Basic Properties of High Power Light Towers|
Article- Sept, 2013 By Larson Electronics.com
Larson Electronics Mega Light Tower 2,400,000 Lumens
Light towers represent an integral part of many industrial and commercial businesses, particularly those within the construction, demolition, mining and utilities industries. High power light towers provide the ability to continue operations after sundown, and provide the illumination needed to maintain a high level of production while also maintaining the safety of the workers on site. Light towers come in a wide variety of types and designs, and no single tower design represents a one size fits all lighting solution. Factors such as site size, operating time, the type of work being performed, and job site fluidity can all play a large role in deciding which light tower is right for the job at hand. To get a better idea of what light tower will work best for your needs, it helps to understand a little about them. The following provides some basics on light tower types and what you can expect from them.
There are really two main types of light towers, the portable light tower and the mobile light tower. Although the names sound similar, they really are two different designs with different intended applications. In the case of portable light towers, these are generally smaller units that can be easily transported, deployed and set up by one person. These comprise tripods and extendable towers usually not exceeding 10 feet or so in height, and they rely on external power sources to run their lights. These towers can usually be broken down and loaded into the back of a car or truck, and then transported and quickly set up wherever illumination is needed. Although these are smaller designs, they can be quite powerful due to the advanced types of lighting fixtures and systems which can be installed on them.
Mobile light towers are generally complete self contained lighting systems capable of illuminating very large areas for extended periods of time. These mobile towers contain their own power generation systems in the form of diesel engines and generators or foldable solar arrays and battery banks, extendable booms that can be raised to heights over 25 feet, large lamp arrays with up to 12 or more fixtures, and everything is mounted to a towable trailer platform that allows the system to be pulled behind vehicles. These mobile towers are commonly used on large constructions sites, emergency scenes, and outdoor events where two or more acres of area needs to be illuminated for extended periods.
Light towers both portable and mobile can be fitted with a wide array of lighting assemblies. The most common lamp types used on portable towers are halogen lamps of 500 to 1,000 watts. Portable towers can also be fitted with metal halide lamps, but this necessitates the inclusion of ballast assemblies as well, increasing the towers weight and complexity somewhat. LED lamps have recently become quite popular on portable towers due to their smaller size, high output and efficiency, and extreme durability, and are often a very good choice for operators who want a tower as compact and light weight as possible.
Mobile light tower systems overwhelmingly utilize metal halide lamp assemblies. These metal halide lamps are preferred on the larger mobile towers due to their extreme high output and good efficiency and when arranged in multiple rows atop a very tall tower are capable of easily illuminating over 5 acres. Metal halide lamps also offer very good light quality and high color rendering indexes, making them well suited to construction sites where safety, close work, and good detail rendering is important to maintaining productivity.
Getting a little more in depth with lighting assemblies, the type of lights used can have a significant effect on the overall performance of a tower. While most people generally assume that light is light, and the brighter the better, this is not the case. Different types of tower lighting assemblies have distinctly different operating properties, and understanding these properties can help make choosing a tower more simplified and effective.
Metal halide lamps are an established lighting technology that has been in use for over 40 years. These are known as HID (High Intensity Discharge) lamps, and produce illumination by creating an arc which ignites gases and salts within the bulb to produce an intense output of light. Some operating properties of metal halide lamps include the following.
High efficiency, producing 100-115 lumens per watt.
Very good color temperature and color rendering, producing clean white light.
Long lamp life approaching 10,000 to 15,000 hours on average.
Slow warmup times, requiring several minutes to warm up to full output.
Slow restart times, requiring 10-15 minutes between shutdown and restart.
Erratic operation as bulb reaches end of life, and distinct color shifting as bulb ages.
LED lamps have become very popular with light tower operators over the last several years due in large part to the major advances in LED design that have been taking place. Although not yet quite as powerful as HID lamps, LEDs still produce on the order of 60 to 90 lumens per watt, making them the second most efficient type of lighting behind metal halide. LEDs do have some distinct advantages over most other forms of lighting. Although not a fully developed technology as yet, they are more than capable of serving very effectively in tower applications.
High Efficiency, producing 60 to 90 lumens per watt.
Good color rendering and color index. Good contrasting.
Instant on, no warmup required.
No delay between on and off cycles. LEDs can be switched on and off with no cool down or warmup period.
Extreme long life. LEDs on average provide 50,000 hour of operation, longer than any other type of lamp. Greatly reduces relamping costs.
High durability. Not affected by cold temperatures and highly resistant to damage from vibration or impacts.
Good lumen and color quality maintenance as the LED ages.
The type of tower you choose depends greatly on the characteristics of the area to be illuminated. Very large sites tend to require the power and coverage of metal halide mobile light towers. Slightly smaller sites can be effectively illuminated with LED mobile towers as well. For sites requiring the highest possible light quality, metal halide should be considered. Portable LED and metal halide towers are ideal for small to moderately sized sites up to and acre or so in size. These towers are ideal for sites where the work site is fluid and operators may be working in one area, then need to shift operations to another part of the site. LED towers are also the best choice for operators looking to maximize tower efficiency as well as cost effectiveness over the long term as their low power requirements and high durability and longevity keep maintenance costs as low as possible.