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 diagnosing and rectifying faults in electrical energy distribution systems. All knowledge and skills detailed in this unit should be contextualised to current industry practices and technologies. KS01-TIS70A Electrical power distribution systems diagnostic Evidence shall show an understanding of diagnosing faults in power distribution systems to an extent indicated by the following aspects: T1 Distribution system overview including encompassing: regulatory conditions of supply and utilisation compliance with Australian Standards. reticulation system including overhead/underground, urban/rural, HV customers and high-rise building systems. The effects of industrial customers methods used to ensure continuity of supply. types of substations in current use. systems of distribution used, (primary and secondary) voltage levels, power factor, wave-form distortion and transient loading supply quality load curve profiles (residential/industrial/commercial) types of feeders distribution systems (urban, rural single-phase systems, SWER, spur, parallel and ring systems etc.) T2 Overhead lines and installation encompassing: industry and safety regulations overhead conductors conductor material current rating factors (heating, voltage drops, power losses) aerial bundled cables (HV and LV) covered conductors - characteristics of lines and cables including the calculation of R, X and B for different arrangements of conductor. Typical values for actual lines. Transposition. Models based on line length. Voltage and line regulation overhead line poles types (wood, concrete and steel) installation of poles (tooling, rake, life, labelling, sinking) maintenance of poles – above & below ground pole strength and loads crossarms types and standard sizes insulators insulation types types (pin, suspension or disc, shackle) creepage, necessary clearances arcing horns, insulator mounting structure types mechanical properties (working strength, maximum tension, limiting size) interpretation of stringing charts determination of sag (by calculations or measurement and/or tension measurement) sight and wave sagging, sag correction stays components, anchorage T3 Use of design schedules encompassing: sample design problems - common design practice line, voltage, structure types used, line deviation, span sag, crossarms, insulators and stays wind loading and line deviation loading basic surveying measurement of levels, deviation angle and compass bearings perform survey of short distribution line extension of produce field notes T4 Underground cables encompassing: cable types, ratings, core material, design considerations, cable dielectrics, insulating materials and abbreviations, electric stress, cable volt drop and volt drop calculations, cable termination, joints and installation. induction and eddy currents cable testing, cable fault location cable drawing T5 Voltage regulations of feeders and associated equipment encompassing: terminology used: distribution system, service line, customer’s terminals, customer voltage, utilisation voltage, base voltage, voltage variation and bandwidth voltage limits and effects of voltage variation causes of variation: inductance, capacitance and reactance of distribution lines, transformers methods of voltage control: off-load, on-load tap changers, voltage regulating relays, line drop compensation, different types of voltage regulators voltage profiles: principles, effect on voltage profiles, limits of voltage, voltage drops due to LV mains transformers, tapsettings feeder and service lines determining volt drops for components within the profile. T6 Control of voltage. Conditions leading to voltage collapse and system disintegration. Effects on the system of high/low volts. Voltage control devices including encompassing: voltage regulators applied to generators and synchronous phase modifiers electromagnetic voltage regulators series and parallel capacitors OLTC transformers and static Var compensations (SVCs) T7 Range of devices covered by SVCs including encompassing: saturated reactor compensations (SRs) thyristor controlled reactor compensators (TCRs) combined TCR/TSCs and production of wave-form distorting harmonics and control devices T8 Importance of the location in the system of voltage control devices. T9 Types of communication systems including telephone, power line carrier, dedicated cable, micro-wave links and fibre optics. Quantities and signals to be communicated. Advantages and disadvantages of the various systems. Equipment requirements. T10 Transient over-voltages in power systems. Switching and lightning overvoltages and their effect on different plant items. Transient over-voltage control and reduction using surge diverters, shield wires and CB are control. Insulation systems, insulation co-ordination, insulation grading in plant items, bushings and capacitor bushings. T11 The principles of operation, voltage and current range, breaking capacity and field of use of the following types of circuit breakers - bulk oil, small oil volume, air break, vacuum and SF6 (double pressure and puffer types). T12 The types of isolators in use. Examples include duo-roll, blade and scissor type. T13 Circuit breaker auxiliary systems encompassing: d.c. systems including battery types, charging and protection systems and earth fault detection systems SF6 conditioning, storage and handling system |