lighting Engineering for Football field: Guide to sports field lighting design
1. Calculation of sports field lighting design
(1) Estimation method of unit area capacity
N=P×A/PL Where: N—number of floodlights; PL—power of each floodlight W; P—power per unit area W/m2; A—illuminated area m2
m=1/η×η1×U×U1×K Where: m—simplification coefficient; η—lamp efficiency; η1—light source efficiency, 1m/W; U—utilization coefficient; U1—illuminance uniformity; K—lamp maintenance coefficient = 0.7~0.8. The m values of different light sources are given according to η=0.6. U=0.75. U1=0.7. K=0.7.
P=m×E Where E is the minimum illumination, lx.
(2) Average illumination calculation method
N=E×A/η×F×K Where: N—number of lamps; E—average surface illumination lx, A—illuminated surface area m2; η—efficiency of lamps; F—luminous flux 1m; K—maintenance factor, take 0.7~0.8. The above two illumination calculation methods are widely used, mainly used for illumination estimation, and are more suitable for the scheme and preliminary design stage.
(3) Point-by-point calculation method of point light source
EΦcosα±D/h×sinαEh=Ψeh Eh: average illuminance lx generated by a lamp irradiating a vertical surface;
Eh=Iθ×cosθ/R2 Iθ—light intensity cd in the irradiation direction at angle θ; R—distance m between the light source and the illuminated surface; h—vertical calculated distance m between the light source and the vertical surface; D—projection m of R on the vertical surface; α—angle between the inclined plane and the horizontal plane, in degrees; θ—angle between the center of the light beam and the horizontal plane, in degrees; Ψ—coefficient, Ψ=cosα±D/h×sinα.
2. Choosing and Arranging sports field Lighting Fixtures
(1) Choosing sports field Lighting Fixtures
For side lighting, use a fan-shaped beam type B or C, while for the four-tower lighting setup, a cylindrical symmetrical beam type A is recommended.
(2) Arranging sports field Lighting Fixtures
For four-tower lighting, the fixtures should be positioned in the area between two lines that intersect the goal center line and the bottom line at a 15° angle, as well as the half-court center line and the sideline at a 5° angle. The lights should be placed along the diagonal of the field.
For mixed lighting, the angle and direction of the mixed-type fixtures can be adjusted as needed, allowing for a reduction in the length of the light strip and the height of the fixtures as well.
3. Sports Field Lighting Power Supply Design
Designing a lighting power supply involves several key steps. First, two power supplies are sourced from the low-voltage distribution room, each typically handling about 50% of the load. This setup allows for continued operation even if one power supply fails. However, it's important to note that gas discharge lamps require a restart time of 10-15 minutes and cannot be ignited immediately. There are two methods for switching: manual mutual switching and automatic switching.
Next, the control of the competition lights is primarily achieved using AC contactors or contactless thyristors. It is recommended to implement a single lamp with individual control.
Lastly, when igniting gas discharge lamps, the initial impact current is quite high. Therefore, when turning on a single lamp, there should be a 0.5-second interval, while for group control, the interval should be between 10 to 30 seconds.