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 57. Gasket joints Check the tightness of Tighten the bolts evenly tobolts.avoid uneven pressure.8. Earth resistance Check earthing Take suitable action, if earthresistanceresistance is high.9. OLTC i) Diverter switch - Draw out diverter, cleanservicing& tighten contacts.ii) Check the contacts - Recondition/ replace, ifof diverter switch required.for burning orpitting marks.10. Bushing topconnectors andarcing horns11. Air bag sealingarrangementwhere provided.12. Cable boxes, ifprovided13. Lighteningarrestors14. Off circuit tapswitch15. Condenserbushingi) Check contactjoints.ii) Clean arcing hornsand check gap.i) Check healthinessof air bag.Check for sealingarrangement for fillingholes. Examinecompound for cracks.i) Examine for cracksand dirt deposits.ii) Measure IR valueof each stack of las.i) Move fromminimum tomaximum tapposition & return tominimum position.ii) Check resistancemeasurement ateach tap.Measure power factor/capacitancemeasurement.16. Electrical tests Carry outi) Resistancemeasurement at alltapsfortransformers withoff circuit tap- Retighten.- Adjust arcing horn gap- Clean, if required.- Replace gaskets, ifleaking.- Replace compound, ifnecessary.- Clean or replace.- In case IR value is poor,replace.- Compare resistancevalues with previousresults. If resistance ishigh, tap switch contactsto be attended to.- Dryout bushing if valuesare abnormal and replaceoil if required.- Compare with previousvalues. Incase ofabnormality investigatecauses.AHEC/MNRE/SHP Standards/ E&M Works – Guidelines for Operation and Maintenance of Small Hydropower Station 49