New technologies help avoid machine faults

Sept. 3, 2009
Sheila Kennedy, contributing editor, explains how new technologies can ease the task of avoiding downtime and cost.

Whether you call maintenance predictive, condition-based, reliability-centered, threat-based or status-based, the goal remains the same. As Don Doan at SmartSignal would say, “If it ain’t broke, don’t fix it. But if it’s fixin’ to break, wouldn’t you want to know?”

Threat-based maintenance: Traditional preventive maintenance (PM) programs don’t provide the foresight necessary to predict and prevent faults. By the time a problem becomes evident, damage has already occurred, and when a machine’s condition doesn’t justify any maintenance, it might be prescribed anyway.


In response, SmartSignal introduced the concept of Threat-Based Maintenance (TBM). It determines each machine’s unique operating characteristics and flags developing problems well before traditional PM programs notice them. It represents a layer of analytics on top of existing data infrastructure investments, including sensors, vibration and oil analysis, DCS and data historian solutions.

Status-based maintenance: What makes GE’s Smart Grid smart isn’t just power delivery efficiency, but also turbine reliability. GE’s new Asset Optimization solution is designed to enable status-based maintenance and upgrades of a full range of electrical transformers, from those on the power grid to industrial arc furnace transformers. Drivers of this offering included the prevalence of transformers that are at or near the end of their design life cycle, and the aging and shrinking maintenance workforce.

GE Energy’s Asset Optimization engineers use predictive modeling software and comparative analysis to monitor performance remotely and to identify potential failure conditions of the transformers and their components, such as tap changers and bushings. GE estimates the service can reduce the risk of unplanned power outages and transformer failure by as much as 80%.

Capacitive sensors: Power turbine design technologies are beginning to be exploited for predictive maintenance. A capacitive probe-based system, used originally to verify gas turbine engine design, now shows potential for monitoring the engine’s condition and blade vibration while in operation. The CapaciSense sensors by Tyco Thermal Controls assess compressor and turbine blade-tip clearance measurements, blade deflection, rotor shaft and disc displacement data in real time, allowing for informed and timely maintenance decisions.

The 5 Series CapaciSense blade tip clearance and vibration monitoring system consists of an electronics package and software. The capacitive sensor is designed for use with AM or FM electronics. Its 400-kHz bandwidth allows the tip timing measurements required for blade vibration monitoring, and the high-temperature system withstands tip temperatures as high as 2,550°F (1,400°C).

Vibration switch: Continuous monitoring of the vibration in critical industrial equipment reveals changes in operating conditions and clues to potential failure. ifm efector’s new VK Series vibration switch monitors vibration using a cost-effective micro-electromechanical system (MEMS) accelerometer. The compact VK switch, based on the ISO 10816 standard for vibration monitoring, is designed to be mounted on a machine quickly and permanently. It monitors real-time RMS vibration velocity, provides an analog velocity output and, if the set point is exceeded, the switch triggers an alarm.

Compared to IEPE accelerometer alternatives, the MEMS technology’s nano-sized mechanical components have nearly no mass or movement, which eliminates problems such as signal drift, resonant frequency and calibration requirements. In addition, it eliminates the spectrum analysis and data collectors associated with traditional vibration monitoring.

Watch the oil: Infrared technology brings portability to predictive maintenance. For instance, Spectro’s FluidScan is a four-pound handheld lubricant condition monitor that analyzes fluid degradation and contamination using infrared spectroscopy. Designed with a patented flip-top sampling cell, it measures base number (BN), acid number (AN), oxidation, nitration, sulfation, incorrect lubricant, additive depletion, soot, glycol/antifreeze and water. The analysis is performed on-site and the feedback is immediate.

Another example is FLIR System’s GF309, a portable infrared camera that “sees through flames,” making it suited to furnace inspections. The high-temperature camera monitors gas-fired furnaces, chemical heaters and coal-fired boilers. The inspections during operation reveal problems such as coking, scaling, ash build-up and flame impingement. Problem assets are tracked using embedded GPS. The nickel-coated heat shield is detachable and the camera operates at a wide temperature range, making the portable GF309 suitable for additional electrical and mechanical inspections including bearings, electrical connections and external fireboxes.

E-mail Contributing Editor Sheila Kennedy, managing director of Additive Communications, at [email protected].

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