Paper Details

Condition Monitoring plays a vital role in assetmanagement plan. Power Transformers are most important andcritical component in electrical power transmission anddistribution. To have a reliable electricity supply it is necessaryto give considerable attention to maintenance of the transformer.To maximize the lifetime and reliability of transformers, it isimportant to be aware of possible faults that may occur and toknow how to prevent them. Since a fault in a transformer canhave a huge repercussion when failures occur, and as, number oftransformers and of those that are difficult to operate in overloadconditions is on the rise, it is important to detect incipient faultsin a transformer and forecast and prevent failures These faultscan all lead to the thermal degradation of the oil and paperinsulation in the transformer. The composition and quantity ofthe gases generated depend on the types and severity of the faults,and regular monitoring and maintenance can make it possible todetect incipient flaws before damage occurs. Any failure intransformer leads to malfunction of whole power system.Unfortunately, the failure rate of these transformers is very highin India, 25 % per annum, which is not favourable as comparedto international units of 1-2 %. Failures happen due to internalreasons or operational hazardless. Transformer insulationdeteriorates as the function of temperature, moisture and time.The core and winding losses, stray losses in tank and metalsupport structures are the principle sources of heat which causeoil and winding temperature rise. There are multiple reasons foroverheating such as improper cooling, excessive eddy currents,bad joints, blocked radiators, overloading, improper earthingand harmonic contents in power supply. This leads to acceleratedaging of oil and cellulosic solid insulation, which generate thegases within transformer and further leads to permanent failure.To prevent such failures, effective analysis and diagnosis needs tobe investigated. The type of gases generated and amount of gasconcentrations in oil efficiently evaluated using Dissolved Gasanalysis (DGA).Generally the degradation products are gases,which will get dissolve in the oil entirely or partially. In the oilthese gases are easily detected at the ppm level by dissolved gasanalysis.Dissolved gas analysis (DGA) is a widely used most powerfulmethod to detect incipient faults on oil filled electrical equipment.The electrical equipment may be a transformer, a load tapchanger or a cableDissolved Gas Analysis (DGA) of transformer oil is the bestindicator of a transformer’s overall condition. Hence this widelyaccepted method is used in routine maintenance of powerTransformers. Transformer oils perform at least four functionsfor the transformer. Oil provides insulation, provides cooling,and helps extinguish arcs. Oil also dissolves the gases which aregenerated due to degradation of oil, moisture and gas frominsulation, deterioration of cellulose, and gases and moisturefrom the surrounding the oil is exposed to. Any deterioration inthe oil can lead to premature failure of the equipment. The mostcommon type of oil used in transformers is of a mineral oilorigin.

Mr.Rahul Soni, Mr.Siddharth Joshi, Mr.Virendra Lakhiani, Mr.Aniruddha Jhala, “Condition Monitoring of Power Transformer Using Dissolved Gas Analysis of Mineral Oil: A Review”, International Journal of Advance Engineering and Research Development (IJAERD), Vol. 2, Issue 14, pp. -, January 2015.