Low cost multifunction-meter (MFM) for highly distorted 3-phase, 4-wire systems

摘要

The paper describes a development of low cost multifunction meter (MFM) based on power to frequency converter (PFC), true-RMS to dc converter and the high performance 16-bit microcontroller (87C196KC) for 3-phase, 4-wire systems. Hall effect current transducers (C.T.) and high accuracy (0.5 %) potential transformers (P.T.) were used for sensing of the phase currents and voltages. The MFM not only measures 32 different electrical parameters (viz., true-RMS V & I, PF, active and reactive power and energy per phase and average, including maximum demand) for accuracy of class 1.0, but also provides intelligent fault diagnostics for various electrical faults. It also provides serial RS-485 interface for industrial PC based energy monitoring and control application. The developed MFM was tested and calibrated for required accuracy (class 1) at National Physical Lab. (NPL), Delhi.