FIELD INVESTIGATIONS INTO HARMONICS POLLUTION AFFECTING TRANSFORMERS

Field investigations on harmonics caused by loads are essential to have a quantitative visualization and formation of premise of research. Field investigations have been carried out covering spectrum of loads and voltage levels right from generation to consumers, as at present. Investigations have revealed that low tension consumers form cluster of non-linear loads and are major contributors of current harmonics. Traction loads are another major category of harmonic pollutant. Industrial consumers do provide reactive compensation which helps to filter out current harmonics partially. However, in absence of any regulatory measure consumers keep polluting current harmonics into the system and also bear with the consequential disturbances. Voltage harmonics are significant only at leaf ends of distribution distribution system, where source impedance, seen by the harmonics generated by the load, is high. Tranasformer is the first major equipment in power system to intercept the harmonics. These harmonics caused accelerated ageing of transformers and even objectionable rise of temperature of cover-plate and turets.