THE POWER PROBLEM The Importance of Power Management in Church A/V Installations

In Uncategorized by tfwm

In church A/V installations, there are often many misconceptions when it comes to the role of power management. For one thing, power is frequently ignored as an issue altogether. When expensive front-end equipment and amplifiers fail, the blame is often placed on the equipment. Consideration is not given to why it failed; it is simply repaired or replaced. Another problem is the budget. Now more than ever, budgets are tight, and when looking at a bid, power management is often the first thing taken off to save money, as it is viewed simply as extra outlets, and not as protection. With that view, it is understandable to want to cut the expense. Unfortunately, these assumptions are incorrect.

The fact is that our power infrastructure was designed over 100 years ago to power motors and lights, not highly sensitive A/V equipment. Power coming out of electrical outlets is not 100 percent clean and stable. Some places are worse than others, but contamination is present in power sources everywhere. The ultra-sensitive circuits in today’s professional A/V equipment are technologically superb, but they are also very fragile. This has made it increasingly imperative to employ an advanced power protection system such as a power conditioner for professional A/V systems.

According to the National Electrical Manufacturers Association (NEMA), a surge or transient is a brief overvoltage spike or disturbance on a power waveform that can vary in intensity from just a few volts to extremes of tens of thousands of volts. These disturbances are not as rare as one may think, and can damage, degrade, and even destroy electronics within a home or commercial building.

Transient spikes, however, are not the only problems faced by today’s sensitive electronics. There are also sustained overvoltage conditions, sometimes called extreme voltages, and they are more common in older facilities due to poor neutral connections that can cause overvoltages in excess of 240 VAC. Many surge suppression devices will not be able to protect equipment from sustained overvoltages, and these conditions are, in fact, the most dangerous and damaging to equipment. They are the kinds of situations that cause the nightmare scenario of powering on your equipment and seeing it go up in smoke. Most extreme voltage conditions will result in destroyed equipment or, at best, a destroyed surge suppression system. In either event, equipment service is certainly required.

Another persistent problem, especially in older facilities, is AC line noise. Noise on the AC line can be particularly troublesome for A/V installs, where distortion can manifest itself in audio content and on video displays.

Correcting this problem requires a power management device with a low-pass noise filter designed to reduce or eliminate the artifacts introduced by culprits such as switching power supplies, deterioration of power lines, and the noise pollution caused by the massive amounts of electronics on the grid. An AC filter with a linear attenuation curve will yield the best results in lowering the noise floor for connected A/V equipment.

Tips For Selecting a Power Management Solution
Before doing anything, the contractor should always have the integrity of the electrical checked by a qualified electrician. They should look for impedance, voltage stability, harmonic distortion, and the quality of the mains power supply transformer. The transformer needs to be in good shape and large enough to supply the current needed. If the power is poor, the transformer may need to be replaced. Poor impedance on the neutral can cause power supplies to get hot and go into thermal shutdown. In this case, the neutral may need to be re-bonded.

Next, the capacity of the system, or how much power will be required, needs to be determined and then compared to how much power is actually available. This will help determine what kind of power management solution is needed, i.e., a 15-, 20-, or 120-A product. When selecting a product, churches should keep in mind that most common AC strips and older power management products feature inexpensive surge suppression devices that are designed to sacrifice themselves when exposed to sustained overvoltage conditions or transient voltage spikes. This will protect your equipment, but there is no indication that the surge suppressor has been compromised, so the next surge will go straight through. Newer power management products are non-sacrificial and feature extreme voltage shutdown circuits, which constantly monitor the incoming voltage, and once the voltage has risen to approximately 15% above nominal, they trigger a power relay to open, thus cutting the supply to all connected components and critical circuits. Once the voltage is corrected, the unit is reset and operation may continue.

Another factor to consider is the training of the personnel. Since church volunteers and untrained personnel are often the main operators of the A/V equipment, great care needs to be taken to ensure that the components are powered on and off correctly. Power sequencing is needed whenever various kinds of equipment must be powered up or down in steps, rather than simultaneously. In audio systems, sequenced powering is often necessary to allow turn-on transients from low-level amplifiers and processors to settle down before any power amps are turned on, because simultaneous powering would result in a loud, annoying, and potentially destructive “pop” reaching the speakers. And in any large system whose components present an inductive load to the AC line (including electric motors, power supplies, and power amplifiers of all kinds), sequenced powering can avoid excessive inrush currents that cause circuit breakers to trip.

Churches should factor power management into their budget. The standard range that should be reserved runs from 3% to 10%. On the lower end, 3% would be for installations in newer buildings with a decent infrastructure already in place. 10% would be for more advanced technology in older buildings where wires can’t be rerun. In these cases, a voltage regulator may be necessary. A voltage regulator accepts a wide range of voltage inputs from the power supply, and then transforms them to a safe, steady voltage rate that is sent on to connected equipment, keeping it performing correctly and preventing damages from surges. As with most power-management products, some technologies are more effective than others. Many voltage regulators use noise-inducing, motorized transformer-based technology. Not only are these products large and expensive, but they are also unreliable and actually add noise to the AC line. This noise ends up masking much of the detail needed for the best-possible audio and video. To avoid this, it’s best to find a regulator that utilizes electronic circuitry.

Power Management as Insurance
Churches should look at power management as insurance, because a single power management product can save thousands on equipment replacement and repair. A good real-life example of this comes from Christos Desalernos, domestic sales manager for Furman. Christos converted his garage into a recording studio. Living two blocks from the power grid, he is subject to a great deal of power outages and fluctuations. Last November, he was in his studio when the power went out. His Furman UPS kicked in and he was able to finish his recording session as normal. When he finished up, he realized that there was a huge power fluctuation when the power came back on, as evidenced by the exploded light bulbs in the kitchen. In addition, all his Furman units were in extreme voltage shutdown. After doing the math, Christos determined that $70,000 worth of equipment was saved by a $135 power management system.

Many church facilities can easily say they have $70,000 invested in electronic gear, as demonstrated by this example, so the benefits of power management to churches and other organizations on a tight budget become crystal clear. Replacing equipment is extremely expensive. With a high-cost A/V system on the line, investing a little to protect the equipment simply makes sense.