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Hybrid Thermocouple Solving Common Problems

Monday, August 2, 2021
Categories : Products

Many frame turbine owners and operators experience premature failures from excessive vibration, heat or tip fretting. These failures can cause turbine trips and unplanned maintenance, making your engine unavailable for power generation. We have worked closely with the OEM turbine manufacturers to qualify and engine test our Hybrid Exhaust Gas Thermocouple as a direct upgrade for those Exhaust Gas Thermocouples.

Excessive Vibration

Problem: Excessive vibration can be caused by running gas turbines in operational modes that were not originally a part of the original test configuration, this also includes running them at very low loading levels. This vibration can shorten the life of your thermocouple and cause them to break at the compression fitting where the thermocouple is mounted into the radiation shield.

Solution: We extended the connection head away from the radiation shield. This helps reduce the mass and energy levels generated by the additional vibration that is experienced during these low loading conditions and increases the yield strength and life.

Excessive Heat

Problem: Connectorized thermocouples have many benefits, including a fast connection and washdown ability. However, this connector is limited to 250° C (482° F). This can become an issue when you experience high ambient temperature conditions or exhaust duct leaks. While the insulation blanket surrounds most of the engine, the area around the thermocouple is cut away to allow the probe to be installed. If there are leaks in the exhaust duct, they can travel under the insulation and exit these cutout areas, directing this extremely hot air onto the thermocouple and cable. This heat causes the insulation in the connectors to break down prematurely in the cable and thermocouple. Initially this may show as intermittent connections prior to a full failure.

Solution: The connectors extend away from the cutout to allow them to be placed in a lower temperature area on top of the blanket. This allows you to experience the advantages of the connectors, including being able to reuse your existing connection cables.

Tip Fretting

Problem: Many gas turbine operators have witnessed the metal sheath on the tip of the exhaust gas thermocouple become worn, causing the thermocouple to fail. This is usually caused by the seat in the radiation shield being worn out. This wear prevents the thermocouple from seating completely and it vibrates excessively in the air stream.

Solution: Our Hybrid Thermocouple does not rely on a seat within the radiation shield to ensure the proper insertion length into the airstream. With a fixed insertion length and heavy oversheath, this thermocouple is easy to install and is no longer susceptible to tip fretting.

The Hybrid Exhaust Gas Thermocouple is a field proven design that reduces the Exhaust Gas Thermocouple failure, related turbine trips and maintenance costs. For more information, please visit our Hybrid Thermocouple product page or contact us.

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