Condition Monitoring

Components of the Condition Monitoring System:

Introduction to Condition Monitoring

Condition Monitoring (CM) is a broad term, which can be understood in different ways. For the FM502_CMS, CM means the acquisition and analysis of high-frequency data. CM does usually not occur in real-time. The data is analysed afterwards. If, however, online CM is controller integrated, real-time reaction, e.g. protection, is possible within the same device and using the same sensors. This feature is supported by AC500 and FM502.

The focus is often merely on mechanical CM. This is due to the fact that the movement or rotations of large masses which are connected to a motor (e.g. electric machine) via a shaft pose the greatest danger. Machines in operation inevitably generate measurable vibration, both free or forced, even in the normal operating states and in absence of any damage.

Yet, in electrical CM, electrical high-frequency quantities like currents, voltages or partial discharges can be measured by suitable sensors and can be analyzed in order to detect electrical failure patterns, e.g. inside electrical machines or equipment (transformers). Some electrically measurable failure patters can be induced by mechanical issues e.g. vibration.

Effective fault detection will only be possible if the data patterns indicating an arising defect can be singled out among the data collected.

Monitoring e.g. the vibration characteristics of a machine in operation gives an understanding of the “‘health” condition of the machine and its development over time and load. This information can be used to detect arising problems at an early stage. Operating a machine until it breaks down might be acceptable if the machine were a “‘disposable” one and the life time was very high and known for sure. But many failures can be considered statistical outliers and occur very early and spontaneously.

However, most machines are not “disposable” due to their cost. Therefore, regular monitoring of a machine’s condition can reveal potential problems. Subsequently, counter measures can be taken at an early stage in order to minimize damage and associated cost. If monitoring is permanent and controller integrated, even spontaneous failures can be detected in real-time, in order to prevent substantial damage to a larger part of the equipment and its environment.

Use cases of FM502_CMS

  • Condition monitoring: Longer data-stream analyses
  • Protection: Fast reaction to e.g. direct or RMS values based on limits
  • Fast and precise analog measurements as with any other AC500 I/O module, but even more precise and faster
  • Data logging: Fast, efficient data storage

Condition Monitoring typically means acquisition of longer data streams, also called “time series” or “signals”. These can be analyzed after measurement in the time domain (e.g. envelope, statistical analysis) or frequency domain (e.g. spectrum analysis).

The Function Module FM502_CMS works independently of the user program and therefore it is able to response quickly to external signals and fast acquisition of the analog channel values.

The analog channels can be configured in different modes. It is also possible to change individually the sample and acquiring settings for each channel. The counter can be configured in different modes. After that, it is activated during the initialization phase (power-on, cold start, warm start).

The data exchange to and from the user program is performed using input and output operands. While integrating a module containing counters in the PLC configuration, the necessary operands are created and reserved immediately. For the fast data acquisition the values are stored inside the module in a file and transferred via file transfer to the PLC after the measurement sequence is finished.