Mike Bacidore is the editor in chief for Control Design magazine. He is an award-winning columnist, earning a Gold Regional Award and a Silver National Award from the American Society of Business Publication Editors. Email him at [email protected].
[sidebar id=5]
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.”
Figure 1. The monitor captures power consumption of each phase.
Source: PCMC
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.”
The second step is that some companies have gone a step further and installed low-cost power quality monitoring and recording devices. “These devices can tell you about factors that may affect TCO figures for a single machine, but they go further than that,” explains Newton. “They make sure you’re actually receiving the quality and amount of power you’re being charged for. They also help to predict system failures and can pinpoint sources of power-related failures, such as transient voltages and voltage dips and surges.”
For example, Opto 22 worked with a customer that implemented one of its energy monitoring units to monitor rooftop air conditioning units. “The data the customer collected exposed multiple problems with some units not cycling correctly and never reaching their set points,” explains Newton. “This caused the units to run continuously.” Once the customer replaced the unit, it was able to show the collected data to the utility and collect a $56,000 rebate for the new equipment.
“Third, companies with a very strong power monitoring strategy are taking the next step and connecting their industrial systems to the Internet of Things,” offers Newton. “With the Internet of Things these companies can use big-data analysis tools to monitor electrical usage against pricing.” They also can factor energy-curtailment programs and peak-demand pricing structures into the cost of manufacturing, he adds.
No movement in the needle
Gary Box, owner, Digital Power Engineering in Minneapolis, believes monitoring’s effect on TCO has been minimal to date. “On the input side, energy consumption and thus efficiency is deceptively difficult to measure, particularly on single-phase equipment without power factor correction,” he explains. “Simple monitoring equipment doesn't account for power factor or harmonics. Some high-end drives and inverters do provide energy monitoring, but the majority of the market can't afford them or can't accommodate the required network connection.”
Because the customer focus is on energy expense, efficiency of the grid-to-shaft system isn't as important as the efficiency of the entire variable-speed system, including the pump or other mechanical device when compared to original, nonvariable-speed systems, explains Box. This makes monitoring energy input before and after conversion a valuable marketing tool, leading to the cost of ownership argument.
“Applying this tool may expose the two elephants in the present variable-speed-technology room,” says Box. “The first is that under the same speed or torque operating conditions, a VFD or IM variable-speed system will actually operate at a lower efficiency than a grid-connected, super-premium induction motor because of the added losses. This is why utilities will not give rebates for adding VFDs to systems that don't take advantage of actually changing the speed. The second is that changing to an inverter-rated motor, adding the VFD, installing the whole system and mitigating whatever EMI or power quality problems that may arise can cost two to four times more than the single-speed, super-premium motor alone. There is an ROI, but it can be long for systems not operated 24/7 or for systems with smaller improvements. These low ROI systems tend to be the more numerous applications like commercial refrigeration, pool pumps or HVAC and present a huge cumulative efficiency improvement for society as a whole. Thus the DOE is working with industry to define system-level standards and verification-testing procedures. That will achieve the cumulative efficiency goal, but will not lower the added cost of variable speed or improve the ROI.”
Energy efficiency monitoring doesn’t directly help measure total cost of ownership, but understanding what and where the efficiencies are can have a large effect on the TCO, explains Derrick Stacey, solutions engineer, B&R Industrial Automation.
“There are two main functions for understanding energy efficiency: power monitoring and energy management,” says Stacey. “Power monitoring is important because it gives the ability to monitor the quality of the supply, the voltage of each leg and the incoming power, among other important information, allowing end users to compare what information their power companies provide to what they are truly receiving. This also allows users to get visibility into the power consumption of the machine in detail, which gives details into a portion of the TCO. For the energy management, we can use the understanding of the incoming mains to set up the machine to put excess energy generated during the braking of motors back onto the mains or to use the energy to maintain a specific bus voltage without pulling from the mains. This decreases the wasted energy that is often released as heat through braking resistors. This portion is not as easily calculated as it may not be consistent during a machine’s running, but, by putting normally lost or wasted energy back into the grid, then it can affect the TCO.”
All in all, the ability to measure energy efficiency should put the ball in the OEM’s court to push them to add energy efficiency as a design goal for systems since they have greater visibility through the advanced monitoring. “This will then trickle down to end users and decrease their TCO, as well as give end users insight as to how their usage habits affect TCO,” says Stacey.
