Most of the indoor arena and sports stadiums use HID (high-intensity discharge) lights for overhead lighting. For that reason, stadium lights have the higher wattage than other lighting applications such as parking lots, roadways, and billboards. Even though HID lamps have proven to be effective for lighting application, they also require substantial time for warm up and thus can achieve the required brightness after they have been extinguished[1]. Still, HID lamps are limited to warehouse, outdoor, and industrial applications because they have the high level of lights output. For example, the incandescent lamp of 60-watts will produce about 800 lumens of light for every output[2]. Industrial and residential applications require lamps that can provide lumens ranging between 800 and 4000 lumens for every lamp.
However, HID lamps can provide more than 15000 lumens from every lamp. This will only make them suitable for factories, warehouses, and sports stadium applications. These are areas, which requires a lot of light. On the other hand, other types of lighting such as halogens lamps, LED (light-emitting diode), and incandescent is used for applications such as general illumination, signage, and signals application. Therefore, the design principle of the stadium light will be based on the design of high-level stadiums lights with the required working efficiency.
Literature review
Because of the high efficiency, excellent color, and long life (20,000 hours), HID lights are widely used for outdoor lighting such as sports stadiums and outdoor arenas. HID has high brightness and excellent color temperature with high lumen as well as long lifetime that make it popular than LEDs.The design of HID lamps is very challenging due to complex lamp requirement, which offers a way to overcome potential issues such poor efficiency[3]. This has also resulted in the introduction of more efficient HID lamps.
Figure 1: figure illustrating HID lamp for stadium lighting
HID lamps are the best lighting systems for the outdoor lights due to high energy conservation and high brightness. Some HID lamps use radioactive substances to improve lamp operating characteristics[4]. For example, krypton-85 that is found in the arc tube of the lamp mixed with argon and thorium at the electrode, ionizing radiation produced by the isotopes causes high ionization energy making arcing easier through the use of Townsend Avalanche. On the other hand, thorium on electrode lowers the work function making arcing easier and thus sustainability.
HID lamps can also be used for indoor gardening, especially for plants and aquariums that require a lot of sunlight within their natural habitat. However, exposure to this UV radiation causes injuries to both human and animals. These might include sunburn, eye arc after every end life of the HID lamp.
The series lamp illustrated in the figure below is a lighting design that delivers unmatched 600,000+ hours L70 life and it also replaces 4000 watts HID fixture per LED fixture. The design layout is always preferred because it has a uniform coverage, which is contributed by the cutting edge optics it possess.
Figure 2: Figure illustrating a series of HID lamp that can deliver unmatched 600,000 + hours of life
Design Concept
The design concept of the stadium light is based on factors such as performance capacity, wattage, and control systems. The expected concept of the design is discussed as follows:
Performance Capacity and Wattage
Different lamps have their unique way of producing light; for instance, incandescent lamps have tungsten filament resistor that heats up to 2200℃ causing the metal atom to produce light however only 10% of the total energy is used, the rest is wasted. Similarly, tungsten filaments for halogen lamps are heated up to 2500℃ causing the filament to get white hot hence light produced due to re-deposition of tungsten atom back on the filament. On the other hand, fluorescent produces light when mercury atom collides with electrons that flow from one filament to the next producing ultra-violent light which is converted to visible light through phosphors coating inside the tube. Unlike fluorescent lamps, HID produces light directly without phosphor, operating at high temperature and pressure with a very short arc length.
Control Systems
Driving HID lamps requires 3-4 kilovolts or up to 20kilovolts for ignition current and a constant power supply while operating at a low frequency of an alternating current (ac) to avoid lamp damage, which is caused by mercury migration. by acoustic resonance i.e. 250-W nominal wattage requires 250-W for HID lamp which works on open circuit that makes high voltage to drop to very low value (20V typical), increasing current to very high value at the time of ignition. However, the voltage starts increasing as current reduces until a nominal value is attained (100V typical). Power also increase wheen regulated to correct level that meet requirements of different operating modes. Also, at critical conduction mode, power-factor correction stage (PFC) boost operation with a constant time and variable off time for rectifying half- wave of each ac cycle, including a free running frequency of a typical range between 200 kHz and 50khz.
Figure 3: Circuit illustrating the design of the HID lamp for the Stadium lighting.
The buck stage is the main circuit controller that converts direct bus voltage to lower lamps (100V) for the steady state at the full bridge. It also measures the lamp power that is fed back to control on time of the buck switch during which current is supplied to the full-bridge as it charges linearly to the peak through the buck MOSFET and inductor[5]. The same continues to flow into the full-bridge via buck diode and inductor during off-time. Induction reset when the current is zero and voltage transitionally start on off-time quickly to signal the circuit making on-time continuously increasing or decreasing loop feedback to keep power lamp constant.
Figure 4: illustration of the operation of the Full Bridge Control of the lighting system.
Figure 5: Illustration of the circuit of the expected design
The microcontroller can be used as a discrete analogue for the full bridge and buck requires external large amount of circuitry due to high and low gate drive signals and a complete circuit is controlled by IC, integrated 600V (high and low). Protecting against fault conditions, the design has necessary circuit that prevent it from failure caused by warm up, arc instabilities, ignition failure and short circuit output which is programmed by programmable fault timer.
Figure 6:Agraph illustrating the performance of the expected HID lighting system.s
The performance of the design can be illustrated using the graph illustrated above. The graph showed that before ignition of the lamp in an open circuit voltage drops to lower voltage (20V) due to the low resistance of the lamp causing the current to increase to a very high value. In that case, warming up of the lamp is therefore limited to a maximum safe level. The power is regulated at a constant level after the nominal voltage has been achieved (100V) for the lamp to produce power and voltage. The same electronic ballast requires different operating modes.
Conclusion
In conclusion, the design principles for the stadium lights requires a lot more than the concepts of the control systems and minimization of the wattage of every lamp. Factors such as cost need to be put into considerations. This is because cost will determine the quality of the design. Perhaps, the client might be looking for the factor that comes with affordability. Moreover, outdoor lighting such as stadium and sports area requires lamps that are of excellent brightness and have good power saving mode. Therefore, the long life of the HID lamps make them suitable choices for the designing of the stadium lights. It can also be incorporated into the standard multistage circuit topology with ease of scalability depending on the required source of power.
Bibliography
Awasthi. O. 2015. Applications of light and energy management. Oxford UK
Du Plessis, U. 1994. "Local sportslighting production". Elektron. 11 (7): 50.
"Lean Tools to Evaluate Lighting Conditions". 2018.
Lamping S.2016. Multidisciplinary design optimisation as strategy for building design.
[1]
Awasthi. O. 2015. Applications of light and energy management. Oxford UK
[2]
Du Plessis, U. 1994. "Local sportslighting production". Elektron. 11 (7): 50.
[3]
Du Plessis, U. 1994. "Local sportslighting production". Elektron. 11 (7): 50.
[4]
"Lean Tools to Evaluate Lighting Conditions". 2018.
[5]
Lamping S.2016. Multidisciplinary design optimisation as strategy for building design.
