Transformer Maintenance Transformers in this range are three-phase and can be manufactured with off-circuit tap changer or on-load tap changer. The tank construction can be a corrugated fin wall type or of a rigid construction type with radiators typically used for larger transformer.Transformer Maintenance • • • • Large distribution transformers are used for receiving energy from higher voltage levels and to transform and distribute this energy to lower voltage . The core is constructed of grain-oriented steel laminations. Transformers provided with on-load tap changer usually have a separate tap winding. Fans can also be mounted on the radiators to provide additional cooling capacity. . The windings are made of either copper or aluminum conductor and wound in a foil or multi-layer configuration. 7 8 9 1/2 or 3/4th No leak HT Tape By sealent Yearly Every Month Yearly Regularly . Transformer oil filtration to be done & BDV values to be check Transformer earthings to be check regularly for proper earthing Painting to the transformer to be done regularly 11 Inspect the insulators for any cracks & leakages.Transformer Maintenance TRANSFORMER MAINTENANCE/ INSPECTION ACTIVITY Standard Sr. Activity limits 1 Check transformer oil level 2 Check transformer oil leakage 3 Check winding temperature < 90 degree 4 Check oil temperature < 90 degree 5 Check colour of silica gel breather Must be Blue 6 10 For outdoor connections use HT Tapes Seal all the cable entries & joints to avoide moisture entry. 12 Change all the necessary gaskets.No. . If acidity is between 0.5 to 1mg KOH.Transformer Maintenance OIL • • • Oil level checking. oil should be kept under observation. Leakages to be attended. BDV. Color and smell of oil are indicative. Oil BDV & acidity checking at regular intervals. Oil when topped up shall be of the same make. Periodic Dissolved Gas Analysis can be carried out. dust. dirt . .moisture can be removed by filtration.Transformer Maintenance • • • • • Sludge. Insulation resistance of the transformer should be checked once in 6 months. It may lead to sludge formation and acidic contents. Megger values along with oil values indicate the condition of transformer. . cement or acid fumes depositions should be carefully noted and rectified.Transformer Maintenance BUSHINGS • • Bushings should be cleaned and inspected for any cracks. Salt or chemical deposition. Dust & dirt deposition. Transformer Maintenance • • • • • • Periodic checking of any loose connections of the terminations of HV & LV side. . Explosion vent diaphragm examination. vines. Regular inspection of OIL & WINDING TEMPERATURE METER readings. Conservator to be cleaned from inside after every three years. Breather examination. Cleanliness in the Substation yard with all nets. Dehydration of Silica gel if necessary. shrubs removed. Magnetic Oil level Gauge. Oil Temperature Indicators. Explosion Vent. Buchholz Relay. Winding Temperature indicators.PROTECTION OF TRANSFORMERS • • • • • • The best way of protecting a transformer is to have good preventive maintenance schedule. . Oil Surge Relay for OLTC. Earth Fault relay tripping. Breather. LT circuit breaker.PROTECTION OF TRANSFORMERS • • • • • • • HT fuse & D. HT Circuit breaker with Over load. HORN GAPS & Lightening Arrestor.O. . fuse. PRV for OLTC. FAILURES & CAUSES • • • • • • • • • • Insufficient Oil level. . Prolonged Short Circuit. Single Phase loading. Faulty Termination (Improper sized lugs etc) Power Theft. Faulty operation of tap changer switch. Seepage of water in oil. Lack of installation checks. Prolonged Over loading. Unbalanced loading. Thank you Keep your transformer Healthy .