Rotating Equipment Condition Monitoring

Rotating equipment is critical to the smooth operation of industries such as oil and gas operations and industrial manufacturing. This critical equipment category poses unique challenges compared to non-rotating equipment. Pumps, motors, gearboxes, and compressors are subjected to constant motion and vibrations, making it more difficult to detect potential problems. These issues may include bearing wear, misalignment, and imbalance.

Additionally, the lubricating oil used in rotating equipment can deteriorate over time, leading to equipment failure. To address these challenges, the right sensors must be used to monitor various parameters such as vibration, temperature, and lubricant condition. However, selecting the appropriate sensors can be challenging.

With the advancements in technology, the market for sensors used in condition monitoring has seen rapid growth in recent years. Understanding the complexities and factors to consider in selecting the appropriate sensors is crucial in ensuring reliable and effective condition monitoring.

The first thing to consider when sourcing sensors for rotating equipment monitoring are the measurement parameters. There are several types of sensors available for rotating equipment monitoring, each with unique advantages and disadvantages.

For critical equipment such as pumps, motors, gearboxes, and compressors, the following sensors are used most often:

• Vibration sensors measure the vibrations and oscillations produced by rotating equipment and are used for early detection of mechanical problems such as bearing wear, misalignment, and imbalance.

• Temperature sensors measure the temperature of rotating equipment and are used for early detection of overheating, which can indicate potential problems such as electrical issues, mechanical problems, or lubrication issues.

• Oil property sensors measure the quality of lubricating oil used in rotating equipment and are used for early detection of issues such as contamination, oxidation, and degradation.

• Pressure sensors measure the pressure within pumps and compressors and are used for early detection of problems such as leaks and declining pump performance.

• Power (voltage & current sensing) sensors are used to monitor the electrical performance of equipment, providing data on the voltage and current being supplied to the equipment. This information is useful in detecting issues such as power fluctuations and increased load on the motor, which can indicate problems with the electrical system or the equipment itself.

• Magnetic flux (B field) sensors are used to monitor the magnetic field generated by the equipment, providing data on the magnitude and direction of the field. This is not as common but can be used to detect if the equipment is energized as well as provide additional information along with other sensors.

• Acoustic noise (ultrasound) sensors are used to monitor the sound generated by the equipment, providing data on the frequency and intensity of the noise. This information is valuable in detecting issues such as increased vibration, which can indicate problems with the equipment such as looseness or mechanical wear.

In addition to measurement parameters, selecting the appropriate sensor for a specific application largely depends on the specific requirements and goals of the condition monitoring program. For example, you might want to consider vibration and temperature sensing for industrial manufacturing applications. These sensors, when reliable and accurate, can provide early warning of bearing wear on motors, shaft misalignment, and detect cavitation and faulty installation issues of pumps. These measurements, in addition to temperature monitoring, can help predict issues that could impact production.

When sourcing sensors for gearbox applications, oil quality sensors are an obvious choice alongside vibration sensors. Oil property sensors provide critical information about the quality of lubricating oil, and high frequency vibration sensors can detect early gear wear, which can lead to longer life of equipment and much less downtime.

• Calibration
  Maintaining the calibration of sensors is important for ensuring accuracy over time. The ideal sensor will be factory calibrated and have high stability, reducing or eliminating the need for periodic calibration.

• Repeatability and Stability
  Repeatability and stability refer to the ability of the sensors to produce consistent and accurate results over time. The reliability and accuracy of the sensors can be impacted by factors such as temperature, humidity, and vibration, so it’s important to choose robust sensors that are designed to operate consistently in these conditions.

• Accuracy
  The accuracy of the sensors is critical for ensuring that the data collected is meaningful and useful. The accuracy of the sensors should be evaluated based on the requirements of the specific application and the type of information that is being monitored.

• Acoustic Noise
  Noise (ultrasound) sensors are used to monitor the sound generated by the equipment, providing data on the frequency and intensity of the noise. This information is valuable in detecting issues such as increased vibration, which can indicate problems with the equipment such as looseness or mechanical wear.

• Durability
  The durability of the sensors is important for ensuring that they will continue to function effectively over time. Durable sensors are less likely to break or fail, and they will produce accurate results over a longer time period. Selecting sensors with IP6X packaging is an effective way to add that durability and provide accuracy over the long term.

• Sensitivity
  While sensors must be robust so as not to lose stability, they must be sensitive too. Sensitivity refers to the ability of the sensors to detect small changes in the monitored parameter. For effective condition monitoring, it’s important to choose sensors that are highly sensitive and able to detect changes in the monitored parameter.
  
  Vibration sensors with piezoelectric technology, for example, are known for their ability to operate at higher frequency ranges, providing more detailed information about equipment vibrations and allowing for early detection of potential issues. On the other hand, micro electromechanical systems (MEMS) technology is widely used in condition monitoring systems due to their low cost and compact size. However, they often have a lower frequency range compared to piezoelectric sensors and may not provide the same level of sensitivity and accuracy in detecting early warning signs of equipment failure. Early detection of equipment wear is essential for minimizing unscheduled downtime.

• Consider the environmental conditions
  Consider the frequent and prolonged exposure to extreme temperatures, vibrations, corrosion, contamination, moisture, high pressures, and impact. The sensors you choose must be sensitive enough to detect changes in specific conditions while remaining robust enough to handle these tough conditions. Look for encapsulated designs, IP6X packaging, ATEX, and intrinsically safe certifications.

• Evaluate both wired and wireless options
  Wired sensors provide a direct connection between the equipment being monitored and the monitoring and control system, which can provide a more stable and reliable signal. However, wired sensors can be more difficult and more expensive to install in existing manufacturing operations. Wireless sensors, on the other hand, can be easier to install and are often more flexible in terms of placement and mobility. However, many wireless sensors are battery-operated, so battery life and replacement must be considered.
  
  Sensors with low power electronics and edge processing can greatly extend battery life. When deciding between wired and wireless sensors, it’s important to consider compatibility with your existing systems. If you already have a wired system in place, it may be more cost-effective and straightforward to continue using wired sensors. On the other hand, if you’re looking to upgrade your system or want greater flexibility in terms of sensor placement, wireless sensors may be the better choice.

• Consider the communication protocol
  Sensors for condition monitoring often use different communication protocols for data transfer. Ensure that the sensors and the monitoring and control systems are compatible in terms of the communication protocol used. The two most commonly used communication protocols are Bluetooth for short-range requirements and LoRAWAN for more remote locations where the sensors are further apart. You must also consider power requirements when evaluating compatibility.

• Choose sensors with user-friendly setup, physical size & form factor
  Look for sensors that are designed to be easy to install, with straightforward and simple procedures. Sensors with user-friendly interfaces are easier to set up and configure. The physical size and form factor of the sensors can also impact the ease of installation and maintenance. Look for sensors that are compact and lightweight, and that can be easily integrated into the equipment being monitored.