GB/T 43683.2-2024Guidance for installation procedures and tolerances of hydroelectric machines - Part 2: Vertical generators (English PDF)

1 Scope

The document gives the installation procedure and the tolerance requirements common to vertical generators. There are many methods of installing a generator, and the document presents one generic installation process. The dimensions of the components of the set, the design of the set, the layout of the power station or the delivery time of the components may lead to additional steps, to the cancellation of certain steps or to a change in the order of installation.

The document is binding only where the contracting parties agree that it shall be.

It applies to the vertical generators specified in IEC 60034-7.

It does not apply to purely commercial uses, unless these are inseparably connected with the installation of the set.

The tolerances specified by different standards may differ; the tolerances in the document are determined from the most common practice and experience.

The document does not cover brushless excitation systems.

Whether or not the document requires the manufacturer to supply documents, drawings or information, every manufacturer shall supply the necessary related material for the equipment it supplies.

2 Normative references

One document is cited: IEC 60034-7, Rotating electrical machines, Part 7: Classification of types of construction, mounting arrangements and terminal box position (IM Code). For dated references only the edition corresponding to that date applies; for undated references the latest edition, including all amendments, applies.

3 Terms and definitions

The document states that it has no terms and definitions that need to be defined. It gives the addresses at which ISO and IEC maintain their terminological databases.

4 Preparation

Components such as the pipework and the foundation plates are covered in the clauses on the embedded parts of the turbine.

5 Installation flow chart

The installation flow chart shown in Figure 1 is drawn up mainly for vertical generators whose thrust bearing lies below the rotor. Where the thrust bearing of the generator lies above the rotor or is supported by the head cover, the flow chart needs to be modified.

Figure 1 separates the work carried out in the machine pit from the work carried out in the erection bay. In the pit the sequence runs from the free state of the turbine shaft and the check of the generator foundation, through the installation of the lower bracket, the concreting of the lower bracket foundation, the installation of the stator, the assembly of the thrust and guide bearing, the installation of the braking and jacking equipment, the lower shaft and the thrust head, the lifting of the rotor, the installation of the upper shaft and of the upper bracket, the separate barring of the generator, the connection of the turbine shaft to the generator shaft and the shaft line adjustment, the concreting of the upper bracket and/or stator frame foundation, the assembly and adjustment of the upper guide bearing, the installation of the slip ring and of the brushgear, the completion of the remaining generator components, the cleaning, painting and inspection before the first test, the completion of the generator installation and, last, the commissioning. In the erection bay the assembly of the lower bracket, of the stator, of the rotor and of the upper bracket is carried out and fed into the corresponding steps in the pit. A key distinguishes the standard tasks, the important events, the steps where turbine and generator work together, the completion of the current installation flow and the references to other flow charts or activities.

Note 1: the flow chart applies to generators whose thrust bearing lies below the rotor. For generators whose thrust bearing lies above the rotor, the starred steps are carried out, wholly or in part, between step 11 and step 12 of the flow chart.

Note 2: the installation of the generator is bound up with the installation of the turbine.

6 Installation steps

Each step is set out under four headings: a) work objective, b) work description, c) points requiring attention and d) additional explanation.

6.1 Step 1, turbine shaft in the free state: see the related content of the turbine part of the document.

6.2 Step 2, check of the generator foundation. Objective: to check the foundation of the upper bracket and/or of the lower bracket, where present, and the stator foundation; to check the openings for the main lead-out and neutral point cables and busbars; to check the pre-embedded oil, air and water pipework. Description: to check the foundations of the upper bracket, the lower bracket and the stator; to check the size of the openings; to check the position of the pipework, and of the second-stage concrete where there is any; to install the foundation bolts; to install the foundation plates. Points requiring attention: the tolerances are supplied by the generator manufacturer; where single-stage concreting is used, the position, the elevation and the orientation of the foundation plates are checked; where two-stage concreting is used, the anchor bolts, the embedded parts and the position, elevation and orientation of the first-stage pit are checked. Additional explanation: there are two concreting methods for the embedment of the base plate, single-stage and two-stage concrete; care is taken during concreting to avoid displacement of the generator foundation; where the two-stage concrete method is used, the whole surface of the first-stage pit is prepared accordingly, so that the first-stage and second-stage concrete bond together; generators of other constructions follow the requirements of IEC 60034-7, and may have no lower bracket or no upper bracket.

6.3 Step 3-1, assembly of the lower bracket. Objective: to assemble the lower bracket. Description: to connect the arms to the centre body as the design requires, by welding, by bolting or otherwise; this work is usually carried out outside the machine pit. Points requiring attention: the tolerances are supplied by the generator manufacturer; where the arms of the lower bracket are connected to the centre body by welding, non-destructive testing (NDT) is required according to the inspection and test plan (ITP). Additional explanation: the installing party should take preventive measures to control welding deformation effectively, so that the lower bracket can be connected to the embedded parts; the lower bracket, the upper bracket, the rotor and the stator are usually the largest components of the set, their assembly takes a long time and is usually carried out in parallel, and the assembly stations are planned and used sensibly, the key point being the planning of the assembly stations and effective cooperation between the parties involved.

