Remote - Fall 2016 - 18

Feature Article Balancing the Load Paralleling Generators in Prime Power Applications Jim Siffring, Generator Product Manager Atlas Copco Construction Equipment Power. It's a necessity that keeps the lights on and equipment running in every building and jobsite. In many cases, it's the true lifeblood of an operation, and an outage can be downright costly in critical operations such as asphalt or concrete plant or mines. In scenarios like these, it's especially important to have predictable and reliable power. While specifying the right size generator is a good starting point, one might find there's greater dependability, cost savings and efficiency in numbers. Balancing Benefits Ever since the advent of portable generators, it has been common practice in many prime power applications to choose a single generator with enough kilowatt (kW) output to power all of the tools and equipment needed. While this certainly serves the immediate need, paralleling several smaller generators to operate in parallel might be a more efficient and versatile option. The synchronizing process (which once involved a vast network of wires, manually adjusting the rpm, and frequently monitoring the loads) is now fairly simple with most portable generators. In fact, some generators feature "plug-and-play" technology that allows the control to be connected with just one cable. After the connection is made, the user connects the power cables to a common bus, sets a few parameters in the controller, then hits the start button and the process takes care of itself. Plug-and-play models feature a special controller that creates a power management system to oversee all of the units. They are often equipped with motorized breakers that allow the units to automatically start and stop as loads fluctuate. Users can parallel as many as 16 generators with some manufacturers' models, and synchronize them much quicker than they could with older models. Paralleling generators for use in prime power applications, such as asphalt and concrete batch plants or construction sites, is common practice in many other countries, but is just starting to be better utilized in the US. Many contractors simply have been unaware of the better power options it presents. Just like in many common standby applications, paralleling generators on these sites can come with many benefits. Perhaps the biggest advantage of paralleling two or more single megawatt generators is peace of mind. The operation won't be completely shut down if one unit breaks down. A complete loss of power can be disastrous. For example, if there is hot asphalt in a hopper and the lone generator on site goes down, operators can be faced with a tough situation. As the asphalt cools, it begins to harden and can damage equipment. It's also extremely difficult and time consuming to remove. Boring and drilling applications also are a good example. If a standalone generator goes down as drilling takes place, the tool can become stuck and can be challenging and time consuming to remove. On the other hand, if these jobsites are equipped with several smaller generators in parallel, operators can simply take one out of service and use the remaining generators with little to no impact on the operation. Reduced fuel consumption is another significant benefit. For example, let's say a worksite needs 5-megawatts of power to operate numerous pieces of equipment. Five 1-megawatt generators that are paralleled can provide the same amount of peak power as two 2.5-megawatt generators, but can automatically power down as usage decreases and power up as it increases, which reduces fuel consumption. Also, as the load falls below certain levels on some larger generators so does the fuel efficiency. For example, if the load requirement falls below 1 megawatt, a 2.5-megawatt unit will be operating less than 30 percent load, which is below optimal operating range. A single or pair of 1-megawatt gensets will be running in a much more efficient operating range. This can lead to better efficiency and considerable fuel savings. Many models allow users to customize the power management system to a large range of parameters. For instance, let's say a jobsite has five paralleled 1-megawatt generators that will run near full power during periods of the day, but at other times the load is just 1/2-megawatt. Users can program the power management system to operate with the minimum power, plus 18 www.RemoteMagazine.com http://www.RemoteMagazine.com

Table of Contents for the Digital Edition of Remote - Fall 2016