage is not visible until the component fails and then it’s too late. The lowest magnitude of power disturbances are those that interfere with the computer’s ability to make proper logic decisions. These disturbances are associated with normal mode noise and common-mode voltage. These disruptive disturbances are responsible for most of the unexplainable failures that happen from time to time. Disruptive power disturbances are known to cause system lock-ups, lost files, communication errors, “no trouble found” service calls, inaccurate test data, and slow system throughput.

    FACT #9: POWERVAR power conditioners protect against all three failure modes.

    POWERVAR power conditioners offer a power protection foundation that protects systems from Destruction, Degradation and Disruption. Then, if software or applications demand, a UPS can be added to the POWERVAR power conditioning solution.

    FACT #10: Surprises can happen.

    POWERVAR wants you to be happy with our products. That’s why we’ve assembled a top notch team of sales representatives and distributors and resellers to assure that you make the right decision for your application and that you can go forward with the confidence that with POWERVAR, a damaging power disturbance is not waiting in your future.

  • Power Viruses +


    POWER VIRUSES

    These six power viruses can kill your productivity. Immunize your system with POWERVAR protection.

    You’ve heard about the dangers of software viruses. But did you know that power viruses can do just as much damage to your system? And that a typical facility experiences as many as 6,000 power viruses or more, every year?

    Some of these power disturbances are obvious, some are almost unnoticeable, but they all cause problems that can seriously damage your productivity, from lost data and lock-ups to communications errors and hardware failures.

    Fortunately, whatever types of power viruses your system is exposed to, you can immunize yourself with complete power protection from POWERVAR.

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    High-Voltage Surges
    Power surges can send your expensive computers and other electronic equipment to the dumpster. Surges can contain substantial amounts of energy, causing outright catastrophic component failure. Some surges contain smaller energy levels that erode components microscopically, leaving them in a weakened state. Surges are addressed with a surge diverter (A) — a device that diverts excessive voltages away from the system by shunting them to ground. Although the surge diverter protects against these major power surges, transient voltages smaller than 250– 300 volts usually slip by the surge diverter, causing equipment to be exposed to degrading energy spikes over the long term.
       
    Common-Mode Voltage
    Surge diverters (as well as noise filters) shunt disturbance energy to ground, resulting in a neutral-to-ground (common-mode) voltage — a situation that’s highly disruptive to digital and microprocessor-based technologies. The low-impedance isolation transformer (B) provides a mechanism for bonding the electrical neutral to the ground in a way that is acceptable to electrical codes. This enhances the operation of surge diverters and noise filters because the transformer bond prevents the formation of neutral to ground voltage. The isolation transformer also acts as an excellent “cushion” against power disturbances in general.
       
    Electrical Noise
    Power line noise filters (C) address the disturbances that slip by the surge diverter along with the low-amplitude, high-frequency noise that the surge diverter is not designed to handle. Typically these disturbances are caused by nearby electrical “neighbors” such as lighting ballasts, appliances, motors, electrical HVAC controls, and even other computer power supplies. Not only can noise wear away electronic components, it can also interfere with the reliable operation of digital circuits. Like surge diverters, noise filters shunt power disturbances to ground.
       
    Voltage Swells And Sags
    Swells and sags can originate outside of a facility but can also be created by equipment used inside the facility. For some electronic equipment with older, linear power supply technology, well-regulated voltage is critical to proper performance. Fortunately, most equipment uses newer-style switched mode power supplies, which are largely immune to voltage irregularities. The need for voltage regulation is infrequent, but when necessary, voltage swells and sags are eliminated with a voltage regulator (D). Various regulation technologies are available, and careful consideration is necessary to select the one that’s best suited for the application.
       
    Power Outages
    If power outages are the problem, an uninterruptible power supply [UPS] (E) will be the answer. A UPS converts DC energy stored in batteries into AC energy to power the electronic load temporarily. All UPS products are not equal. Some UPS products are online and others are standby, and some have true sine wave outputs and others have square wave or modified square wave outputs. Some units provide power conditioning and most do not. POWERVAR UPM products provide conditioned, sine wave, AC power — the kind your equipment was designed to use..
       
