Condition monitoring system cuts unplanned downtime

Providing an early warning of machine failure

Avoiding unplanned downtime of rotating machinery is an important tool for improving productivity for manufacturers. Modern VSD have offer a wide range of protective functions to protect both the drive and connected motor. Adding a condition monitoring system extends this protection to critical fans, pumps, and gearboxes and other equipment.

The condition-based monitoring solution developed by Mitsubishi Electric  and e-F@ctory Alliance Partners Schaeffler moves the game on still further. It uses special application code in the Mitsubishi 800 Series VSD to work in directly conjunction with Schaeffler sensors. By processing the valuable data from the sensor enables the  VSD to provide the operator with actionable insights in real-time.

It provides a “plug and play” solution allowing operators to monitor the health of the complete drive train from VSD and motor through to the driven equipment. It supports  two individual sensors per VSD for monitoring both the motor and a gearbox, pump, compressor, or fan by the VSD.

How does a condition monitoring system work?

All rotating electro-mechanical equipment will vibrate to some degree. Over time vibrations increase due to wear and tear or damage. According to Mitsubishi Electric, analysing and interpreting vibration patterns as something of a ‘dark-art’.  Recognising these patterns is the function of the Smart Condition Monitoring System.

The system monitors physical vibrations from drive elements such as motors, pumps and fans transmitted through the metal housings. 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 provides a trend curve over time giving users an early sign of changes. Temperature monitoring is also included in the device to allow for monitoring and cross-reference with an additional related trend.

Given some basic parameters, the smart sensor determines the appropriate alarm thresholds. When enough measurement data is available, the pre-set alarm thresholds are  replaced by the newly determined ones. It can monitor specific frequencies, such as those found in damaged rolling bearings, gear teeth and fan propellers.

The SCM includes component templates for entering operational data for fans, pumps, toothed belt drives, clutches, gearbox stages and shafts. A teach function allows the SCM sensor to learn how the machine behaves in its normal operating state. It then creates a memory map of the vibration readings. A database integrated into the sensor also contains data from Schaeffler for standard rolling bearings. By recognising imbalance, misalignment and knocking, the system detects damage to the relevant components.

Smart sensor

The smart sensor mounted on the rotating equipment feeds information back into the VSD and the VSD compares these vibrations with a look-up table held inside the VSD’s internal PLC. This then determines the condition of the motor and the VSD reports this information in one of three ways. To an Andon beacon; through the VSD’s keypad, or to an HMI.

This system works with any brand of motor and the user requires no prior knowledge of vibration analysis to interpret the alarm codes. The SCM is available for new drive systems, but users can retrofit it into any Mitsubishi Electric F or A800 E2 model VSD. Regardless of configuration, it offers peace of mind for both VSD and drive train, giving practical early warning signals and preventing costly downtime and loss of production.

Growing the system

The next step is a full Smart Condition Monitoring solution that includes multiple sensors, a PLC, and an HMI. The SCM is an integrated solution that collects and analyses live data from the same Schaeffler sensors. It and then provides updates and warnings to devices like smart phone, HMIs, or multiple levels of management systems.

The ability to link multiple SCM sensors back to a single controller allows the monitoring of several machines or a complete production line. Working as a stand-alone system or as part of an integrated predictive maintenance solution gives total flexibility and scalability.

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