Austin Bonnett
Austin Bonnett Engineering, LLC
Gallatin, MO
The paper "Expand Your Business: Benchmark Customers’ Motors" by Austin Bonnett, presented at the EASA Convention 2010, emphasizes the importance of benchmarking motors to enhance maintenance practices and prevent failures. Benchmarking involves collecting and analyzing data from motors at various stages—new, repaired, and in situ—to identify changes in operating conditions and prevent unplanned outages. The paper outlines methodologies for benchmarking and provides case studies to illustrate its benefits.
Bonnett discusses the evolution of maintenance practices from reactive to reliability-based maintenance (RBM), which includes preventive, predictive, proactive, and smart motor approaches. Preventive maintenance involves regular lubrication, cleaning, and visual monitoring, while predictive maintenance relies on condition-based monitoring of vibration, temperature, and current. Proactive maintenance uses root cause failure analysis (RCFA) and benchmarking to reduce unscheduled downtime. Smart motors incorporate onboard devices for real-time monitoring of operating conditions.
The paper presents two case studies highlighting the value of benchmarking. In the first case, a 300 hp motor in a petroleum refinery experienced repeated bearing failures due to misalignment and excessive vibration, ultimately causing a major plant fire. Benchmarking could have detected the degradation of the bearing and provided advance warning to shut down the process. In the second case, a 300 hp motor in an air compressor cabinet suffered repeated winding faults due to chemical and salt corrosion. Benchmarking load current, ambient temperature, and insulation resistance could have identified the root cause and prevented the failures.
Bonnett suggests methodologies for benchmarking motors at three stages: new, repaired, and in situ. For new motors, factory testing options include vibration testing, winding insulation tests, no-load testing, performance data under loaded conditions, noise testing, and in-process testing. These tests provide valuable data for assessing motor performance and detecting anomalies.
For repaired or retrofitted motors, benchmarking involves comparing current or vibration levels to historical records to reveal deterioration of the base or driven equipment. Benchmarking should include vibration levels, voltage, current, and operating conditions. This helps identify the root cause of failures and prevent repeat occurrences.
In situ motors require regular monitoring of variables such as system vibration, load current, speed, voltage, partial discharge, motor current signature analysis, and infrared thermography. These benchmarks help detect changes in the system and prevent failures.
The paper emphasizes the importance of root cause failure analysis, which involves examining the failed motor and its system to identify the stresses that caused the failure. This methodology includes inspecting the failed part, the entire motor, and acquiring information about the application, appearance, and maintenance history.
Bonnett concludes that benchmarking can reduce unforeseen downtime, lower repair costs, improve maintenance scheduling, and enhance safety by preventing catastrophic failures. A successful benchmarking program prioritizes equipment from critical to non-critical and applies the procedure to new and repaired motors.
Key Points Covered:
- Evolution of maintenance practices to reliability-based maintenance (RBM)
- Importance of benchmarking motors at various stages
- Case studies illustrating the benefits of benchmarking
- Methodologies for benchmarking new, repaired, and in situ motors
- Factory testing options for new motors
- Comparison of current or vibration levels for repaired motors
- Regular monitoring of in situ motors
- Root cause failure analysis methodology
Key Takeaways:
- Benchmarking motors can prevent failures and reduce downtime.
- Reliability-based maintenance includes preventive, predictive, proactive, and smart motor approaches.
- Factory testing provides valuable data for new motors.
- Comparing current or vibration levels to historical records reveals equipment deterioration.
- Regular monitoring of in situ motors detects changes and prevents failures.
- Root cause failure analysis identifies the stresses that caused the failure.
Related Reference and Training Materials
Print
