Abstract: A liquid level monitoring system for monitoring the level of liquid in a tiltable tank, which may tilt or rotate in a tilt or rotation plane about a tilt axis. The system comprises a pair of pressure sensors comprising a first pressure sensor for sensing the pressure of the liquid in the tank at a first position located towards the bottom of a tank and a second pressure sensor for sensing the pressure of the liquid in the tank at a second position located a known pre-defined distance above the first sensing wherein the two sensing positions are located on a sensing line substantially orthogonal to and passing through a liquid surface dividing line, said liquid surface dividing line being the line along and extending past the surface of liquid in the tank whose position relative to the tank walls remains the same as the tank tilts about the tilt axis.

Abstract: The present invention relates to a system (100, 300, 400) for detecting abnormal movement of a gas turbine shaft. The system comprises: a magnetic circuit (104, 302, 402) comprising a first magnetic portion (110, 304) and a second portion (112, 404), and including at least one air gap between the first portion and the second portion; and a detection coil (106) wound around the first magnetic portion. The second portion is coupled to or moveable with the shaft to reduce the air gap, on axial movement of the shaft to change the reluctance of the magnetic circuit and thereby induce a voltage in the coil. The system may comprise a controller (108) for shutting off power to the gas turbine when the induced voltage exceeds a threshold voltage.

Abstract: A liquid level monitoring system for monitoring the level of liquid in a tiltable tank, which may tilt or rotate in a tilt or rotation plane about a tilt axis. The system comprises a pair of pressure sensors comprising a first pressure sensor for sensing the pressure of the liquid in the tank at a first position located towards the bottom of a tank and a second pressure sensor for sensing the pressure of the liquid in the tank at a second position located a known pre-defined distance above the first sensing wherein the two sensing positions are located on a sensing line substantially orthogonal to and passing through a liquid surface dividing line, said liquid surface dividing line being the line along and extending past the surface of liquid in the tank whose position relative to the tank walls remains the same as the tank tilts about the tilt axis.

Abstract: The present invention relates to a system (100, 300, 400) for detecting abnormal movement of a gas turbine shaft. The system comprises: a magnetic circuit (104, 302, 402) comprising a first magnetic portion (110, 304) and a second portion (112, 404), and including at least one air gap between the first portion and the second portion; and a detection coil (106) wound around the first magnetic portion. The second portion is coupled to or moveable with the shaft to reduce the air gap, on axial movement of the shaft to change the reluctance of the magnetic circuit and thereby induce a voltage in the coil. The system may comprise a controller (108) for shutting off power to the gas turbine when the induced voltage exceeds a threshold voltage.

Abstract: A sensor element for use in a backing sensor to monitor a gas turbine shaft. The sensor includes an oscillator circuit 30 having an oscillator and a resonance circuit 42, and a frequency detector 31 for monitoring the frequency of the oscillation circuit. Abnormal movement of the shaft cuts the circuit in the sensor along a cutting line (15). The cutting of the sensor changes the capacitance and/or inductance of the resonance circuit and thereby changes the frequency of oscillation.

Abstract: Apparatus and method of monitoring for obstructions in a pipe or channel.

Abstract: A sensor element for use in a backing sensor to monitor a gas turbine shaft. The sensor includes an oscillator circuit 30 having an oscillator and a resonance circuit 42, and a frequency detector 31 for monitoring the frequency of the ossilation circuit. Abnormal movement of the shaft cuts the circuit in the sensor along a cutting line (15). The cutting of the sensor changes the capacitance and/or inductance of the resonance circuit and thereby changes the frequency of oscillation.

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: 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 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: 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: 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: 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.