In recent years, machine builders and system integrators have found ways to bring energy savings to customers by monitoring use and utilizing more appropriate components. Energy is a real cost. And now that plants have discovered the impact of savings and actually assigned that responsibility to individuals, energy monitoring has become an important tool that makes its impact felt down to the equipment level.
Concept Systems, a system integrator in Eugene, Oregon, has a customer that uses variable frequency drives (VFDs) for energy savings. It monitored power usage to create an energy use baseline, before working with its local energy trust and then monitored after VFD installation, garnering incentive dollars for energy saved. “Some other things we have done are look at the power factor on whole plant systems and the effect VFDs have," says Sam Cafferata, principal engineer at Concept Systems. "VFDs isolate underutilized motors—low power factor—by providing a near unity power factor. Another good one is air control with VFDs instead of constant speed motors with manual air control dampers. We have worked with a client on this one and have put a number of VFDs on fans and eliminated the manual air control. We also use a VFD to accelerate and decelerate a high-inertia load to prevent over-torque on the mechanical elements of the system.”
Total cost of ownership
Paper Converting Machine (PCMC) in Green Bay, Wisconsin, has implemented energy monitoring devices on some of the equipment that it builds, explains Jason Stover, senior project engineer at PCMC (Figure 1). Its press power monitor brings real-time press power usage to operator stations. Line voltage, current, real and reactive power are all displayed and can be logged and trended. This promotes energy-saving practices. The kWh from an energy bill can be entered to calculate the cost per job/day/month.
“While this information does give our customers a better view of the overall machine cost, where we have seen more benefit is in allowing them to see a true and accurate cost of the jobs they run on our equipment,” says Stover. “The machines with the monitoring solution do not run a continuous product day-in and day-out. This is especially true on our flexographic printing presses. Many of our customers are contract converters running various print jobs for many different clients. The different print jobs vary in the number of colors run, width of product and amount of drying required. All these variations affect energy usage. With the power monitoring in place, it gives them a very good picture of what it costs to run that particular print job or order.”
Knowing that true cost allows them to make better decisions, explains Stover. “They can arrange the print jobs that need to be run for the day, such that higher-costing jobs can be scheduled during off-peak hours when energy is cheaper,” he says. “Or they can see that for a particular job it is more cost-effective to run it on one machine asset versus another.”
A benefit in knowing this true cost of ownership is that it allows end users to make strategic and accurate decisions when bidding on jobs, explains Stover. “Sometimes margins can get very tight in competing for business with their end customers, so having the information allows them to confidently set a price point that will win the business and also allow them to make money,” he says.
Until recently, the idea of TCO was only that—an idea that seemed mostly like a justification for more expensive equipment, explains Matt Newton, director of technical marketing at Opto 22. “Now that the price of power monitoring equipment has dropped, companies that want to be competitive are pursuing the idea for real,” he says. “They’re checking up on TCO figures and seeing how their actual cost for power compares.”
Newton sees companies taking three steps in this direction.
“First, it’s easy now to monitor exactly how much power a piece of industrial equipment draws using small, inexpensive power-metering devices,” he notes. “When you do, you start noticing that Pump A consistently uses more power than Pump B, for example. Maybe Pump A is older; maybe it needs maintenance. Or maybe the next time you buy a pump you’ll decide to get it from the manufacturer of Pump B. Companies that monitor power use have a much richer picture of their equipment. They can factor power cost into product pricing and determine more accurately how long it will take to achieve a return on investment.”