KCF Technologies Blog

Wireless Vibration Monitoring Breezing into Wind Industry

The following article, authored by KCF Technologies employee Christopher Shannon, was published on RenewableEnergyWorld.com on August 8, 2013.

A SmartDiagnostics®
wireless vibration sensor
mounted on a wind turbine
blade root.
Wind turbines can, and do, fail. And, when they do fail, they do so in spectacular fashion. A quick search on YouTube for “wind turbine failures” yields numerous videos of exploding wind turbines, wind turbines on fire, or involved in other high-stress calamities. 

However, predictive maintenance with wireless vibration monitoring can offer a solution.  By using wireless vibration monitoring to continuously monitor the health of wind turbines, wind turbine operators can access information that can be used to reduce operational downtime.  By tracking vibration patterns that indicate an urgent need for maintenance the operator can take action to repair the turbine before a catastrophic failure occurs.

Furthermore, by using the vibration monitoring information to indicate when maintenance activities need to be performed the operator can reduce unnecessary maintenance and shutdowns, enabling additional significant savings to be realized.  First, let us look at five specific phenomenon that vibration monitoring may detect to avoid excessive downtime or failure.  Then, we will take a look at the potential value of wireless vibration monitoring on a hypothetical fleet of 100 turbines.  Finally, a real-world use case will be discussed.  Read the rest of the article on RenewableEnergyWorld.com.

Photo courtesy of Trans-Tag.  All rights reserved.

Vibration Monitoring Works on Low-Speed Equipment, Too

State College, Pa., home to both The Pennsylvania State University and KCF Technologies, shares the same time zone with Chile's Universidad de Concepción,even though the two are about 5,400 miles apart from north to south.  Still, it says a lot about 21st-century technologies in the Americas that both these esteemed institutions of higher learning and their neighboring industries share a passionate interest in predictive maintenance technologies.

Founded in 1915 as the Technical Association of the Pulp and Paper Industry, TAPPI is today a registered not-for-profit international organization of about 14,000 members--pulp and paper engineers, scientists, managers, and academics.  Two such academics, Pedro Saavedra and Edgar Estupiñan of the Mechanical Engineering Department at UdeC, coauthored a paper in the May 2002 TAPPI Journal titled "Vibration analysis applied to low-speed machines in the pulp and paper industry."  This peer-reviewed predictive maintenance column "used some real-world historical cases from the pulp and paper industries to illustrate that with an integrated analysis of the vibration spectrum and waveform, and the use of averages and a fine frequency resolution, it is possible to detect defects in bearings of low-speed machines."  These are defined by them as machines operating at speeds from six to 300 cycles per minute.

"Most mills have been using the technique for some time to identify deterioration of vital equipment components...predicting and preventing catastrophic failures.   However, monitoring of low-speed machines is more complicated than general machinery monitoring.  In low-speed machines, the magnitude of the dynamic forces generating the machine vibrations decreases as the rotational speed of the machine decreases.  In addition, low-speed machines are typically massive in size.  Therefore, the resultant vibration on the bearing housing...is often very low and can be hidden by background noise."

The six-page article uses numerous images of vibration spectra and waveforms to show how the analysis was done, and how the detected low-frequency aberrations appeared in practical applications during the study.  "Frequency (or spectral) analysis is the most commonly used method for detecting machines faults such as rotor unbalance, shaft misalignment, mechanical looseness, and bearing damage.  The fundamental idea of frequency analysis is to find the relation between the spectral component frequencies and the frequencies of the dynamic forces producing the faults."

The authors conclude that "...research has shown that it is possible for field engineers and technicians to monitor the condition of low-speed machines by using integrated vibration analysis techniques and by paying strict attention to the selection and use of vibration measurement equipment.  Concerted efforts to improve the signal-to-noise ratio of the measurement are required."

More candid still are the "Insights" Saavedra and Estupiñan added following the article itself, including this: "Mill maintenance staff can use vibration analysis to predict faults, but the most important thing is the correct analysis of the information.  Significant cost savings are possible through enhanced maintenance planning and fault prediction."

SmartDiagnostics® Feature Highlight: Customizing Monitoring Bands

In order to make it easier for you to set the same monitoring bands for multiple machines, SmartDiagnostics®provides the ability to create a template of monitoring bands and give that template a name.  Then later on, for other machines, you can apply that template rather than create more individual bands.

