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Wherever you are working, you will need power to run equipment.

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When Disaster Strikes, a Construction Genset's a Good Thing to Have on Hand

A remote site may not be miles away in the Middle of Nowhere. As far as your equipment is concerned, a remote site is one where your equipment and tools do not have access to the diet they consume every day. The site could be a section of town hit by a natural disaster like a hurricane or tornado; the site could be a new residential or commercial development, not miles from home but isolated in its way. Capabilities become more important than brand names or whatever’s in stock when it comes to selecting power for your equipment at remote sites.

“Get the right unit, in size and capability” seems to be the most basic and frequent advice. It’s similar to advice from experienced contractors about the attachments to use. You use attachments that your equipment can handle; you don’t try to run a 7,000-pound hammer from a skid-steer loader. Suppliers of gensets, engines, generators, and compressors (not all power is electric) have the information you require. Before purchase or rental, make sure the unit you intend to use has enough power to do what you want, but not too much. It’s the same principle as not using a 30-ton excavator when a compact model would do the job well. An oversized power source is a waste of money, and the mathematics of working out exactly what you will need are simple enough, especially for manufacturers or dealers who want your business.

Photo: Ingersoll-Rand

Photo: Terex-Amida

Power You Already Own
One source of power at your site may be there already, waiting for you to realize its potential. You probably drove it yourself and, for much of the day, it may sit idle in the corner. The City of Fayetteville, NC, uses an Ingersoll-Rand Onboard Power Solutions system, installed on a truck, to cut construction time and costs on some projects. In a recent application, the city was to provide water service for a new customer and the water line needed to be moved across a street. With an eye on saving labor costs, a four-person crew was directed to complete the job. By using the Onboard Power Solutions integrated system on the truck, the crew was able to get the compressor power needed for the job without having to worry about unnecessary trips to retrieve equipment, such as the backhoe loader that was being used on the site. Everything the crew needed to finish the job was with the truck, minimizing the time during which the crew was disrupting the road traffic to finish the job. The crew used the truck to run an air mole and an air tamp. The Onboard Power Solutions system can provide power to jackhammers, boring tools, impact guns, and air wrenches.

Fayetteville has also discovered that Onboard Power Solutions can help cut fuel costs, a significant benefit with today’s gas prices. “It minimizes the road time required to go back and forth hauling equipment, or having the truck tied up with a pull-behind compressor,” explains Joe Holland, project coordinator of the City of Fayetteville Public Works Department. “The truck with this onboard equipment is a big savings on fuel and time.” If the crew had used a towed air compressor, they would have needed an extra truck or had to make an extra trip to haul the backhoe loader to the job site.

Your truck could be the power source you need for an underhood compressor to run those pneumatic tools. This system (VMAC is a leader in this sector) comprises the drive system, a belt-driven rotary screw air compressor, an oil cooler, an air/oil separator tank, and a throttle control. You won’t need to tow a compressor, and the system takes up little room; the separator tank mounts on the frame rail of the truck, and the other components are under the hood. You still have plenty of room in the back for the tools because you don’t have to mount a hydraulic or gas drive compressor there. VMAC’s system offers air-on-demand technology to match air output to air demand. As your tools need more air, the truck engine increases its revolutions per minute (rpm). With rotary screw compressors, you can run 100% duty cycle without having to wait for the air supply to catch up. Among tools that these underhood compressors have run are impact wrenches, grinders and sanders, concrete breakers, jackhammers (to 90 pounds), drills, lube systems, post pounders, tampers, and sand blasters.

Specialized Power
Equipment does break, and there are other jobs for a welder on a construction site. You could use a welder onsite, and a generator, and a compressor. What if you could have all three of those helpers in one neat package? One of the events in product manufacturing that always encourages confidence in customers is the combination of equipment from reputable manufacturers to make one good product. This is what you have in the Air Vantage 500, a welder-generator-compressor from Lincoln Electric. The product is described as something to have “when you need it all,” and it has proved successful for utilities, rental fleets, and construction contractors.

The air compressor is a VMAC rotary screw, direct-drive air compressor rated at 60 cubic feet per minute (cfm), 100 pounds per square inch (psi), and 100% duty cycle. It delivers plenty of air for plasma cutting (with the plasma cutter, of course, sold separately) and arc gouging, and it manages air tools such as an impact gun. This VMAC compressor converts engine horsepower efficiently to usable output for the user. There are no belts to change and no magnetic clutch to wear out. (Yes, it’s the same VMAC mentioned above for its “Underhood” compressor equipment.) “It continues to perform without failure under the most extreme work conditions” and “This compressor has been very reliable and produces a high volume that we need for our air tooling” have been comments on this compressor’s quality and performance. The compressor of the Lincoln Air Vantage 500 can be turned on or off with an easy-to-reach toggle switch on the control panel. The full output of 60 cfm is available when the engine is set to high idle mode, and there are 40 cfm available when the engine is in low idle mode. The air shut-off valve can be closed simply for connecting or disconnecting an air hose, with the valve conveniently (and safely) placed in a recessed area below the control panel. There is automatic compressor shutdown for high compressor temperature.

