Tech-tips ’“ AC Power Management

Which technology is the right one for you? Garth Powell, Senior Product Designer at Furman sound recommends letting the application determine the solution.

Power problems

Any AV system in whatever setting will always require power and power distribution for its components.
However it’s important to know that, at best, our AC power infrastructure is based on a 100-year-old technology that is not sufficient for optimum – or even reliable – operation of today’s sensitive microprocessor-based circuits. Add to that the challenges mobile or outdoor applications that may need to work from an AC generator as the power source, and the entire system is in jeopardy of facing problems or failure without the proper tools in place.

Too many TLA’s?

Some definitions to get your through power management.

RFI – Radio Frequency Interference
EMI – Electromagnetic Interference
UPS – Uninterruptable Power supply
Linear filtering - A low-pass filter designed to reduce unwanted noise caused by AC power in the audio/video frequency range.
Balanced Power – Utilizes a center-tapped transformer to virtually eliminate AC noise by splitting incoming voltage from the line to balanced signals on the line and neutral, in equal but opposite polarity with respect to earth ground.

Technology options

Transient & Extreme Voltage protection

These are the minimum requirements for each system. They provide protection from not only catastrophic surges and wiring faults, but just as importantly the numerous transient spike that occur daily and degrade sensitive circuits over time, reducing performance and reliability. Those seemingly random lock ups occur for a reason, and that gradual loss of picture and sound quality isn’t your imagination – it’s your unprotected AC power source.

Installations are often highly sensitive to power anomalies, while at the same time relied upon to perform flawlessly with zero downtime.

The best protection should include an extreme voltage shutdown circuit to ensure that a mis-wired or defective power feed in excess of 275 volts can never pass the protection device.

Power Conditioning / Filtering

Another basic need, but for the reasons you might think. For a long time basic notch filters have provided the means to limit RF and Electromagnetic interference from coupling into components. However, these days AC noise is many times greater than ever due to switching power supplies and the broad bandwidth of noise they feed back into our AC supply.

This noise can cause interference with sensitive circuits, contribute to lock-ups with others, and in the digital high-definition age, mask valuable signal content – the very content that makes high definition. A reliable, high-resolution system must have advanced AC noise filtering.

The wider the frequency range and the most consistent the reduction of this noise (such as those found with linear filtering circuits), the greater the system performance and reliability.

AC Voltage Regulation

Voltage regulation technologies convert abnormally low, high, or inconsistent incoming AC voltage and regulate them to a stable and consistent output. This is critical when AC power is supplied from a generator, as this scenario virtually never produces reliable voltage. In a corporate setting this may not be necessary unless there are known voltage issues, but for sound reinforcement this is a must-have technology.

Balanced Power & Isolation

This technology provides the cleanest AC power to critical, high resolution components in the digital age, and is recommended for critical listening or recording installations.

Recording or broadcast environments often require noise reductions of greater than 90 dB, and balanced power and isolation technologies provide the greatest noise reduction, and thereby yield the greatest resolution from your system components!

Power Sequencing

Power sequencing allows complex A/V installations to be safely powered on and off from a single location. This is critical in multi-zone installations where a live back-line could be several metres from a control technician, or installations that may be operated by non-technical personnel. Furthermore, power sequencing can be a great aid in assuring that the current in-rush from large power amplifiers is controlled to a manageable level by staggering the activation.

Battery back-ups

With the proliferation of digital components in A/V installations, battery backup components are now finding their way out of server closets and into A/V racks. Battery backup is ideal for components that rely flash memory/presets or hard drives and any components that need to shut down properly in the event of a blackout. Care should be taken to limit the use of battery backup however as the inverters and regulation circuitry common in these units tend to raise line impedance considerably, which can cause problems for power amplifiers and other high-current equipment.

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