RTD Sensors for Motors & Bearings

The unexpected failure of large rotating equipment—such as industrial motors, generators, pumps, and compressors—often results in significant operational downtime and costly repairs. Monitoring the temperature of critical components is one of the most effective methods for early fault detection.

Precision RTDs are the standard choice for this application, providing highly accurate, stable, and repeatable measurements that allow control systems to detect subtle thermal increases before catastrophic damage occurs.

Excessive heat in a motor or generator can originate from electrical overloading, poor ventilation, or the degradation of winding insulation. In bearings, temperature spikes typically indicate lubrication failure, misalignment, or mechanical wear.

Because the operating temperatures of these components generally remain below 200°C, RTDs are perfectly suited to the task, offering significantly better accuracy and resolution than base-metal thermocouples in this range.

For bearing monitoring, compact, vibration-resistant Pt100 RTDs (often spring-loaded) are inserted directly into the bearing housing to maintain contact with the outer race.

For stator winding monitoring, specialized flat 'stick' RTDs are embedded between the winding coils during motor manufacture or rewinding. These sensors must possess high dielectric strength to prevent electrical tracking.

When installing bearing RTDs, the sensor tip should rest firmly against the bearing's outer race without exerting excessive force that could deform the sheath. A thermally conductive paste is occasionally used to improve response time, though spring-loading is generally sufficient.

Stator RTDs must be carefully positioned during the winding process. Care must be taken not to pinch or sharply bend the lead wires, and the sensor must be thoroughly void-free during the vacuum pressure impregnation (VPI) process.

• Early warning of lubrication failure or mechanical wear before bearing destruction.
• Prevention of stator insulation breakdown by monitoring localized hot spots.
• Enables predictive maintenance strategies, reducing unplanned equipment downtime.
• Provides data to safely maximize motor output without exceeding thermal limits.