There is ample AC generator power in the generator part of Lincoln Electric’s Air Vantage 500. The generator is 20-kilowatt continuous three-phase, 240V AC, and it will operate industrial equipment such as pumps, plasma cutters, grinders, and inverter welders. There is 12-kilowatt continuous single-phase AC generator power for your common construction tools (and lights). The generator will let you simultaneously weld and use three-phase AC power. You could, for example, have 12,000 watts available at the same time as you are welding up to 250 amps. With the three-phase 240V receptacle on the control panel you do not require hard-wired connections; there is a matching plug included. In this product, the Air Vantage 500, Lincoln Electric seems to have put together an impressive union of technologies and products, not least the reliable VMAC compressor. The welder has the three-year Lincoln warranty and the engine and compressor are warranted by their individual manufacturers.

Choosing the Right Portable Generator
Earlier we mentioned that capabilities may be more important than brand names, but you should learn which brands are intended for light use (such as home applications) and which are for the more rugged demands that your site will make. The generator that is good enough for home use is unlikely to be what you require for your business. Your power source at the site will probably be starting and running heavy power loads and you will have it running for as much as eight hours at a time. It must work well in unkind environments and, today, it must run quietly. Here are some excellent manufacturers among those who could be suitable: Sullair, Multiquip, Kohler, Wacker, Ingersoll-Rand, Caterpillar, Cummins, Detroit Diesel, Atlas-Copco, Magnum, Marathon, Perkins, Coleman, Volvo, Onan, and Waukesha. Check out their Web sites for details of available and suitable models. “Once the generator is properly sized, you will be confronted with a wide variety of models and price points,” observes Marc Leupi, the Pump, Power & Light product manager for Wacker Corp. “Within the same power class, there is a significant price difference between the lowest-priced units and the most expensive premium units. The old adage about getting what you pay for applies here. The key challenge is to assess your power needs accurately. Many purchasers of premium generators have gone the economy generator route first, only to discover that economy generators cannot do what they need and end up costing more in downtime, damaged power equipment, and repairs.”

Among other factors that are emphasized by Mr. Leupi are those that give the generator the ability to start a load. Does that sound too simple? Don’t you believe it! There’s a saying from experienced users of power generators that declares, “If you can start it, you can use it.” Top-end generators have a brush alternator design with an automatic voltage regulation (AVR) to give superior tool starting and voltage regulation. Many tools require from two to five times the running amperage to start! A recent trend in alternator design is to incorporate a separate excitation winding which powers the AVR and rotor independently from the stator to ensure that, even under heavy startup loads, the generator will continue to create electricity. These are features that your generator dealer or rental store should know about. Basically, as said above, your job-site generator is going to be better (and more expensive) than one you’d use at home. It has more work to do.

There are other features that both manufacturers and users recommend you investigate before acquiring a portable generator for site use. The engine is critical to success. If the engine on the model you look at is of lower grade, beware. Lower grade? You need a commercial-grade engine; it will usually have a cast-iron sleeve, low oil shutdown, and a multiple-year warranty. Some of today’s better engines now have an overhead cam design (like a car) and that offers quieter operation, fewer moving parts, more power, and a lower engine operating temperature, all items that usually mean longer life and better performance. Another fairly recent development in better engines is the ground fault circuit interrupter (GFCI) sensor to monitor and protect against ground faults on all outlets (not just on the 120v duplex outlets as in most generators). It’s amazing how many users complain about the maintenance required for what used to be the standard GFCI outlets.

Other (technical) ideas you’ll hear about may be inverter generator technology and auto idle systems. The more expensive generators often use auto idle systems that will throttle down the engine after a time of no load (four to 10 seconds, for example). Said like that, it may seem insignificant, but it can save fuel, reduce noise, and extend the runtime of the generator. Your generator may run all day, but it is not running constantly at full load, so the auto idle can build up a good savings with no weakening of capability. In cases were high power demands are infrequent and you’re looking for a genset with a low noise profile, Subaru’s Robin Silent Series offers inverter generators from 1,650 to 4,300 watts. Advanced inverter generators run the engine at a slower speed for low power use and automatically increase speed as more electrical power is required. Further sound reduction is achieved through the reverse cooling design, allowing the genset to be fully enclosed in a sound-absorbing poly-resin enclosure for near-silent operation. It’s a technology that is still relatively expensive but one to keep your eye on.

Fuel for the Power Source
Diesel engines seem to be the favorites for commercial generators. Engines powered by natural gas or propane tend to be quieter and they comply well with emissions requirements, but they can be more expensive to run than diesel units (as much as three times as expensive) and their life expectancy is considerably less. Don’t ignore gaseous powered engines, because many are most efficient, but do make sure they will serve you as you wish.

Liquid-cooled, 1,800-rpm diesel engines can, if properly serviced, give you some 20,000 hours of reliable operation. (Engines at 3,600 rpm can offer 10,000 to 15,000 hours.) Something you may wish to consider is that diesel generators are engineered for off-road applications and they can run on the dyed (farm/construction) diesel fuel that is less expensive because it pays no road tax. Make sure you are allowed to use it!

