Electromagnetic flowmeter
AssigneeYamatake Corporation
InventorsKouji Okuda, Shin Suzuki, Ichiro Mitsutake
Life of this patent
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Abstract
An electromagnetic flowmeter includes a coil, exciting section, noise eliminating section, and arithmetic processing section. The coil applies a magnetic field to a fluid flowing in a pipe line. The exciting section supplies an exciting current to the coil. The noise eliminating section eliminates noise from a measurement signal detected from the fluid under excitation by using a differential frequency component between a commercial power frequency and an exciting frequency. The arithmetic processing section calculates a measurement flow rate on the basis of the measurement signal output from the noise eliminating section.
Claims7
An electromagnetic flowmeter comprising:
- a coil which applies a magnetic field to a fluid flowing in a pipe line;
- exciting means for supplying an exciting current to said coil;
- noise eliminating means for eliminating noise from a measurement signal detected from the fluid under excitation by using a differential frequency component between a commercial power frequency and an exciting frequency;
- and
- arithmetic processing means for calculating a measurement flow rate on the basis of the measurement signal output from said noise eliminating means, wherein said noise eliminating means comprises:
- band elimination filter means for attenuating a component with a frequency f, of frequency components contained in a measurement signal detected from the fluid under excitation by supplying, to said coil, an exciting current with a frequency lower than both first and second commercial power frequencies used as commercial power, which satisfies
- f=|m1fex±n1fac1|=|m2fex±n2fac2|
- where fex is an exciting frequency, fac1 is a first commercial power frequency, and fac2 is a second commercial power frequency;
- and
- A/D conversion means for converting an output from the band elimination filter means into a digital signal.
Dependencies are inferred from the claim text.