초록 ▼

A microprocessor-based valve motor control system which provides control, predictive control and diagnostic functions for a motor operated valve. A microprocessor periodically tests the status of the motor operated valve, and turns off the valve\s motor if certain predefined criteria for the valve s

A microprocessor-based valve motor control system which provides control, predictive control and diagnostic functions for a motor operated valve. A microprocessor periodically tests the status of the motor operated valve, and turns off the valve\s motor if certain predefined criteria for the valve stem position and the valve stem load are satisfied. The periodic testing by the microprocessor includes the testing of a position criterion (comparing both the current valve stem position signal and a predicted stem position with a preselected target position); and a stem load criterion (comparing both the current valve stem load and a predicted stem load with a preselected maximum desirable stem load). When the control system is being used with a gate valve for fully opening and fully closing a valve, the control logic can use either a predicted position criterion or a predicted stem load criterion to determine when to turn off the valve motor. When the control system is being used with a flow control valve, the use of a predicted position criterion minimizes overshoot problems which cause the motor to be reversed one or more times while moving to a target position. Motor overload protection is provided by periodically measuring the actual load on the motor and turning off the motor if the measured motor load exceeds any one of a plurality of preselected maximum motor load values for a corresponding period of time.

대표청구항 ▼

A valve motor control system for use with a motor operated valve, said motor operated valve including a valve having a valve stem for opening and closing said valve, and a motor for driving said valve stem so as to controllably move and position said valve stem between open and closed valve position

A valve motor control system for use with a motor operated valve, said motor operated valve including a valve having a valve stem for opening and closing said valve, and a motor for driving said valve stem so as to controllably move and position said valve stem between open and closed valve positions; said valve motor control system comprising: position detection means for detecting the position of said valve stem; monitor means coupled to said motor and said position detection means for controlling the operation of said motor, said monitor means including: means for turning on said motor to move said valve stem from its current position to a specified valve position which is between the open and closed positions for said valve; and computer means for periodically, as said valve stem is moving, calculating a predicted final resting position of said valve stem assuming that said motor were turned off; and means for turning off said motor when said predicted valve stem position is equal to or beyond said specified valve position.