standards / manuals / guidelines for small hydro development - AHEC

S.No.Item to beinspectedInspection ProcedureAction required ifunsatisfactory conditionindicatedApplicable fortransformersApplicableUATS, SSTS anddistributiontransformerswhen ticked √1 2 3 4 54. OLTC Examine contacts, - Replace all the worn outCheck step by step and burnt contacts. Setmechanism operation, limit switches inend position limit position. Clean / replaceswitches and brakes. brake shoe lining.Check that wiring isintact and all terminalsLubricate all bearing andcoupling points suitably.are tight.Tighten terminals iffound loose.5. Marshalling box Check wiring and that - Tighten them if found6. Oil intransformer7. Oil in diverterswitch8. Insulationresistance9. Oil bag sealingarrangementwhere provided.F. Half Yearly1. Alarm, trip andprotectioncircuitsterminals are tight.Check for dielectricstrength and moisturecontentCheck for dielectricstrength and moisturecontent.Measure IR valuebetween windings andto earth.Check presence of oiloutside the oil bag inthe conservator.Check operation ofalarm / trip contacts ofeach protection byactual initiation andalso check display andannunciation on thepanel.2. Oil in bushings Check BDV andmoisture content of oil.3. Vibration level Measure vibrationof tank walls for level.shunt reactors.loose.- Take suitable action torestore quality of oil-do-- Compare with previousvalues. The comparisonshould be done withthose values wheretransformer/ reactor isconnected externally tothe line and bus ducts. Ifthe values are low,measure IR values afterisolating it.- If oil is present checkleakage in the oil bag byapplying air pressure.- In case of faultyoperation, check contactsand wiring circuits.- If values are low, filter oilor replace with fresh oil.- Compare with previousvalues.AHEC/MNRE/SHP Standards/ E&M Works – Guidelines for Operation and Maintenance of Small Hydropower Station 47