A lot has changed since light towers first appeared on construction sites nearly a half-century ago. At the time, light towers revolutionized the industry by allowing crews to work into the night on outdoor projects previously limited to daylight hours. The addition of trailers allowed light towers to be transported to virtually any jobsite creating opportunities across the industrial and commercial spectrums to include not only construction but mining, security and airport applications, to name a few. However, with increased usage came the increased possibility of misuse.
Problems arose with portable light towers. As the sun came up, workers didn't realize light towers were left on — in some cases, all day — adding operation hours to the engine and prematurely consuming the machines' life expectancy. Light towers were typically shut down without turning the lights off first, potentially damaging the generator being shut down under load. Light towers often ran out of fuel, burning up the starter motor or fuel solenoid attempting to re-prime the diesel engine. In addition, insufficient warm-up before turning the lights on took a toll on the engine. Operating costs rose and serviceable life shrank.
To combat these problems, manufacturers developed a recommended start-up/shut down process. The operator was instructed to start the engine and allow the generator set to warm up before turning on the lights. When it came time to shut the tower down, the instructions were to turn the lights off first before shutting down the engine. For projects utilizing only a few towers on a manned site, this procedure worked well. The challenge emerged when multiple light towers were operated on multiple sites or in remote locations needing to be controlled and monitored. Costs skyrocketed as a result of additional personnel operating and monitoring towers on different sites.
Although auto-start packages were available for engines, none had the capability of controlling the lights of a light tower. Until recently, the technology for a light tower auto-start/sequence controlled system simply wasn't available until the first auto-start system with light sequencing control was introduced to the market. The system consists of an electronic package that manages the portable light tower from engine start to control of the lights and engine shut down with virtually no human interaction. Light sequence control systems eliminate the need to micromanage multiple light towers at different locations and reduce excessive engine wear and wasteful fuel consumption.
Automatic sequencing
Light sequence control systems prevent possible generator set damage by ensuring the engine is up to speed and warm before the lights are turned on, and shut down only after lights are turned off. When the start sequence is initiated, the glow plugs run as needed, the engine is started, and when it reaches a given temperature, the lights are turned on. Conversely, light sequence systems have the capability of turning the lights off prior to shutting the generator down. This system can be controlled by a photocell sensor, digital timer or a wireless communication device. Light sequence control systems enable light towers to be totally self-sufficient, saving time and labor and maximizing life expectancy of both the lights and the generator.
Photocell start
Utilizing a preset photocell sensor, light sequence control systems allow light towers to be automatically turned on and off as needed — without human interaction. When set in the automatic mode, the photocell sensor detects ambient light. As daylight fades to a preset light value, the photocell sensor triggers the auto-start package and initiates the start-up sequence. Conversely, as the sun rises in the morning, the photocell senses the increase in ambient light and turns the lights off to begin the shut down sequence.
The automatic photocell mode allows the user to set the tower up for long-term use over a period when the sun rises and sets at varying times. For example, a tower is set up on a jobsite the first week of March when the sun rises fairly early. It is programmed to run in the automatic mode and will sit in the same place for four months. When daylight savings time begins in April and sunrise is an hour later than the previous morning, there is no need to reprogram the light tower.
Digital timer
The photocell start option is ideal when the light tower needs to run all night. However, in some cases, the towers only need to be lit at certain intervals during the night or only one day a week. For these situations, a light sequence control system offering a digital timer start option provides the best solution. Able to hold up to eight events in a day, programmable timer systems can accommodate virtually any lighting schedule. Giving the user the ability to program the light tower to run only when needed, a digital timer system cuts down on wear and tear and reduces fuel and maintenance costs.
Another advantage is the flexibility to easily handle applications with varying lighting schedules. For example, an airport has planes coming in from 10 p.m. to 3 a.m. on Mondays and from 8 p.m. to midnight on Tuesdays. Light sequence control systems featuring a digital timer allow runway personnel to program light towers ahead of time to turn on and off at specified times, allowing them to concentrate on the job at hand. The light tower will run on the pre-programmed schedule.
Wireless modem
In addition to the programmable timer and the automatic photocell sensor modes, some light sequence control systems feature a wireless modem start option that activates the start-up or shut down sequence. Wireless modem modules function similar to a computer with a dial-up modem. The operator calls the modem embedded in the light sequence control system from a wireless communications device, such as a cell phone. Through this device, the operator has the ability to control and monitor one or multiple light towers from a central, remote location. This enables operators to sequentially start or shut down towers in the case of a schedule change, bad weather or a cloudy evening. It limits the need to run from jobsite to jobsite to manage several light towers with different settings.
Shut down sequencing
Photocells, digital timers and wireless modems allow the user complete control over the light tower start-up and shut down sequences. However, there are situations out of the users' control that can increase maintenance concerns. Some sequence systems offer safeguards for those “uncontrollable” situations.
One of the most common maintenance problems with light towers stems from the diesel engine running out of fuel. Completely starving the fuel system creates the need to re-prime the engine, which can result in starter damage if the engine is over-cranked during the process. Light sequence control systems offering an automatic low-fuel shut down feature eliminate this concern by initiating the shut down sequence when available fuel reaches 10 percent of capacity. With this feature, the engine will never run completely out of fuel and, as a result, will not require bleeding upon refueling — eliminating possible damage due to over-cranking.
Other than regular engine maintenance, the light tower only requires attention for refueling. A typical user will come to know the fuel capacity of their light tower. Taking that into account, along with the number of hours they have programmed into the lights, one can establish a refueling schedule.
