The Transfer Coefficient of Magnetic Circuit of Electromagnetic Flow Meter

Abstract

The signal of electromagnetic flow meter depends on distribution of magnetic flow density in active zone of meter. The measurement errors appear, if the distribution of magnetic field varies in process of measurement. The equivalent electric schema of magnetic circuit is composed. It evaluates parameters, which can wary in measurement process. There are two possibilities of circuit parameters stabilisation: the stabilisation of current of magnetic field excitation and the stabilisation of created magnetic flux. The expressions of transfer coefficient of magnetic circuit are obtained for both cases. The expressions of relative variation of transfer coefficient are obtained, when the relative variations of magnetic resistance of core, of active zone and of walls are known. There are shown, than, when the magnetic flux is stabilised, the transfer coefficient is not sensitive to variation of magnetic resistance of core, about 50 times less sensitive to variation of magnetic resistance of active zone and 10 times more sensitive to variation of magnetic resistance of wall in comparison with the case, when the excitation current is stabilised. Ill. 2, bibl. 5 (in Lithuanian; summaries in Lithuanian, English, Russian).