Making predictive maintenance more predictable with thermal monitoring

No matter the industry or facility, the ability to respond faster to sudden degradation in asset performance reduces the potential for catastrophic failure and helps curtail damage costs. During the last decade, maintenance managers have grown to rely more and more on thermal imaging for preventive maintenance and troubleshooting in manufacturing processes. The reason is simple: Heat is often an early indicator of degradation, and cold spots often suggest blown fuses or failed capacitors. Identifying abnormal thermal patterns before a failure can help extend asset life and enhance the facility’s condition-based or proactive maintenance capabilities.

Thermal imagers — also called infrared cameras — help maintenance, reliability and operations professionals quickly identify hot spots and cold spots that could indicate potential problems, helping them avoid unexpected downtime and equipment damage. Maintenance technicians can use an infrared camera to inspect an entire area or a piece of equipment at a specific time. As anomalies are identified, the technician can zero in on irregular areas to determine the magnitude of the problem.

Multiplying thermal imaging capabilities

The enhanced capabilities, decreased cost and dramatically improved ease of use offered by recent generations of thermal imagers has greatly improved the ability to catch many potential breakdown-causing problems before they cause a failure. Maintenance personnel would rather find an impending problem than have to respond to a critical equipment failure after it happens.

This explains why many facilities are expanding their thermal imaging practice to include “thermal monitoring” with semi-fixed, always-on wireless infrared sensors. In the past, troubleshooting intermittent problems required a technician to be in the right place at the right time, which was not always possible. Installing semi-fixed thermal imaging sensors on multiple components provides managers with a more comprehensive thermal view of equipment assets simultaneously, in real time over long periods of time, making them much more likely to catch intermittent faults in the act.

Thermal imaging sensors simultaneously capture thermal images of multiple motor, fan, pump and conveyor components to help spot abnormal thermal patterns in bearings, shafts, casings, belts, gearboxes and other components. Managers can compare these images across an entire duty cycle to see what else is going on when warning signals appear. They can then respond proactively to problems and head off potential failures in other equipment down the line. The thermal monitoring sensors provide more data to help maintenance and reliability professionals better determine whether they need to address the problem immediately or whether they can wait for off-peak hours or until the next regularly scheduled maintenance period.

How thermal imaging sensors work

Semi-fixed thermal imaging sensors operate on battery or alternating-current (AC) power and can easily be installed and moved to monitor the thermal profile of different components across extended periods of time. They can be mounted on almost any surface using magnets or adhesive discs, or they can be mounted using the included adjustable bracket with a 360-degree gimbal that allows positioning at many angles to capture targets that would be hard to reach with a handheld camera. For optimal results, the sensors should be mounted at a distance of 4 to 20 feet from the asset. Users can set temperature thresholds for each sensor that trigger alarms if those thresholds are exceeded.

Each thermal monitoring sensor captures sequences of infrared images at intervals the technician specifies. Typically, it works best to start by taking images at frequent intervals to identify how quickly surface temperatures change. Then technicians can adjust the frequency to suit specific monitoring needs. For example, you might start with one image per minute, and if the surface temperature changes very slowly, you can change the setting to one image every 30 minutes.

Because all images in the sequence are captured from the exact same location, the angle and distance are identical. Using software on a mobile device or PC, end users can compare multiple images of the same asset or images of multiple assets taken simultaneously so hot and cold spots stand out. This provides a more complete picture of where problems are brewing and how thermal anomalies in one component are affecting other production assets.

On battery power, the sensors operate for up to 10 hours on one charge in high-performance mode and up to three days in energy saving mode. With AC power, there is no time limit.

Key advantages of semi-fixed thermal imaging sensors:

• Troubleshooting: The sensors automatically capture a series of thermal images over an extended period of time. This allows maintenance technicians to view the results from any connected device. They make spotting abnormalities that develop over time easier.
• Versatility: Sensors are easy to install and move. They mount on almost any surface with magnets, adhesive or the included bracket complete with a 360-degree gimbal that can be targeted at difficult angles.
• Data correlation: Condition monitoring software allows managers and technicians to receive alarms based on their determined thresholds, remotely monitor multiple assets and create multiple graphs per asset that correlate thermal monitoring with current, voltage, contact temperature and power quality monitoring.
• Portability: The sensors can operate on battery power for up to 10 hours in high-performance mode, three days in energy saving mode, and indefinitely if connected to AC power. This allows technicians and managers to monitor thermal readings out of harm’s way.

View and analyze results from anywhere

Wireless thermal imaging sensors send the captured images to the cloud, using point-to-point Bluetooth or Wi-Fi connectivity, with no need to run cables, get into equipment wiring, or connect with the local area network. The smartphone app then transfers data by cellular signal or Wi-Fi connection to secure cloud storage. The entire process is managed by the condition monitoring software that also provides reporting and graphing capabilities, and the ability save images and measurements to work orders. This software establishes a reliable traceable asset history that managers and maintenance professionals can access anywhere at any time through a mobile device or PC.

