Portable generators are invaluable for bringing power to work sites where no electricity is available and are essential for restoring services following storms and other disasters. Most electrical contractors have multiple units, and they are widely available from equipment rental outlets. While low-cost generators are available for home use, professionals understand they are not suited to daily operation on construction sites.
The adage “you get what you pay for” certainly applies to the state of portable generators today, said Brad Meissner, senior project engineer—manufactured components at Kohler Power Systems, Kohler, Wis.
“Commercial generators today have a variety of features that make operation on job sites easier and more effective for electricians and other professionals,” he said. “Improvements include larger, angled fuel inlets for easier refilling, maintenance minders that display hours of runtime and notify the operator when preventative maintenance is required, and various accessories, which allow users to customize their generator for a specific task by adding wheels, legs, lifting hooks, extension-cord management systems and more.”
In addition, there have been many innovations to the engines that power these generators. For example, tri-fuel engines can be installed on select generators without voiding the manufacturer’s warranty. These engines allow the generators to run on gasoline, natural gas and propane by simply tuning a dial and switching out the fuel hose. Low-carbon-monoxide engines also are available.
“These engines are ideal for generator applications and significantly lower the amount of carbon monoxide emitted—good for the environment as well as the health and safety of equipment operators,” Meissner said.
He believes the most significant portable generator advancement is how reliable and durable commercial-grade models have become.
“Features are great, but at the end of the day, a generator needs to perform on the job site day-in and day-out and must be the primary focus for generator manufacturers,” Meissner said.
Kohler offers a full lineup of durable gas-powered generators ranging between 5 kilowatts (kW) and 12.3 kW. To power sensitive electronic equipment, some generators deliver exceptional digital voltage and frequency regulation as well as low levels of harmonic distortion.
“We also offer a battery-powered 1.8-kW inverter,” Meissner said. “It is an ideal way to keep cordless tools charged. This unit doesn’t run on gas, so it can be used indoors. It can be charged with a standard 120-volt [V] AC wall outlet or any solar panel and offers silent operation, requires no fuel, and produces zero emissions.”
A better fit
Generators have become smaller, lighter, more fuel-efficient and quieter. Many are being designed to fit into tighter spaces, said David Bush, marketing strategist, American Honda Motor Co., Torrance, Calif.
Bush believes the benefits of lighter weight units in smaller package sizes is driving a transformation on the job because these smaller, lighter inverter generators can be located closer to the user. They can be connected in parallel to double the output when needed.
“On the market today are open-frame inverter models with rugged, full-frame protection that offer lightweight and quiet operation as well as high-quality power, fuel efficiency and long run times,” Bush said. “In other models, features like color-coded startup components, easier oil fill/drains and new fuel shutoff valves are making portable generators easier to use and maintain than ever before.”
Regulatory requirements have affected modern generator features.
“Changing regulations dictated by the National Electrical Code and the Occupational and Safety Health Administration [OSHA] have impacted generators on job sites,” Bush said. “Examples are requiring ground-fault circuit interrupter receptacles and reduction of sound levels is important on sites near residential property.”
The ability for contractors to generate power without sacrificing portability has brought a major shift in how generators are being used.
“While some construction company owners still use two or three conventional generators to offer power at job sites, the trend now is to have each worker use an individual power source, which offers greater flexibility,” he said.
Bush said generators equipped with automatic voltage regulation (AVR) constantly monitor load changes and adjust output to produce a clean sine wave. AVR constantly adjusts the fields and loads to maintain the revolutions per minute of the generator at 60 cycles, which provides good quality power for most applications.
“While AVR-regulated generators provide good quality power, inverter generators produce the best quality power,” Bush said. “Inverter technology processes the raw power produced by the generator and passes it through a special microprocessor to produce the most stable power. This means sensitive equipment can operate from a remote location with a reduced possibility of interrupted service or damage to the equipment.”
