Abstract: A magnetic flowmeter for measuring a fluid flow includes a flow tube assembly receiving the flow and having a coil with first and second coil wires for receiving a coil current and responsively producing a magnetic field thereby generating an EMF in the fluid representative of a flow rate. An EMF sensor is arranged to sense the EMF and generate an output indicating the flow rate. Current supply circuitry applies a current supply signal to the coil. A load leveling boost supply provides power to the current supply circuitry. In another aspect, power scavenging circuitry recovers power from the coil.

Abstract: A magnetic flowmeter includes a flow tube assembly, an electromotive force (EMF) sensor, a power amplifier, a current sampling circuit, and a controller. The flow tube assembly receives the fluid flow, and includes a coil configured to receive a coil current and induce an EMF in the fluid flow that is proportional to the flow rate. The EMF sensor generates an output indicating the induced EMF. The power amplifier is configured to generate unfiltered current pulses at a first frequency. The power amplifier includes a low pass filter that attenuates the unfiltered current pulses to form coil current pulses at a second frequency that form the coil current. The current sampling circuit samples the coil current pulses at a sampling frequency. The controller is configured to change a relationship between the sampling frequency and the first frequency, and adjust the coil current based on the samples.

Abstract: A magnetic flowmeter for measuring a fluid flow includes a flow tube assembly receiving the flow and having a coil with first and second coil wires for receiving a coil current and responsively producing a magnetic field thereby generating an EMF in the fluid representative of a flow rate. An EMF sensor is arranged to sense the EMF and generate an output indicating the flow rate. Current supply circuitry applies a current supply signal to the coil. A load leveling boost supply provides power to the current supply circuitry. In another aspect, power scavenging circuitry recovers power from the coil.

Abstract: A magnetic flowmeter includes a flow tube assembly, an electromotive force (EMF) sensor, a power amplifier, a current sampling circuit, and a controller. The flow tube assembly receives the fluid flow, and includes a coil configured to receive a coil current and induce an EMF in the fluid flow that is proportional to the flow rate. The EMF sensor generates an output indicating the induced EMF. The power amplifier is configured to generate unfiltered current pulses at a first frequency. The power amplifier includes a low pass filter that attenuates the unfiltered current pulses to form coil current pulses at a second frequency that form the coil current. The current sampling circuit samples the coil current pulses at a sampling frequency. The controller is configured to change a relationship between the sampling frequency and the first frequency, and adjust the coil current based on the samples.

Abstract: A magnetic flowmeter includes circuitry for sensing coil current, coil voltage, or coil resistance. Based on the sensed coil current, voltage, or resistance, a digital processor determines whether a power limit or a coil current limit is exceeded and either halts operation until it receives a new configuration with a new coil current setpoint, or determines a new coil current setpoint itself and adjusts the magnetic flowmeter to that new coil current setpoint.

Abstract: An optical isolator is provided. The optical isolator includes a printed circuit board having a first surface and a second surface opposite the first surface. The printed circuit board has a recess extending only partially through the board. The first photoelement has an active surface and is mounted relative to the first surface of the printed circuit board. A second photoelement has an active surface and is mounted relative to the second surface. The second photoelement is configured to interact with the first photoelement. At least one of the first and second photoelements has its active surface disposed at least partially in the recess. A portion of the printed circuit board is interposed between the first and second photoelements.

Abstract: A magnetic flowmeter for measuring flow of a process fluid in a pipe includes a magnetic coil disposed adjacent to the pipe configured to apply a magnetic field to the process fluid. First and second electrodes are disposed within the pipe and electrically coupled to the process fluid and configured to sense an electromotive force (EMF) induced in the process fluid due to the applied magnetic field and flow of the process fluid. Input circuitry is coupled to the first and second electrodes and provides an output related to the sensed EMF. Diagnostic circuitry coupled to the input circuitry is configured to identify a saturation related condition and responsively provide a diagnostic output. In another embodiment, saturation prevention circuitry prevents saturation of the input circuitry.

Abstract: A magnetic flowmeter for measuring flow of a process fluid in a pipe includes a magnetic coil disposed adjacent to the pipe configured to apply a magnetic field to the process fluid. First and second electrodes are disposed within the pipe and electrically coupled to the process fluid and configured to sense an electromotive force (EMF) induced in the process fluid due to the applied magnetic field and flow of the process fluid. Input circuitry is coupled to the first and second electrodes and provides an output related to the sensed EMF. Diagnostic circuitry coupled to the input circuitry is configured to identify a saturation related condition and responsively provide a diagnostic output. In another embodiment, saturation prevention circuitry prevents saturation of the input circuitry.

