Magnetic flowmeter with drive signal diagnostics

摘要

A magnetic flowmeter includes a flowtube arranged to receive a flow of process fluid. A coil is positioned proximate the flowtube and arranged to apply a magnetic field to the process fluid in response to a drive current alternating direction. First and second electrodes are arranged to sense a voltage potential in the process fluid in response to the applied magnetic field. The voltage potential is indicative of flow rate of process fluid through the flowtube. A sensor is coupled to the first and second current paths which has a sensor output related to the drive current. Diagnostic circuitry provides a diagnostic output as a function of a transient change in the sensor output when current flowing through the coil alternates direction.

主权项

1. A magnetic flowmeter, comprising:
a flowtube arranged to receive a flow of process fluid; a coil proximate the flowtube arranged to apply a magnetic field to the process fluid in response to an alternating coil drive current; first and second electrodes arranged to sense a voltage potential in the flowtube in response to the applied magnetic field, the voltage potential indicative of flow rate of process fluid through the flowtube; and a sensor coupled to the coil having a sensor output related to the drive current; and diagnostic circuitry having a diagnostic output as a function of identification of a transient step change in the sensor output when current flowing through the coil alternates direction.