The powertrain system service manuals that manufacturers provide commonly reflect best preventive maintenance practices under typical operating conditions. However, real-life conditions for prime movers vary. In one application, the time a motor or turbine operates and the load it carries may fluctuate. In another, power demands may be constant. Air quality, flow and temperature may vary depending on geographical location or the placement within a plant, as can the quality of lubricants and replacement components service personnel use. One-size-fits-all maintenance schedules are clearly inadequate.
The preventive approach has another downside. Time-based or frequency-based maintenance tasks can be inefficient and costly. Service administered too late results in unplanned downtime, production stoppages and emergency repairs. Service performed before an actual need is present is wasteful and exposes the equipment to risks. For example, the process of checking the oil introduces the opportunity to close the lid improperly, which can allow dirt to enter the oil. Each time a bolt is loosened, it may not be tightened properly, or components may become aligned improperly or unbalanced.
A more proactive, predictive approach to maintenance is more efficient and economical. Predictive maintenance is based on the actual condition of the equipment and material. For example, if control system indications suggest a turbine bearing failure is imminent, the equipment can be scheduled for repair or swapped immediately with backup equipment. Predictive maintenance tells you the health and lifespan of a powertrain system. It’s a practice that prevents unplanned downtime, and recognizes and corrects conditions leading to excessive energy consumption.
The manufacturers’ role in PdM
Many original equipment manufacturers (OEMs) provide strategic asset repair services, and some offer comprehensive third-party plant operation and maintenance (O&M) services. Placing the responsibility for prime mover reliability on the OEM motivates it to employ advanced predictive practices.
GE, for example, services prime movers from every manufacturer for its clients in the utility, pulp and paper, metals, chemical, transportation and general industrial markets. Services include rebuilding and repairing AC and DC motors, stator rewinds, upgrades and redesigns of motor windings, with full on-site service capabilities. GE uses state-of-the-art diagnostic testing and monitoring, and failure analysis techniques. GE Energy is one of the world's largest third-party providers of plant O&M services.
Rolls-Royce powertrain systems are used in aviation, energy utilities, oil and gas, chemical and other industries. They provide automation and control systems for engines, turbines and compressors, including high-performance control systems and commercial, off-the-shelf programmable logic controllers (PLC).
Tools that enable PdM
Vibration analysis, thermography, lube oil analysis, acoustic leak detection, motor current analysis, off-line electrical testing and valve diagnostics are important tools for detecting impending mechanical failure before the condition deteriorates significantly. Additional diagnostic inputs include maintenance history and logs, process and performance data, design information, batch tests and inspections.
Implementing PdM
Predictive maintenance implementation blends efficient data collection with condition monitoring, diagnostics, life-cycle simulation and corrective action management. The OEM’s service manual, combined with service histories, can help identify which equipment and components should be monitored. Prime candidates for predictive maintenance include assets that incur the greatest costs (essentially anything with rotating parts) and components that are most prone to failure, such as bearings.
Data Systems & Solutions stresses “management by exception” with a focus on operational aspects that are, or may soon be, nonperforming. Through its software and consulting services, it helps companies implement and manage effective predictive maintenance programs. Data Systems & Solutions also builds and supports physical and virtual asset optimization centers. These control centers for integrated, preemptive, information-based asset management are designed to help companies monitor proactively, which reduces and eliminates problems, and expedites corrective actions. The company was spawned from Rolls-Royce and Science Applications International Corporation (SAIC). Rolls brought expertise in engineering and controls, and SAIC furnished the skills in systems integration and information technology.
The future for powertrain management
Maintenance practices will evolve as engineering and diagnostics improve. The Powertrain Control Research Laboratory at the University of Wisconsin-Madison is an independent research program breaking new ground through experimentation and analysis. “We are focused on powertrain systems, their modeling, control, diagnostics and transient testing,” says Professor John J. Moskwa, the lab’s founder and director. “As such, we are exploring potential future ways of controlling, diagnosing or testing these systems to improve their performance or decrease costs and time.”
E-mail Contributing Editor Sheila Kennedy, managing director of Additive Communications, at [email protected].
For more information see:
www.geopower.com
www.rolls-royce.com
www.ds-s.com
www.powertrain.engr.wisc.edu
www.fordpowerproducts.com
www.asme.org