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BHEL GUIDE: HYDRO GENERATORS SL.NO. DESCRIPTION PAGE NO. 01 GENERATOR ASSEMBLY

BHEL GUIDE: HYDRO GENERATORS SL.NO. DESCRIPTION PAGE NO. 01 GENERATOR ASSEMBLY AND ERECTION 02 GENERATOR SUB-ASSEMBLIES & AUXILIARIES. 03 STATOR 04 ROTOR 05 LOWER BRACKET 06 UPPER BRACKET 07 THRUST BEARING 08 LEVELLING OF THRUST BEARING. 09 CENTERING OF STATOR, UPPER AND LOWER BRACKETS. 10 MAGNETIC CENTERING OF STATOR AND ROTOR. 11 AIR AND OIL COOLERS 12 ASSEMBLY OF PMG STATOR. 13 ASSEMBLY OF BRUSH ROCKER WITH SLIP RING. 14 EXCITATION SYSTEM. 15 BOXING OF BEARINGS. 16 UNIT CONTROL BOARDS. 17 EXTERNAL OIL LP LUBRICATION SYSTEM. 18 BRAKE JACK SYSTEM. 19 FIRE EXTINGUISHING SYSTEM. 20 PREPARATION OF HYDRO GENERATOR FOR STARTING AND COMMISSIONING. 21 DRYING OF THE GENERATOR. 22 TESTING OF THE GENERATOR. 23 PUTTING INTO OPERATION. 24 INSTRUCTIONS FOR CHECKING AND PROVING, BEDDING OF GUIDE AND THRUST BEARING PADS. 25 INSTRUCTION ON CLEANING OF OIL PIPE LINES. GENERATOR ASSEMBLY AND ERECTION Ensure readiness of following customer inputs for starting assembly and erection of generator. • Power house roofing completed, sides, windows and entry covered. • Service bay is concreted and embedment if any are installed. • Generator barrel and floor concreting and curing completed. • Generator stator and lower bracket foundation are checked, chipping completed and pockets are clear. • Generator barrel and its floor painted from inside. • 3 phase 4 wire construction power supply, tapping points available in power house. • Ventilation and water supply arrangements. • EOT crane commissioned and load tested. • Proper precautionary measures to avoid flooding of P/H either from U/S or from D/S. (U/S: Upstream, D/S : Downstream). 1 FOUNDATIONS: STATOR/LOWER BRACKET 1.1. Check depth of foundation pocket with a sample stud. 1.2. Check foundation pocket and other openings in generator barrel are as per drawing. 1.3. Check elevation of foundation and chip off the loose concrete of foundation surface to expose hard surface. 1.4. Check surface flatness of foundations with a machined plate and correct by chipping and grinding, to obtain 80% of contact, evenly spread over the entire area to ensure sound seating for foundation plates, packers and taper wedges etc. 2 FOUNDATION PLATES AND STUDS. 2.1 Check and prove matching of foundation plates, bolts with stator frame. 2.2 Check and prove threads of foundation studs and nuts. 2.3 Assemble foundation plates with stator frame to check and ensure 80% of contact between the foundation plates/stator frame. Match mark the foundation plates and stator frame. 2.4 Remove protective paint from foundation plates and stud surfaces in the areas, to be embedded in concrete. 2.5 Remove paint from packer plates and complete deburring. In case, taper wedges are supplied, check the machined surfaces for flatness and contact. 2.6 Install foundation plates, studs and position them to approximate elevation and to unit axis within 1mm. GENERATOR: Generator of a hydro station consists of the following sub-assemblies and auxiliary equipment. A. SUBASSEMBLIES. 1. Stator. 2. Rotor with fans. 3. Lower bracket with brakes and jacks. 4. Upper bracket. 5. Thrust bearing. 6. Guide bearings. 7. Air, oil coolers and pipe lines. 8. SSG: speed sensing gear. 9. Excitation system. B. AUXILIARIES 1. Unit control board. 2. Hydrostatic lubrication system. 3. External/LP oil cooling system. 4. Brake jack system/power pack. 5. Dust collector. 6. Stator heater. (Anti condensation heater). 7. Air, oil and water pipe lines 8. Fire extinguishing system / CO2 system. 1. STATOR Stator of a generator depending on its overall size is dispatched to site either partially wound or completely wound, fully assembled or in segments. Partially wound segments are assembled and the balance winding at the joints of segments is carried out at site OR Stator frames, punching and winding materials are dispatched as loose components for assembly of stator core in the form of a ring. In which case, assembly of stator frame, core building, core shake testing, laying of winding, bus bars etc. including stage testing, final testing is carried at site. Assembly of stator may be done as per manufacturer’s instructions either in service bay or in the place of installation. 1.1. PREPARATION • Transport wound sectors of stator to power house service bay and place them on raised platform or supports. • Check core and winding for mechanical damage if any and take corrective action. • Clean and debur stator joining flanges, megger the stator winding to ascertain, winding healthiness. • Prove and assemble stator turning device. (If any). • Cut extra length of binding ring and bus bar connections if any noticed during inspection. • Check all threaded holes for any damage and retap them if necessary. 