Patent ID: 7434478

Claim:
An electromagnetic flowmeter characterized by comprising: a measuring tube through which a fluid to be measured flows; an electrode which is placed in said measuring tube and detects an electromotive force generated by a magnetic field applied to the fluid and a flow of the fluid; an exciting unit which applies, to the fluid, a time-changing magnetic field asymmetrical to a first plane which includes said electrode and is perpendicular to an axial direction of said measuring tube; a signal conversion unit which extracts a ∂A/∂t component irrelevant to a flow velocity of the fluid from a resultant electromotive force of an electromotive force based on the ∂A/∂t component and an electromotive force based on a v×B component originating from the flow velocity of the fluid; and a flow rate output unit which removes a variable factor for a span as a coefficient by which a magnitude V of a flow velocity of the v×B component in the resultant electromotive force is multiplied, on the basis of the extracted ∂A/∂t component, and calculates a flow rate of the fluid from a result obtained by removing the variation factor.