Motor measures
The packaging lines built by Cavanna Packaging Group in Varese, Italy, use two sources of energy: electrical and compressed air. “It’s very hard to make comparisons with the past because it’s hard to collect meaningful data about the past. But monitoring, collecting and presenting the right data supporting energy-efficiency improvements is the right way for the future,” explains Luca Durante, SW/electronic and electrical designing manager at Cavanna. “Our equipment contains a lot of brushless motors coupled to high-efficiency gear boxes. A clever mechanical design also decreases dynamic friction. We substituted ac motors, used on large belts, with a mechatronic integrated brushless motor with an onboard electrical drive and gear box. This device has a very high initial torque useful to win initial static friction. In this way, a lower-size motor with a lower torque is enough to win dynamic friction when moving at a constant speed. So a 0.55 kW model can replace up to a 2.2 kW ac motor. We made four lines with such design and motors, obtaining a global electrical power saving in the order of 30%.”
Next, Cavanna is working to reduce use of compressed air, replacing air-powered devices, where possible, with electrically powered ones. “Some tests we’ve made indicate the expected saving is very high, compensating the higher cost of electrical devices within one or two years of lower operating expenditures for the final customer,” says Durante.
“Total cost of ownership for a motor has four main components: cost to purchase, cost of electricity to operate it, cost for repairs and maintenance to keep it running, and cost of downtime if it fails,” explains John Malinowski, senior industry affairs manager, Baldor Electric. “Generally, more than 90% of the lifetime cost of a motor is related to the cost of electricity to operate it over its entire lifetime. Determining the cost of the electricity to operate the motor can be gathered by either a monitor installed by the utility or doing a manual calculation based on the cost of the electricity, the hours of operation, the motor load and the efficiency at that load point.”
When a utility monitors the energy usage, it is a verified measurement that can be used to compare the new motor-driven system’s energy use to that of the older system being upgraded, says Malinowski. “This is what utilities call ‘measurement and verification’ and is used in many of their incentive plans,” he explains. “A software calculation can be used to see if the project has savings potential before proceeding. In this way, it’s easier for a user to estimate the financial benefit an energy-efficiency motor brings over its lifetime.”
When choosing an electric motor, a buyer needs to look beyond purchasing price, agrees Vijay Anand, ABB regional product specialist—Americas, motor and generator condition monitoring & diagnostics. “The total cost of ownership is comprised of critical components, such as purchasing price, cost of running and cost of not running the motor,” he says. “Cost of running is optimized by motor efficiency. Monitoring tools can help to assess actual operating efficiency, enabling accurate cost calculation. Cost of not running can be minimized by extending mean time between failures to the maximum which in turn is made possible by implementing proper monitoring processes. Thus, the cost of ownership of motors can be greatly influenced by good monitoring practices.”
Plant life
“The total lifetime of a plant is about 60 years,” explains Ed Subay, practice lead and business development manager, data services, Siemens. “Do owners actually force their builders to have better lifecycle costs? We see that more and more often. We see the tension when you have a set of specs from the owner. This is how much it will cost to build. This is how much it will cost to operate. The machine builder is impacted when the specs are written and tries to show the benefit of the more energy-efficient equipment.”
OEMs are actually driving specs with the engineers, so the components are part of a specification when the engineer goes out to bid on a machine, says Subay. “When energy costs were low, no one paid too much mind,” he explains. “Today is different. Everyone pays attention to how much they’re spending on operating costs. The benefit of monitoring energy usage of a production line or a machine is in the holistic view that brings you to the lifecycle costing, understanding how you’re spending money from an holistic standpoint. You cannot manage what you don’t measure. The big advantage is in the holistic picture of the whole plant (Figure 2).”
Figure 2. The 80/20 rule applies to plant’s energy costs, as 80% occurs during operation and deconstruction, according to the International Energy Association.
Source: Siemens
Energy is an important component in the cost of ownership for many types of manufacturing machines and processes, says Thomas Mort, chief operations officer at Mission Point Energy, an energy technology consulting company in Louisville, Kentucky. “Also, support equipment such as chillers, boilers, and air compressors are often not accurately considered in the cost of operation or ownership,” he says.