Abstract: A magnetic flowmeter for measuring flow of a process fluid in a pipe includes a magnetic coil disposed adjacent to the pipe configured to apply a magnetic field to the process fluid. First and second electrodes are disposed within the pipe and electrically coupled to the process fluid and configured to sense an electromotive force (EMF) induced in the process fluid due to the applied magnetic field and flow of the process fluid. Input circuitry is coupled to the first and second electrodes and provides an output related to the sensed EMF. Diagnostic circuitry coupled to the input circuitry is configured to identify a saturation related condition and responsively provide a diagnostic output. In another embodiment, saturation prevention circuitry prevents saturation of the input circuitry.

Abstract: An industrial process variable transmitter includes a process variable sensor configured to sense a process variable. Measurement circuitry is coupled to the process variable sensor and provides a measured output as a function of the process variable. Output circuitry includes a loop connection configured to couple to a process control loop. An optical sensor receives the measured output from the measurement circuitry. A switching device applies pulses to the process control loop in response to an output from the optical sensor. Power supply circuitry powers the optical sensor, a comparator, and/or the switching device with power received from the process control loop and loop connection.

Abstract: An industrial process control field device includes a process variable transducer configured to sense or control a process variable. Field device circuitry is configured to couple to the process variable transducer and communicate information related to the process variable to another location. The field device circuitry includes an optical isolator having transmit circuitry on a first side of a galvanic isolation configured to transmit an optical signal which is pulsed on and off across the isolation. Receive circuitry is located on a second side of galvanic isolation and configured to receive the optical signal with an optical sensor. The optical sensor enters an “on” state when it receives a pulse and is otherwise in an “off” state. The receive circuitry provides a secondary side output based upon the received optical signal. The receive circuitry enters in a low power state when the optical sensor is in the “off” state.

Abstract: 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.

Abstract: A magnetic flowmeter includes circuitry for sensing coil current, coil voltage, or coil resistance. Based on the sensed coil current, voltage, or resistance, a digital processor determines whether a power limit or a coil current limit is exceeded and either halts operation until it receives a new configuration with a new coil current setpoint, or determines a new coil current setpoint itself and adjusts the magnetic flowmeter to that new coil current setpoint.

Abstract: An optical isolator is provided. The optical isolator includes a printed circuit board having a first surface and a second surface opposite the first surface. The printed circuit board has a recess extending only partially through the board. The first photoelement has an active surface and is mounted relative to the first surface of the printed circuit board. A second photoelement has an active surface and is mounted relative to the second surface. The second photoelement is configured to interact with the first photoelement. At least one of the first and second photoelements has its active surface disposed at least partially in the recess. A portion of the printed circuit board is interposed between the first and second photoelements.

Abstract: 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.

Abstract: An industrial process variable transmitter includes a process variable sensor configured to sense a process variable. Measurement circuitry is coupled to the process variable sensor and provides a measured output as a function of the process variable. Output circuitry includes a loop connection configured to couple to a process control loop. An optical sensor receives the measured output from the measurement circuitry. A switching device applies pulses to the process control loop in response to an output from the optical sensor. Power supply circuitry powers the optical sensor, a comparator, and/or the switching device with power received from the process control loop and loop connection.

Abstract: A magnetic flowmeter for measuring flow of a process fluid in a pipe includes a magnetic coil disposed adjacent to the pipe configured to apply a magnetic field to the process fluid. First and second electrodes are disposed within the pipe and electrically coupled to the process fluid and configured to sense an electromotive force (EMF) induced in the process fluid due to the applied magnetic field and flow of the process fluid. Input circuitry is coupled to the first and second electrodes and provides an output related to the sensed EMF. Diagnostic circuitry coupled to the input circuitry is configured to identify a saturation related condition and responsively provide a diagnostic output. In another embodiment, saturation prevention circuitry prevents saturation of the input circuitry.

Abstract: An industrial process control field device includes a process variable transducer configured to sense or control a process variable. Field device circuitry is configured to couple to the process variable transducer and communicate information related to the process variable to another location. The field device circuitry includes an optical isolator having transmit circuitry on a first side of a galvanic isolation configured to transmit an optical signal which is pulsed on and off across the isolation. Receive circuitry is located on a second side of galvanic isolation and configured to receive the optical signal with an optical sensor. The optical sensor enters an “on” state when it receives a pulse and is otherwise in an “off” state. The receive circuitry provides a secondary side output based upon the received optical signal. The receive circuitry enters in a low power state when the optical sensor is in the “off” state.