Technical
• Processed signals : Signals which are derived from the instantaneous signal , which can include statistical distribution ( maximum , minimum , mean , and standard deviation values ), frequency domain analysis or mission profile indicators .
• Analytics signals : Signals which provide indications of the condition of the drive , motor , and application . The signals are used to trigger maintenance or lead to system design improvements .
For this purpose , key parameters are selected as indicators to identify developing faults .
In this case , planning maintenance actions provides many advantages such as :
• Downtime reduction ;
• Elimination of unexpected production stops ;
• Maintenance optimisation ; and
• Reduction in spare part stock inventory
Motor current signature analysis techniques enable the drive to monitor the condition of the motor and application . The technique allows the system to potentially eliminate physical sensors , or extract early fault signatures that might not have been possible to detect . For example , using the technique makes it possible to detect winding faults in advance or mechanical load eccentricity .
The concept of the drive as a sensor hub involves connecting external sensors to the drive , thus saving the need for a gateway to connect the physical sensor to the data network . Vibration sensors , pressure sensors , and temperature sensors are examples of sensors which can be connected to the drive .
The advantages of the concept include as well as being able to correlate sensor data with different types of data present in the drive .
WHY IS CONDITION-BASED MAINTENANCE NEEDED ? The condition of a piece of equipment typically degrades overtime . The introduction of Industry 4.0 and the availability of sensor data means that condition-based and predictive maintenance is now possible . The idea of condition-based maintenance is to detect the potential failure before an actual failure occurs . Such maintenance strategies use actual sensor data to determine the condition of the equipment in service ( condition-based maintenance ) or to predict future failures ( predictive maintenance ).
Condition-based maintenance acquires data from the equipment itself and uses it to monitor the health of the equipment in service .
Condition monitoring follows a three-step procedure :
• Establish a baseline
• Define thresholds
• Perform monitoring
CONCLUSION Today , drives are more than simple power processors – they are vital elements in modern automation systems , with the ability to act as sensors and sensor hubs , and to process , store and analyse data , along with connectivity capabilities .
Drives are often already present in automation installations and therefore present a great opportunity to upgrade to Industry 4.0 . This enables new ways of performing maintenance , such as condition-based maintenance . The functions are already available in some drives and early adopters have already started using the drive as a sensor . RACA
" The introduction of Industry 4.0 and the availability of sensor data means that condition-based and predictive maintenance is now possible . "
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RACA Journal I June 2022 www . hvacronline . co . za