# US 2009/0260452 A1 · Method for Operating an Electromagnetic Flowmeter and Electromagnetic Flowmeter

> Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt

- Number: US 2009/0260452 A1
- Document ID: US20090260452A1
- Status: Published application
- Kind: A1
- Application number: 11/992,435
- Filed: 2005-09-21
- Published: 2009-10-22
- Earliest claimed: 2005-09-21
- Assignees: Siemens Aktiengesellschaft
- Inventors: Claus Nygaard Rasmussen
- Web page: https://patentgrep.com/patent/US20090260452A1

## CPC

- G01F 25/10: of flowmeters
- G01F 1/588: {combined constructions of electrodes, coils or magnetic circuits, accessories therefor}
- G01F: MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME

## Abstract

Disclosed is a method for operating an electromagnetic flowmeter and a flowmeter. A measuring tube provided with a coil arrangement for producing a magnetic field at right angles to the direction of flow. The direction of current flow in the coil arrangement is altered periodically, and the current is kept essentially constant in one period after a rise to a predetermined value. the voltage applied to the coil arrangement and/or its derivative is determined and compared with an associated reference value. If this voltage or derivative does not fall below the reference value in a desired minimum time within a measurement period, an error message can be emitted in order to indicate a fault. If the voltage or derivative falls below the reference value, it is ensured that the magnetic field is sufficiently stable and measured values for a voltage which can be tapped off at measurement electrodes.

## Claims

### Claim at position 1

-8. (canceled)

### Claim 9

A method for operating an electromagnetic flowmeter having a measuring tube and a coil arrangement for generating a magnetic field at right angles to the direction of flow through the measuring tube, comprising:
periodically varying the direction of the current flow through the coil arrangement;
maintaining an electrical current flowing through the coil arrangement substantially constant;
determining a voltage applied to the coil arrangement and/or its derivative; and
comparing the determined voltage or voltage derivative with an allocated reference value.

### Claim 10 (depends on 9)

The method as claimed in claim 9, wherein the evaluation of a voltage detected at the measuring electrodes for measurement value determination begins when the voltage at the coil arrangement and/or its derivative falls below the respective allocated reference value when the coil current is maintained constant.

### Claim 11 (depends on 10)

The method as claimed in claim 10, wherein the time point at which the voltage and/or its derivative falls below the respective allocated reference value is compared with a further reference value and that an error message is output if this time point falls below a further reference value.

### Claim 12 (depends on 11)

The method as claimed in claim 11, wherein evaluation of the voltage detected at the measuring electrodes is interrupted if the voltage applied to the coil arrangement and/or its derivative exceeds the relevant allocated reference value.

### Claim 13 (depends on 12)

The method as claimed in claim 12, wherein the reference value for the voltage applied to the coil arrangement is 5% higher than a product of the electrical resistance of the coil arrangement and the coil current which is maintained constant.

### Claim 14 (depends on 13)

The method as claimed in claim 13, wherein, on the basis of the measured voltage applied to the coil arrangement, according to a predetermined functional relation, a correction value is calculated, by which the voltage detected at the measuring electrodes is corrected for measurement value determination.

### Claim 15 (depends on 14)

The method as claimed in claim 14, wherein the voltage determined and/or its derivative is first filtered with a low pass filter.

### Claim 16

An electromagnetic flowmeter, comprising:
a measurement tube;
a coil arrangement for generating a magnetic field at right angles to the direction of flow through the measuring tube, wherein the direction of the current flow through the coil arrangement is periodically varied and, within a period, following a rise to a predetermined value, the current is kept substantially constant; and
a measuring device with which, with the coil current kept constant, the voltage applied to the coil arrangement and/or its derivative can be determined and that an evaluating device is configured such that the respective value determined is compared with an allocated reference value.