Abstract: This invention relates to a method and apparatus for output current control. The invention provides an output module slice for controlling an output current comprising: an output field interface controller for controlling an input voltage to a first field effect transistor; an analogue to digital converter connected to read the current flowing through said first field effect transistor and to provide a digital signal dependent thereon to said output field interface controller.

Abstract: This invention relates to fault detection in electrical circuits. The invention provides an input module for electrically isolating an input signal received via a field sensor to be transmitted to a plurality of processors, in which the input module comprises a plurality of optical coupler/controller circuits; and each optical coupler/controller comprises a light emitting diode drive sub-circuit driving a light emitting diode; and an input sub-circuit; and in which a sensor voltage representing said input signal and a supply voltage are connected to each input sub-circuit; and each of said light emitting diode drive sub-circuits are connected in series between the supply voltage and ground.

Abstract: This invention relates to a speed monitor apparatus for monitoring speed and acceleration of rotating turbine equipment (turbomachinery) and for operating an overspeed trip to shut down the equipment in the event that the speed or acceleration exceed predetermined thresholds. The invention provides a speed monitor module having an input conditioner comprising: a multiplexer; an amplifier; and a comparator; in which the multiplexer selects an input signal from the sensor, or an input signal via a feedback loop from the comparator in dependence upon a test input, such that the input circuit may be tested by confirming that the amplifier oscillates when the feedback loop is enabled by the test signal.

Abstract: This invention relates to a speed monitor apparatus for monitoring speed and acceleration of rotating turbine equipment (turbomachinery) and for operating an overspeed trip to shut down the equipment in the event that the speed or acceleration exceed predetermined thresholds. The invention provides a speed monitor module having an output switch comprising a plurality of armature clamped relays such that first armatures form a first electrical path only when both first armatures are open or when both first armatures are closed and second armatures provide a second electrical path when either or both second armatures are open or closed such that the second electrical path is discontinuous when either first armature is stuck in an open or closed position causing either second armature to remain floating between an open and closed position.

Abstract: This invention relates to line frequency synchronisation for use in diagnostics for alternating current electrical circuits. The invention provides a method of synchronising measurement system frequency with an alternating current line frequency comprising the steps of: adjusting the frequency of the measurement system frequency using a frequency locked loop until the measurement system frequency is within a predetermined range of said alternating current line frequency; and when the measurement system frequency is within a predetermined range of said alternating current line frequency adjusting the phase and the frequency of the measurement system frequency using a phase and frequency locked loop.

Abstract: This invention relates to fault detection in electrical circuits. The invention provides an input module for electrically isolating an input signal received via a field sensor to be transmitted to a plurality of processors, in which the input module comprises a plurality of optical coupler/controller circuits; and each optical coupler/controller comprises a light emitting diode drive sub-circuit driving a light emitting diode; and an input sub-circuit; and in which a sensor voltage representing said input signal and a supply voltage are connected to each input sub-circuit; and each of said light emitting diode drive sub-circuits are connected in series between the supply voltage and ground.

Abstract: This invention relates to fault detection in electrical circuits. The invention provides a switch for a fault tolerant digital output module comprising: an output transistor pair for enabling and disabling an alternating output current; and a current limiter for clamping the output current to a predetermined maximum value.

Abstract: This invention relates to a method and apparatus for output current control. The invention provides an output module slice for controlling an output current comprising: an output field interface controller for controlling an input voltage to a first field effect transistor; an analogue to digital converter connected to read the current flowing through said first field effect transistor and to provide a digital signal dependent thereon to said output field interface controller.

Abstract: This invention relates to fault detection in electrical circuits, in particular it relates to fault detection for a plurality of adjacent input circuits. The invention provides a method and apparatus for detecting a control or communication fault on an analogue circuit by digitally simulating said analogue circuit; driving the digitally simulated circuit with a control input also used to drive said analogue circuit; and comparing an output of said simulated circuit with a reference output and setting an error condition in the event that the compared outputs differ.

Abstract: This invention relates to overload protection for a circuit driving a direct current (DC) load.

Abstract: This invention relates to fault detection in electrical circuits. The invention provides a method and apparatus for testing an input circuit by generating a periodic test signal having a predetermined phase and a predetermined amplitude; summing the test signal and an input signal to provide a summed signal; processing the summed signal to provide an output signal; generating an extracted test signal from the output signal; comparing the extracted test signal with a reference signal representing said periodic test signal; generating an error signal in dependence upon the result of said comparing step. The invention also provides a method and apparatus for testing a plurality of adjacent input circuits.

