• measurement of transformer insulation polaristation spectrum -RVM method • frequency response analysis (FRA) • dielectric response analysis - NEW!!! Power and Instrument Transformer Diagnostics Power transformer diagnostics Power transformer diagnostics is an integral element of preventive maintenance, whose purpose is to determine the condition of main transformer parts: windings, core, bushings and insulation system. Special diagnostics methods are used to determine causes and locations of transfomer faults/failures, or as a part of special investigations: • PD testing - Acoustic Emission (AE) Method • OLTC diagnostics - measuring of resistances with 200 Amps (R vs. I characteristics) • thermovision • measurement of insulation resistance • measurement of C & tanS of windings • measurement of C & tanS of bushings • low voltage measurement of no-load current • measurement of winding resistance • measurement of leakage inductance (Lx) In the last more than 30 years, about 2700 power transformers were tested in Croatia, Albania, Austria, Bosnia and Herzegovina, Czech Republic, France, Macedonia, Montenegro, Serbia, Slovenia, Spain and UAE KONCAR Electrical Engineering INSTITUTE

PD acoustic emission detection This method is used to locate discharges (PD), bad contacts or localized hot regions in transformers (> 200 °C) Acoustics Emission (AE) method enables: • to locate the source of the potential problem on site • assess the option for its elimination, • assess risks of running problematic transformers The accuracy of acoustic detection is equal to size of a soccer ball – approx ±15 cm. PD acoustic detection method is not susceptible to electrical interference, what makes it applicable to transformers in service. PD can be detected at an early stage (~500 pC) Transformer...