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1 Introduction
1.1 Description of SmartCal positioner
The SmartCal valve positioner is an electro-pneumatic servo system that continuously controls the
position of a valve based on a 4 to 20 mA input signal. The SmartCal is an instrument that
derives its power directly from a control systems current loop. The instrument senses valve
position via a non-contact Hall effect sensor and controls valve position through a current to
pressure transducer.
Calibration of the SmartCal can transpire by two means. Non-HART® calibration is through an
on-board keypad. Communication using HART® protocol allows calibration and access to on-line
diagnostics via a Rosemount® 275 hand-held terminal or through FDT/DTM software.
The positioner has a local liquid crystal display which indicates valve position and set-point in
percentage open. It also indicates whether the positioner is in calibration mode.
The SmartCal has the capability to monitor operation. If a failure condition occurs, an error
message is displayed on the local liquid crystal display.
1.2 Principle of operation
Unlike conventional positioners, the SmartCal positioner feeds back valve position without the
need for linkages, levers, or rotary and linear seals. Position sensing is performed totally by
non-contacting means, permitting use of advanced control strategies where knowledge of valve
position is used in predictive and other algorithms. By the integration of multiple components into
a singular, cost efficient unit, microprocessor-based intelligence can now be used to implement
advanced functions such as early warning diagnostics and fugitive emissions monitoring.
The SmartCal positioner provides intelligence for the control valve through a microprocessor-based
diagnostic system utilizing the HART® protocol. Accurate measurement of valve stem position,
input signal, actuator pressure and travel time can be recorded during normal operation, thereby
providing information for control valve signature generation.
AVID SmartCal valve positioner
Installation & operating instructions
LINEAR VALVE
Magnet
Magnet
Sensor
Magnet
Valve stem
Sensor
Magnet
