Drives and rotating machines are at the heart of most production processes. Providing early warning for failing drives systems is straight forward in application and cost effective when using predictive maintenance. To a high degree, modern drive systems are reliable, but when failures occur, they are costly and time consuming. Direct and indirect costs from unplanned maintenance include lost material, lost production, lost sales and obtaining replacement plant.

By giving practical early warning signals for failing drives systems, prevents unexpected and costly downtime and loss of production due to both VSD and drive train failures. They can be supplied as completely new systems or retrofitted to any machines using Mitsubishi Electric F800 or A800 E2 model VSD.

Modern VSDs

Many VSDs include some form of predictive maintenance feature that helps preserve the health and life of the drive. They vary from a simple set of maintenance timers giving running time, to more advanced monitoring functions. Once the set period has elapsed on a timer it will flag an output as a reminder of further maintenance needs.

Some drives go much further by checking the main capacitors and circuit board inrush currents for anomalies. These more advanced measures can provide one of many life checks supported as standard on a higher-end drives. Furthermore, they can track the load characteristics of the equipment the VSD is controlling. This for example ensures that a motor driven pump is running within its optimal pumping curve.

Condition based monitoring is an additional unit from Mitsubishi Electric and e-F@ctory Alliance Partner Schaeffler to take it further. It allows a specific application code within the PLC functionality built-in to an 800 Series VSD to work in conjunction with the multiple sensors. It harnesses the sensor data and uses the VSD to process the information into actionable insights.

This “plug and play” solution allows the Mitsubishi 800 Series protect both itself and the general health of the complete drive train, from the motor through to the driven equipment. The programme also supports two individual sensors per VSD to allow monitoring of the motor and a gearbox, pump, compressor.

Failing drives systems

All rotating electro-mechanical equipment vibrates. The role of the Smart Condition Monitoring (SCM) is vibration monitoring, and the recognition, analysis and interpreting of vibration patterns. The system records three general parameters: ISO10816, RMS, and the peak-to-peak value based on the acceleration signal and its curve envelope. The information converts to a trend curve, and over time and anomalies are thus identified by the SCM. Temperature monitoring is also included in the device which allows for monitoring and cross-referencing with an additional related trend.

After establishing some initial machine parameters, the smart sensor automatically determines the appropriate alarm thresholds. When enough measurement data is available, the pre-set alarm thresholds are overwritten by new determined ones. It can also monitor specific frequencies, such as those found in damaged rolling bearings, gear teeth and fan propellers.

The system includes component templates for entering operational data for fans, pumps, toothed belt drives, clutches, gearboxes and so on. A teach function allows the SCM sensor to learn the machine’ normal operating state and creates a memory map of the vibration readings. The VSD compares the information fed back with a look-up table held inside the drive’s PLC. This determines the condition of the equipment and the VSD reports this information visually or as an alarm. SCM works will all motors and the user need no prior knowledge of vibration analysis to interpret the alarm codes.

Expanding the system?

The SCM allows later expansion to include multiple sensors, PLC, and HMI. It collects sensor data for analysis and sends updates and warnings of failing drives systems to smart phone, HMIs, or the management information system. Linking several SCM sensors to a single controller allows the monitoring of several machines or a complete production line. Moreover, the system works both stand-alone and as part of an integrated predictive maintenance solution. Critical data transfers either to an edge computing layer or direct to the enterprise level for total flexibility and scalability.