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Method of monitoring the condition of a motor operated valve system

Patent ·
OSTI ID:5981446
Method is described of identifying, during valve-in-use operation, an unacceptable degredation of the operating condition of a motor operated valve system, which system is comprised of a valve driven by a valve stem which is driven by a valve actuator which is driven by an electric motor, said method comprising the steps of: establishing, for a specific valve system, a value (referred to as BASE) representative of actuator output torque during baseline running conditions, baseline running conditions being defined as near to normal, non-degraded running condition as possible for the valve; establishing, for the valve system, a value (referred to as MAX'') representative of the maximum actuator output torque to be allowed during running condition, based on a predefined, allowed degraded stem factor; determining the maximum allowed percentage increase in the actuator output torque from BASE during running condition by the formula: [vert bar]MAX-BASE/BASE[vert bar] [times] 100/SAFETY FACTOR = warning level percentage, wherein safety factor'' is a number greater than or equal to one; establishing, for the valve system, a value of a selected power related parameter of the motor during baseline running conditions; determining a warning value of the selected power related parameter as equal to the warning level percentage of the established baseline value of the power related parameter; monitoring the selected power related parameter associated with the valve system during valve-in-use conditions; and evaluating changes in the value of the selected power related parameter over the monitoring period, whereby, an increase in monitored power related parameter value indicates a potential problem and an increase in the monitored parameter to the warning value indicates operational readiness may be compromised.
Assignee:
Westinghouse Electric Corp., Pittsburgh, PA (United States)
Patent Number(s):
A; US 5239874
Application Number:
PPN: US 7-540577
OSTI ID:
5981446
Country of Publication:
United States
Language:
English

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