Predictive maintenance grows in sophistication with new robotic inspection crawler
As the required time-to-market for industrial products becomes ever more aggressive, so does the need to keep machinery and other assets working efficiently. Alongside this is the equally urgent requirement to reduce the cost of maintenance and speed-up time-sensitive repairs.
One area where maintenance is especially vital is in heavy process plants, energy, and power utilities. Inspecting the stator and rotor of large synchronous motors and generators can often cause costly production outage periods. A routine inspection can last up to 20 days, with most of this time spent removing and reinstating the rotor. The outage period may even exceed 20 days because of the added complication of crane access and associated risk of damaging the rotor when removing and replacing it.
Inspections should identify issues such as wear and aging parts, blocked air ducts, partial discharge, damaged core, and deep contamination. Conventional inspection devices, however, can only be applied to turbo/hydro generators with a large air gap between stator and rotor. Companies today are not only looking to shorten inspections, but also improve inspection accuracy to extend the availability of their generators.
To address this need and refine in-situ inspection techniques to enhance preventive maintenance, ABB launched an innovative, super-slim robot inspection crawler known as the Air Gap Inspector. Equipped with five cameras – three in front, one at the rear, and one that focuses on the rotor – the crawler travels in the narrow air gap between the stator and rotor to perform accurate inspections. These include indications of stator wedge movement, detailed visual examination of the rotor, and winding insulation inspection. These visual inspections cover the entire length of the core and take place without removing the rotor, making maintenance not only more effective but also highly cost-effective.
The device provides a live, 360-degree high-definition video survey, that is recorded as it traverses the stator core laminations using a magnetic roller mechanism. Configurable linkages between the tracks and crawler body, allows the crawler to be adjusted to fit in a wide variety of motor and generator designs.
The front-mounted, side-facing cameras can be angled to provide the best possible view of objects such as the inner surfaces, windings, wedges, stator teeth, air ducts, rotor support blocks, and parts of the end windings. LEDs, with variable intensity settings, are mounted next to the cameras to provide light.
The camera output passes through the tether to the display, with the resultant video data offering an invaluable and comprehensive insight into the condition of the stator and rotor. The crawler can also capture still images if required. Unlike conventional inspection devices, the low height of the robotic inspection crawler allows it to operate in all synchronous motors and generators with an air gap of 10 mm or more. The crawler head can operate in temperatures up to 50⁰C.
As part of the service, an expert team from ABB conducts the inspection and analyses the video to locate faults accurately and determine their severity. Robotic inspection dramatically extends the scope of motor and generator maintenance, as the team can also provide an action plan for the next recommended maintenance actions. The service is ideal for inspections during minor production outages or in cases where it’s difficult or impossible to remove the rotor.
Performing the visual inspections in-situ with the rotor still in place can significantly reduce outage time when compared to traditional methods, allowing plant operators to reduce maintenance costs, optimize maintenance planning, and increase the availability of motors and generators.
The ABB in-situ robotic visual inspection equipment comprises a robotic crawler including track modules, tether for connecting the crawler to a control system, and a control system to operate the crawler.
The changing perception of maintenance
As industrial customers become increasingly aware of the growing maintenance costs and downtime caused by unexpected machinery failures, predictive maintenance solutions are gaining even more traction. Whereas maintenance has traditionally been seen as a necessary evil, perceptions started changing in the 2000s when maintenance started to be viewed as an important support function that can be planned and controlled.
Today, attitudes are shifting towards perceiving maintenance as an integral part of the business process that creates additional value. A properly planned maintenance regime can have a significant impact on the overall equipment effectiveness (OEE) of the plant and process. Maintenance technicians are now moving from reactive maintenance to proactive and predictive maintenance. The ABB AbilityTM Predictive Maintenance service, for example, helps customers to not only improve plant reliability and productivity but also to reduce costs by avoiding unnecessary maintenance.
This offering is undertaken during a maintenance outage, combining the air gap inspection with vibration analysis, a life expectancy analysis (LEAP) of the stator winding insulation system, and a maintenance history assessment. The stator winding insulation is the most uptime critical component in high-voltage motors and generators. ABB Ability™ LEAP helps to detect potential problems with the insulation well before they become critical.
The data from these services can help with issues that might otherwise only be visible during a later regular maintenance, or after a failure occurs. Predictive maintenance is a highly sophisticated form of maintaining equipment. It helps to detect any signs of possible failure at an early stage, so maintenance can be planned in advance. This strategy gives operators much more control over the operations of their equipment and helps them to avoid unplanned downtime.
Peter Wright, Product Manager Field Service, ABB Motion
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