The topic of AC power protection has become somewhat one-dimensional for many who regularly work with sound systems, because the concept of a power problem is tied to a specific unpleasant memory of a power disturbance that caused a great deal of grief, and perhaps a small fortune in recovery costs.
This explains why some are convinced that power protection is all about guarding against power outages or regulating voltage, while others obsess about power line noise or prevention of voltage surges and transients. It’s not uncommon to find surge protectors, voltage regulators, and noise filters all labeled as “power conditioners.”
We see a lot of discussion about the need to protect systems from power problems, but there’s little discussion about the nature of power disturbances themselves. This is unfortunate in an industry where so much depends on digital electronics that must perform reliably and produce the highest quality sound.
Because microprocessors and other sensitive circuitry are a critical part of almost every system, it’s important to think differently about the interplay between the electronic equipment and the electricity that powers it.
A good place to start is by understanding some basics. There are four ways in which modern A/V systems can be affected by power quality anomalies, and these can be called “The Four D’s.”
SURGES & OTHER TERMS
The first D is destruction. So much energy is involved with a power problem that a single occurrence results in the immediate destruction of an integrated circuit or transistor. We typically refer to these events as voltage surges, impulses, or high-energy transients, and they’re usually associated with lightning.
However, there are other causes. Voltage surges can be caused by large industrial loads turning on and off, a windstorm blowing power lines together, or even something more mundane the aging ballast of a fluorescent lighting fixture.
Whatever the source, the destructive power disturbance overwhelms the electronic device and leaves smoke, charring, and visible damage in its path.
The second D is degradation. The energy level of degrading power disturbances is insufficient to destroy an integrated circuit immediately. Rather, slowly degrading disturbances erode internal semiconductor material, much like rust eats away at unprotected metal. Thus damage is slow, cumulative, and invisible.
Eventually, the semiconductor device breaks down internally, and unfortunately, when failure does finally occur, it’s often difficult to establish cause and effect.
The third D is disruption. Any system with a microprocessor is subject to disruptive power disturbances. These disturbances contain the least amount of energy but are far more mischievous because disruptive disturbances have two power pathways to gain access to a system.
The first pathway, between the hot and neutral conductor of the electrical system, is called the normal mode pathway. When high frequency, low voltage, normal mode power disturbances are present, they may easily couple through the power supply or enter a system via numerous parasitic pathways. Often mimicking legitimate level signals, they can still cause microprocessor lockups, errors, or other unexplainable operational problems.