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 supply transmission systems. All knowledge and skills detailed in this unit should be contextualised to current industry practices and technologies. KS01-TIS71A Electrical power system transmission faults Evidence shall show an understanding of electrical power system transmission faults to an extent indicated by the following aspects: T1 Overview of the transmission system including lines, buses, transformers and cables. Line/bus layouts including single and double switching, breaker and a half systems and HV crossing methods. T2 The principles involved in high voltage a.c. transmission including tower types and configurations, choice of towers or poles (economic and environmental), insulator types and configuration, types of conductors, their configuration and standard nomenclature. Typical line spacing and ground clearances. Line ratings based on ambient temperature. Conductor terminating and clamping equipment including vibration damping principles and equipment. T3 The principles involved in d.c. transmission including the economics, harmonic generation, VAR requirements and protection difficulties. Types of connections and transformer requirements. Advantages and disadvantages of d.c. transmission. Typical overseas systems. Likely (future) use in this country. T4 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 air blast air puffer vacuum and SF6 (double pressure and puffer types). T5 The types of isolators in use. Examples include duo-roll, blade and scissor type. T6 Circuit breaker auxiliary systems including: high pressure air systems and air storage and handling processes d.c. systems including battery types, charging and protection systems and earth fault detection systems SF6 conditioning, storage and handling system T7 The 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. The transmission of power (P) and VARs (Q). T8 Control of voltage. Conditions leading to voltage collapse and system disintegration. Effects on the system of high/low volts. Voltage control devices including: voltage regulators applied to generators and synchronous phase modifiers electromagnetic voltage regulators series and parallel capacitors OLTC transformers and static Var compensations (SVCs) T9 Range of devices covered by SVCs including: saturated reactor compensations (SRs) thyristor controlled reactor compensators (TCRs) combined TCR/TSCs and production of wave-form distorting harmonics and control devices T10 Importance of the location in the system of voltage control devices T11 Use of graphical methods to calculate the size of VAr regulating plant T12 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 T13 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 T14 Factors leading to the generation of corona. Consequences of corona. Reduction of corona including conductor bundling, grading rings and conductor surface treatment |