· Why is power quality so critical to the smooth operation of audio and video systems?

· What power quality standards did the semiconductor industry establish?

· I'm confused. Isn’t my gear most susceptible to power outages?

· But isn't my uninterruptible power supply providing the protection I need from spikes, noise and common-mode voltage?

· What power protection components do I need?

· What’s the difference between an isolation transformer and a balanced power transformer?

· What element is most often missing in the UPS?

· What are switch mode power supplies?

· Why is ETA Systems a good source for my power protection needs?

· What are the four Ds of power quality?

· ETA power conditioners and UPMs cover all 4 Ds?

· I've already got a good UPS. Do I have to start all over?

· Does ETA Systems offer a UPS that conditions power, too?

· This all sounds pretty simple, but I've come to learn that even simple things can have surprises. How do I make sure that I'll be doing the right thing?

Q. Why is power quality so critical to the smooth operation of computer systems?

A. Like most other electronic systems, audio and video gear is migrating into the digital world. Embedded microprocessors, programmable systems, and highly specialized computer hardware is becoming everyday routine. All these systems are 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. And of course, the need to protect professional gear from outright damage or destruction caused by catastrophic power disturbances remains as important as ever.
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Q. What power quality standards did the semiconductor industry establish?

A. 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.
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Q. I'm confused. Isn’t my gear most susceptible to power outages?

A. It's true - 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 audio and video gear needs to be protected from them constantly, not just when the lights go out.
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Q. But isn't my uninterruptible power supply providing the protection I need from spikes, noise and common-mode voltage?

A. Excellent question. 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. In addition, not all UPS systems are created equal. Some output non-sinusoidal voltage waveforms that are electrically noisy and a poor choice for operating sophisticated electronics.
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Q. What power protection components do I need?

A. First a surge diverter. Surge diverters take high voltage transients and divert them safely away from your gear. 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.
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Q. What’s the difference between an isolation transformer and a balanced power transformer?

A. Both devices have two windings – a primary winding that is connected to the building electrical system and a secondary winding that is electrically separate but magnetically coupled to the primary winding. The secondary winding of each provides power to the electronic gear. In a balanced power transformer, the building’s safety ground (green wire) conductor is connected to the transformer’s metal enclosure. Meanwhile, the transformer’s secondary winding is center-tapped to provide the electrical ground for the gear. The other two secondary connections become the phase and neutral conductors that provide power to the gear. In a balanced power configuration, each of these conductors is 60 volts away from ground and 180 degrees out of phase with the other conductor. The theory is that any noise imposed on the transformer secondary will be imposed equally across the secondary and that since the phase and neutral are perfectly out of phase with each other, the noise will perfectly cancel. In practice, balanced power transformers are useful because of their ability to cancel noise in this fashion. It should also be noted that noise is not always imposed symmetrically across the secondary and so perfect cancellation may not always occur. An isolation transformer has its output neutral (one side of the secondary winding) bonded to the safety grounding conductor of the electrical system as well as the transformer enclosure. Isolation transformers are useful in eliminating neutral to ground noise voltages (common mode) because of this connection. This is a function, which balanced power transformers cannot provide. Through careful design, it’s also possible to design highly effective filters around the characteristics of the transformer secondary making the isolation transformer a very efficient device for the complete attenuation of both normal mode and common mode noise. Isolation transformers are a better selection for the protection of digital electronics for this reason.
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Q. What element is most often missing in the UPS?

A. 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.
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Q. What are switch mode power supplies?

A. These are the kind of power supply used in almost every type of system designed and sold today. They replace earlier generation linear power supplies which were larger, less efficient, and more expensive. Switch mode power supply technology is one reason modern equipment is smaller, cooler operating and more economical.
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Q. Why is ETA Systems a good source for my power protection needs?

A. Because ETA Systems understands electrical power and how to make it work for you. We don’t follow a “one size fits all” philosophy. We know that you may have a mixture of hardware – some analog and some digital – and we have power quality solutions for both applications. We also know that you have power control, sequencing, and management requirements, too. Our product family reflects the broad needs of the audio and video industries. ETA Systems is the one source for all your power quality, control, and management needs.
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Q. What are the four Ds of power quality?

A. Your gear can be affected by power disturbances in four different ways. We call these "the 4 Ds." They stand for Destruction, Degradation, Disruption, and Dynamics. 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 data, communication errors, “no trouble found” service calls, and slow system throughput. Power line noise and high impedance power sources affect Dynamics by altering the sound you hear and the quality of the image you see.
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Q. ETA power conditioners and UPMs cover all 4 Ds?

A. Yes. ETA power conditioners and UPMs offer a power protection foundation that protects systems from Destruction, Degradation and Disruption while simultaneously improving Dynamics by lowering the system’s noise floor.
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Q. I've already got a good UPS. Do I have to start all over?

A. Maybe not. Another benefit of ETA power conditioners is that they are designed to be compatible with many UPS products. Provided that the your UPS is a sine wave design, there’s a pretty good chance you can select an ETA power conditioner that will be a perfect match. No need to throw away the investment you've already made. And with a wide selection of different models in our standard plug-and-play product line, you're sure to find one that matches the electrical requirements of your current UPS.
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Q. Does ETA Systems offer a UPS that conditions power, too?

A. Yes. UPM or Uninterruptible Power Manager family provides fully conditioned power and uninterruptible power in a "one box" solution.
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p Q. This all sounds pretty simple, but I've come to learn that even simple things can have surprises. How do I make sure that I'll be doing the right thing?

A. ETA Systems 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 ETA Systems, a damaging power disturbance is not waiting in your future.
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