Gas Turbine Temperature Sensors — EGT · TIT · Compressor Inlet

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

Direct-immersion EGT thermocouples provide continuous measurement of turbine exhaust temperature. An unsheathed or lightly sheathed bare-wire junction maximizes response speed in high-velocity gas streams. MIMS construction with an Inconel 600 or 625 sheath and an ungrounded junction helps prevent ground-loop interference in multi-sensor installations.

Turbine Inlet Temperature (TIT) Sensor

High-temperature noble-metal sensors are used for turbine inlet temperature measurement where gas temperatures approach the metallurgical limit of base-metal alloys. Type R or S platinum-rhodium wire is housed in alumina twin-bore insulation with a refractory ceramic or platinum-rhodium sheath. MIMS platinum-sheathed constructions are available when the cleanest possible measurement is required.

Compressor Inlet / Discharge RTD

Pt100 RTD assemblies for compressor inlet temperature (CIT) and compressor discharge temperature (CDT) measurement, where accuracy is critical to turbine efficiency calculations. IEC 60751 Class A, 4-wire, with flanged or threaded process connection, stainless or Inconel sheath, and spring-loaded tip for thermowell installations.

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 MIMS tails, common mounting flange, and thermocouple extension cable or circular connector for control cabinet termination.

Vibration-Rated 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. MIMS 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.

Inconel 625 for Highest Corrosion Resistance

Inconel 625 provides superior resistance to oxidation and sulfidation at elevated temperatures compared to Inconel 600, and is the preferred sheath material for turbines burning fuel with elevated sulfur content or wet steam injection.

Special Limits of Error Wire

EGT measurement accuracy directly affects fuel efficiency calculations and hot-section inspection intervals. Thermometrics offers Type K and N MIMS 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.