In my last blog I stated reasons, both ethical and professional, as to why a backup generator might be needed. If you decide a backup generator is the way to go there are several options. (Here comes the tech stuff.)
1) Splitting your system between multiple power sources (generators) is one method that has been used over the years. In this configuration you might run the décor lighting from generator # 1 and run the stage lighting from generator #2. While this is a simple and cost effective solution, the generator will cost you more in the long run due to additional installation, distribution equipment and cables. It will also complicate the systems required for Audio and Video which are not as easily split as the lighting system might be. In addition you will not have true redundancy. In a generator failure situation you will end up with half a show at best.
2) Using two generators with either a “MTS” (manual transfer switch) or “ATS” (automatic transfer switch) is the next best option. Both have the benefit of being less expensive and simpler than a true “twin pack” system and of being truly redundant to enable the entire show to go on, but both have flaws. An “MTS” needs someone to turn the switch in the case of a failure which can take some time if they aren’t standing right there. An “ATS” will switch itself if it senses the primary generator is no longer producing power after 10 seconds. With both of these switches you will experience a complete power failure before being able to restore power. You will need to reboot all of your systems. Any video projectors and moving lights in your system will take up to 10 minutes to come back on-line depending on the fixture and how hot the lamp is since they need to cool before restrike.
3) Using what is commonly called a “twin pack” is the ultimate backup / redundancy approach. In simple terms a twin pack is two generators that are wired together running simultaneously in parallel. Special circuitry enables the two generators to be synchronized so that they both can power the same distribution system at the same time. Each generator handles up to 50% of the power load and since each is already running and “on line” each will instantly make up for any issues with the other machine, whether it be a voltage spike or a shutdown. This is by far the most complex of your three options and requires specialized training, but it is the most reliable option. I know you’re thinking “wow that seems complicated”. Don’t worry, your generator company has technicians for a reason, this is what they do.
The best people to advise you on the issues of electrical power distribution will be either your generator contractor, or many times your lighting contractor. It is important that you make them aware of all the potential electrical power needs for your event. Remember to include catering, production offices, safety lighting, dressing rooms, restroom trailers and anything else that will need electricity to operate. After gathering all this data your professional will be able to plan a power system that safely meets your needs.