Fault-tolerant analog output network
First Claim
1. An analog output network for controlling an actuator in dependence upon an input signal received from a sensor, comprising:
- control means, operatively connected to the sensor, for providing control signals in dependence upon the input signal;
analog output circuits, each of said analog output circuits comprising;
actuation means, operatively connected to said control means, for generating an analog output signal in dependence upon one of the control signals;
internal loop means, operatively connected to said actuation means, for outputting the analog output signal and providing a current path; and
loop sensing means, operatively connected to said internal loop means, said actuation means and said control means, for generating a feedback signal in dependence upon electrical current flow in the current path provided by said internal loop means, andexternal loop means, operatively connected to said analog output circuits and the actuator, for providing alternate current paths, the current path provided by said internal loop means in each of said analog output circuits being connected in parallel with one of the alternate current paths.
1 Assignment
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Accused Products
Abstract
An analog output network provides multiple communication paths for control of an actuator in response to an input signal. The analog output network includes at least two controllers, each of which is connected to an analog output circuit and a controller selector which is connected to each of the controllers and the analog output circuits. The controller selector ensures that at least one of the analog output circuits is enabled at all times and identifies one of the controllers as an on-line controller. The analog output circuit connected to the on-line controller generates an actuation signal which passes through the actuator and the other analog output circuit. An alternate current path comprising a diode string with a voltage drop larger than the voltage drop of the actuation signal in the other analog output circuit is provided so that if an analog output circuit is removed or defective, the actuation signal from the on-line analog output circuit is still provided with a current path.
26 Citations
28 Claims
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1. An analog output network for controlling an actuator in dependence upon an input signal received from a sensor, comprising:
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control means, operatively connected to the sensor, for providing control signals in dependence upon the input signal; analog output circuits, each of said analog output circuits comprising; actuation means, operatively connected to said control means, for generating an analog output signal in dependence upon one of the control signals; internal loop means, operatively connected to said actuation means, for outputting the analog output signal and providing a current path; and loop sensing means, operatively connected to said internal loop means, said actuation means and said control means, for generating a feedback signal in dependence upon electrical current flow in the current path provided by said internal loop means, and external loop means, operatively connected to said analog output circuits and the actuator, for providing alternate current paths, the current path provided by said internal loop means in each of said analog output circuits being connected in parallel with one of the alternate current paths. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. An analog output network in an integrated control system for a pressurized light water nuclear power system, said network controlling an actuator in the nuclear power system in dependence upon an input signal received from a sensor, said network comprising:
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first and second controllers, operatively connected to the sensor, each generating a demand signal in dependence upon the input signal; controller selector means, operatively connected to said first and second controllers, for indicating to said controllers which of said controllers is in an on-line mode and which is in a back-up mode; first and second analog output circuits, each comprising; first and second output terminals; actuation means, operatively connected to said controller selector means and one of said first and second controllers, for outputting an actuation signal at first and second outputs in response to the demand signal from the one of said first and second controllers; a diode connected between the first and second outputs of said actuation means and to the first output terminal; and a resistor connected to said diode and the second output terminal, an expected voltage drop occurring when a normal operating current flows from the second output terminal through said said resistor and said diode to the first output terminal; and feedback means, operatively connected to said resistor, said actuation means and the one of said first and second controllers, for outputting a feedback signal indicating current flow through said resistor; a first diode string having a first end connected to the actuator and the first output terminal of said first analog output circuit, and a second end connected to the second output terminal of said first analog output circuit and the first output terminal of said second analog output circuit, and having a first diode string voltage drop from the second end to the first end, the first diode string voltage drop being greater than the expected voltage drop; and a second diode string having a first end connected to the second end of said first diode string, the second output terminal of said first analog output circuit and the first output terminal of said second analog output circuit, and a second end connected to the actuator and the second output terminal of said second analog output circuit, and having a second diode string voltage drop from the second end to the first end, the second diode string voltage drop being greater than the expected voltage drop. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20, 21)
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22. An analog output network for controlling an actuator in dependence upon an input signal received from a sensor, comprising:
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controllers, operatively connected to the sensor, each of said controllers generating a demand signal in dependence upon the input signal, a control signal and a pulse signal; controller selector means, operatively connected to said controllers, for generating status signals indicating whether each of said controllers is operating normally and enable signals indicating which of said controllers is in an on-line mode and which of said controllers is in a back-up mode; analog output circuits, each of said analog output circuits, operatively connected to said controller selector means and one of said controllers, providing a current path for an analog signal supplied to the actuator; and external loop means, operatively connected to said analog output circuits and the actuator, for providing alternate current paths, each of the alternate current paths being connected in parallel with the current path provided by a corresponding one of said analog output circuits. - View Dependent Claims (23, 24, 25, 26)
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27. An analog output network in an integrated control system for a pressurized light water nuclear power system, said network controlling an actuator in the nuclear power system in dependence upon an input signal received from a sensor, said network comprising:
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first and second controllers, operatively connected to receive the input signal, each of said controllers generating a demand signal, a control signal and a pulse signal; controller selector means, operatively connected to said first and second controllers, for providing a status signal indicating to each of said first and second controllers whether said second and first controllers, respectively, are operating normally, and enable signals indicating which of said controllers is in an on-line mode and which of said controllers is in a back-up mode, said controller selector means comprising first and second selector circuits operatively connected to said first and second controllers, respectively, each of the first and second selector circuits comprising; a controller status circuit, operatively connected to a corresponding controller, for indicating that the corresponding controller is operating normally in dependence upon the pulse signal and the control signal generated by the corresponding controller; on-line selection means for indicating that the corresponding controller is selected to be in the on-line mode; a first AND gate operatively connected to said controller status circuit and said on-line selection means; a first inverter, operatively connected to said controller status circuit, for outputting the status signal to a non-corresponding controller; a second AND gate operatively connected to said controller status circuit and to receive the status signal for the non-corresponding controller; an OR gate having inputs operatively connected to said first and second AND gates and having an output; and a second inverter, operatively connected to the output of said second OR gate, the inputs of said first OR gate in the other selector circuit of said controller selector means and the non-corresponding controller, for producing a corresponding enable signal; first and second analog output circuits, operatively connected to said first and second controllers and said second inverter in the first and second selector circuits, respectively, of said controller selector means, for providing first and second current paths for an analog signal supplied to the actuator, respectively; and external loop means, operatively connected to said analog output circuits and the actuator, for providing first and second alternate current paths connected in parallel with the first and second current paths provided by said first and second analog output circuits, respectively. - View Dependent Claims (28)
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Specification