Thermometrics minature temperature sensors used in rotating machinery are designed to measure the critical temperature of the bearings shoes operating in turbines, generators and other rotating equipment. Monitoring the bearing temperature of rotating equipment is very critical and can provide an early warning of the lubricating oil breaking down when it becomes too hot, allowing machine shutdown and necessary maintenance to take place.

4 Stages Of Bearing Failure 

Stage 1

Vibration analysis is used to detect the earliest signs of bearing faliure.  Ultasonic frequency bands around 250 KHz to 350 KHz start to give signals.  Roughly, there is approximately 10-20% remaing life on the bearing.

Stage 2

Signal appears at the first harmonic frequency of the bearing at (500 to 2,000 Hz).   Faliure of the bearing begins to "ring" translation to 5-10% remaing life.

Stage 3

Fundemental frequency is apparent with bearing faliure harmonics.  Inner and outter race defects are now noticable on vibration analysis of the noise signal.

Stage 4

High vibration indicates bearing faliure.  The harmonics and fundamental start to actually degrade, while random noice greatly rises, and bearing temperature rapidly increases.  These signs indicate about one hour to  one percent of remaining life.

 

 

Methodology of Bearing Sensors

• Bearing sensors which monitor the temperature are attached in close range to all the bearings on a common shaft or axle.
• The bearing sensors feed temperature readings back to a sensing unit that is self-contianed and has wirelss technology for communication with warning devices implemented.
• The temperature data from each bearing sensor is analyzed and compared electronically.
• If any bearing sensors temperature varies more than 59°F (15°C), an alarm is triggered.
• There is a maximum allowable temperature in case all bearing sensors are out of their normal operating range.