    Unstable AC Frequency
    AC power in North America is generated at a frequency of 60 Hz, while in Europe and many other locales, AC power is generated at 50 Hz. In developing countries, or where power is sourced from an electrical generator, the frequency may not always be stable. In such cases, a frequency regulator (F) is required. An online UPS or AC inverter is one answer for ensuring stable-frequency AC power for predictable equipment performance.
       
    Ground Loops
    When electronic systems are connected into a network, multiple branch electrical circuits are involved in powering the various network components. Along with these different circuits come different safety ground impedances. The result is the formation of “ground loops” in which noise currents flow in the loops created by the grounding and shielding conductors of the signal cables used to connect the network. These loop currents cause communication errors and data packet collisions. Large loop currents will easily destroy the communication drivers on interface cards. For many years, the only solution for addressing ground loop issues was the dedicated-isolated electrical circuit. POWERVAR’s Ground Guard technology (G) is highly effective in preventing the formation of ground loops and eliminating the need for special dedicated-isolated electrical circuits.
       
    Voltage Spikes And Impulses
    Like electrical noise, this virus is also spread by equipment inside your facility. When elevators, motors or air conditioners stop and start, they can cause sudden large increases in voltage inside the electrical system. Other causes include electric utility switching and lightning strikes (which can cause transients so intense they literally “blow up” sensitive electronics). Unlike surge diverters, which can only slow down or weaken this virus, a POWERVAR system stops it dead by giving you complete protection from small and large transients.
       
    Voltage Regulation
    In the past, unregulated voltages wreaked havoc with linear power supplies, making it hard for computer-based equipment to function. Failures were common. But thanks to the switch-mode supplies used in today’s computers, today’s systems have developed their own immunity to voltage regulation viruses. (This immunity is a by-product of the same technology that makes switch mode supplies smaller and more economical.)
       
    Blackouts
    Although they’re the most visible—and memorable—of power viruses, blackouts account for comparatively few power disturbances each year. An uninterruptible power supply (or UPS) will keep your system up and running during a blackout, but it won’t immunize against the other power viruses. That’s why we’ve made sure POWERVAR systems are compatible with all types of UPS systems—so you can have full immunity, all the time.
       
    Backdoor Disturbances
    This virus infects your system via a pathway you’d least expect: the backdoor. Even though it’s not an AC power connection, damaging electrical disturbances can enter electronic systems through modem and phone lines, network connections, and I/O cables. Fiber optic connections are one means of protection, but if your system uses ordinary communications wiring and connections, you need to immunize it against this often unrecognized but very dangerous virus. Once again, POWERVAR is your source for complete protection.
  • Power Words +


    GLOSSARY OF POWER TERMS

    Alternating current (AC): An electrical system in which voltage polarity and current flow alternates direction on a regular basis. Your home is an example of a system that is powered by AC.

    Amp: A unit of electrical flow. In a water system, the flow of millions of water molecules would be expressed in terms of gallons per minute. In an electrical system, the flow of millions of electrons is expressed in terms of amps or amperes.

    Apparent Power: The amount of power that is apparently consumed by a load. Apparent power is measure in VA or volt-amperes and is calculated by measuring the current consumed by the load and multiplying it by the voltage powering the load.

    Backdoor disturbances: This virus infects your system via a pathway you’d least expect: the backdoor. Even though it’s not an AC power connnection, damaging electrical disturbances can enter electronic systems through modem and phone lines, network connections, and I/O cables. Fiber optic connections are one means of protection, but if your system uses ordinary communications wiring and connections, you need to immunize it against this often unrecognized but very dangerous virus. Once again, POWERVAR is your source for complete protection.

    Blackouts: Although they’re the most visible—and memorable—of power viruses, blackouts account for comparatively few power disturbances each year. An uninterruptible power supply (or UPS) will keep your system up and running during a blackout, but it won’t immunize against the other power viruses. That’s why we’ve made sure POWERVAR systems are compatible with all types of UPS systems—so you can have full immunity, all the time.

    Common Mode Voltage: A voltage of any amplitude or frequency that is measured between the phase conductor and the ground conductor or the neutral conductor and the ground conductor. Neutral to ground voltage is a common mode component that frequently causes computer system malfunction. Neutral to ground voltages should always be limited to .5 volts (one half of one volt) or less.

