Introduction
This report describes a trial made with SPM’s Airius wireless vibration sensors on a scrubber fan, utilizing the Condmaster Ruby condition monitoring software and including the Condmaster.NET dashboard. Sensors were installed on each of the machine bearing housings, giving the possibility to measure a number of parameters in three axes, including velocity, acceleration, enveloped acceleration (bearing condition), and temperature. Velocity measurements indicate mechanical faults such as imbalance, misalignment, and looseness. Enveloped acceleration and temperature are an indication of bearing condition and can be used to detect not only bearing distress but also lubrication deficiencies.
Conclusion and summary
The combination of velocity, enveloped acceleration, and temperature data collected periodically over three axes provides all the information necessary to track machine condition in a simple, easyto-understand green, amber, and red format. Alarm emails are used for notification of machinery running out of range as a prompt to review either the system dashboard or supported mobile app for detailed machine information to determine corrective maintenance actions. The effectiveness of the condition-based maintenance program is tracked by the maintenance management team using Plant Performer according to defined KPIs.
Image 1 Condmaster.NET dashboard.
Reviewing Condmaster Ruby provides an automatic diagnosis of machine fault symptoms when an alarm is generated. The system detected minor defects relating to guard scraping, misalignment, and worn belts. These are described on pages 13 and 14.
System setup
For the pilot, a local WLAN was established and data was transmitted to a locally-sited laptop computer with SPM software installed. Airius sensors were installed by gluing the mounting feet to the motor and fan bearing housings. Using an extremely energy-efficient communication protocol, the sensors send raw measurement data through a Wi-Fi network.
The data (which can be encrypted for security reasons) travels through the internal Wi-Fi network to CES (Condmaster Entity Server) with a virtual DSP (Digital Signal Processor), where it is processed and analyzed. The virtual DSP processes and turns a single measurement from Airius into several results, including machine fault symptoms such as misalignment or imbalance.
Image 2 The Graphical Overview in Condmaster Ruby, showing the fan and the measuring point positions.
Sensors were mounted and oriented according to their reference plane:
• X-axis – horizontal plane
• Y-axis – axial plane
• Z-axis – vertical plane
All measuring points utilized the same frequency ranges and resolution for the vibration velocity, acceleration, enveloped acceleration (bearing condition), and temperature measurements. The setup is shown overleaf.
Image 3 Vibration velocity assignment configuration.
Image 4 Bearing condition assignment configuration.
Image 5 Motor NDE vibration and machine symptom parameters.
Image 6 Motor DE vibration and machine symptom parameters.
Image 7 Fan DE vibration and machine symptom parameters.
Image 7 Fan DE vibration and machine symptom parameters.
Image 8 Fan NDE vibration and machine symptom parameters.
Condition and alarm management, fault diagnosis
Alarm limits were established using a combination of ISO 10816 guidelines for vibration velocity – part 3, group 1, flexible support, rotational speed > 600 RPM. Condmaster Ruby’s Condition Manager was used for statistical alarm management for bearing condition and machine fault diagnosis symptoms
Image 9 Alarm limit configuration.
Condmaster Ruby’s Condition Manager was used for statistical alarm management for bearing condition and machine fault diagnosis symptoms
Image 10 Condition Manager with a distribution graph.
Image 11 Automatic fault symptom diagnosis.
Case descriptions
Case: Sheave misalignment and worn belt on Motor NDE and Fan DE
Image 12 Velocity Rms readings in the amber zone.
The vibration level exceeded theISO 10816 alarm level. Sheave misalignment and a worn belt were detected on the motor non-drive end sheave.
Image 13 Vibration spectrum.
Image 14 The same spectrum zoomed-in, with symptom markers for worn belt and misalignment on the motor DE.
Automatic fault recognition diagnosed the fault as a misalignment. In addition, worn belt frequencies were also present.
The Condition Manager was used to automatically alert and describe changes in machine condition and define fault symptoms.
Case: Guard scraping on the fan shaft
Image 16 Fan NDE, time domain
The fan shaft scraping on the guard was audible and visible. This was noted on the installation of the sensors. Impacting can be observed in the time waveform; there were higher enveloped acceleration values on the Fan NDE in comparison to Fan DE. Higher velocity readings were measured on the Fan NDE; however, no matches with unbalance (1X).
In addition to vibration in three axes, Airius also collects temperature data, and a comparison between bearing temperatures showed 41 degrees on the Fan NDE and 35 degrees on the Fan DE. The motor bearing temperature was 31 degrees.
Economic justification
A bearing failure on the scrubber fan would mean at least a two-hour stop with downtime at £10K/ hour (£20K).