Honda Power Equipment markets a complete line of generators for commercial and consumer applications. Lightweight, compact Honda generators produce between 1,000–10,000 watts, providing smooth, dependable power for recreation, construction, rental and home emergency use.
A constant need
Portable power is a constant need, and generator features vary by model, said Nate Hall, product manager, Multiquip, Carson, Calif. Inverter generators are known for being quiet, and pipe-frame generators remain ubiquitous on construction sites for their durability and versatility.
“The most popular generator size remains 6.0 kW, but contractors are realizing not all generators are created equal,” Hall said. “Construction professionals are attentive to the overall product design to ensure it will meet their job site needs. Consumer-grade generators that sell for a few hundred dollars may do the trick for a short while, but they don’t withstand the daily rigors encountered on job sites. A close comparison among professional models reveals features like tachometers, voltmeters and automatic-idle control are left off consumer-grade products as cost concessions. Professional contractors realize the benefit of buying an industrial-grade generator for their projects to receive the features they need along with a longer service life.
Inverter generators, once considered a novel concept, are now common in the marketplace. They are quiet and can fit a number of jobs. Many single-cylinder engines now use carbon canisters for emissions compliance.
“Units equipped with AVR or that of inventor-based designs can control the output voltages closer than generators that rely specifically on the engine rotating assembly to maintain frequency,” Hall said.
Multiquip offers a range of portable generators from 2.5 kW through 9.7 kW.
Portable generators continue to get more feature-rich, said Art Aiello, public relations manager, Generac, Waukesha, Wis.
“For professionals, it is important to make sure a generator is OSHA-compliant and will be usable on job sites,” he said. “That means having long running times, oversized and easy-to-use touchpoints—especially those that can be used with a gloved hand—and ease of maintenance. Among consumer-grade products, inverter generators continue to be popular for their light weight, clean power and their paralleling capabilities, which allow users more flexibility in the amount of power needed for a project.”
Total harmonic distortion (THD), the measure of the overall cleanliness of the electric power output is important when dealing with sensitive tools or devices. This is one reason inverter generators are increasing in popularity.
“The way in which they produce electricity also results in extremely clean power,” Aiello said. “And many inverter generators come with USB ports for connecting smartphones and tablets.”
Other important features include easy mobility and durability.
“Consider a unit with covered outlets to keep dirt and debris out,” he said. “Locking outlets also are important, because many tools used professionally require that type of outlet.”
Generac offers a variety of generator options, ranging from 1.6 kW to one of the largest portable generators available, delivering 17.5 kW.
Renting Portable Generators
Portable generators are one of the most popular type equipment to rent, widely available at general rental centers and equipment specialists. Across North America, United Rentals, based in Stamford, Conn., has an inventory of more than 11,000 generators from 5 kW to 2,000 kW, said David Scott, the company’s vice president of power and HVAC.
United Rentals has invested in portable generators that have integrated voltage regulators and frequency controls, which make them ideal for powering computers and sensitive equipment in on-site field offices.
“Our experience is that the needs of electrical contractors run from the basic to the complex, but the equipment they most often rent falls into the range of between 100 kW and 500 kW,” Scott said. “A field site visit is important before the rental. If that’s not possible, the basic information that must be provided by the contractor is the load size in amps, the generator voltage (traditionally 480V or 208V), the distance from the generator to the connected load and confirmation that a portable unit may be placed nearby, and whether an external fuel tank is required for prolonged run-time.
“Customers tend to focus on generators that are easy to operate. They value features like integrated electrical distribution panels, extended run-time fuel tanks, three-way fuel valves, battery chargers and environmental spill containment systems.
“We’ve also seen an increase in the demand for telematics that give contractors remote access to operating data about the equipment, including system warnings and even how much fuel is left in the tank. From our standpoint, it starts with strategic approach: we specify solutions that meet specific requirements, and that drives the choice of features,” Scott said.—J.G.