Gas Turbine Temperature Sensors — EGT, Duct, and Compressor Temperature

Gas Turbine Sensor Fit-Up

Gas-turbine thermocouples are selected around exhaust temperature, vibration, mounting geometry, response time, and control-system termination.

Gas Turbine Sensor Configurations

Exhaust Gas Temperature (EGT) Thermocouple

EGT thermocouples are selected around exhaust temperature, vibration, mounting geometry, response time, and control-system termination. Sheath material is application-dependent; 316 stainless steel is a common starting point where service conditions allow, with higher-alloy materials reviewed for hotter or more corrosive locations.

Duct and Compressor Temperature Sensors

Duct temperature sensors, compressor inlet sensors, and compressor outlet or discharge temperature sensors can be built as thermocouple or RTD assemblies depending on the measurement range, required accuracy, installation style, and existing instrumentation.

Hot-Section and Turbine Support Points

Where the measurement point is closer to the hot section, sensor construction is reviewed around sheath alloy, junction style, insulation, vibration exposure, and routing through the turbine package.

Gas Turbine Sensor Data

Multi-Sensor Rake Installations

Gas turbine EGT measurement typically uses a multi-sensor rake or harness with 8–16 thermocouple elements distributed around the exhaust annulus. Each element is individually calibrated and wired to a dedicated channel of the turbine control system. Thermometrics supplies complete EGT harness assemblies with individual MI cable tails, common mounting flange, and thermocouple extension cable or circular connector for control cabinet termination.

Vibration-Rated MI Cable / MIMS Construction

MgO-insulated metal-sheathed cable is the only thermocouple construction capable of withstanding the continuous broadband vibration of a gas turbine casing. Wire-wound elements in ceramic insulation will fracture. MI cables have no internal mechanical joints susceptible to vibration fatigue.

Ungrounded Junction — No Ground Loops

With 8–16 sensors in a single EGT harness, a grounded junction in any sensor creates a parallel electrical path through the turbine structure. Ungrounded (isolated) junctions eliminate this source of measurement error and simplify fault diagnosis.

Sheath Material Selection

316 stainless steel, Inconel, and other sheath materials may be considered depending on temperature, corrosion exposure, vibration, and customer specification. Material selection should be confirmed during application review.

Special Limits of Error Wire

EGT measurement accuracy directly affects fuel efficiency calculations and hot-section inspection intervals. Thermometrics offers Type K and N MI cable with Special Limits of Error wire — approximately ±0.4% of reading rather than the standard ±0.75% — to improve absolute temperature accuracy across the fleet.

AS9100D Manufacturing

All gas turbine sensor orders are processed under the Thermometrics AS9100D quality management system. First Article Inspection Reports (FAIRs) per AS9102, material certifications, and NIST-traceable calibration certificates are included with every order.

Repair & Recertification

Thermometrics provides repair and recertification services for EGT harness assemblies removed from service. Individual elements can be replaced, re-sheathed, and recalibrated without replacing the full harness. AS9100D documentation is issued on repaired assemblies.