Turbo machinery speed monitor
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.
1. A turbine speed monitor module comprising:
a sensor for generating a sensor signal in dependence upon rotational speed of a turbine
a module arranged to receive said sensor signal and arranged in operation to generate a trip signal in dependence thereupon;
wherein said sensor signal is converted to a digital signal by 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.
2. A turbine speed monitor module according to claim 1 in which said module comprises a module slice and an output switch and the module slice comprises said input conditioner;
a trip controller arranged to receive said digital signal and to generate an overspeed or overacceleration signal therefrom; and
an output controller arranged to receive said overspeed or overacceleration signal and to generate said output signal therefrom.
3. A turbine speed monitor module according to claim 2 , in which said module comprises three identical module slices and said trip signal is generated by the output switch, the output switch being arranged to receive an output signal from each one of the module slices, and in which the output switch comprises a two out of three voter arranged to receive a signal from each slice and generate a trip signal therefrom.
4. A turbine speed monitor module according to claim 3 , in which said module is arranged to generate a plurality of trip signals and said output switch comprises a plurality of two out of three voters each arranged to receive a signal from each module slice and generate a trip signal therefrom.
5. A turbine monitor module according to claim 4 , wherein each module slice comprises three input conditioners connected to three trip controllers and the output controller is arranged to receive an overspeed or an overacceleration trip signal from each one of said trip controllers, and in which said output signal is generated according to a two out of three voting arrangement.
6. A turbine monitor module according to claim 5 , further comprising a further output controller arranged to receive an overspeed or an overacceleration trip signal from each trip controller, and arranged to generate a further output signal according to a two out of three voting arrangement.