시스템 인티그레이션

시스템 인티그레이션

[펌] Power Conditioning

Author
장호준
Date
2009-01-29 08:30
Views
3609
Power Viruses and The ABCs of Power Conditioning

Fortunately, whatever types of power problems your equipment is exposed to, there’s an ETA solution that protects your equipment and helps it perform at the highest professional level.

In many respects, power problems are like a biological virus. Just like a regular virus, power problems enter your gear unseen, and by the time they become evident, major damage has already occurred. And like a virus, prevention of power problems is preferable to curing them after the fact. Let’s examine the various types of power viruses, and the generic protection devices that are available to combat each type of power problem.

ABCs-Graphic1.jpg

btn_vsi.gifProblem: High voltage surges
High voltage surges can send expensive sound and video equipment to an early grave. Surges can contain substantial amounts of energy causing outright catastrophic component failure. Some surges contain smaller energy levels that only erode components microscopically leaving them in a weakened state. Surges are addressed with a surge diverter – 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 substantial degrading energy spikes over the long term.
btn_cmvp.gifProblem: 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 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 the surge diverter 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.
btn_en.gifProblem: Electrical noise
Power line noise filters 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” like lighting ballasts, appliances, motors, electrical HVAC controls, and even other computer power supplies. Not only can noise wear away electrical components, it can also interfere with the reliable operation of digital circuits. Like surge diverters, noise filters shunt power disturbances to safety ground.
btn_vr.gifProblem: Voltage swells and sags
Swells and sags can originate outside of a facility but can also be created by equipment use inside a facility, too. 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. Various regulation technologies are available, and careful consideration is necessary to select the one that’s best suited for the application.
Frq_icon.jpgProblem: Unstable AC frequency
AC power in North America is generated at a frequency of 60 Hz, while in Europe and much of the rest of the developed world; AC power is generated at 50 Hz. In developing countries, or where power is sourced from an electrical generator, the frequency may not be stable. In such cases, a frequency regulator is required. An online UPS or AC inverter is one answer for ensuring stable-frequency AC power for predictable performance of audio and video equipment.
btn_b.gifProblem: Power outages
It’s hard for the show to go on when the power goes off. If power outages are the problem, some type of uninterruptible power supply (UPS) will be the answer. A UPS converts DC energy stored in batteries into AC energy to power the electronic load. All UPS products are not created equal. Some UPS products are on-line and some are standby. Some have clean sine wave outputs and others have square wave or modified square wave outputs. Some provide power conditioning and some do not. ETA Systems UPM products provide conditioned, sine wave, AC power – the kind your audio or video system was designed to use.
btn_bd.gifProblem: Ground loopsWhen electronic systems are connected together, the natural differences in electrical ground impedance cause noise currents to flow in the loops created by the grounding and shielding conductors of signal cables. Low-frequency ground loop currents may cause audible audio hum; or roll bars and distortion in a video image. High-frequency loop currents (>100 kHz.) may create system reliability issues and communications errors for a data network. Good installation practices, single-ground power sources, and careful cable installation can often help address low frequency ground loop issues. Other technologies exist to address high frequency ground loops.

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