Abstract: A method (and corresponding apparatus) for monitoring gas turbine blades. The output from an eddy current sensor monitoring the movement of turbine blades past the sensor is processed to determine when the signal train from the sensor omits a signal or pulse corresponding to one of the shaft's full complement of blades. The signal processor compares sensed blade periods with average blade periods.

Abstract: A mounting terminal head of a thermocouple head unit having a metal casing for an end of a thermocouple wire, and thermocouple signal terminals 4 for connection to a thermocouple wire. The thermocouple head unit includes an insulating support member 8 extending around the outside of the thermocouple head unit and supporting the thermocouple signal terminals.

Abstract: A method is provided for determining timing points indicative of the passage of a blade in a turbine engine. The method comprises the steps of: providing a s first sensing coil proximate to a path of the blade, providing a second sensing coil proximate to the path of the blade, the second sensing coil spaced from the first sensing coil in a direction parallel to the path of the blade, and comparing a signal generated in the first sensing coil with a signal generated in the second sensing coil to derive a timing point indicative of the passage of the blade.

Abstract: The invention provides a total gas temperature sensor for measuring the temperature of gas in a gas flow. A gas temperature sensor in accordance with the invention comprises a measurement chamber having a gas inlet and a gas outlet; an outlet valve located at the gas outlet, operable to seal the gas outlet when in a closed position, and a temperature sensing element located in the measurement chamber. The sensor is simple to manufacture, is robust, provides for a low recovery correction and does not suffer from significant boundary layer problems.

Abstract: There is provided a variable reluctance sensor for sensing the speed or torque of a shaft in a gear box or gas turbine engine, comprising a magnetic pole piece a conductive wire wrapped around the pole piece a housing surrounding the pole piece, the housing having a front face and at least one side wall, wherein, in use, the front face is positioned proximate to an object to be sensed wherein the pole piece is rigidly fixed to the side wall of the housing. This arrangement reduces microphony in the sensor.

Abstract: The invention provides a vibrating cylinder transducer for measuring the pressure or density of a fluid medium comprising: a cylindrical vibrator, in use having at least one surface coupled to a fluid medium to be measured; a drive means for vibrating the cylindrical vibrator; a sensor for detecting the resonant frequency of the cylindrical vibrator; and an output coupled to the sensor, the output configured to provide an output signal indicative of the pressure and/or the density of the fluid medium; wherein the surface coupled to the fluid medium is coated in a corrosion resistant polymer layer. Preferably the corrosion resistant polymer layer is formed from parylene.

Abstract: A probe with plural output channels for sensing the movement of a body of magnetic material. The probe includes a magnetically energizable pole piece and a plurality of electrically conductive circuits, coupled to the magnetic pole piece, such that a change in magnetic flux in the pole piece caused by movement of the body relative to the pole piece induces a voltage in each of the circuits. The electrically conductive circuits are wound around each other in a symmetrical fashion such that in the vicinity of the magnetic pole piece each circuit experiences substantially the same change in magnetic flux. A probe of this type provides a plurality of substantially identical output signals and is easy to manufacture and replicate.

Abstract: A method (and corresponding apparatus) for monitoring the rotational speed of the shaft of a gas turbine having a number of spaced blades on or rotating with the shaft. The invention compensates for the errors which arise from the relative movement of turbine blade tips by deriving a correction factor for each blade and continually updating that correction factor.

Abstract: Method and apparatus for monitoring the rotational speed of a shaft, in particular a shaft having a number of spaced features on or rotating with the shaft. Preferred embodiments of the invention are concerned with methods and apparatuses for processing signals in order to calculate, with high accuracy and a fast response time, the rotational speed of a gas turbine shaft. The invention recognizes that it is possible to accurately measure speed between two eddy current sensors (5, 6) by determining the time take for a turbine blade to pass therebetween provided that appropriate compensation is made for the effect of apparent changes in the magnetic distance between the sensors.

Abstract: The invention provides a transformer probe for sensing movement of a body of magnetic material, having multiple output channels wherein the output in each output channel is substantially unaffected by faults in other output channels.

