standards / manuals / guidelines for small hydro development - AHEC

v) In case the runner is found to be irreparable arrange to replace the same withnew one.vi) In case of Kaplan runner hydraulic test is also required to be done.9. Turbine Auxiliaries1. DPMi) Inspect top cover drain system; overhaul the ejector and drainage pumps.ii) Check pipe lines and valves. Replace gaskets and other parts, if necessary.10 Oil Cooling Uniti) Overhaul cooling pumpsii) Attend all the valves and pipe line for leakage11 Centralised Grease lubrication Systemi) Overhaul greasing pump.ii) Check whole greasing lines. Replace worn out valves and gaskets etc.iii) Check all the nylon pipes connected with the guide vane bushes. Replacedamaged pipes.iv) Check that all the guide vanes are receiving grease properly.12 Oil Leakage Uniti) Check the oil leakage unit overhauls the pumps.ii) Clean tank and check that float is properly working.iii) Checking all the pipe liens and valves for leakages.4.1.6 Major Maintenance Problems of Hydro TurbinesSome of the major problems encountered in the hydro turbines are damage in runners due toerosion, cracking and cavitation due pressure pulsation in draft tube, instability of operationat partial gate opening. Failure of turbine bearings, leakages of water through of turbine guidebearings, leakage of water through guide vane seals and turbine gland seals, these problemsare discussed in detailed in the following paras.A. Runner1. Erosion due to siltThe problem of erosion of turbine runners guide vanes and other under water parts hasassumed serious proportions especially in some of the run-of-river schemes, The rivers in thenorthern region carry enormous silt loads especially during mansoon periods so much so thatthe power stations has to be closed down to prevent serious damage to the turbines part andwater passage. Greater attention should, therefore, be paid to effective desilting arrangementin such power station. Heavy damages have been observed on the runner labyrinth, seals,guide vanes, inlet valve, shaft seals and draft tube cone. The wear due silt occurs so fast thatthe unit has to be taken out for reconditioning every few years in some stations. The remedyappears to lie in effective desilting arrangements and manufactures of turbine parts withharder and erosion resistant material like stainless steel of popper grade and also design ofrunner for such conditions.AHEC/MNRE/SHP Standards/ E&M Works – Guidelines for Operation and Maintenance of Small Hydropower Station 22