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Elements and Performance Criteria
Range Statement
Performance Evidence
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Evidence required to demonstrate competence in this unit must be relevant to and satisfy all of the requirements of the elements and performance criteria and include knowledge of: |
polyphase power circuit analysis, including:polyphase supply system encompassing:advantage of three phase system compared to single phase systemsdouble subscript notationphase sequence120 degree operatorgiven circuit component parameters, solve practically-based problems using:equivalent circuits of transformers, lines and loadscomponent values using rectangular and polar notationcurrent divider and potential divider rules using complex impedancesthe "per unit" values of voltage, current and impedance to a common VA basetypes of three phase system connections encompassing:supply to balanced star, three and four wire loadssupply to delta connected loadseffects of phase reversalrepresentation of currents and voltages as complex phasors for three phase, and three phase and neutral quantitiescalculation of the values of, and drawing labelled phasor diagrams, not to scale, to represent complex values of current and voltage for balanced and unbalanced loads for star and delta systemscalculation of values of P, Q and S for balanced and unbalanced systemsdraw and label single phase diagrams to represent one phase of a complex three phase systemrepresent unbalanced voltages or currents as symmetrical componentsphase-to-phase currentsphase-to-neutral/earth currentsbalanced three phase loads encompassing:calculations of balanced loads connected in starcalculations of balanced loads connected in deltacalculation of steady state values of fault current for various configurationsevaluation of the symmetrical component impedances for the various distribution system components, transformers (earthed neutral case) and generators (high impedance earth)calculation of fault currents using the per unit approachcalculation using the "worst case" values based on transformer impedance only (i.e. a short circuit fault)estimation of peak values using accepted multiplierseffects of the direct current (d.c.) component on the instantaneous magnitudes of fault currents in transformers and generatorsunbalanced three phase loads encompassing:star – four wire systemsdelta systemsstar – three wire systemsstar - four wire with neutral impedancepower in three phase circuits encompassing:summation of phase powers and power in balanced loadsmeasurement of power in balanced loads – two Wattmeter methodsreactive three phase power encompassing:power triangle calculationmeasurement of VARpower factor correctionfault currents encompassing:symmetrical componentspositive, negative and zero sequence impedancefault current breaking and let-through energy capacities of circuit breakers and fusesimportance of fault/arc impedancecalculation of fault currents - phase-to-earth faultscalculation of fault currents - phase-to-phase faultsanalysis of asymmetrical fault currentsharmonics in three phase systems encompassing:presence of triple in harmonics in three phase systemseffects of three phase harmonics for different star and delta connectionsmethods for reducing harmonics in three phase systemsproblem-solving techniquesrelevant checks and isolation of circuitsrelevant manufacturer specifications and operating instructionsrelevant materials, tools, equipment and testing devicesrelevant job safety assessments or risk mitigation processesrelevant WHS/OHS legislated requirementsrelevant workplace documentationrelevant workplace instructions, policies and procedures. |