standards / manuals / guidelines for small hydro development - AHEC

Problem in electrical circuit and checks• No supply at control panel inspite of turning on main switch – check fuses.• Incoming supply healthy but volt meter not showing – check fuses of voltmeter circuit• Motor is running even after pressing stop push button• Immediately put main switch off• Check contacts of motor control contactor & push button contacts. If damaged replacethese• Reset O/L relay before starting again• O/L relay trippedCheck control fuseIf fuse OK check control transformer• Gate is creeping down & restoration has failed indicating lamp is glowing but alarmnot ringing• Check position to toggle switch (it should be in reset position)• Indication of lamps are not glowing.• Check by pressing lamp test push button replace bulbs, if found fused.4.4.2 MAINTENANCE OF MAIN INLET VALVESThe turbine may have either a butterfly or spherical valve. This valve is used eachtime the unit is shut down. Valve seats, seals, operating links, bearings, bushings, powersource and hydraulic links are the main primary maintenance concern.The valve function should be verified periodically through test or normal frequentoperation.Butterfly valves (head upto 120 m)• Butter valves generally consists of a disc or lattice mounted on a shaft that rotates incylindrical body• Usually, the disc and lattice profile is contoured in the flow direction to provide asmooth hydraulic flow and balance forces on the valve.• The disc is oriented parallel to the flow to minimize any restriction when opened andat right angle to the flow to provide full closure• Valve seals are on the circumference or in contact portion of the valve body• These seals can be replaced or adjusted without removing the disc from the valve.• Valves have flanged connections and spool pieces to facilitate dismantling. Sometimewelded connection are preferred to save costMaintenance procedure- Check operating system daily and ensure it is working smoothly- Check for any leakage through connection daily- Replace seals in annual maintenance- Overhaul operating system annually- Replace gaskets in flanged connection during overhaulAHEC/MNRE/SHP Standards/ E&M Works – Guidelines for Operation and Maintenance of Small Hydropower Station 53