Dropping the ball, or dropping the lights? Approaches to mitigating interruptions in lighting at sporting events
When you’re attending a game or watching it on television, the last thing you think about is the lights going out. We certainly never thought we’d witness a power outage at the nation’s biggest sports event of the year, but while watching the third quarter of Superbowl LXVII on Sunday, February 3, that’s exactly what happened. After a large group of HID light banks suddenly went out, fans, officials, crews, and players were left in near darkness for about 34 minutes.
Hundreds of reports as to why the lights went out at the Superdome in New Orleans were released into the media, and commentary flooded the Internet. One report stated that electrical equipment connecting the stadium to the electric utility was replaced in December — and that the problem didn’t appear to be related to that equipment. Metering at the Superdome indicated nothing more than a normal load during that game. Another account stated that Superdome officials were concerned about the facility’s electrical system months before the game. Many vital repairs were made, but not all were able to be completed. Testing of the feeders that power the stadium indicated some power quality problems. Ultimately, protection relays on the power feed to the stadium detected the problem, and automatically shut down the system. No matter what the culprit was behind this outage — whether it stemmed from faulty equipment, improper maintenance, or human error — the bottom line is this outage caused a severe interruption to the game and significant impact to the financial success of the event.
Lighting the way
As was evidenced by the recent Superbowl outage, providing proper illumination for sporting events is no trivial matter on any level. Indoor arenas and outdoor stadiums typically cut no corners when it comes to lighting.
Like any other lighting system, one designed for sports lighting requires maintenance. Prior to the use of high-intensity discharge (HID) lighting, incandescent lamps were the standard for sports lighting. Today, the standard is metal-halide HID lamps. Most applications use either a 400W, 750W, 1,000W or 1,500W metal-halide lamp. However, many still use probe-start lamps, while some have upgraded in the last 20 years to pulse-start units. All applications today still use the magnetic ballasts designed for HID lamps. For a comparison of warm-up and re-strike times, dimmability, and full-spectrum performance for various lighting technologies, see the Table.
Days before a game, each bank of HID lights is tested by arena or stadium officials to ensure they start up properly and come up to full illumination. If the numbers of failed and weak lamps are too high, they are replaced immediately. Illumination levels and color are checked at various locations on the court or field to ensure proper lighting for TV cameras. Lights are turned on way before dusk to provide enough time for camera checks and adjustments. In addition, lights remain on for hours after a game is over, giving crews time to clean the court, clear the field, and pick up the messes spectators leave behind.
Like other customer facilities, spectators and even stadium/arena crews and game officials take power to the stadium for granted. Depending on the size of the sports complex — a local high school football stadium, basketball arena, or a superdome for professional football — the complex may be powered by more than one electric utility feeder. Stadiums and arenas require power for a complex array of loads. While the outdoor lighting represents the majority of the load, there’s much more to it than that. These facilities require power for scoreboard systems, audio systems, office equipment, HVAC systems in bathrooms and skyboxes as well as power on the court or field for support equipment.
Approaches to mitigating interruptions in lighting
There are three possible scenarios for preventing the dropout of an HID lighting system at a sports complex, as shown in the Figure. First, you may choose to inject energy at some point along the AC power system to keep energy flowing to the lighting system when energy is depleted from the system during a power outage. Secondly, you can “override” the HID lamp by adding a hot-restrike system. Lastly, you may provide a premium power feed to the sports complex. Let’s take a look at some options in more detail.
Contract for premium power. Some electric utilities can provide a distribution feeder with higher reliability. Such feeders have been recently upgraded and are either dedicated lines from a substation or have only one or two customers sharing the line. Such feeders may also have historical power quality data available for review, indicating their reliability. Customers will pay a premium price for this service. However, given the infrequent use of most arenas and stadiums, providing premium power may not be the best choice.
Install hot-restrike gear on each HID luminaire. Some manufacturers provide an add-on hot-restrike system for metal-halide lamps. Such systems can sense when a lamp extinguishes and provide a high-voltage starting pulse higher than that typically needed to start a lamp. The pulse will achieve breakdown in the lamp’s arc discharge tube, allowing the lamp to restart while hot. These systems do require energy while in standby mode, which will — to some extent — degrade energy performance of the lighting system. These systems can be bulky and expensive, as well as difficult to fit into certain types of lighting fixtures. Some may also require you to install new lamps.
Install an uninterruptible power supply (UPS) on the lighting system. Uninterruptible power has solved a lot of power quality problems when line voltage is not available. Some UPS manufacturers produce systems specifically designed for HID lighting. It is not economical to install a UPS on all HID lighting systems. Depending on the size of the HID system, how frequently it is used, and the financial impact to the customer’s business when the lamps go out, a UPS system may not be the best choice either. In addition, using a UPS system will add to the customer’s facility load, take up floor space, and require a significant capital investment.
Retrofit the HID lighting system to another system. Another viable option may be to replace the existing HID system with another lighting system. However, because sports complex lighting applications have some unique requirements, lighting technology choices for replacing sports lighting may be limited. Although the use of a lighting system for actual game time occurs only a few dozen times per year, the lighting system must be powered up for practices and other local events requiring the use of the complex. Therefore, reducing the energy consumption of the lighting system is a definite advantage to the arena and stadium operators.
Dimming is not presently used in sports lighting. However, it may soon become very useful, because arena /stadium officials and broadcasters require a check of the lighting system before dusk. Once the lighting system is verified with the TV cameras, its power could be reduced and then increased as game time approaches. The warm-up time that induction lamps offer over HID lamps will also be of benefit to arena and stadium officials and broadcasters as they desire to have light levels at full output very quickly. A short warm-up time is also extremely complimentary with a zero restrike time that induction lighting offers. In the event of a power problem, the lights will instantly restart and return to full output in less than one minute. With this, no time will be lost during the game, and broadcast schedules can be preserved.
Full-spectrum lighting is the closest in wavelength to actual daylighting conditions. Today’s television cameras are fully digital designs that operate on full-spectrum light. Use of full-spectrum lighting from induction lamps will improve TV image capture and camera performance during the dynamics of sports and game plays under diverse conditions players must endure during a game.
Keebler is a principal engineer and partner at KCE Engineering, LLC located in Knoxville, Tenn. He can be reached at firstname.lastname@example.org. Evans is VP technical services with KCE Engineering, LLC. He can be reached at email@example.com. Reid is laboratory manager with KCE Engineering, LLC. He can be reached at firstname.lastname@example.org.