For the past two decades, Mort has been using small portable data loggers to analyze energy use in hundreds of factories and thousands of machines, which helped him to identify energy waste and or improper setup of machines. Significant improvement opportunities were identified in analyses ranging from North America to Europe and Asia:
- machines operating without production
- identical machines using more power than others due to wear, friction or setup issues
- pumps and fans operating outside of the peak efficiency curve points
- exhaust CO or O2 being out of the best efficiency range
- multiple compressors operating at part load when one at full load would be more efficient
- lights on without people
- building environments warmer, colder or excess make up air than needed for the level of activity
- operator differences resulting in different production rates or quality
- waste heat not being used to pre-heat a process or even for building heat in winter.
“Another measurement often neglected is called electric interval data, or the measurement of the total facility electric usage typically measured on 15-minute intervals,” explains Mort. “Graphs of this information, along with good understanding that electricity has different costs at different times, and combining this knowledge with equipment production schedules, also brings value. A non-energy saving of high value has been in the ability to do troubleshooting. Everyone has had machines give trouble when you are not looking.”
Plants with the ability to closely tie energy usage to production from total building levels down to machine levels had significantly better energy-to-part rations and therefore improved cost of ownership, explains Mort. “As with other technologies, the availability of data loggers and sensors has drastically come down in price and remarkably improved in ease of data collection and display,” he says. “I’ve always considered data loggers and sensors as very low-cost employees who work 24/7 for minimal costs.”
Machine-level monitoring
Monitoring at the machine level has grown in recent years for several reasons, says Clinton S. Hommel, product marketing specialist—energy monitoring & management, Phoenix Contact USA. “One of the most predominant reasons for monitoring equipment is to have a good and clear idea of what the machine is doing, how reliable it is and how much money it costs to operate daily,” he explains. “It’s one of the best ways to measure cost of ownership because it allows the customer to keep track of downtime, wear and tear and, of course, energy usage—the three most expensive components of operational and ownership costs.”
Also read: How to gain the upper hand with energy-smart machine design
Measuring the energy use of each individual machine used to be an expensive undertaking, requiring a custom kWh metering device, remembers Cindy Green, industrial engineer at AutomationDirect. “The procedure was to install current and potential transformers to measure current and voltage, respectively, and to connect the outputs of these transformers to the metering device,” she says. “The metering device then needed to be linked to the PLC or HMI, which often required custom coding.”
But with modern energy monitoring systems, all that’s needed is to install the current and potential transformers and connect them directly to PLC inputs, as most PLCs now have the ability to calculate power usage, explains Green. “Once the data is in the PLC, it’s easy to display it on the HMI or other local operator interface device and to send it to higher-level, plant-wide systems for analysis and action.”
What gets measured can now be controlled, allowing end users to cut machine energy usage by monitoring its power consumption. This helps users to understand if a machine is idle, running production or purging product, and can help to identify where energy use is the highest. This data can highlight areas for improvements in machine operation, thereby lowering total cost of ownership.
“If measured data shows a machine is waiting for product 50% of the time, this might indicate problems with upstream equipment or with operators,” explains Green. “It may also show that the downstream equipment could be run more slowly to save energy. With good energy data in hand, efficient control of the machines can become a reality, while unused machines can be shut off or turned down to run at lower speeds wherever possible.”
Another area for energy saving is powering down idle conveyors, auxiliary equipment and machines, either as a matter of procedure or as a programmed automatic function triggered by a machine idle timeout event.
“Some applications can be slowed down to match the cycle rate of the line,” explains Green. “While not all motors benefit from running at reduced speed, fan and pump applications in particular can save significant energy when run at a slower rate as dictated by a variable frequency drive.”
At COP21 in Paris, ABB pointed out that variable-speed-drive technology has only penetrated 10% of the potential market; and that took 30 years, says Digital Power Engineering’s Box. “Clearly the cost-of-ownership argument isn't breaking down the barrier of higher initial cost with the existing variable-speed technology,” he explains. “At Digital Motor Holdings, we’re addressing this with our Resonant Field Exciter technology, which takes the highly efficient workhorse of high-power electric motors, the wound field-synchronous motor, and makes it practical at 1-10 hp at up to 50% less cost than today's VFD/ IM system.”