Thermal monitoring sensors can seamlessly integrate with a software platform that gathers data from many other sensor types, including AC/direct-current (DC) voltage, current, power and contact temperature. Whether measurements come from a sensor or a technician with a handheld meter or infrared camera, the software automatically saves the data and uploads it to the cloud. From there, end users can correlate other measurements taken by different devices (handheld or semi-fixed) to identify equipment issues. For example, excess heat may indicate a current spike in a motor or pump. Taking current measurements simultaneously with thermal images can provide a more comprehensive picture of overall equipment health. End users can then associate the measurements to equipment, build hierarchies and track historical trends in the software.

Putting thermal imaging sensors to work

Thermal monitoring with infrared camera sensors combined with voltage, current, power quality and contact temperature sensors can help troubleshoot and improve the reliability of many components of the manufacturing process, including:

• Motors, pumps, drives and compressors: Thermal imaging is particularly helpful when monitoring rotating equipment because overheating accompanies many impending failures. Sensors can be installed on multiple motors in a row allowing maintenance technicians to compare surface temperatures and quickly isolate failing (overheated) motors. This way, suspect components can be repaired or replaced before they cause unexpected downtime.
• Process instrumentation: Valves, pipes and hoses are critical to delivering fluids to processes at precise moments. Thermal imaging sensors can help locate leaks, stiction or excess friction in valves and tubes. Proactive thermal monitoring of pipes can help locate obstructions before an entire loop fails. Thermal monitoring can also be used to monitor liquid levels and conduct rough checks of dry bulk material levels in tanks.
• HVAC systems and condensers: In data centers, cooling is key to keeping servers from overheating. Thermal imaging sensors can be used to monitor server racks or heating, ventilation and air conditioning (HVAC) valves and condensers that are indoors. They can also identify uncharacteristically cool surfaces that might indicate a problem, such as an imbalance in the HVAC system.
• Small transformers: Thermal monitoring can quickly identify bad electrical connections, uneven or inadequate power supply, overloads, harmonics and other conditions that precede impending electrical equipment failures.
• Pre-commissioning tests: Technicians need to run mechanical, electrical and visual tests on a new transformer before it can be commissioned in the field. The combination of condition monitoring software and sensors for thermal imaging, voltage, current and contact temperature, can confirm that the transformer is operating properly and establish baseline data for future inspections.

Enhancing preventive maintenance with wireless infrared monitoring

The flexibility, performance and portability of thermal monitoring sensors can have a major positive impact on a facility’s reliability, efficiency and performance in multiple ways.

Move from a reactive to a proactive mindset

Most facilities house seemingly countless components, from rotating assets to small transformers. Chasing problems as they surface puts a strain on even the most capable of maintenance teams, making it a challenge to try to get ahead of the wave. If the maintenance staff is spread thin and is constantly hustling to handle the latest equipment failure, response time can suffer. As noted, warning signs, such as a significant rise or drop in operating temperature, precede most equipment failures. Thermal imaging sensors and condition monitoring software can help maintenance staff recognize the indicators that may lead to downtime if left unchecked. This helps maintenance managers make better decisions about maintenance schedules, work orders and prioritizing situations that demand an urgent response.

Increase efficiency and maximize human resources

Many facilities with smaller maintenance teams don’t always have enough technicians who are trained to perform regular equipment inspections with a handheld thermal imager, often resulting in the outsourcing of this function. Thermal imaging sensors are so simple to install and use that team members can get up to speed quickly and monitor the sensors from their mobile devices. This makes it possible for managers to replace some infrared camera inspection rounds with automated collection of sequential images with thermal sensors. Thermal inspections with a sensor can cover more ground without having to increase overhead.

This also allows teams to monitor more equipment with more precision and develop a better idea of the overall health of a facility’s equipment.

Safely inspect hard-to-reach assets

Because thermal imaging sensors are non-invasive, they can be installed while assets are operating. Because they can be easily positioned at different angles in an enclosure or difficult-to-reach location, they allow maintenance teams to find problems in areas that might typically be missed because they are too difficult to access.

Once the sensors are installed, technicians can monitor components that might not otherwise be measurable, on their mobile device from anywhere, around the clock. The sensors present minimal safety risks (except for live voltage, which still requires full electrical safety precautions).

Improve ROI

Storing sequential thermal images and other temperature, electrical and power quality measurements on the cloud creates a rich equipment history that is easily accessed through mobile devices or PCs. Having this data close at hand saves time in searching for baseline measurements and enables maintenance managers to conduct smarter evaluations.

By helping maintenance teams detect a multitude of potential issues before they cause failures, wireless thermal imaging and other condition monitoring sensors in concert with a comprehensive condition monitoring software solution can make predictive maintenance even more predictable.