If the light malfunctions during operation, the diagnostic LED fault protection indicates if the machine has been shut down due to low oil pressure, high water temperature or low fuel or if the engine failed to start during the automatic start sequence. There is an oil pressure shut down circuit that shuts everything down immediately without going through the sequence to turn the lights off. The same process occurs when there is a breach in water temperature. Eliminating the sequence in emergency situations saves the engine from further damage and lowers maintenance costs.
Smart circuitry
Most diesel engines come equipped with glow plugs. Glow plugs preheat the air into the cylinders to facilitate starting. However, the amount of time required for glow plugs to do their job varies by engine and manufacturer, sometimes as much as 45 seconds. Additionally, ambient temperature fluctuations affect how long glow plugs are required.
To handle varying ambient temperature conditions and accommodate a variety of engine requirements, some light sequence control systems include circuitry that manages glow plug dwell time. Controlling all necessary starting procedures, the circuit senses engine water temperature and determines the glow plug time requirement and schedules repeat intervals, if necessary, to start the diesel engine.
For instance, if the engines on a particular jobsite are all cold and it's 0 F outside, the circuitry embedded in the light sequence control system will run the glow plugs for the maximum amount of time recommended by the engine manufacturer. If the engine has been running or it's 70 F outside, most light sequence control systems are smart enough to know that the engine is already up to 70 F. Consequently, it may only run the glow plugs for a few seconds or not at all.
A commanding savings
Portable lighting has advanced greatly since the mid-20 century. Not only have light towers revolutionized construction and expanded into multiple industries, but they have also evolved into completely self-sufficient machines requiring almost no human interaction. With innovations constantly on the horizon, light sequence control systems provide today's latest technology to light towers allowing a huge savings to owners by cutting labor, fuel and maintenance costs. Proper use of light tower technology ensures a safer, more efficient and more productive operation, leading to satisfied crews and higher profits.
Doug Dahlgren is product manager for Allmand Brothers Inc., Holdrege, Neb.
Terex
The Terex-Coleman and Terex-Amida line of light towers and detour lighting provide contractors with cost effective options for acquiring the right lighting equipment for their business. And efficient, portable design combined with ease of maintenance and many safety features make Terex lighting products able to withstand the rigors of rental. Uses for these units include evening construction projects, sporting events, civic outings and roadwork or just about anywhere else that portable lighting may be needed.
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Wacker
The new LT series of light towers from Wacker comes with a redesigned lighting system that offers brighter illumination. The improved lighting is achieved through the use of distinctive elliptical light fixtures. The fixtures allow the lamps to be mounted horizontally, allowing more light to travel directly from the source to the work area. This improved lighting is accomplished with the industry standard 4- by 1,000-watt lamps.
“Lowering the winch was easy,” says Andy Schumacher, branch manager for Lincoln Contractors Supply, West Allis, Wis. “The easy to grip t-handle made adjusting the lights without any tools quick and simple, and the unit is compact and lightweight, making it easy to tow.”
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Ingersoll-Rand
The IR LightSource is specifically designed to meet the requirements of the rental market and incorporates features such as a 6kW generator, an extended generator warranty, 68 hours of operation, standard power receptacles and a 30-foot tower extension. It is capable of operating four, 1,000-watt metal-halide or high-pressure sodium floodlights. The standard metal-halide floodlights provide a NEMA-six beam spread for better light distribution and area coverage. The control panel features individual lamp switches and controls that include GFI-protected, 120-volt/15-amp duplex and 240-volt/20-amp twistlock receptacle, a key-switch ignition and an hourmeter.
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Allmand Bros.
Allmand Bros. introduces the LSC100 light sequence commander, the industry's first automatic lighting sequence and command control system. Available with all of Allmand's portable light towers, the product uses a preset photocell sensor that allows the light tower to be automatically turned on and off as needed. At dusk, the sensor engages the power unit and then activates the lights. As light increases in the morning, the sensor automatically switches off the light and power unit.
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Multiquip
Multiquip's 7,000-watt DA7000SS generator, 225-amp diesel-driven welder/generator, 250-amp gas-driven welder/generator or any available AC power source can interchangeably power its light towers. The 50-inch wide units are designed to withstand rough transport, use on uneven terrain and winds up to 72 mph when deployed with gensets or up to 45 mph with the trailer only. In addition, zinc-dichromate tower sections, outriggers and socket tubes reduce corrosion and promote longer life. The unit's tower-tensioning system provides the necessary tension to safely control the pivot of the tower.
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Magnum Products
The Nightbuster MLT3060 from Magnum is only 48 inches wide and has a full tubular steel frame. The product incorporates the brand new start limit breaker. The SLB eliminates the potential of starting the engine with a load on the generator. This safety feature protects the generator and any loads connected to it. It also features four individual ballast boxes; four individual ballast indicator lights; four individual circuit breakers; stable 4-point outrigger stance; coiled mast cord; low oil/high temperature automatic shutdown; hour meter; 120V GFIC and 240 twist lock outlets; and 30-foot extendable, 360-degree rotation mast; and 30-gallon fuel tank.
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Bull Dog
New Silver series includes quartz halogen floodlights that light up work sites from 5,000 to 10,000 square feet. Weatherproof lights feature 500-watt high intensity quartz halogen bulbs and pebble finished reflectors to diffuse light for broad coverage. Tubular steel tri-pods are heavy duty with telescoping masts. The models include the S10110 with a 500W single lamp and 4 to 8 feet adjustable mast; the S10111 with two 500W lamps and a 3- to 7-foot height adjustment; and the S10112 with two 500W lamps and a height adjustment from 3 to 6 feet.
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