Electromagnetic Flow and Heat Meters in Lithuania

Abstract

Theory of electromagnetic flow and heat meters is developed in Lithuania from 1972 year. Original electromagnetic flowmeters with quasiintegration are created during this time. Theory of these meters is created and practical constructions are proposed. The main areas of it’s application are fast control, information systems and measurement of instant velocity without dynamic errors. Electromagnetic flowmeters with integration are created for precise measurement of stationary flows. The original circuit is used in this flowmeter for attenuation of parasitic galvanic electromotive force. The quantitative estimation of this attenuation is made. This disturbance has no influence to measurement accuracy when the quantity of fluid is measured. These flowmeters are manufactured in Kaunas firm “Katra” from 1996. Main attention of theoretical research is divided to reliability of these flowmeters. An equivalent electrical diagram of electromagnetic flowmeter magnetic circuit is presented. Transfer coefficient is function of the diagram parameters. The diagram for transfer coefficient stability control is proposed, using the measurement data of mutual inductance of. magnetic field excitation coil. The construction of manufactured electromagnetic flowmeters is researched using program COSMOS 1.75M. This program uses method of finite elements. The 2D and 3D problem are solved. The variation of flowmeter signal do not exceeded ± 0,74% when the mean velocity is not extreme. The flowmeter sensitivity can be increased 4,4-fold when the magnetic field is concentrated.