standards / manuals / guidelines for small hydro development - AHEC

4.1.3 Monthly Maintenance ChecksAll the checks covered in weekly maintenance as above are carried out monthly also. Butwhile carrying out these checks more attention is paid and short shutdowns, if required, forrectification are taken.4.1.4 Annual Inspection and Maintenance of Hydro TurbineAfter successful running of plant for about one year few weeks are required to be allotted toinspect rotating parts, control equipment and measuring instrument setc. And analyse causeof change in the performance charactersitcs, if any. Modify / repair / replace (whereverrequired) the worn out parts in order to prevent forced outages of machine at later date.After every five years it is necessary to inspect the machine more critically for abnormalitieslike fatigue defects for excessive wear and tear of some parts or any change in originalparameters / clearances etc. This exercise becomes very essential in cases whereperformance level has been observed to have gone down in 5 years operation.The checks for annual and five yearly maintenance designed for a hydropower station areenlisted below:1. Foundation Parts:i) Check condition of water path system. The damage due to cavitation and wearto be rectifiedii) Check painting of spiral casing.2. Runner:i) Check the condition of the surfaces of the runner hub and the blades. Thedamage due to cavitations & wear to be rectified by welding and grinding.ii) Check the runner blade seals by pressurizing the system. Change seals ifiii)necessary. No oil leakage is to be allowed (Kaplan only).Check the runner sealing for hermetic tightness, leakages of water in therunner hub is not to be permitted (Kaplan only).3. Guide Apparatus:i) Check the presence of rubber sealing cords and the tightness of the rubbersealing between the adjacent guide vanes in fully dosed position of guideapparatus.ii) Change oil in the regulating ring.iii) Replace damaged shear pins.iv) Check cup sealing of guide vane journals and replace, if necessary.v) Check the bushes of guide vanes and change the worn out bushes of guidevanes journals.vi) Inspect the servomotor and change the seals, if these are worn out.4. Guide Bearing:i) Check the condition of rubbing surfaces of guide bearing. Clean the surfaceand polish it with the help of chalk powder.ii)iii)iv)Adjust the clearances of moving the segment with the help of adjusting bolts.Thorough cleaning of housing if necessary.Check all the RTDs and TSDs replace damaged one.AHEC/MNRE/SHP Standards/ E&M Works – Guidelines for Operation and Maintenance of Small Hydropower Station 19