The goal is to build a compelling argument to not only meet the new DOE standards with a variable-speed system with a faster ROI on new equipment and the grid-to-shaft efficiency of a super-premium motor, but to financially encourage replacing the 90% of existing applications that are still single speed, says Box.
Equipment builders see the light
OEMs are aware of the available technologies for improving the energy efficiency of their equipment and machines, says Mark Duncan, segment marketing manager, machine solutions, Schneider Electric. “But, while many OEMs are conscious of the growing pressure and demands coming from the market, they are reluctant to make changes due to the perception that new technologies will make their machines more expensive to sell,” he warns. “In reality, permanent savings through active energy efficiency practices can be realized without dramatically added cost. Machine engineering can be a key source of improvement in the energy consumption of machines.”
Motion control is a field of innovation that benefits the industry and brings new machine value to machine builders, but other opportunities in energy savings are available to machine builders. “Application engineering can bring strong energy-efficiency benefits, for example, monitoring operating modes and status through automation,” offers Duncan. “End users do not always use the full capacity of their machines and equipment, depending on their production objectives. Some key areas are frequently stopped intentionally in order to activate only the needed resources. These techniques can be efficiently applied in conveying, such as becoming active only when the load arrives rather than running continuously.”
The automation control system also consumes power, not at the level of actuators, but optimization can be implemented by picking the right offer and making the right decision, suggests Duncan. “Depending on the application, the right automation architecture can have a favorable impact on energy consumption of the overall control system,” he explains. “For example, a decentralized architecture can double the consumption of a centralized architecture. Of course, depending on the size of the application, as well as safety and performance criteria, the choice of a decentralized architecture is sometimes necessary.”
Optimizing the number of 24V power supplies can induce energy saving up to 25% by avoiding numerous power supplies and their associated losses, says Duncan. “Furthermore, looking at the choice of contactors, HMIs, use of LEDs, and power-factor correction are among the additional opportunities where application engineering can bring strong energy-efficiency benefits,” he explains. And, of course, measuring the energy consumption of a machine brings immediate benefits.
“With new design approaches and the introduction of new technologies, OEMs are able to bring new values and contribute strongly to the sustainable approach that end users are now implementing,” says Duncan. “Automation and control functions are bringing a wide range of possibilities to improve energy efficiency and reduce waste; therefore, they should be considered systematically. The active approach to energy efficiency gives end users the possibility to optimize the energy consumption of their production investments for both immediate and long-term savings.”
Energy measurement is an eye opener for users, says Rainer Neufeld, electronics manager at SEW Eurodrive. “We’ve done tests were the energy was about 45% less than it was in the old installation,” he reports. “If you take that in consideration for hundreds and may be thousands of drives, this is significant savings. In one project the end user was able to reduce the infeed power transformer, which saved a lot of money. Often it’s also about educating them on the way the drives are sized. It used to be that everything is well oversized, and then, on top of it, the next size higher was chosen. For example, calculated power was 1 hp. Then there was a safety factor from 1.5, so you’d select the next size up—2.2 hp. This means that the drive will never run at its highest efficiency point.”
End users sometimes don’t understand system efficiency, says Neufeld, who notes that he often sees conveyors with high-efficient units on worm gearboxes on a belt. “That makes no sense from an overall perspective,” he says. “The high-efficient motors only add a couple percent to the system. The overall efficiency gets dragged down by the worm gearbox and the belt. Sometimes it even makes it worse because high-efficient motors tend to have a higher inertia, and, in cyclic applications, you actually use more power.”
System-integrated monitoring
Digital Power Engineering’s Box sees accommodation emerging for energy or efficiency monitoring from system-level OEMs selling complete pump, compressor or HVAC equipment. “On single-phase, OEMs are adding power factor correction (PFC), which allows accurate input energy measurement with just a digital Volt meter,” he explains. “The downside is the additional PFC circuitry adds cost, complexity and loss, actually reducing grid-to-shaft efficiency.”
On the drive output side, direct voltage measurement is complicated by the presence of pulse-width modulation, and current may not be truly sinusoidal. “At best, this results in an estimate of power flow,” says Box. “If the motor is an induction motor, calculation of torque is yet another estimate. This is done better on more expensive field-oriented drives, but it’s still an estimate. Thus at the grid-to-shaft system level, the overall efficiency is still an educated guess.”
