Find Power Problems: Energy strategies that can influence your facility's bottom line
It is not news that energy management in all sectors is becoming more critical every day — and many of those who manage maintenance departments are showing leadership in reducing energy consumption. PEM checked in with some experts about some of the direct, easy-to-identify actions and strategies plant managers are using to make broad and specific improvements in energy efficiency.
“Many plant managers can have their energy costs reduced by 40 per cent,” asserts Thierry Desjardins, vice-president of engineering at Québec City-based Ecosystem, an award-winning, ISO-certified energy efficiency firm. He says the first 35 per cent of these energy cost savings can be achieved through optimally designed and implemented energy conservation measures (ECMs), like boiler room retrofits, switching to more efficient motors/variable frequency drives, using geothermal systems, undertaking lighting system retrofits and replacing chillers.“However, one of the most critical factors for reaching optimal energy savings and maximizing your ROI is to make sure that the correct ECMs are selected and implemented at the same time, based on a nuanced understanding of how each measure can interact with the others,” Desjardins explains. “Too often, plant managers lose out on the full benefits of a retrofit because the ECMs are assessed, designed and implemented in isolation.”
He calls this “a major opportunity lost” that can have a significantly negative impact on cost-return timelines. He stresses that “the order in which measures are implemented can have a major impact on project payback and feasibility.” Here’s a simple example scenario showing how a chosen ECM can interact negatively with others to prevent maximal energy cost savings: “If you replace the central chiller before carrying out a lighting conversion,” Desjardins explains, “you’re going to end up purchasing a machine that is too big. Not only will you have paid too much for your chiller, but the efficiency won’t be optimal because the equipment isn’t optimally sized.”
To maximize ECM decision-making benefits, he strongly recommends turning to an expert for an energy audit of the facility. “This step is crucial because all buildings are different, and each building is far more than the sum of its mechanical parts,” he says. “You really need an experienced ‘outside eye’ to look at the building’s unique energy infrastructure and get a grasp of how energy is generated, distributed and used throughout.”
Proper maintenance of all mechanical systems — such as a steam trap survey and replacement, and fixing leaks in compressed air networks — typically amount up to the remaining five per cent of energy savings, Desjardins says. Even though five per cent might seem insignificant, it adds up over time.
“Without proper maintenance, the most efficiently designed buildings will not achieve energy goals,” agrees Kris Bagadia, president of U.S.-based Peak Industrial Solutions. “As mechanical systems are used to heat and cool a building, system performance degrades as sensors and meters drift out of calibration. If these systems are not maintained, they begin to consume more energy as equipment wears.”
That’s why he says it’s critical to effectively track and manage energy consumption. “That’s where a CMMS (computerized maintenance management system) plays an important role,” he says. “It allows you to gather and manage maintenance and energy data, which go hand-in-hand for effective maintenance management.” A CMMS can provide the ability to schedule inspections of energy-consuming equipment, to collect and store historical energy-consumption data that can be used to identify problem areas related to energy (such as leaks) and to establish an effective energy-reduction plan. “It also provides the ability to provide tracking of energy-consumption with user-defined criteria,” Bagadia says, “and correlate those criteria to how much energy is being consumed, as well as details of how much energy is being consumed by an individual asset, location, or building or facility.”
Both the two main types of maintenance planning — preventive maintenance (PM), also known as calendar-based maintenance, and predictive maintenance (PdM) — are effective strategies in achieving both consistent production goals and energy savings, says Peter Hachey, business development specialist of power quality and more for Fluke Electronics Canada. “Either way, the right tools must be used to properly diagnose the problem in a given situation,” he notes.
Below, Hachey examines three examples of energy-related challenges that a maintenance manager may typically face — as well as the lessons learned as the problems were solved.
1) Sub-metering of plant compressor group
“While a vital component of many manufacturing facilities’ operations, air compressors can be a source of energy waste,” Hachey notes.
He says the two most typical sources of waste are leaks in piping and improper time-of-day usage. Both can occur at once, and require different tools to diagnose the problem.