Abstract: This invention relates to a speed monitor apparatus for monitoring speed and acceleration of rotating turbine equipment (turbomachinery) and for operating an overspeed trip to shut down the equipment in the event that the speed or acceleration exceed predetermined thresholds. The invention provides a speed monitor module having an output switch comprising a plurality of armature clamped relays such that first armatures form a first electrical path only when both first armatures are open or when both first armatures are closed and second armatures provide a second electrical path when either or both second armatures are open or closed such that the second electrical path is discontinuous when either first armature is stuck in an open or closed position causing either second armature to remain floating between an open and closed position.

Abstract: This invention relates to a speed monitor apparatus for monitoring speed and acceleration of rotating turbine equipment (turbomachinery) and for operating an overspeed trip to shut down the equipment in the event that the speed or acceleration exceed predetermined thresholds. The invention provides a speed monitor module wherein the speed monitor module may be may be plugged in to the same chassis as a module which is controlling the speed of the turbine, and wherein the turbine speed monitor is arranged to receive configuration parameters relating to the overspeed threshold and the overacceleration threshold only when the turbine is operating at a speed lower than a predetermined threshold.

Abstract: This invention relates to a speed monitor apparatus for monitoring speed and acceleration of rotating turbine equipment (turbomachinery) and for operating an overspeed trip to shut down the equipment in the event that the speed or acceleration exceed predetermined thresholds. The invention provides a speed monitor module having an input conditioner comprising: a multiplexer; an amplifier; and a comparator; in which the multiplexer selects an input signal from the sensor, or an input signal via a feedback loop from the comparator in dependence upon a test input, such that the input circuit may be tested by confirming that the amplifier oscillates when the feedback loop is enabled by the test signal.

Abstract: This invention relates to an emergency valve shutdown system having an integrated test facility. The invention provides an apparatus for testing emergency shutdown valves in a process industry comprising: a valve having a plurality of limit switches each limit switch arranged to indicate that the valve has reached a corresponding one of a plurality of predetermined valve positions; a valve monitor module arranged to send a signal to said valve to initiate movement of said valve and to receive feedback relating to said limit switches; wherein said feedback is provided via a single feedback signal between the valve and the valve monitor module.

Abstract: The present invention relates to a pipe liner assembly for sealing and rehabilitating the walls of an underground structure. The system includes an inflation bladder, a woven liner and a non-porous membrane. The woven liner has an inner surface adjacent the inflation bladder, an outer surface, and longitudinal edges. The liner also has a first fastener system adjacent the liner edges for releasably securing the liner edges so that the liner surrounds the bladder. The non-porous membrane is adjacent the outer surface of the liner. The membrane has longitudinal edges, and a second fastener system adjacent the membrane edges for releasably securing the membrane edges so that the membrane surrounds the liner. The present invention is also directed to an apparatus for curing a resin impregnated pipe liner, as well as methods of making and installing a reinforcing liner for an underground structure.

Abstract: A light assembly, suitable for use on a motorized vehicle, provides both active and passive illumination via optical elements carried by a single platform/structure. Active illumination and passive illumination elements provide illumination from separate and distinct, yet intermingled, surface areas of the single platform/structure of an assembly. The active illumination elements are interspersed/interleaved with the passive illumination source(s). Furthermore, the passive illumination is provided by “retro reflective” material that reflects light back at its source within a wide range of angles of incidence. In an embodiment of the invention, the active illumination is carried out by light emitting diodes mounted upon a platform of the light assembly that also holds the retro reflective passive illumination source.

Abstract: A mould is provided having a surface which defines a mould cavity, and the mould surface includes on at a least part thereof a compound comprising a nucleation agent. The mould is heated. A metal heated to a temperature 0-15.degree. C. above the liquidus temperature is poured into the heated mould cavity and the molten metal is solidified in the mould cavity.

Abstract: When heating and bending glass sheets in a furnace, it has been found to be desirable to raise the glass sheets towards the furnace heat sources to increase obtainable temperature differentials and reduce heating power. An apparatus for bending the glass sheets includes an elongate furnace divided along its length into a plurality of heating zones, each heating zone having an upper part. A plurality of heat sources are arranged in the upper part of such heating zone and a plurality of carriages are arranged in succession along the length of the furnace below the furnace heat sources. A drive device propels the carriages through the zones of the furnace in intermittent steps, and a mould lift raises the bending mould towards the furnace heat sources. The bent glass sheet may be used in the manufacture of a vehicle glazing.

Abstract: When heating and bending glass sheets in a furnace, it is desirable to raise the sheets towards the furnace heat sources to increase obtainable temperature differentials and reduce heating power.