Invensys Systems, Inc.

Warren E Cook

James H Vignos

Peter E Allstrom

Joseph J Lewicke

Vladimir Dimitrov Kostadinov

Two-wire transmitters are described in which the required voltage that a control room must supply to the transmitter is lower at high current than at low current, thus freeing up more voltage for other uses, and in which a constant set of operating voltages may be maintained. A corrected pressure in a vortex flow meter may be determined that reflects the mass flow rate. Thus, the mass flow rate may be determined based on the corrected pressure reading and a measured volumetric flow rate. Density may be determined from pressure and temperature using a table containing error values based on a standard density determination and a relatively simple approximation. During operation of a flow meter, the stored error values may be linearly interpolated and the approximation may be computed to determine the density from the stored error value.

Multi-measurement vortex flowmeter

Multi-measurement vortex flow meter

A process control instrument includes a sensor/actuator portion and a transmitter portion connected to the sensor/actuator portion. The transmitter portion is operable to communicate with other process variable transmitters through a communication network. The transmitter includes a processing module and a power module operable to generate a power output supplied to at least the transmitter portion, wherein the power module is operable to adjust the power output based on a power control signal. Moreover, the power control signal may be generated by a controller device remote from the process control instrument and communicated to the process control instrument over the communication network. Additionally, the power module includes a power control module for adjusting the power output. This power control module includes an amplitude limiter operable to limit a power input to the process control instrument according to a controllable amplitude limit, and a power rate of change unit operable to limit a rate of change of the power input to the process control instrument according to a controllable adjustment rate limit.

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Upton, MA, United States of America

Warren E Cook