A survey of voltage and current harmonics in various industries connected to a state electrical grid

The objective of the paper is to assess the quantum of harmonics found in supply voltage and load current in industries connected to a State Electrical Grid and their compliance with the regulations. The trend, of using more and more switched mode power converters for improving the efficiency, has also increased the harmonics in the electrical system. Harmonics cause considerable amount of losses and failures in the electrical system. IEEE has specified the maximum allowable limits for harmonics. In India, the national level Central Electricity Authority and all State level electrical Utilities have specified limits for harmonics based on IEEE 519 recommendations. The utilities have also proposed penalties for non compliance. Identification and measurement of harmonics require a Power Quality Analyser (PQA). The measurements, carried out by the authors in various representative industries connected to the state electrical network at different bus voltages, indicate that the observed harmonic levels are higher than the limits specified in IEEE 519.