“Power tends to corrupt, and absolute power corrupts absolutely.” (Lord John Dalberg-Acton 1834-1902)
Have you ever had a service call on a projector or a display where the customer said the unit was unresponsive? What about phantom problems that seemed to appear from nowhere and slipped back into the ether just as mysteriously, never to be heard from again – except at the worst possible moment? Maybe you’ve had multiple devices in a single installation fail prematurely. In many situations, issues such as these can be traced to a problem with electrical power – corrupt or otherwise. Lord Acton was not referring to electrical power. Yet, for a person born in the 19th century who never saw anything remotely like today’s AV systems, he had some impressive insight into our world of Pro AV.
I’ve had clients call me for emergency service while they were attempting a remote recording of a live concert – the input gain on their digital audio workstation (DAW) appeared to be stuck wide open and everything was distorting. Not my system design, but my client to service. Turns out, the external hard drives in the system were not connected to any type of power conditioning. The DAW interface and hard drives were both sharing the same USB buss and a surge to the drive’s PSU caused an error in the interface’s CPU. A simple reboot of the host computer fixed the problem, but they missed recording part of the concert. I’ve seen this exact situation happen more than once, with different interface manufactures, different drive manufactures and even with both Macs and PCs. (How the problem was isolated to the HD specifically is best left for another article on troubleshooting.)
In another incident, a client contacted me after cancelling training sessions due to a loss of image from their projector. Pressing the power switch didn’t change anything. Directly connecting sources to the projector, bypassing wall plates and intermediate devices, proved fruitless. The only sign of life was the lonely “lamp” LED blinking repeatedly – as if was letting out a tiny “Help Me…. Help Me…” in Morse code. The lamp was relatively new. As the trainees filed out of the room, the training manager was left scratching his head as he stared up at this sole little light on the projector….
The cause was traced to a temporary electrical power issue and the unit was revived with a hard reset by unplugging the unit, counting to ten, and then restoring power to the unit. Fortunately, this projector was mounted in an easily accessible location making this hard power reset a reasonable task for someone onsite. However, the training opportunity was already lost for the client and stress levels needed to be brought back to a lower orbit.
While each of these situations caused moderate financial losses and inconvenience for the clients, there were no catastrophic implications. Yet, who knows how severely the lifespan of the equipment was impacted by these incidents. Not everyone is this lucky. (It’s a good thing displays in the board room or a front-of-house audio console didn’t hiccup as well.) “Power corrupts absolutely” and permanent system failures are to be expected when a system is not protected. Problems can be avoided with the proper power management designed into the system. Additionally, some power management devices provide remote monitoring and power cycling to minimize client downtime, improving your service response times, and reducing costs for both resellers and end-users – not to mention what it does for blood pressure.
If we used an oscilloscope to view the waveform of idealized power at a 110V outlet, we would see something like the 60Hz sine-like wave with overtones, shown in figure 1.
However, we rarely have such clean power coming directly from a wall outlet. Several types of corruption commonly occur.
Spike and surges (See Figure 2)
Temporary significant increases in voltage can originate from activity far outside of an installations location. A myriad of causes are to blame – ranging from a neighbors air conditioner kicking in or fluctuations from the power grid itself.
Sags or other voltage fluctuations (See Figures 3a and 3b)
Power companies will sometimes intentionally reduce output voltages in order to keep up with high power demands. Additionally, as the power comes back up, it does not always return to the ideal level. This can lead to temporary over-powering.
AC power is similar to an unbalanced audio signal, except at a much higher level, and is therefore subject to much of the same types of interference. Line noise from other signals being inducted into the AC path is shown in Figure 4. Causes range from Radio Frequency Interference (“RFI”) to “wireless” intercoms and similar devices that “transmit” over existing power cables.
Finally, one of the most dreaded types of power is illustrated in Figure 5.
Yes, that is a blackout.
As we can see, there can be a big difference between the electrical power “signal” most devices expect, and what is actually coming out of the wall. Modern Pro AV equipment, particularly devices with a CPU or embedded processing, can have a particularly hard time with this.
So, what is the solution? With over 2500 different options, just from a single manufacturer, where is a system designer to start? There are three steps to make this easy.
- Instead of trying to know every product, perhaps start by knowing the general types of power-related solutions and their function.
- Add to that a few basic models and where they can be applied.
- Then depend on resources, such as your Almo rep, to help you find the specific solution for your application.
Let’s dive in….
- Surge Suppression – Minimizes potentially damaging short-term high-voltages. Correcting what is illustrated in figure 2.
- Voltage Regulation/Stabilization – Maintains a constant output voltage even if the input voltage increases or decreases. Uncontrolled voltage fluctuations can manifest in a variety of symptoms in electronic equipment – ranging from a random malfunction to total shut down.
- Line Conditioning – Varies by manufacturer, but typically involves removing “noise” from the power that can corrupt other signals. This addresses the issue shown in figure 4.
- Back Up/Redundancy/UPS – Provides power even if the main power is lost. The need for power back up and redundancy extends beyond the Mercedes-Benz Superdome for the Super Bowl and hospital operating rooms. Most live events, situations where recreating a particular setup is labor intensive, and equipment requiring a shut down period can benefit from this class of protection. For example, skipping cool down for a projector due to a power loss can result in premature lamp failure. In some cases, the replacement lamp may even cost more than a UPS. Computers that abruptly lose power may suffer permanent data loss or may not properly reboot at all.
- Distribution – Allows multiple power sources to be split off a single source. This can be as simple as a power strip or a rack mounted series of outlets.
- Control – Provides the ability switch power on or off from another location – either at the same site or remotely. Helpful for sequencing power up or down, cycling power in difficult to reach locations, or for conducting a hard power reset without dispatching a service technician.
- Diagnostics – Helps maintain an eye on systems to make sure they are functioning properly and to avoid problems before they occur.
Step 2 – a couple examples from the above items:
- Both the Tripp Lite AV2FP and Furman AC215A provide surge suppression and line conditioning in a form factor small enough to fit behind a flat panel display or with a projector.
- For voltage regulation in a rackmount format, both the Furman – PL-PRO DMC and Tripp Lite 2400W Rack Mount Line Conditioner provide a constant output voltage even if the input voltage varies up or down significantly. They both also provide surge protection and line conditioning.
- Properly choosing a UPS or backup device requires a more thorough understanding of the specific application and being able to answer some key questions. Are there acceptable transfer times to backup power or is a zero transfer time required? What type of circuit does the equipment require and how much power does it draw? How long must equipment be able to run on backup power? What type of input circuit is available? One example of a UPS is the Tripp Lite – SU1500RTXLCD2U. Extended run times are available with an external battery pack, such as the BP48V242U.
- When it comes to control and diagnostics, each manufacturer has their own unique approach. Some opt for end user simplicity with widespread browser-based compatibility. Others opt for more comprehensive solutions that may require manufacturer certification in order to deploy or maintain. It is worthwhile to see a demonstration of various solutions before choosing one for a particular application.
Even though “power corrupts absolutely”, choosing the right power management solutions for each project will protect you and your clients. While it may seem like there are a lot of options and variables to absorb, there is comfort in knowing that you don’t need to know them all – or even most. Instead, depend on your Almo representative to help you in the process. Our team has the expertise and resources to ensure you select the proper solution for your project. So the next time you call, ask for details and take advantage of distribution on a personal level.