standards / manuals / guidelines for small hydro development - AHEC

Table 2.11Technical CharacteristicsRated voltage kV 72.5 123 145Rated frequency Hz 50/60Rated power-frequency withstand kV 140 230 275voltageRated lightning impulse withstand kV 325 550 650voltageRated normal current A 2500Rated short-circuit breaking current kA 40Rated short-circuit making current kA 100Rated duration of short circuit s 3Circuit Breaker Specific Technical CharacteristicsOpening Time ms 38 38 38Break time ms 50 60 60Closing time ms 85 106 1062.9 Power Line Carrier EquipmentThe carrier equipment required for communication, relaying and telemetering isconnected to line through high frequency cable, coupling capacitor and wave trap. Thewave trap is installed at the line capacitor. The coupling capacitors are installed on theline side of the wave trap and are normally base mounted. The wave traps for voltagelevels upto 145 kV can be mounted on the gantry structure on which the line isterminated at the substation or mounted on top of the capacitor voltage transformer.However, the wave traps for voltage levels of 245 kV and above generally requireseparate supporting insulator stacks mounted on structures of appropriate heights.2.10 Substation Auxiliary FacilitiesAuxiliary facilities for step up sub station in SHP are designed in conjunction with powerhouse auxiliaries and are discussed in a separate guideline.2.11 Bus Bar SchemesSimple single bus bar schemes or single sectionalized bus bars schemes are generallyprovided in small hydro scheme.2.12 Inspection and MaintenanceAdequate facilities must be provided in the substation for inspection and maintenance ofvarious equipment and at the same time to ensure safety of personnel and maintain properand other clearances.1-18