Electrical Lessons

Editors note: this is the second part in a series on Lewis & Clark Community College’s installation of several Sennheiser K-Array systems.

As far as this project is concerned, my responsibility has been primarily to design the system and connect all the ins and outs correctly. One aspect that has been a learning experience for me is the area of electric. Now, I realize how important electricity is to the systems we install. Without it, we have nothing. Something I have learned over the years is the importance of keeping our equipment on the same phase.

A quick primer for those not familiar with what I mean by phase. When electricity is created, back at the power plant, a generator spins around very quickly powered by everything from coal to nuclear power. This generator has a three-spoke ‘wheel” of sorts. Each “spoke” is considered a phase. Hence the term single-phase system, three-phase system, etc. Most of the AV systems you will work on will only require the single phase. If you work in a large facility like a hospital or college campus, the facility will be getting three phases of power. Each phase will go to several different power/breaker boxes throughout the building. Depending on where each outlet in the room is coming from, they may be on different phases.

This leads me back to our system. We have a control system, video processors, and audio processing going on in one part of this large banquet hall. The projectors are flown, so they are powered from the ceiling. The subs on the K-Array system also act as the amplifier, so power is needed at their locations as well. Working with a local electrician, the one thing I wanted to make certain of was that they were all on the same phase. If they are on different phases… let’s just say bad things can happen. It isn’t like the system will implode. More like you will get random lines or artifacts in the video, a hum in the audio, or just weirdness all around. These are ghosts you will chase forever unless you know about the phase. This is exactly the scenario by which I learned about phase.

If you are installing a new system, or are just on the outset of a project, make certain your architect and electrical contractor know about your wishes to keep all the AV equipment on the same phase. It’s easier in the design phase than it is after the fact. Another thing I learned the hard way.

Thanks so much for taking the time to read my blog. Have a great week.

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