8) This describes the essential skills and knowledge and their level, required for this unit. Evidence shall show that knowledge has been acquired of safe working practices and developing engineering solutions for energy supply power transformer problems. All knowledge and skills detailed in this unit should be contextualised to current industry practices and technologies. KS01-TIS73A Power transformers diagnostics Evidence shall show an understanding of power transformers to an extent indicated by the following aspects: T1 Transformer construction and operating principles encompassing: various types of lamination style and core construction used in single phase, three phase, double wound and auto transformers. different winding styles/types used in transformers. how input current is limited on no load and how power is transferred from primary to secondary when a load is connected. using the transformation ratio to determine an unknown quantity of V, I, VA. significance of nameplate data items. operation of a transformer under load/no load conditions. the reason any particular type of transformer is used in a specific application. safety features specified in regulatory standards with respect to transformers. safety features specified in regulatory standards with respect to isolating transformers. basic insulation resistance, continuity and winding identification tests. T2 Transformer parameters encompassing: the percentage impedance of a transformer by test. percentage impedance of a transformer by calculation. the equivalent circuit of a transformer. calculation of voltage regulation. losses that occur in a transformer. tests to determine losses. efficiency and state typical values. the all day efficiency of a transformer. T3 Cooling methods encompassing: methods of natural and forced cooling. properties of transformer oil. tests performed on transformer oil. auxiliary equipment the purpose and operation of the types of auxiliary equipment used on transformers - bushings, explosion vents, surge diverters, tap changers, conservator, breathers and desiccants, gas relays, temperature indicators. T4 Instrument transformers encompassing: construction of current transformers. uses and ratings of current transformers. construction of voltage transformers. uses and ratings of voltage transformers. safety techniques when using instrument transformers. T5 Transformer connections encompassing: vector group of a transformer from a connection diagram. connections of a three-phase transformer to create a particular vector group. reasons for using the different vector groups. purpose of tertiary windings. consequences/effect of an incorrect connection. T6 Parallel operation encompassing: polarity markings for the windings of a transformer. conditions/restrictions for parallel operation of transformers. calculation of loading on transformers operating in parallel. connection of transformers in parallel to supply a common load. the consequences/effect of an incorrect connection. T7 Harmonics in transformers encompassing: how harmonics are generated in transformers. problems caused by harmonics in transformers. measurement of the harmonics in a transformer. methods/equipment used to overcome harmonics in transformers. T8 High voltage isolation encompassing: the term high voltage. procedures for isolating high voltage apparatus. regulations with respect to access permits. clearances to be observed with respect to high voltages up to 33 kV. the term ‘step’ and ‘touch’ potential. |