Interview with Peter Kytka: Descriptors – The Heart of Asset Reliability

By Published on May 20, 2022


Let’s start with the basics – can you explain what a “descriptor” actually is?

The word “descriptor” = “describing something” by using a “scalar value”. In our condition monitoring business, this value may describe a specific asset failure mode like the “unbalance” of a component – such as a shaft.

Many other scalar values can be represented using Descriptors, temperature, overall vibration, a single peak in a spectrum, or even the age of your grandmother could be a “descriptor”

Where are descriptors used, and how are they generated?

In condition monitoring, descriptors may be part of any condition monitoring solution and are the “heart of asset reliability.” They carry condensed information about “asset health” within a plant. For example, our innovative EDGE device VCM-3 could be described as “the mother” of descriptors.

Within the VCM-3, descriptors are created from processing “raw” time signals provided by sensors connected to the VCM-3. This is happening continuously (ONLINE) and, subject to the power of the VCM-3 processor and customizable configurations, an infinite amount of descriptor types can be created, processed, and used to monitor the assets in your plant.

You’ve explained what descriptors are, but how are they derived?

Each “descriptor type” needs to be derived (or specified). This is remarkably easy, using a structured approach based on the asset type to be monitored.

Different asset types within your plant, such as pumps, are built up from individual components, such as shafts, couplings, gearboxes, and rolling element bearings. Each asset is first mapped via its machine components.

The next stage is to create descriptors that map typical failure modes associated with each component – such as rolling element bearing faults. An example of a failure mode could be an “outer ring fault” of the rolling element bearing.

Once each failure mode has been specified and configured, a “template” will be created, which can be uploaded to the VCM-3 and so your Condition Monitoring journey begins…

What are the benefits of using descriptors?

The philosophy behind descriptors is to minimize the need for experts in spending time evaluating either time waveforms, spectra, or Fast Fourier Transforms (FFTs) by assigning any “potential failure mode” to a single descriptor. Each descriptor of a failure mode can be used for the generation of a trend and alarm limits can be set, e.g. alert, danger, etc.

This happens either within the CM system or by exporting descriptors and alarms to other plant systems (such as Historian, SCADA or DCS, 3rd party IoT suppliers) that can easily process it.

The trend of these descriptors over time allows you to see how the “condition of your component” degrades. By the way, by combining different descriptors with process inputs and even other descriptors, new insights can be generated to capture previously undetectable faults represented again by a single descriptor.

By comparing the trend to alarm limits, “actionable insights” are created which give a base for decision making that can be understood by non-experts. Even more, by applying further statistical analysis, descriptors can be used as a base to predict how particular faults will develop over time… a look into the future. This enables predicted assessments of the “remaining useful life” of your components.

What does an “actionable insight” for a non-expert look like in practice?

Imagine you are a plant manager, meeting with your maintenance staff to discuss current issues with the plant. You might be using a “dashboard” that shows the status of each asset. In our example, we will follow the descriptor for the “outer ring fault” of the rolling element bearing, showing how our trend guides the actions of the maintenance staff:

Rolling element bearing type REB-XYZ in location “M1-NDE; Section A; Machine Train F” has an outer ring fault BPFO – Severity 1 (Alert). Severity 2 (Danger) likely in 2 months +- 2 weeks (RULs).

Prognosis: Production stoppages of Product X, leading to lost production value of 100 of k€’s. Plan your overhaul within one month. 

Actions:

  • Create purchase order in SAP for amount # bearings of type REB-XYZ
  • Generate Maintenance Work Order for 22 July 2022 for maintenance procedure ABC123
  • Consider also…
How can I create a business case to submit to my business manager, showing how improvements in asset reliability and reductions in operating cost could be achieved through using descriptors?

You will need a title for your business case which reflects the answer to your question. In short, you may choose: “Descriptors maximize UPTIME.” By maximizing UPTIME as per our conversation, the following direct business impacts are obvious:

  • Improved Efficiency – Keep production running and maximize throughput
  • Lower Maintenance Costs – Avoid unplanned stoppages and optimize labor through “just in time” maintenance
  • Reduce Inventory – Minimize spares holding, especially for expensive parts, by predicting the remaining useful life of components
  • Improved decision-making – Actionable insights allow faster, more accurate decision-making, which in turn increases productivity.
What final thoughts do you want to leave with people considering descriptor philosophy?

Historically, Condition Monitoring has been viewed as a “black art” and just for experts. What descriptors do is provide a set of powerful and easy-to-use tools to “non-experts.” By combining the VCM-3 descriptor approach with other plant systems such as higher-level networks, IoT, Clouds, huge benefits can be easily achieved in terms of productivity and cost reduction. VCM-3 with its versatile “descriptors” is a simple approach that just delivers Uptime.

I would like to conclude my final thoughts in 2 items only:

–              Descriptor based condition monitoring is THE FUTURE

–              Do not forget, it’s a scalar value only!

If you have questions about monitoring assets in your plant, contact us today. You can also find information in our knowledge base.

Dr. Peter Kytka – Global Sales Specialist

Peter works as a Global Sales Specialist and has worked with Balance of Plant applications and instrument technologies for the last 10 years. During his 12+ year career at B&K Vibro, he has held various positions in product- and project- management, sales -control, -consulting, and -training. Peter has studied control and automation technology with a degree in electrical engineering and afterward obtained his doctoral degree in mechanical engineering at the Technical University of Darmstadt.

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