2-wire magnetic flowmeter

摘要

PROBLEM TO BE SOLVED: To enhance measuring accuracy by adopting an offset compensation circuit to intermittent excitation.;SOLUTION: This two-wire type electromagnetic flowmeter includes an excitation circuit 24 that applies an excitation current I_E for exciting an excitation coil 22 so as to intermittently excite the excitation circuit 24 by providing a resting time period, a computation means that samples a detection signal detected by an electrode so as to compute a flow rate of fluid to be detected passing through a flow channel in a measurement pipe on the basis of the detection signal, and an offset compensation circuit 344 that intermittently excites the excitation coil 22 in such a manner that P-side excitation and N-side excitation wherein the direction of the excitation current I_E flowing in the excitation coil is alternately switched are performed at least one time so as to compensate an offset component of a low frequency signal with the detection signal at a previous time as a reference. The offset compensation circuit 344 performs the P-side excitation and N-side excitation during the excitation time period in such a manner that the number of total times of the excitation becomes an odd number. The offset compensation circuit utilizes the excitation at the first time in each excitation time period for referencing in order to compensate the offset component, thereby sampling the detection signal in the succeeding excitation.;COPYRIGHT: (C)2010,JPO&INPIT