In this example, the air compressor was believed to be the culprit when a year-to-year increase in plant power consumption was noticed — an increase that could not be tied to a change in production practices. “Because the compressor piping circuit had never been included in any PM, the logical first step was to inspect the piping in order to locate any air leaks along in the network,” Hachey notes. “The most effective tool for this task is an ultrasonic leak detector, which will detect any type of pressurized gas/air leak.” The maintenance technician mapped the plant’s compressed air piping system and several leaks were found.
The technician also checked out any further issues. Because he was unsure of the usage sequence of the compressors, he decided the best course of action was to use a three-phase power quality analyzer to record power consumption on the compressor circuit, set to record for one full week.
“The analyzer’s trend mode delivered a surprising result — the compressors were left running even when the plant was shut down for the weekend,” he notes.
“The solution here was to institute a policy of shutting down the compressors whenever operations are suspended. … Needless to say, annual inspection of the compressor system was added to the PM list.”
2) Poor lighting-cicuit configuration
Hachey makes the case that upgrades to existing lighting systems for the purpose of energy savings have to be done correctly — or lighting energy waste issues may occur.
In this example, a plant manager requests that the maintenance/facilities manager increase the efficiency of the plant’s lighting configuration. His tasks include measuring light levels in order to add lighting as required, installing new high-efficiency electronics ballasts and installing a PLC to automate light levels according to time-of-day need.
A light meter is employed to identify areas where lighting is insufficient. “The levels are recorded and a lighting specialist is called to specify the correct number of fixtures to achieve the desired brightness,” Hachey says. “Steps two and three, installing the new ballasts and integrating the system into a PLC, are then carried out in the newly-installed lights as well as throughout the plant.”
However, shortly after the job had been completed, equipment performance issued began to occur. “This was despite the fact that these systems were part of regular PM and PdM checks,” Hachey notes. “The two most frequent performance issues were nuisance tripping on variable speed drives and increased noise and temperature at specific transformers.”
The maintenance team began troubleshooting procedures to discover the root cause of the problems. “The team first ran a thermal imaging scan on the affected systems to see if there was an increase in temperature,” he says. “They noted a 10°C rise on Phase C of the lighting circuit panel, as well as a similar rise in temperature at the circuit’s transformer.” The next step was to identify the problem causing the temperature increases. Using a three-phase power quality analyzer, they were able to record a 12-per-cent phase unbalance between A, B and C phases. The imbalance was due to all new light fixtures being added to Phase C. “As there was ample capacity in this distribution panel, the fix in this case was simple,” Hachey says. “Redistribute the load to all three phases.” Next up was to find the source of the nuisance tripping. “The maintenance team realized the affected drive was connected to the same distribution panel as the recently modified lighting system,” he notes. “They again used their three-phase power quality analyzer to diagnose the problem.” They found high levels of fifth harmonic distortion and high levels of reactive power (decreasing the power factor level), and energy costs increased significantly on this circuit due to poor power quality.
“The nuisance tripping was caused by an under-voltage condition and was easily corrected by sequence adjustment among the machines in the circuit,” Hachey says. “The harmonics issue was solved by adding line reactors — and this also solved the overheating and noise problem at the trans former.”
3) Repeated motor failure on pump assembly
In this last example, a pump motor had failed four times over three years, causing not only increased energy consumption issues, but also the loss of thousands of dollars in production. Hachey explains how at this point, the maintenance manager decided to use a vibration tester to monitor the motor on a monthly basis.
“This strategy enabled the maintenance department to not only predict when the next failure would occur, but also identify the root cause of the problem,” he notes. “In this example, the issue was angular misalignment on the motor shaft.”
In addition to ending the cycle of premature motor failure, the alignment correction resulted in a decrease in power demand, as the motor no longer had to fight the added torque created by the alignment error.
By implementing conservation strategies so that synergies are maximized, and by continuing to improve upon testing and maintenance activities, significant savings can be achieved. If you have an unusual or significant energy-saving story, please let us know about it.
Treena Hein is a freelance writer based in Pembroke, Ont.