Microprocessor-based control and diagnostic system for motor operated valves
AssigneeElectric Power Research Institute, Inc.
InventorRobert A. S. Lee
Life of this patent
Estimating the term…
Abstract
There is described a microprocessor-based valve motor control system which provides control, predictive control and diagnostic functions for a motor operated valve. A valve stem position sensor measures the stem position and a load sensor measures the load on the valve stem. When the valve is being opened, the system predicts the position of the valve stem at a predefined time in the future and turns off the motor if the predicted valve stem position is beyond a preselected open valve position. When said valve is being closed, the system predicts the load on the valve stem at a predefined time in the future and turns off the motor if the predicted load value exceeds a preselected maximum desirable stem closing load.
Claims22
A valve motor control system, fur use with a motor operated valve including a valve stem for opening and closing said valve and motor means for driving said valve stem so as to controllably open and close said valve, said valve motor control system comprising:
- position means for measuring the position of said valve stem and producing a valve stem position signal;
- load means for measuring the load on said valve stem and producing a valve stem load signal;
- monitor means coupled to said motor means, position means and load means, for controlling the operation of said motor, including a digital computer programmed to:
- periodically compare said valve stem position signal with a preselected open valve position when said valve is being opened;
- periodically compare said valve stem load signal with a preselected maximum desirable stem opening load when said valve is being opened, and with a preselected maximum desirable stem closing load when said valve is being closed;
- turn off said motor when said valve stem position comparison does not meet predefined valve stem position criteria, or when said valve stem load comparison does not meet predefined valve stem load criteria;
- periodically, when said valve is being opened, predict the position of said valve stem at a predefined time in the future;
- and
- turn off said motor if said predicted valve stem position is beyond said preselected open valve position.
A method of controlling a motor operated valve having a valve stem for opening and closing said valve, and motor means for driving said valve stem so as to controllably open and close said valve;
- the steps of the method comprising:
- measuring the position of said valve stem and producing a valve stem position signal;
- measuring the load on said valve stem and producing a valve stem load signal;
- periodically comparing said valve stem position signal with a preselected open valve position when said valve is being opened;
- periodically comparing said valve stem load signal with a preselected maximum desirable stem opening load when said valve is being opened, and with a preselected maximum desirable stem closing load when said valve is being closed;
- turning off said motor when said valve stem position comparison does not meet predefined valve stem position criteria, or when said valve stem load comparison does not meet predefined valve stem load criteria;
- periodically, when said valve is being opened, predicting the position of said valve stem at a predefined time in the future;
- and
- turning off said motor if said predicted valve stem position is beyond said preselected open valve position.
A motor operated valve comprising:
- a valve, including a valve stem for opening and closing said valve;
- motor means for driving said valve stem so as to controllably open and close said valve;
- and
- a valve motor control system including:
- position means for measuring the position of said valve stem and producing a valve stem position signal;
- load means for measuring the load on said valve stem and producing a valve stem load signal;
- monitor means coupled to said motor means, position means and load means, for controlling the operation of said motor, including a digital computer programmed to:
- periodically compare said valve stem position signal with a preselected open valve position when said valve is being opened;
- periodically compare said valve stem load signal with a preselected maximum desirable stem opening load when said valve is being opened, and with a preselected maximum desirable stem closing load when said valve is being closed;
- turn off said motor when said valve stem position comparison does not meet predefined valve stem position criteria, or when said valve stem load comparison does not meet predefined valve stem load criteria;
- periodically, when said valve is being opened, predict the position of said valve stem at a predefined time in the future;
- and
- turn off said motor if said predicted valve stem position is beyond said preselected open valve position.
A valve motor control system, for use with a motor operated valve including a valve stem for opening and closing said valve and motor means for driving said valve stem so as to controllably open and close said valve, said valve motor control system comprising:
- position means for measuring the position of said valve stem and producing a valve stem position signal;
- load means for measuring the load on said valve stem and producing a valve stem load signal;
- monitor means coupled to said motor means, position means and load means, for controlling the operation of said motor, including a digital computer programmed to:
- periodically, when said valve is being opened, determine the rate of change of the position of said valve stem, and predict the position of said valve stem at a predefined time in the future in accordance with said rate of change of valve stem position;
- and
- turn off said motor if said predicted valve stem position is beyond a preselected open valve position.
A method of controlling a motor operated valve having a valve stem for opening and closing said valve, and motor means for driving said valve stem so as to controllably open and close said valve;
- the steps of the method comprising:
- measuring the position of said valve stem and producing a valve stem position signal;
- measuring the load on said valve stem and producing a valve stem load signal;
- periodically, when said valve is being opened, determining the rate of change of the position of said valve stem, and predicting the position of said valve stem at a predefined time in the future in accordance with said rate of change of valve stem position;
- and
- turning off said motor if said predicted valve stem position is beyond a preselected open valve position.
Dependencies are inferred from the claim text.