    Common-mode voltage problems: Probably the most serious virus facing computer users today, common-mode voltage problems can cause unexplained data losses, glitches, system failures and “no trouble found” service calls. The only way to immunize against common-mode voltage is to install a power conditioner or UPS that has an isolation transformer output. All POWERVAR power quality solutions include an integral isolation transformer for that reason.

    Constant Voltage Transformer: Maintains a relatively constant output voltage for variations up to 20% in the input voltage. CVT’s are frequently a ferro-resonant style of transformer in which the voltage is regulated by means of current stored in a magnetic field. CVT’s are generally high impedance devices that are unsuitable for most modern computers with switch mode power supplies.

    Current: The “flow” of electricity. Much like water, a current will follow the path of least resistance. As a result, electric current always finds the easiest path to ground. Current is measured in amps or amperes.

    Dedicated Circuit: An obsolete method for providing clean, noise free power to a computer system. A dedicated circuit is one in which dedicated phase, neutral, and safety grounding conductors are run continuously from a distribution panel to an electronic load. The conductors may service only the dedicated load and the phase conductor must have its own circuit breaker. Furthermore, the dedicated conductors must run in their own dedicated metallic conduit or raceway with no other conductors present. The neutral and ground conductors may not be “daisy chained” or shared with any other circuit. The ability of dedicated circuits to guarantee a noise and disturbance free environment is insufficient for the high processing speeds, low operating voltages, and mission critical nature of modern technology.

    Direct current (DC): An electrical system in which current flows in one direction only. A battery is an example of a direct current source.

    Dip: See “Sag”.

    Disturbance: Any departure from the nominal values of the power source. Disturbances can include transients, electrical noise, voltage changes, harmonics, outages, etc.

    Drop: A slang word sometimes used to describe voltage sags or under voltages.

    Electrical Noise: This virus is spread by electrical neighbors such as electronic lighting ballasts, appliances, printers, photocopiers and even other computers. Over time, and in connection with low-voltage spikes, noise can wear away electrical components and cause them to fail for no apparent reason. Fortunately, a POWERVAR system can eliminate noise and keep your system’s health from deteriorating.

    Flicker: A voltage variation of short duration but long enough to be noticeable to the human eye as a light flicker.

    Frequency: In an AC system, the value of the voltage sinewave rises from zero to a maximum, falls to zero, increases to a maximum in the opposite direction, and falls back to zero again. This would describe one complete cycle. The number of complete cycles occurring in one second is called frequency. The General Conference on Weights and Measures has adopted the name hertz (abbreviated Hz) as the measurement of frequency. In North America, the frequency is 60 Hz. In Europe and most of Africa and Asia it is 50 Hz.

    Glitch: A slang term for a voltage transient or voltage variation that causes equipment to misbehave.

    Grounding Conductor: The physical conductor connecting the chassis of an electrical or electronic device to the electrical system’s grounding means. Sometimes referred to as the safety ground, this conductor may be a green insulated conductor, a bare copper wire, conduit, gutter or raceway. The purpose of the grounding conductor is provide a low impedance pathway for fault current in the event of a short circuit so that a circuit may be quickly de-energized to prevent a fire hazard or electrocution.

    Grounded Conductor: Refers to the neutral conductor of the electrical system, which is bonded to the facility’s utility field earth reference in order to reference the facility electrical system to ground.

    Harmonic: A whole multiple of the basic power frequency. On a 60 Hz system the 2nd harmonic is 120 Hz, the third harmonic is 180 Hz, the fourth is 240 Hz and so on.

    Harmonic Distortion: The alteration of the normal voltage or current wave shape (sine wave) due to equipment generating frequencies other than the standard 60 cycles per second.

    Impedance: Impedance is the opposition offered by a material to the flow of an electrical current in an AC electrical system. Impedance has two parts – resistance and reactance. Impedance is measured in ohms.

    Interruption: See “Outage”.

    Inverter: Device that converts direct current (DC) power into alternating current (AC) power.

    Isolated Ground: An insulated equipment grounding conductor that is run in the same conduit as the supply conductors. This conductor is insulated from the metallic raceway and all ground points throughout its length. An isolated grounding conductor may only be connected to the grounding of the electrical system as a point where the facility neutral (grounded conductor) is bonded to ground. An example would be at the service entrance or at a distribution sub-transformer.

