Sifting Through the Noise: A Practical Guide to Condition Monitoring for Rotating Equipment
It’s no secret that successful implementation of a condition monitoring system can result in increased equipment availability, less downtime, and an overall lower total cost of ownership. While global competition in manufacturing is pushing facilities to ensure that their operation performs at optimal levels, the market for remote monitoring technologies has exceeded $1B annually and is continuing to grow. With factors such as declining sensor costs and improved communication protocols fueled by the mega-trend of IoT, it seems everyone is talking about condition monitoring. With so much buzz on the topic, it can be difficult to know how to get started or who to turn to for support.
As the saying goes, “hope isn’t a strategy”, so while it may be tempting, it isn’t recommended to simply buy sensors off of the internet and hope for the best. This guide will walk through practical considerations to help you determine the right type, size and scope of monitoring technology and/or services for your application.
Why Condition Monitoring?
Condition monitoring is the use of sensors placed on rotating mechanical equipment to measure parameters such as vibration, strain, temperature, power, current, voltage, pressure and torque. This performance data can be tracked and trended in real-time, to help detect potential failures early, eliminate unplanned equipment outages and maximize uptime. In addition to having the ability to find problems before they happen in a predictive or proactive maintenance fashion, there are other key benefits to using remote condition monitoring. With remote monitoring, it’s easy to have one person monitoring dozens of plants. This ability to remotely monitor in a distanced way has become increasingly important during the COVID-19 pandemic. With this precedent set, it is expected this growing reliance on remote monitoring will continue in the future.
Remote monitoring can replace inspections entirely, decrease the number of regular onsite inspections or indicate where focused inspections should occur. For example, a company who is regularly conducting monthly preventative maintenance inspections could transition to continuous monitoring and significantly increase the interval of their manual inspection cycle (or eventually eliminate the time-based manual inspection altogether). The key is that the need to conduct onsite inspections doesn’t exist until the condition indicates a potential issue. Then, maintenance visits can be scheduled at a time that makes sense (during off hours, when other maintenance is being conducted, etc.). When condition monitoring is guiding the maintenance approach, manpower needs are decreased and safety improves because maintenance personnel are not climbing over equipment, rushing through urgent repairs or working around other operating equipment. Improved safety and labor efficiency lead to an overall decrease in operational cost.
While it’s clear that condition monitoring for rotating equipment makes sense, one solution doesn’t fit all. It’s important to find a flexible, adaptable monitoring provider who can ask the right questions about your facility and specific needs. We’ve outlined some of the most critical considerations in the sections that follow.
Types of Predictive Measurements
Installed sensors can help identify and detect performance issues and potential fault situations with various types of measurements. Each predictive measurement tool is considered and often tools are used in parallel when approaching customers issues, in order to produce the desired outcomes.
Sensors can be used individually or in combination to detect and identify potential equipment problems. Some of the more common diagnostic sensors are accelerometers to measure vibration, temperature sensors to measure thermal changes, strain gauges to measure torque and load, ultrasonic sensors to measure ultrasound energy and current/voltage transducers to measure electrical changes in equipment such as electric motors. Some examples of the uses of this equipment are provided below:
- Bearing damage
- Lubrication issues
- Gear/component interference
- Excessive load
- Mechanical motor signatures
- Gear load conditions and faults
- Bearing loads, lubrication and fault conditions
- Shock energy throughout the entire driveline
- Equipment imbalance issues
- Failure location identification
- Excessive load
- Equipment performance such as jams, slippage events and stalls
- Drive train health/deterioration trending
- Transient events (high speed, very short duration)
- Very slow speed equipment
- Low criticality equipment
- Lubrication issues
- Bearing damage
- Mechanical wear (rubbing)
Motor Current Signature Analysis (MCSA)
- Identify the energy used, loading condition and incipient faults as they are developing
- Voltage and current imbalances and how they affect the load
- Applied torque and horsepower to view potential overloading
- Mechanical and equipment faults in bearings, gearboxes and spindles
- Usually finds faults earlier than other technologies
MCSA in conjunction with torque and vibration monitoring provide a complete picture of monitored asset conditions in real time and over time in the trend cycle.
Wired vs. Wireless Sensors
The types of measurement data your assets require will help determine if a wired or wireless monitoring system is best for your plant.
Wireless sensors allow for quick and easy deployment of condition monitoring. They are ideal in cases where accessibility makes it difficult to connect wires. Wireless monitoring is also preferred when there is some distance between monitoring locations. A wireless system can reduce cost by not having to run long wires. Because wireless sensors are battery operated, they do not collect data constantly. Instead, wireless sensors collect data based on a predetermined schedule or event triggers that are set during installation.
Wireless monitoring should be used for assets where gaps in the data stream will not have a detrimental effect on system reliability. The gaps in the data are usually inherent to the data collection logic, which is often set up to collect data at certain times of day or when other conditions are met. Most wireless monitoring systems are best suited for steady state machines that are either on or off. Examples include fans, pumps or other process equipment that do not have frequent starts and stops within a day.
The ability to detect faults at the earliest stages of failure, especially for low-speed equipment, may require more sophisticated technologies than the capabilities of wireless systems. Wired systems can run and collect data 24/7. Wired continuous monitoring systems provide the ability to record and act on alarms at any time based on real-time events. A wired system is often the best choice for critical equipment when immediate alerts are required.
Number of Sensors
Another factor to consider when deploying condition monitoring at a site is the number of sensors required. The number of sensors can vary from one to dozens or even potentially hundreds depending on the size of the equipment and overall scope of the project. For example, it might be possible to use just one sensor on a small motor or gearbox, but for a larger system one sensor won’t allow for the proper machine health diagnostics and analysis.
Study of Existing Equipment
A careful study of the existing equipment will reveal which types of sensors and locations of those sensors will yield the best data for evaluating the health of the equipment. Typically, these locations will be selected on parts of equipment that have had historical problems, such as a pump that frequently has bearings fail. Sensors are also placed on high criticality components and equipment that would cause the most downtime if they failed unexpectedly.
A third use of sensors can be on equipment located in remote locations of a facility. Often, these areas don't benefit from the flow of human traffic sensitive to subtle changes in noise, dripping fluids, etc. These machines often become “out of sight, out of mind”. Sensors can be the maintenance staff’s eyes and ears in locations that are rarely visited, such as equipment located in tunnels, on roofs or rafters, or equipment that isn’t stationary such as a crane or mobile equipment.
Interpreting All That Data
Interpreting and acting on condition monitoring data is paramount in sustaining a successful remote monitoring program. If resources to interpret the data are not available at the facility, it would be wise to consider utilizing third party automation software and/or certified analysts to ensure the data is being leveraged to positively impact the bottom line. The reality is most companies don’t have the manpower or technical expertise and can benefit from utilizing third party experts when it comes to monitoring.
Remote monitoring systems typically utilize annual service contracts which include periodic reporting, telemetry system maintenance, automated analysis and alerts and custom cloud-based dashboards. These monitoring systems can be customized to fit nearly any location and application. In some cases, shorter term diagnostic services are also available to help customers evaluate equipment health or to diagnose specific pain points.
Turn to the Experts
Now that this practical guide has provided the basics of condition monitoring, it’s time to turn to the experts. Scheduling time with reliability experts will ensure a successful remote monitoring system implementation suited to your facility and your needs.
To learn more about Regal’s condition monitoring solution and how it can power your business, visit Perceptiv™ Products & Services.