Control signal protection device
AssigneeFisher Controls International LLC
InventorStephen G. Seberger
Life of this patent
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Abstract
A control signal protection device protects a current-receiving field device from an undesirable interruption in a control signal provided to the field device. The control signal protection device includes a first terminal to connect the signal protection device to a control system and a second terminal that connects the control signal protection device to a field device. The control signal device further includes a power storing element for temporary accumulation of electric energy and a switching circuit for controlling operational mode of the signal protection device. Electric energy is stored in the power storing element in a first operational mode. Electric energy stored in the power storing element is supplied to a positive terminal in the second terminal pair in a second operational mode.
Claims21
A control signal protection device having a first operational mode and a second operational mode, comprising:
- a first terminal to connect the signal protection device to a control system, wherein the control system provides a control signal;
- a second terminal to connect the signal protection device to a field device for providing the control signal to the field device;
- a power storing element for temporary accumulation of electric energy;
- and
- a switching circuit coupled to the first terminal, the second terminal, and the power storing element, the switching circuit configured to control the operational mode of the signal protection device in response to detecting a decrease in the level of electric current at the second terminal of the control signal protection device, wherein
- electric energy is accumulated in the power storing element in the first operation mode, and
- electric energy accumulated in the power storing element in the first operation mode is transferred to the second terminal in the second operational mode.
A method of protecting a control signal provided to a field device in a process control system, the method comprising:
- providing a host station;
- communicatively coupling the host station to an input output (I/O) system having a plurality of I/O cards including a first card and a second card, wherein operation is selectively switched from the first card to the second card;
- providing a control signal from the host station via the I/O system to an input of a control signal protection device, wherein an output of the control signal protection device is communicatively coupled to the field device;
- and
- causing the control signal protection device to switch from a first operational mode to a second operational mode during a transition of operation, in the I/O system, from the first card to the second card, wherein the control signal protection device transitions from the first operational mode to the second operational mode in response to detecting a decrease in a level of electric current at the output of the control signal protection device.
A system for controlling a field device in a process control system, comprising:
- a host station;
- a plurality of input/output (I/O) cards coupled to the host station for providing a control signal to the field device, wherein the plurality of I/O cards includes a primary I/O card and a back-up I/O card;
- an I/O card controller configured to selectively switch between the primary I/O card and the backup I/O card;
- and
- a control signal protection device having an input communicatively coupled to the I/O cards and an output communicatively coupled to the field device, wherein the control signal protection device is configured to transition from a first operational mode to a second operational mode in response to detecting a decrease in a level of electric current at the output of the control signal protection device to sustain the control signal at the output of the control signal protection device during a switchover operation between the primary I/O card and the backup I/O card.
Dependencies are inferred from the claim text.