Predictive maintenance has become an accepted practice worldwide and is being implemented by almost every category of industry.
Locating, identifying and acting on potential problems in order to avoid its incipient breakdown as well as to ensure the best performance and operating safety is the goal of predictive maintenance. Monitoring is the most effective tactic for locating potential problems and can reduce unnecessary downtime and breakdown costs. With the monitoring and storage of data collected and analysed by advanced algorithms, numerous issues can be identified and rectified, thus avoiding unplanned downtime and ensuring more efficient operation.
Monitoring using modern equipment allows plant managers to dictate their own downtime, improve their plant operations and quickly identify equipment that needs maintenance or replacement.
Which assets to monitor
When establishing a Product Data Management program or bettering an existing one, setting out which machines should be monitored should be the first consideration. Criticality, number of starts in a given period, ambient temperature, labour and spare parts availability must be considered among others. Each situation is different and each requires unique considerations, but the main goals will be similar. We should prioritize machines that have a history of poor performance.
It is vital to the success of the predictive maintenance program that the recommendations suggested by the algorithm are followed and that repairs and adjustments are entered into the system and stored.
How to monitor
Predicting impending failures requires experience, knowledge and the usage of the correct tools. The more tools a technician has and uses correctly, the more likely he or she will be able to predict the health and longevity of the assets in use. Combined with data, monitoring has become a vital tool that must be considered and used to obtain a successful diagnosis of the machine condition.
The machine element encompasses structural components such as chassis, bearings, lubricants and mechanisms that control movement for instance gearboxes, cam systems, belts or drive chains. Also, the motors themselves have numerous components, including copper windings and their insulation, bearings and other mechanical and electrical characteristics that must be monitored. Monitoring equipment’s with enhanced algorithms can effectively assess the status of these assets.
When the data collected is correctly processed and analysed, it will help to predict the machine’s ability to remain in service and if and when repairs and/or adjustments can be indicated.
Understanding the efficiency of a motor
One of the key factors that is identified and tracked through monitoring is efficiency.
Efficiency is defined as the ratio of the useful work done to the energy spent on its production (output power divided by input power). Efficiency is usually described using one of three metrics: nominal efficiency, operational efficiency, or minimum efficiency.
Rated efficiency is the value assigned by the manufacturer and designated on the motor nameplate. Operating efficiency is the true efficiency of the engine as it is operating within its real and normal environment. Minimum efficiency is the lowest efficiency value that any motor within a “test sample” must maintain. Monitoring equipment will define the operating efficiency of the engine being monitored.
Why is motor efficiency so important?
In the European Union there are approximately 8 billion motors that consume almost 50% of all electrical energy produced by the EU. Recent reports show that energy costs can be significantly reduced by using more energy efficient motors. Higher efficiency motors would save billions of euros in energy costs every year, and a monitoring system can easily assist in deciding when it is the right time to replace motors or retrofit control components. The state of the crucial structural machine components will have a huge impact in the motor performance.
How to improve efficiency?
Machines and motors are affected by numerous electrical and mechanical issues, many of which can be rectified or improved. These issues are usually corrected through improvements, replacing the control components with more recent and efficient equipment, in the case of harmonic issues, they can be mitigated with various components, such as reactive filters, shielded cables, etc. Misalignment, imbalance and other mechanical issues are often easy fixes. Small adjustments can often add years to a motor’s life and result in big savings thanks to greater efficiency. In addition, the costs of replacing poorly performing motors with more efficient motors will quickly be offset by savings in energy costs.
Summary
Energy costs constitute an important part of the expenses of any installation and in a factory the machines and their motors represent the majority of these expenses. Monitoring the performance of these assets and making the necessary adjustments will improve reliability, extend their useful life and reduce the overall cost of operating the facility.