What is Condition Monitoring?
Condition monitoring is the process of monitoring machinery or equipment during its operation to identify potential failures before they happen. Condition monitoring techniques help determine the condition of your equipment and know when something needs to be fixed or replaced. It allows you to schedule maintenance tasks and prevent unexpected breakdowns resulting in reduced downtime, maintenance costs and product losses while increasing reliability, equipment life, availability, and uptime for machines.
How Does It Work?
Condition monitoring is a non-intrusive method for finding faults before breakdown through monitoring of a parameter, such as power, vibration, temperature, oil analysis or acoustic measurement and changes which indicates that a failure is developing. This helps a company shift from traditional preventative maintenance to a predictive maintenance model.
Predictive Vs Preventative Maintenance
Preventative maintenance is performed to prevent assets from unexpected failure, usually involving a physical inspection as part of periodic maintenance to determine any damaged or defective parts. To be effective periodic maintenance needs to take place ahead of any potential degradation of performance and therefore needs some downtime and loss of efficiency as service intervals need to be regular enough to ensure that any potential problems are captured. An analogy is the periodic replacement of oil in a car at a specified mileage or time interval.
Predictive maintenance utilizes a known parameter (or set of parameters) to monitor the condition of the equipment, this allows maintenance to take place only when it is required, both reducing maintenance and preventing unscheduled down time. No downtime of machine is required as this analysis can be performed while assets are performing their regular functions and helps avoid maintenance that is not necessary, reducing maintenance costs. To continue the analogy, modern cars monitor the state of the oil to extend or reduce the service interval in response to the way the car is driven.
What are the Benefits?
Condition based monitoring is conducted with the machines ‘running’, increasing the productivity and effectiveness of your maintenance planning and resource management, and helping improve:
- Overall equipment performance
- Reliability.
- Degradation identification.
- Productivity issues.
- Compliance and safety.
- Energy consumption and efficiency.
- 97% of the total cost of ownership of an electric motor are running costs1. A properly maintained motor can consume up to 14 percent less electricity2.
Applications
Condition monitoring in equipment is an important part of any manufacturing process. It is estimated that equipment downtime costs $50 billion each year, with equipment failure accounting for 42% of the total3. Reducing downtime saves millions of dollars every day.
Condition monitoring is used in a range of applications, from motors and generators to pumping equipment and conveyors. Monitoring rotating equipment is indispensable for uninterrupted and continuous production and processes such as power generation, oil and gas, manufacturing, and food processing.
The type of solution and value of condition monitoring varies from application to application. For some it is in flagging issues far in advance – sometimes months – of a failure occurring, allowing maintenance teams to plan for the rectification of the fault. For other applications, real-time monitoring allows the user to identify developing faults immediately without endangering people, equipment or materials.
Protecting equipment and controlling the process, however, are completely different requirements. Communication is key, whether as part of a wider system or by alerting an operator. In some applications creating a change in the output to set off an alarm or disconnect a motor or VS drive from the power can be crucial, in others the early warning of issues is key.
EXAMPLE: Glass processing equipment for bevelling and edging use up to 12 abrasive wheels driven by individual motors. These wheels wear at varying rates and need to be replaced on a regular basis. Just one not working at its optimum can lead to the entire piece of glass being discarded.
With limited time to respond and remedy degradation before issues occur, operators need to closely monitor the motor draw via a series of individual meters displaying current. The close monitoring of the AC current of these motors to know when and to the degree wear is taking place, and conducting timely maintenance is crucial in eliminating damage and reducing downtime.
Overload or underload can represent different issues. Overload conditions can be an indication of equipment failure and costly in terms of repair and downtime. Underloaded motors operate inefficiently (consuming more power) and increase power factor.
In pumping equipment, for example, an underloaded motor and can indicate restricted pump intake and clogged filters. In conveyors or HVAC it can be issues from a broken or slipping drive belt or loose couplings. These require equipment to be stopped and manually checked. In these situations, early knowledge of a fault before having to perform a manual inspection improves both efficiency and safety.
Methods and Techniques
There are several condition monitoring methods such as thermal monitoring and vibration monitoring that need costly sensors, while current monitoring may not need any additional sensing.
- Monitoring AC current usually requires installing a current transformer (CT) where a change in current trips a relay or produces an analog signal.
- Monitoring DC current levels requires reading the voltage across the shunt.
With the rapid rise of digitalization, online monitoring methods are becoming the norm. In the online status monitoring method, critical equipment can be monitored using cloud and IoT-based software providing even greater levels of information and communication.
Conclusion
Condition monitoring is an important solution for a wide range of applications, resulting in real economic gains. It can be implemented in different ways and in different systems to meet practical requirements and helps predict failures earlier, and with greater accuracy, improving asset management, maintenance planning and equipment life, resulting in potentially huge efficiency savings and cost reductions.
2 Electric Motors Performance Analysis Testing Tool Demonstration Project, Pacific Gas & Electric, 2001
3. https://www.tandeltasystems.com/the-true-cost-of-equipment-downtime/
