From local to cloud-based condition monitoring28 October 2017

Condition Monitoring (CM) no longer needs to be restricted to highly skilled, experienced engineers. With the advent of cloud-based CM systems, users can now share data with experts via the cloud, enabling improved fault diagnosis, faster reaction times and reduced machine downtime, as Mark Venables discovers

Rolling bearings are critical components used extensively in many types of rotating plant and equipment. If they fail unexpectedly, this can result in high repair and replacement costs.

Condition Monitoring (CM) has been used for many years as an integral part of a Predictive Maintenance (PM) strategy. Measuring vibration is one of the most widely used CM techniques for detecting and diagnosing equipment faults.

To date, most CM systems have predominantly been used as local systems, collecting vibration data from machines and using analysis algorithms and a rolling bearing database to check for signs of wear, defects or other unusual behaviour. “While this works very well for many companies, imagine the added value of being able to share and compare your local machine condition data, via the cloud, with other similar items of equipment across your plant, or better still, with other equipment at multiple plants within your business, wherever they are located in the world?” says Dr Steve Lacey, technology centre manager at Schaeffler UK. “Furthermore, rather than having to rely on the local knowledge and experience of a skilled maintenance technician, a cloud-based CM system can provide a direct link to a specialist in vibration analysis at the bearing supplier or the supplier of the CM system.

“Some CM systems now provide a direct link to the cloud, to which data from CM systems and devices can be transferred. Automated diagnosis signals are processed from the raw data transmitted by the CM system and any other data that is available.” This means that vibration data is not only processed in the CM system itself – it is also processed in the cloud, which offers greater processing power and more extensive analysis options, due to the combination of this data with other machine control data. This increases the reliability of the diagnosis information the customer receives.

The latest CM systems are quick and easy to install and set up, with the user requiring no specific skills or knowledge of vibration diagnosis. “When changes occur in the condition of the equipment, the CM system automatically generates plain text messages on a display, providing the user with clear instructions for action, enabling any corrective maintenance work to be undertaken and any replacement parts to be ordered, if required,” Lacey adds. “These ‘automatic fault assessment’ systems are truly ground-breaking, as they help to minimise the skills, knowledge and experience required of maintenance staff or operators.”

With ready-to-use, pre-set measurement configurations, these CM systems can identify the main causes of faults: bearing damage, imbalance, friction/cavitation (for centrifugal pumps) and temperature increases. For general changes in vibration patterns that cannot be clearly attributed to one of the above, the CM system can request, via the cloud, additional analyses from a specialist.
CM systems can be preconfigured to monitor a range of rotating equipment (typically from 100rpm to 15,000rpm) that is supported by rolling bearings, such as electric motors, compressors, gearboxes and pumps.

Subsea monitoring
Subsea 7 is a world-leading seabed-to-surface engineering, construction and services contractor to the offshore energy industry. Operating in such harsh environments places a premium on the reliability of vessels and their equipment. Failure of a critical asset while at sea could jeopardise the vessel schedules. At the same time, the company needs to keep the time required for planned maintenance and overhaul activities tightly under control, so its assets can spend more of their time working on projects for its customers around world.

In its continual efforts to maximise performance, the company is moving from time-based overhauls to a condition-based maintenance strategy for several critical assets in its fleet. By monitoring the behaviour and performance of equipment, the company’s engineers aim to ensure that equipment overhaul and replacement activities are carried out at the optimal frequency, maximising vessel performance and availability. As part of this new strategy, Subsea 7 is now conducting regular static testing on several critical electrical machines in its fleet. Those assets include the generators and thruster motors used to keep vessels in the correct position over the work site.

The electrical testing services are provided by SKF, using the SKF Static Motor Analyser Baker AWA-IV. This performs tests on motors while in a static, or powered-down, state. Static electrical testing can provide early warning of issues in electrical machines, allowing timely intervention before a problem occurs, minimising impact on operations and vessel availability. A sequence of tests is conducted to analyse the winding circuit, and the dielectric strength of the insulation between windings and earth, as well as turn-to-turn and between phases. For example, studies have shown that 80% of the electrical failures in motors begin with a failure of the thin insulation around individual wires in their coils. As this insulation degrades, the inrush of voltage during motor starting and stopping can cause arcing, further degrading the insulation and creating a conductive carbon path that will eventually lead to a short circuit and complete failure. A special test, known as a surge test, is used to detect weak turn-to-turn insulation before a short occurs. Testing is conducted while vessels are docked for other scheduled maintenance activities.