    Isolation Transformer: A device that electrically separates and protects sensitive electronic equipment by buffering electrical noise and re-establishing the neutral-to-ground bond. By virtue of the neutral-to-ground bond, isolation transformers eliminate neutral-to-ground voltage – one type of common mode disturbance.

    Line Conditioner: A device that provides for the electrical power quality needs of the connected electrical or electronic load. In the case of a linear power supply, a line conditioner might be a voltage regulator. In the case of a switch mode power supply, a line conditioner might be an isolation transformer with a noise filter and surge diverter. In the case of a simple electrical device like a motor, a line conditioner might be as rudimentary as a surge diverter. The term line conditioner is frequently misused. It must be understood that not all line conditioners function alike, and the capabilities of a line conditioner must be matched to the power quality needs of the connected load.

    Linear Power Supply: A power supply which converts AC power into the DC power that is needed to operate an electronic circuit. In a linear supply, the AC voltage is first stepped down, then rectified, and then regulated using a series regulation device. Linear supplies obtain their name from the fact that there is a linear relationship between the value of the AC sine wave voltage and the power supply’s consumption of current from the AC circuit. Linear power supplies are generally less efficient because the series regulator dissipates large amounts of heat in the process of producing and regulating the DC output voltages. In addition, linear mode power supplies may require well regulated AC input voltage. One benefit of linear power supplies is that they produce little electrical noise.

    Mission Critical Load: Devices and equipment identified as important or essential to the safety of personnel or the economic health of a business.

    Momentary Outage: A brief interruption in power commonly lasting between 1/30 (2 cycles) of a second and 3 seconds.

    Nines of Reliability: The reliability of an electrical system is a combination of both its availability (freedom from outages) as well as it’s quality (freedom from disturbances). Reliability is expressed in percentages. 99% would be expressed as two 9s of reliability. 99.9% would be three 9s reliable, 99.99% would be four 9s reliable and so forth. The average well managed electrical system in North America has about three 9s of reliability. In a 24 x 7 operation, that translates into about 88 hours per year in which the availability and quality of the electrical system are unsatisfactory to reliably power a mission critical electronic load.

    Noise: An unwanted high-frequency electrical signal that alters the normal voltage pattern (sine wave). Noise may be either high amplitude or low amplitude.

    Normal (Nominal) Voltage: The normal or contracted voltage assigned to a system for determining voltage class.

    Normal Mode Voltage: Any voltage (other than fundamental 50 Hz or 60 Hz) that is measured between the phase conductor and the neutral conductor in a single phase system or between any two phase conductors of a three phase system. Normal mode voltage can be any amplitude or frequency. Normal mode noise voltages can interfere with the reliable operation of a computer system or degrade and destroy components. Normal mode power disturbances should be limited to 10 volts or less.

    Ohm: A unit of resistance and impedance.

    Ohms Law: The relationship between voltage, current and resistance in a DC circuit. If two values are known the other can be calculated. This relationship is expressed many different ways. The basic relationship is voltage (V) is equal to current (I) multiplied by resistance (R). Ohm’s law must be applied in a modified way to AC circuits. AC circuits have impedance rather than resistance. Impedance causes AC circuits to exhibit power factor, which must be factored into any calculations

    Outage: Complete loss of electrical power.

    Overvoltage: An increase in voltage outside the normal voltage levels (10% or greater) for more than one minute.

    Phase Relationship: The timing relationship between voltage and current. If voltage and current cross through zero in a cycle at the same time they are said to be in phase. Phase differences are expressed in degrees. A cycle is 360 degrees. In a totally capacitive circuit, current leads voltage by 90 degrees. In a totally inductive voltage leads current by 90 degrees. In a circuit that is purely resistive, voltage and current are in phase.

    Power Factor: The ratio between Watts and Volt-Amperes. This ratio is generally expressed as a decimal fraction. A power factor of 1.00 is unity.

    Reactance: Reactance has two components, capacitive reactance and inductive reactance. The values of reactance are determined by the values of the individual capacitor or inductor as well as the frequency of the current flowing in the circuit.

    Real Power: The amount of power that is actually consumed by the load. Real power is measure in watts and is calculated by measuring the current consumed by the load and multiplying it by the voltage powering the load and then multiplying by the power factor of the load.

