Patent ID: 8453516

Claim:
An electromagnetic flowmeter comprising: a measuring pipe through which fluid to be measured flows; an electrode that is provided in the measuring pipe and detects an electromotive force generated by a magnetic field applied to the fluid and a flow of the fluid; an exciting unit that applies, to the fluid, a time-changing magnetic field that is symmetrical with respect to an electrode plane that includes the electrode and is perpendicular to an axial direction of the measuring pipe; a signal line that is connected to the electrode at one end thereof and provided so as to be inclined with respect to a direction of a magnetic field parallel to the electrode plane and such that an electromotive force is generated by a change in the magnetic field with passage of time; a signal conversion unit that is connected to another end of the signal line and extracts a ∂A/∂t component that is unrelated to a flow speed of the fluid and results from a change in the magnetic field with passage of time, from a resultant electromotive force of: an electromotive force of the ∂A/∂t component; and an electromotive force of a v×B component that results from a flow speed of the fluid, the resultant electromotive force being detected by the electrode and the signal line; and a flow rate output unit that eliminates, on the basis of the extracted ∂A/∂t component, a variation factor as to a span that is a coefficient applied to a magnitude V of a flow speed of the v×B component in the resultant electromotive force, and calculates a flow rate of the fluid on the basis of a result in which the variation factor is eliminated.