The generators installed on vessels can contain up to five separate windings and each undergoes a comprehensive series of tests to determine the overall health of the machine. The companies have collaborated to design and tailor the service and solution to deliver the maximum value to their operations during tight overhaul schedules. This includes documented preparation instructions, and a review of the equipment profile and test procedures in advance of each planned overhaul. Any early identification of a pending issue or deterioration in equipment performance allows Subsea 7 to intervene during the scheduled maintenance period to prevent future problems. This means the fleet can operate with complete assurance that its electrical equipment will deliver optimum performance. Regular testing is also helping the company improve its overall understanding of asset performance and reliability, says Julien Manach, DP, electrical & control systems group lead at Subsea 7. “By performing electrical condition monitoring on both new builds and existing ships in service, we can
build up a picture of changes in equipment health and performance, plan maintenance and, if necessary, take action before a major breakdown occurs. Both marine and construction equipment is often located in areas which are difficult to access or perform in-situ repairs. Therefore, the earlier a developing fault is detected, the more effective the operational intervention can become, averting a possible failure, reducing both the risk of vessel downtime and cost.”

Connected compressors and Industry 4.0
Back on dry land, the term Internet of Things (IoT) has become ubiquitous in recent years and is now seemingly being applied to any instance in which a device is connected, communicative and data-driven: whether it is a smartphone, fridge freezer or car. Arguably, though, it is the manufacturing sector that stands to benefit the most.

The challenge for equipment suppliers is that companies are now moving beyond talking about Industry 4.0 to wanting to know how it can and will be applied in practice.

As one of the world’s major industrial energy sources, which is estimated to account for 10% of all energy used in industry globally, compressed air will undoubtedly have a significant role to play in shaping the smart factories of the future. But, you may ask, what is being done now within the compressed air industry to embrace Industry 4.0?

The concept of adding intelligence to air compressors by connecting and enabling them to communicate over the internet is not new. In fact, as of today, Atlas Copco has over 100,000 connected compressors operating at more than 35,000 customer sites in the world. These compressors are delivering more than 150 data measurements per second. This is proving vital, on one hand in enabling data mining engineers to intelligently analyse performance patterns and, on the other, by helping design teams to apply the data in the development of new and more customer-suited compressed air technologies.

There have been such major leaps forward in this area that it has led to the creation of a new sub-set of the Industry 4.0 movement known as Preventative Maintenance 4.0. “In the realm of compressed air technology, the major development in preventative maintenance has been the introduction of technology that combines hardware with customisable data monitoring software,” states Stef Lievens, business line manager for compressor technique service operations at Atlas Copco Compressors UK and Ireland.

“This enables maintenance and service engineers to remotely track indicators, such as specific energy and compressed air pressure calculations, so that immediate improvements can be made when needed. During this process, data is gathered, compared, and analysed; and, when required, warnings can be sent out to prevent downtime, and to allow local service providers to plan and prepare their interventions.”

Analysis of available data has proven that uptime is greatly improved on regularly serviced compressors and can make a difference of 3.5% to a compressor’s availability. This may not sound high at first. However, as it equates to an additional 210 production hours over the course of a year, based on a compressor running for 6000 hours per annum, the potential business benefits quickly become clear.

Knowing the status of compressed air equipment at all times is the surest way for plant managers and maintenance professionals to spot any developing problems, uncover potential energy savings and achieve maximum uptime of both compressors and the production lines they support. “These insights can be realised through a remote data monitoring system, which is illustrated by a number of recent use cases,” Lievens adds. “For instance, when a period of cold weather caused a cereal manufacturer’s compressors to run at a particularly low ambient temperature, a remote data monitoring programme picked up warnings from the units’ electronic condensate drains and triggered a visit to the site by a service engineer. This early intervention saw the customer fit temporary heaters to prevent the drains freezing up, which could have led to compressor element damage, condensate reaching the air network and substantial breakdown costs.”

In another use case, a remote data monitoring system picked up an instance where the element temperatures were inefficiently high in all of the compressors at a steel manufacturer’s site. On inspection, a service engineer found that the compressor room was poorly ventilated, leading to a temperature of +400oC in the room. A complete re-design of the compressor room was recommended. Beforehand, engineers made sure the compressor coolers were kept clean and the oil was topped up to prevent overheating

Adam Offord

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