What is Condition Monitoring?
Condition Monitoring is the process to detect a fault in a machine or equipment by observing parameters such as vibration, temperature and current. Condition Monitoring systems give the opportunity to spot faults that can lead to catastrophic failures and allows maintenance teams to program their schedule. This provide a unique value proposition for taking care of life-shortening faults & malfunctions before they make equipment unserviceable. Condition Monitoring Techniques are generally used for rotating equipment and auxiliary systems such as compressors, pumps and gear boxes. There two types of it; Online Monitoring and Offline Monitoring.
Offline Monitoring is used for low and semi-critical equipment and generally vibration is recorded periodically and analyzed. Offline Monitoring is performed with a handheld measurement tools and the data on the defined equipment is measurement. This process is both exhausting and requires qualified workforce. This method is used when periodical measurements are enough and generally vibration is measured. On the other hand, Offline oil analyses are commonly performed. For these analyses, viscosity, water levels and quality of the oil defined by taking samples.
Online Monitoring is performed with the sensors deployed on the certain points of certain equipment. Although it is more costly than offline, it provides great benefits where there is no qualified personnel available for offline monitoring; continuous production lines such as automotive, concrete, cement plants or plants containing critical equipment such as Natural Gas Compressor Stations, Wind turbines etc. With the help of online monitoring, you can stop or program schedule for maintenance before a fault causes a catastrophic failure. For the scope of HSE, you can get safer measurements by not using your personnel in toxic and explosive environment. Typically, this method is used for rotating equipment, secondary and auxiliary systems such as pumps, compressors and internal combustion engines.
There are various methods applied in industry for this. The methods vary from machine to machine but generally vibration, temperature and current are monitored. At this point, choosing the most suitable method makes the job easier. For example, a current sensor can be applied for an electric motor to detect failures. On the other hand, a current sensor cannot provide you a meaningful data for pumps, compressors and fans. For these kinds of machines, it is better to use a vibration sensor. Due to this reason, the equipment on the manufacturing line should be classified and determined about how critical they are. This will lead to choose the right sensor and method. If a critical equipment will be measured and continuous data should be kept, online monitoring must be used.
In Condition Monitoring systems, the time between failure and detection of a fault is a critical parameter for choosing the right sensor. On the graph above, we can check P-F curve. This curve represents the relation between potential failure (P) and functional failure (F). Potential failures are the point where the equipment starting to show defects. For example, from the moment when GRMS value of a bearing exceeds 3 G, till the moment when this bearing is unserviceable; there are 15 days. On P-F curve, you can measure time from horizontal axis and the state of the equipment can be seen on vertical axis. The bearing in this example should be kept under monitoring for potential failures.
Condition Monitoring is a critical tool to detect the time interval on P-F curve. By using these methods, you can maximize this time interval. As you can see on the curve, oil analyses, acoustic emission, thermography and other methods exist. But the important point is maximizing the lifetime of an equipment instead of changing it regularly. This increases the efficiency and decreases the costs.
Rotating equipment is a term defining motors, reducers, pistons and centrifugal machinery. In industrial applications, condition monitoring is generally applied to rotating equipment. The most common method for these items is vibration analysis. Vibration analysis is the technique to measure vibration severity and spectrum. The data gathered are used to define the condition of machine and detect potential faults. By this method, problems such as imbalance, bearing faults, looseness, crooked shaft and even cavitation can be observed. Vibration allows you to detect potential faults up to 3 months before faults become failures. If you are interest in vibration analysis, you can reach our blog post by clicking the link above.
There are various representations of data in condition monitoring systems. The most common method is following up trends of parameters. Following up trends is performed by collecting data for a certain time interval, comparing data day by day and analyzing it regularly. Trends are analyzed to determine potential failures when certain limits are exceeded. In Online Monitoring systems, the sensors are set to measure periodically and transmit telemetric data and set alarms with certain thresholds for potential failures. By this way, the critical equipment in your production line can be monitored and the monitoring process can be automized. On the other hand, defining overall limits instead of interpreting data/spectrum cannot always spot potential failures. The certain decisions should be made after interpreting spectrum. Each piece of equipment provides different spectrums. Some frequencies peak up when a defect occurs. But trends show overall values and cannot define these faults. To solve this issue, Sensemore allows you to set alarms for different frequencies.
These systems provide unique value propositions such as minimum maintenance cost, energy-saving, minimum downtime and less spare part cost. Consider that VRMS values are measured in a system. By the time, VRMS value in a component increases and you spot a potential failure or set an alarm for a limit and system informs you. You send redirect your maintenance personnel or schedule their time for fixing. By this way, you can save energy both from that machine and the energy of your workforce. Also, by avoiding a catastrophic failure you minimize downtime and spare part cost.
The current state of technology allows online tools to be available in the market. The sensors and the software connected to internet can provide you measurements all day. These measurements are kept in integrated platforms to monitor and analyze. These tools give you the opportunity to solve a problem when it occurs or to schedule your time to fix it. To perform these tasks, all these tools are connected in the system such as sensors, receivers, software and mobile.
Instead of a reactive approach, these systems provides you a proactive/predictive approach to maintenance and by the integration to your facility, you can monitor the health of your equipment and show you a clear picture for all your equipment.
