standards / manuals / guidelines for small hydro development - AHEC

SI. No.1Criteria2SF 6 circuit breaker 3Vacuum circuit breaker41. Number of operationsbetween servicing,referred to operatingmechanism.500 to 20,000 C-O Operations 10,000 to 20,000 C-O operation2. Service life ofinterrupters5000 to 20,000 Cooperations(Between over hauls)20,000 to 30,000 Cooperations or(manufacturers guidelines)3. Service interval Lubrication of operatingmechanism after 5 to 10 years(if limiting number ofoperations not reached)Lubrication of operatingmechanism after 10 years (iflimiting number of operations notreached.4. Expenditure onoverhaul ofinterrupters.5. Supervision of Circuitbreaker condition.6. Refilling of arcquenching mediaOverhaul involves completedismantling of interrupter.Labour costs high, materialcosts low.Supervision of SF6 gas pressurepossible (Pressure guage withcontacts for remote signalling.)PossibleTester used to checkvacuum level. If necessaryreplace interrupter. Lowlabour costs. High material costs.Checking the insulation andquench media not easily possible-But generally supervision ofvacuum level not necessary(sealed for life)Not possibleIII. RELIABILITY1. Failure rate Lowest (7-13 per 1000 CB-Yrs) Lowest(7-13 per 1000 CB-Yrs)2. Mechanical life Good Excellent3. Fire Hazard Zero Zero4. Interrupting capacity incase of leakage.Switching of rated current stillpossible.Not possibleIV. COST1. Cost of production Sightly higher than VCB -2. Maintenance cost Lowest negligible cost forminimum 10 years.Lowest negligible cost forminimum 10 years.4-5