1.2. ASSEMBLY AND INSTALLATION. • Turn the stator sectors after assembling device to make it vertical (if transported in horizontal condition) and remove stator turning device. Transfer and position the sector on stator foundation plates already kept aligned in situ or on stools in service bay as the case may be. • Install dowel between foundation plate and stator frame. • Support stator sector on screw jacks to avoid its tilting, also arrange for a temporary holding arrangement. • Prepare adjoining sector of stator, lower and assemble with the sector already placed in generator barrel to form one half or 2/3rd of stator. • Use leatheroid or CAF packing between the core at the joints as specified in the drawing. • Install dowels and fasteners of joint flanges and complete tightening of fastners. • Install dowel of stator frame and foundation plate. • Carry out assembly of remaining two sectors as described above to form another half of stator by maintaining a gap of 10mm between the two halves. In case complete stator is supplied in four quadrants. • Finally assemble two halves together, install dowels, fasteners and complete tightening checking of joints. • Check elevation of stator on the upper machined flange and correct if need be. • Check and correct horizontality of stator frame by adjusting taper wedges or adding or removing the packers installed underneath it. • Check magnetic axis of stator core with respect to turbine flange top is as per design requirement. • Position piano wire with plumb bob at the center of stator bore within 0.1mm, checking by inside micrometer. Shift stator with respect to center of turbine shaft bore within a tolerance of 0.1mm. (remove dowels of foundation plates while stator centering). • Check stator core diameter (ID) as per requirements of FQA. (Refer Sketch No.1). • Position, foundation plates of stator with respect to stator frame. Install dowels and fasteners. • Install temporary working platform at the joints of stator. Carry out winding of stator and installation of busbar etc. as per technical instructions of manufacturer and relevant drawings and instructions. • Complete checking insulation resistance testing, dry out HV testing of winding as per technical instructions/standards. • Paint stator end winding with redgel coat (refer instruction for painting issued by manufacturer). • Complete painting of stator core and winding as per guide lines of drawing. • Remove temporary platforms, installed for the purpose of winding. Note: In the event of assembly of stator sectors done in service bay. Stator sectors are assembled over stools and winding is carried out. Completely assembled stator is then transferred and positioned in generator barrel with respect to turbine center and elevation to technical requirements. 2. ROTOR The rotor of a hydro generator consists of following sub-assemblies. • Shaft • Rotor spider • Rotor rim • Poles and their inter connections • Current carrying leads • Brake track • Rotor fan • Slipring 2.1 ASSEMBLY AND ERECTION OF ROTOR 2.1.1 ROTOR SPIDER Depending on type of thrust bearing arrangement of generator and size of spider is dispatched to site in one of the forms detailed here under. 2.1.2 UMBRELLA TYPE GENERATOR With load bearing bracket and bearing arrangement below rotor. • Rotor spider is bolted type. • Shaft is dispatched with rotor bush mounted on it and spider portion separately. In such construction, assembly of rotor rim, poles etc. is done in erection bay and the spider is bolted to rotor bush at the place of installation in stator bore. 2.2 UMBRELLA TYPE MACHINE • Prepare and install shaft, vertically upright on base plate of rotor erection pedestal and then fasten it by means of nuts and bolts. Check that shaft is vertical. • Prepare spider, shaft collar mating surfaces, conical studs for assembly. • Lift spider fairly levelled, with the aid of crane, lower it on the shaft collar. • Complete tightening of collar studs. • Depending on construction, sometimes fixing of spider to rotor bush is done at the place of installation, after lowering spider in the stator bore, in which case following procedure is adopted for assembly. • Shaft with the bush fitted on it is lowered and made to rest on thrust bearing. • Assembly work of rim, poles etc. with spider is done on erection bay, except the hot wedging of rim keys. (Refer tech. requirement). • Spider assembly is lowered over shaft, placed in the stator bore to complete assembly of spider with rotor bush. • Rim keys uploads/Industriel/ bhel-guide-hydro-generators.pdf