To do this, create your monitoring bands on a monitoring location once by hand as described in the manual in Section 4.5.1 Configuring an Individual Monitoring Band.  When you are ready to save the whole group of monitoring bands as the template, do the following:
  1. Click the Save As Template button on the Monitoring Bands Summary view to show the Save Monitoring Band Template pop-up as seen near by.
  2. Type in a unique name to use for your template in the Name entry field to create a new template or select a name from the Existing Templates List to repalce the monitoring Bands in that template.
  3. Click the Save button to save the template for use on another machine.
 To use an existing template of monitoring bands on your monitoring location, do the following:
  1. Click the Apply Template button on the Monitoring Bands Summary view to show the Monitoring Band Templates pop-up as seen near by.
  2. Select the template you want to use on the monitoring location and press the Apply Template button.
If you want to remove an existing template from the system simply click the Remove Template button on the Monitoring Band Templates pop-up.

The value of the monitoring bands template feature is that it allows you to easily configure the same type of monitoring locations on different machines of the same type.  You simply create the monitoring bands once, save them as a template, and you can apply the same bands to each machine at that monitoring location to allow for consistency and ease of configuration.

In reality, similar machines may still operate somewhat differently.  Therefore, once you have applied a template, you can override it to allow for the uniqueness of each machine.  Remember, too, that operating frequency levels are often listed in the User's Manual for each particular piece of machinery, can be obtained by contacting a dealer's representative or main office, or may be available from professional maintenance organizations.

You can learn much more about KCF Technologies' SmartDiagnostics® technology here.

There's a Major Difference Between Vibration Monitoring and Vibration Analysis

A SmartDiagnostics® wireless vibration sensor on a pump at a wastewater
treatment facility.
Dating back to 1905, Gardner Denver Nash --"your source for industrial vacuum and compressed gas solutions" -- has its offices in Pennsylvania, Brazil, Germany, and China.  The firm provides improved global service and technical support for Nash liquid ring vacuum pumps, compressors, and engineering systems serving the chemical, petroleum, power, paper, mining, environmental, food, and wastewater treatment industries.  It also produces a thought-provoking quarterly newsletter.

One of its newsletters last year featured a brief, unsourced piece on "Vibration Analysis vs. Vibration Monitoring."  It's conclusion was unexceptional: "Implementing the proper maintenance plan will have a positive impact on the longevity of you equipment."  But, it found that the difference between monitoring and analysis can be the difference between merely piling up a lot of numbers and insightful comprehension of actual machine performance.

"Companies heavily depend on maintenance to keep equipment running, but simply monitoring bearing vibrations at set intervals may not be the best way to evaluate equipment.  When monitoring and analyzing bearings the trend data, the equipment may seem to be operating correctly when in fact it is not.  An example of this comes from a 2007[-09] case study at a wastewater facility in Washington, D.C."

"Briefly, the wastewater treatment facility began tracking the reliability of it's pumps in 2007 using vibration analysis.  Working with a simple analyzer, a rotating machinery technician examined any pump with high vibrations.  Due to the quantity of pumps and the multiple plant locations, it was difficult to service the pumps before they had issues.  By the time attention was given to problematic pumps, extensive repair was needed--which increased the cost as well as the downtime."

In 2009, the company shifted...to a monthly monitoring schedule.  This new approach helped to reduce the cost associated with catastrophic failures.  The problem with monthly trending is that you can occasionally have higher than normal vibration peaks and they could go unseen in the overall trend data.  Even though they were having fewer failures, they were still not able to determine the problem pumps before there was an issue.  After discussion with an outside consultant, it was determined that a continuous monitoring system would solve their problem."

Triaxial vibration/temperature sensors on the pumps were connected to data modules that sent measurements by radio to a communications module, which relayed the signals to a tower, which transmitted them to a company network.  The result?  "Plant technicians, maintenance personnel, and other operators could view the data directly on their computers, via the internet, from any location.  The results showed that vibrations spiked from a low level of approximately 0.05 inches per second...to a high level that was close to the 0.5 inches per second alarm level.'

Predictive, preventive, and proactive maintenance all have their places in any water and wastewater treatment system.  But, vibration monitoring--just observing that pumps vibrate from time to time--is by no means the same as vibration analysis--recording patterns of vibration when and as they happen, tracking non-standard patterns and peaks, and intervening in time to schedule needed maintenance and avoid downtime.

Photo by Christopher Shannon/KCF Technologies.  All rights reserved.

KCF Making the Things You Work with Smarter