Abstract: A ceramic thermocouple (10) in which the hot junction is defined by the junction between a first element (3) of molybdenum disilicide and a second element (2) of silicon carbide. The molybdenum disilicide element is formed by a layer of molybdenum disilicide on a molybdenum support.

Abstract: The invention provides a system for monitoring an operational parameter of a gas turbine, including a magnetic coupling between a signal source and a data output terminal. The magnetic coupling comprises a primary coil electrically connected to the signal source and wound around a first magnetic core section, and a secondary coil electrically connected to the output terminal but electrically isolated from the primary coil and wound around a second magnetic core section, wherein the first and second magnetic core sections are physically separated from one another.

Abstract: A method for generating a series of output signals represented by a series of measurement signals which is particularly useful in the compensation for jatter, missing spurious pulses or plates when applied to the processing of signals from a speed probe monitoring the speed of a rotating bladed shaft. The method includes the steps of predicting a value for a first measurement signal from a historical measurement signal value, generating a first output signal from the predicted value of the first measurement signal; comparing the measurement signal to its predicted value, and: if the measurement signal is within a predetermined range of acceptable values, using the first measurement signal to predict a value for a second measurement signal; if the measurement signal is outside the pre-determined range of acceptable values, using the first predicted value to predict a second measurement signal, and generating a second output signal from the predicted value of the second measurement signal.

Abstract: A gas turbine shaft speed sensor including a sensing coil comprised of a central conducting wire, the sensor and conducting wire is surrounded by a layer of mineral insulator and the mineral insulator is surrounded by a metallic, non magnetic, sheath. A sensing coil formed with this construction allows the high operating temperatures and is robust.

Abstract: A probe for sensing the movement of a body of magnetic material comprises a magnetically energisable pole piece and a plurality of electrically conductive circuits, coupled to the magnetic pole piece, such that a change in magnetic flux in the pole piece caused by movement of the body relative to the pole piece induces a voltage in each of the circuits. The electrically conductive circuits are wound around in a symmetrical fashion each other such that in the vicinity of the magnetic pole piece each circuit experiences substantially the same change in magnetic flux. A probe of this type provides a plurality of substantially identical output signals and is easy to manufacture and replicate.

Abstract: A method (and corresponding apparatus) for monitoring gas turbine blades. The output from an eddy current sensor monitoring the movement of turbine blades past the sensor is processed to determine when the signal train from the sensor omits a signal or pulse corresponding to one of the shaft's full complement of blades. The signal processor compares sensed blade periods with average blade periods.

Abstract: A method (and corresponding apparatus) for monitoring the rotational speed of the shaft of a gas turbine having a number of spaced blades on or rotating with the shaft. The invention compensates for the errors which arise from the relative movement of turbine blade tips by deriving a correction factor for each blade and continually updating that correction factor.

Abstract: Method and apparatus for monitoring the rotational speed of a shaft, in particular a shaft having a number of spaced features on or rotating with the shaft. Preferred embodiments of the invention are concerned with methods and apparatuses for processing signals in order to calculate, with high accuracy and a fast response time, the rotational speed of a gas turbine shaft. The invention recognises that it is possible to accurately measure speed between two eddy current sensors (5, 6) by determining the time take for a turbine blade to pass therebetween provided that appropriate compensation is made for the effect of apparent changes in the magnetic distance between the sensors.

Abstract: The invention provides a total gas temperature sensor for measuring the temperature of gas in a gas flow. A gas temperature sensor in accordance with the invention comprises a measurement chamber having a gas inlet and a gas outlet; an outlet valve located at the gas outlet, operable to seal the gas outlet when in a closed position, and a temperature sensing element located in the measurement chamber. The sensor is simple to manufacture, is robust, provides for a low recovery correction and does not suffer from significant boundary layer problems.

Abstract: A mounting terminal head of a thermocouple head unit having a metal casing for an end of a thermocouple wire, and thermocouple signal terminals 4 for connection to a thermocouple wire. The thermocouple head unit includes an insulating support member 8 extending around the outside of the thermocouple head unit and supporting the thermocouple signal terminals.