Turbines and generators are the most expensive equipment in a power plant. Both rotate thousands of times per minute for months without stopping, supported by bearings separated from the shaft by only a thin film of oil. When that film is disturbed, bearing temperature can climb within minutes, and the resulting damage can take a unit offline for weeks.
That is why nearly every turbine and generator bearing is fitted with a temperature sensor. The sensor is usually embedded in the bearing metal (babbitt) or mounted close to the bearing surface, so heat from friction is picked up immediately. RTD Pt100 is the common choice here because of its high precision across bearing temperatures and its long-term stability. For critical bearings, sensors are often installed in pairs so that one failed sensor does not remove protection.
Bearing temperature data is generally used at two levels. At the first limit, the system raises an alarm so operators can check lubrication and load. At a higher limit, the protection system can trip the unit automatically before the bearing is damaged. Because trip decisions depend on these sensors, accurate and reliable readings are essential.
Generators have additional measuring points in the stator windings. Sensors embedded between the windings track the heat generated by electrical current, while the generator cooling system, whether it uses air, hydrogen, or water, is also monitored at its inlet and outlet. Windings that run too hot for too long will age their insulation faster.
Lubricating oil is the link between the bearings and their cooling. Oil is pumped from the tank through a cooler and then to the bearings. Sensors in the tank, after the cooler, and on the drain line from each bearing show whether the oil is cooling properly. A rise in drain temperature at one bearing while the others stay normal is usually the first clue to a problem at that bearing.
The same principle applies in hydropower, gas-fired, and biomass plants. Bearings on boiler feed pumps, large fans, and high-power motors are also worth monitoring this way, since their failure can force a unit to reduce load.
Signals from bearing sensors are usually sent to the DCS or the turbine protection system. A temperature transmitter with a 4–20 mA output helps keep the signal stable in an environment full of electrical fields, especially around the generator.
CV. Rach Tekindo Makmur supplies Temperature Sensors & Temperature Transmitters for a wide range of industrial instrumentation needs. If you need sensors, transmitters, or consultation on configuration and installation for your temperature system, contact us on WhatsApp at 0877-8620-5656 to discuss your technical requirements and request a quotation tailored to your application.