    Rectifier: A device that converts alternating current (AC) power to direct current (DC) power.

    Reactive power: Reactive power is the difference between apparent power and real power. It is calculated by subtracting real power from apparent power. Reactive power is measured in VAR (volt-amps reactive) or kVAR (kilovolt/amps reactive)

    Resistance: The opposition offered by a material to the flow of a steady electrical current in a DC circuit. Resistance is measured in ohms.

    Sag: Any short-term (less than 1 minute) decrease in voltage.

    Spike: See “Transient”.

    Standby Generator: An alternate power supply usually driven by a gas or diesel engine.

    Surge: A sudden dramatic increase in voltage that typically lasts less than 1/120 of a second.

    Surge Protective Device (SPD): A device that is designed to limit instantaneous high voltages. Also known as a surge suppressor, surge arrestor and transient voltage surge suppressor (TVSS). These units are satisfactory for reducing the amplitude of catastrophic events. However, they function by diverting excess voltage to the safety ground of the electrical system. In the process they create a common mode disturbance which can disrupt the function of microprocessor based electronic systems.

    Swell: Any short-term (less than one minute) increase in voltage.

    Switch Mode Power Supply: A power supply technology in which the AC power is converted into DC power for use by an electronic system. SMPS technology uses switching transistors operating at very high speed to keep a capacitor reservoir sufficiently charged to produce the appropriate DC voltage needed by the electronic circuit. SMPS technology is very efficient because it does not utilize the “lossy” series regulator found in the linear power supply. Current is consumed from the circuit only when the charge state of the capacitor reservoir requires it. SMPS technology is “constant power” in that when line voltage decreases, the supply’s current consumption increases and when line voltage increases, current consumption decreases. SMPS technology is relatively immune to voltage regulation issues. However, the technology does not employ a stepdown transformer on the front end, which means that it does not satisfactorily isolate the electronic system from the electrical supply. SMPS technology produces electrical noise as a result of the high speed function of the switching transistors.

    Transient: See “Surge”

    True Power: See “Real Power”

    TVSS: See “Surge Protective Device”

    Undervoltage: A decrease in voltage outside the normal voltage levels (10% or greater) for more than one minute.

    Uninterruptible Power Supply (UPS): A system designed to automatically provide power in the event that utility power is interrupted. A UPS may be standby, line interactive, or on line. A UPS is not necessarily a power conditioner, and care must be taken to ensure that the UPS provides all the power quality requirements that are needed.

    Volt: A unit of electrical pressure. In a water system pressure might be expressed as pounds per square inch. In an electrical system, the pressure that causes electrons to move is called voltage. The voltage found in most homes is 120 and 240 volts. Businesses will typically utilize voltage at 120 and 208, or 277 and 480 volts.

    Volt-Ampere (VA): The product of volts times amps. A kilovolt-ampere (kVA) is equal to one thousand volt-amperes. VA is also known as apparent power.

    Voltage: The electrical “pressure” that creates the flow of current.

    Voltage Regulator: A device that maintains output within a desired limit despite varying input voltage. These devices usually provide little to no protection against voltage transients or noise.

    Voltage regulation: In the past, unregulated voltages wreaked havoc with linear power supplies, making it hard for computer-based equipment to function. Failures were common. But thanks to the switch-mode supplies used in today’s computers, today’s systems have developed their own immunity to voltage regulation viruses. (This immunity is a by-product of the same technology that makes switch mode supplies smaller and more economical.)

    Voltage spikes and impulses: Like electrical noise, this virus is also spread by equipment inside your facility. When elevators, motors or air conditioners stop and start, they can cause sudden large increases in voltage inside the electrical system. Other causes include electric utility switching and lightning strikes (which can cause transients so intense they literally “blow up” sensitive electronics). Unlike surge diverters, which can only slow down or weaken this virus, a POWERVAR system stops it dead by giving you complete protection from small and large transients.

    Watt (W): A unit of power equal to the product of the value of current of one ampere flowing in phase with the pressure of one volt. A kilowatt is a thousand watts. Watts are an expression of real or true power.

    Watt-Hour (Wh): A unit of energy equal to the power of one watt for one hour. A kilo-watt hour is a thousand watt-hours.

    Waveform Distortion: Any power quality variation in the wave shape of the voltage or current.