Diesel engines love to work hard. One of the negatives fired at diesel engines is a condition from which they can suffer called “wet stacking.” If the engine runs for a long time with a light load (less than 40% of its rated load, say), it may start to smoke and run rough. That’s because the injectors become carbonized and the engine has been what you may describe as over-fueled. The solution is simple, say users. If you run a heavy load, the problem will usually be solved, rectifying the over-fueled condition and letting the engine get back to normal. Another negative about diesel engines that you are probably already aware of is that, in some states, they are banned from running more than a certain number of hours per year. That’s worth checking at your site. A final negative mentioned about diesel gensets is that, initially, a high-quality diesel genset will cost significantly more than an inexpensive air-cooled gaseous genset of the same size. Will you be concentrating on the initial cost of your power source or on its lifetime cost of operation? It’s the same with durability. At your site, your power source needs to be rugged. Some generators and gensets are obviously less sturdy than others; you can tell that from their frames. Every time you are shown a potential purchase, ask yourself how it will stand up to the everyday demands of your work and your workers. Even if you require only a small generator, its frame should be strong, not like the legs of some occasional tables you see available at many garage sales. You don’t want a puff of wind to blow it over.

What Do You Look For?
Let’s look at those features of power sources that some leading manufacturers emphasize, and we’ll come up with some good questions to ask the supplier with whom we deal. “The quality advantages of Wacker’s portable generators start with the rotating field alternator with automatic voltage regulation and separate excitation winding,” notes Julie Shuster for the manufacturer. “The result is a machine that offers excellent voltage regulation and superior motor starting ability compared to most competitive generators on the market. This greater motor starting capacity is a real advantage, allowing operators to start larger tools for its size than in the past. The alternators are sized to ensure cool winding temperatures and, therefore, long life.” Wacker’s new line of premium portable generators offers seven models, ranging from 3,800 to 6,600 watts, and they now feature a central GFCI system for all receptacles including 120- and 240-volt twistlocks. Wacker’s new GFCI is UL approved and meets National Electronic Code requirements for job sites.

Unlike most contractor-grade generators, Wacker’s new GFCI sensor offers personal protection to operators no matter which receptacle is being used, by monitoring all outlets for current leakage and tripping the main circuit breaker in the event of a current leakage. This system improves durability and reliability because the GFCI sensor only monitors current, eliminating the possibility of damage from over-current. If a current leakage is detected, the GFCI triggers the main circuit breaker, which is rated to handle the total current output of the entire generator and can withstand current surges and repeated tripping without problem. Conventional GFCI-protected generators use small auxiliary breakers built into each 120-volt duplex receptacle, which can be damaged by over-current or repeated tripping and are a frequent maintenance item on rental generators. Built for the construction, industrial, commercial, domestic, and farm applications, Wacker’s premium portable generators are backed by a two-year warranty and a first-class sales support team.

Last year Caterpillar introduced some diesel generator sets with ACERT Technology. That successful technology comprises an ADEM A4 controller, HEUI fuel system, and cross-flow cylinder heads. The generator set offers an Air-To-Air After Cooler cooling system, an advanced EMCP 3 control system, and multiple control panel and power connection options, plus enhanced package-mounted circuit breaker options. The generator (with Class H insulation) is brushless and self-excited. The rating ranges of the new generator sets are 225 ekW–275 ekW and 250 ekW–300 ekW. It is the first EPA Tier 3–certified generator set to be offered in the North American marketplace. The generator set is used primarily for standby, prime, and load management applications. Operating at 60 Hz, the clean diesel generator set is powered by the new 8.8-liter Cat C9 engine. Caterpillar engines, too, are used in many generator systems from other manufacturers; they have earned a reputation for long life and reliability.

All power on the job site is not electric. Air compressors have been popular for years for running tools. We counted 27 models in Sullair’s North American range of air compressors. What features does this leading manufacturer emphasize? The range covers needs from 125 to 1,900 cfm in standard, high-pressure, and utility models. They know you use (and often leave) these compressors at the site overnight; large service doors can be padlocked. The capacity control goes from 0% to 100% for total control. There are two-stage dry-type air filters, curbside instrument panel, diagnostic shutdown indicator system, protective shutdown switches, and all-weather fluid. All of Sullair’s compressors can be towed on highways, with mounting options that include single-axle, tandem axle, four-wheel steerable, and without running gear. Sullair uses Caterpillar and John Deere diesel engines for power. And, of course, there are options available to suit your exact site needs.

Power sources are available. It’s the same principle for them as it is for your loaders, dozers, and excavators. From the vast selection available, choose the model that will most exactly suit your needs. If your need is temporary, perhaps you should rent the most suitable model. This power source is going to work most of the day, so durability and reliability are top considerations. Your dealer and your fellow contractors can give good advice on this aspect, and don’t be shy about asking experienced users for any hidden problems with certain brands or styles. They may be small items but they can affect the smooth operation. The right power source is out there, not far from you, so be persistent in your research and you’ll find it. It can make the project go well and profitably.

Paul Hull writes on construction and environmental topics for several international magazines.

GEC - September/October 2006

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