Also read: Energy revolution leads engineers to work smarter
However, total cost of ownership is quickly becoming the primary set of metrics to measure the level of production processes optimization, as well as the efficiency of plant operations, explains Kurt Wadowick, technical support engineer at Beckhoff Automation.
“Modern I/O solutions with integrated measurement technology provide a cost-effective, robust solution for integrating this type of monitoring and connect to field measurement devices across a machine or plant,” he says. “These I/O terminals can be directly connected to a small embedded PC from Beckhoff, which runs TwinCAT PC-based automation and controls software. With multi-tasking software platforms like TwinCAT, it’s possible today for users to program measurement and condition monitoring functions in the same environment used for PLC, motion control, safety, robotics and more. This is a system-integrated way to enable operations monitoring, including energy-efficiency measurements, in addition to all general control functions required on a machine. Users can also add measurement functionality to track vibration, ambient heat, pressure and much more, directly through standard I/O terminals. Bundling this functionality into the main automation controller and distributed I/O system costs considerably less than the thousands of dollars for stand-alone energy monitoring systems. This permits efficient monitoring of lower energy loads, where previously it would have been prohibitively expensive.”
System-integrated monitoring of all types has become more precise, as significantly finer resolution via high-performance industrial Ethernet protocols highlights exactly where the energy is being used, explains Wadowick. “In practical application, concepts such as predictive maintenance become not only possible, but cost-effective and a value-added component in a universal control platform. Deviations in power usage from determined averages could indicate impending machine issues, such as higher-than-average current draw indicating a pump starting to clog or, conversely, lower-than-average current draw indicating a leak in the system. Addressing these problems before they cause downtime is immensely valuable in maximizing operational efficiency and profitability.”
Overall, system-integrated measurement and monitoring facilitates a much more insightful look into manufacturing operations, enabling enterprises to implement concepts such as cloud databases to connect operational sites from around the world, which is also a means to access this high-value monitoring data remotely, suggests Wadowick.
What does TCO cost?
End users use total cost of ownership as an evaluation tool typically when purchasing a machine, explains Phil Kaufman, business manager for industrial energy management, Rockwell Automation. “They’re measuring efficiency for direct energy savings, which is energy lifecycle management,” he says. “To understand the actual cost to produce a product, companies ultimately need to know more than how a plant or piece of equipment consumes energy. They need visibility into how energy is consumed at the device or machine level relative to each product. This level of data can help managers to determine the energy required to bring a given product to market, evaluate the true overall costs of that product and make changes to maximize profitability.”
By treating energy as direct, variable costs, organizations can gain visibility into which processes, machines or lines are consuming the most energy, continues Kaufman. “With visibility into energy use, plant managers can make changes to use energy more productively,” he explains. “For examples, managers could schedule production intelligently, take advantage of more efficient equipment or design processes more efficiently. This could include reusing waste heat in their processes. They also can use cheaper power by scheduling production or product mix when energy is least expensive, such as during off-peak hours.”
Once the data is collected, consumption trends can be evaluated and baselines established, which allows the correlation of energy use to operations. “Manufacturers can then begin to estimate the amount of energy needed for various products or outputs and subsequently lower energy usage through intelligent production scheduling,” says Kaufman.
“Monitoring equipment is the key to increase efficiency,” says Dominique Blanc, U.S. general manager for eWon. New gateways are opening a new paradigm of benefits, such as ease of deployment, cost effectiveness and compliance with IT security policies.
“This allows more systematic involvement of monitoring for each machine,” says Blanc. “Monitoring a single unit is cool but the benefits of monitoring a population of remote equipment distributed in multiple factories and applications are greater.” For example, monitoring run time, alarms and errors, change of condition, analysis of wear and tear provides great insights to analyze cost of ownership.
“The remote connectivity gateways and IoT tools make it extremely easy to measure and aggregate data for multiple machines,” says Blanc. “Users and managers can quickly analyze, compare and identify and then isolate the equipment with the best potential of improvement and engage adjustment and modification to improve the total cost of ownership. Many machine builders and OEMs can now better understand how their machines are used in the real-world factory and make sure the new design will be implemented on the next machine, which leads to tremendous support and warranty improvement. This results in more machine availability, better factories and a better cost of ownership.”