6.4 Step 3, installation of the lower bracket. Objective: to install the lower bracket in its design position. Description: to place the lower bracket on the foundation plates; to adjust and control the elevation, the level and the concentricity of the lower bracket. Points requiring attention: the elevation, the level and the concentricity of the lower bracket are checked, the tolerances being supplied by the generator manufacturer; in determining the correct installation elevation of the lower bracket, account is taken of the deflection produced together by the total mass of the rotating parts and by the axial hydraulic thrust acting on the runner under the given operating conditions. Additional explanation: different designs need different tolerances, so the tolerances are recommended to be supplied by the generator manufacturer; the lower bracket is concentric with the bottom ring, and the turbine shaft may be used as a relative reference, while other reference points may also be used to adjust the centre of the lower bracket; in some cases step 7, the installation of the braking and jacking equipment, is completed within this step.

6.5 Step 4, concreting of the lower bracket foundation. Objective: to concrete the lower bracket foundation. Description: grouting and concreting of the anchor bolts or foundation bolts and of the foundation plates. Points requiring attention: before the foundation is concreted, it is checked that the reinforcing measures cannot affect the foundation plates and the foundation bolts. Additional explanation: it is ensured that air can escape upwards during concreting; for designs that do not need second-stage concrete this step is omitted; depending on the design, the foundation plate of the lower bracket may have to be concreted before the lower bracket is installed; care is taken during concreting to avoid displacement of the lower bracket foundation.

6.6 Step 5-1, assembly of the stator. Objective: to assemble the stator. Description: to assemble the stator frame by bolting or welding; the lamination of the core; the installation of the winding; the electrical tests and the mechanical measurements. Points requiring attention: see step 15, shaft line adjustment; the tolerances are supplied by the generator manufacturer. Additional explanation: the stator is assembled in the erection bay, in the machine pit or beside the pit; the stator may be assembled in segments, a segmented stator comprising the core, the winding and the frame; alternatively the frame is first assembled on site and the core is then completed by lamination; where drilling and welding work is carried out nearby, all the winding components are protected.

6.7 Step 5, installation of the stator. Objective: to install the stator in the machine pit. Description: the level, the elevation and the position of the stator meet the tolerance requirements. Points requiring attention: see step 15, shaft line adjustment; the elevation of the magnetic centre line of the stator and the verticality of the core should be checked, the tolerances being supplied by the generator manufacturer. Additional explanation: relative references are used to make the stator concentric with the bottom ring, the turbine shaft serving as a relative reference, while other references may also be used to adjust the stator centre; during the shaft line adjustment of the set, see step 15, the stator centre is checked, and in some cases it may need to be adjusted.

6.8 Step 6, assembly of the thrust and guide bearing. Objective: to assemble the combined thrust and guide bearing. Description: the components and fittings of the thrust and guide bearing are installed in the oil trough of the thrust bearing support; the oil trough is checked to make sure it does not leak. Points requiring attention: the thrust bearing and the bearing support are concentric, and their elevation and level meet the requirements; the tolerances are supplied by the generator manufacturer. Additional explanation: the concentricity of the thrust bearing and the bearing support is a necessary condition for normal operation of the thrust bearing; the concentricity of the thrust bearing, of the thrust bearing support and of the rotating parts is checked during step 15, shaft line adjustment, and in some cases the position of those components needs to be adjusted. Note 1: for this step, Chinese practice is generally to keep the thrust bearing support and the bearing pads on the bracket to the design concentricity, so as to meet the requirements of the later construction; to install the rotor, at least four lower guide bearing pads spaced 90 degrees apart are installed. In some designs the thrust bearing may be installed in the upper part of the head cover; in that case the thrust bearing support is made concentric with the head cover, and the thrust bearing and the bearing support are made concentric. In some designs the lower guide bearing of the generator is arranged separately from the thrust bearing; in other designs the diameter of the lower guide bearing of the generator is small, so the thrust head cannot be installed by the flow given above. The insulation of the thrust and guide bearing should be checked. Note 2: the thrust bearing support means the bracket, lower or upper, on which the thrust bearing lies; for a thrust bearing lying below the rotor, the thrust bearing support is the lower bracket.

6.9 Step 7, installation of the braking and jacking equipment. Objective: to install the brakes and the jacking equipment. Description: to install the jacking equipment as the design requires, on the arms of the lower bracket or on a concrete support; to assemble the pipework; to install the accessories, such as the air compressor, the control panel, the air receiver and the oil trough. Points requiring attention: the level and elevation tolerances of the brake plate are supplied by the generator manufacturer. Additional explanation: none.

6.10 Step 8, installation of the lower shaft. Objective: to install the lower shaft of the generator, where there is one, so that it can be connected to the turbine shaft. Description: to install the lower shaft in the machine pit. Points requiring attention: the elevation, the level, the concentricity and the verticality should be checked against the tolerance requirements supplied by the generator manufacturer. Additional explanation: none.

6.11 Step 9, installation of the thrust head. Objective: to install the thrust head and assemble it with the shaft. Description: to assemble the thrust head with the mirror plate; to connect the thrust head to the lower shaft where the thrust bearing lies below the rotor; to connect the thrust head to the upper shaft where the thrust bearing lies above the rotor. Points requiring attention: the elevation, the level, the concentricity and the verticality should be checked against the tolerance requirements supplied by the generator manufacturer. Additional explanation: the mirror plate is generally regarded as already connected to the thrust head; when the thrust head and the main shaft are installed, different designs have different items to check; in some designs the thrust head is connected to the generator shaft or forms one body with it, in others it is connected directly to the rotor, and in still others it is connected to the turbine shaft, the installation steps being adjusted accordingly; where the thrust bearing lies above the rotor, the work description of step 12 is followed.

6.12 Step 10-1, assembly of the rotor. Objective: to complete the assembly of the generator rotor in the erection bay. Description: to hang the rotor arms as the design requires, the arms being connected to the centre body by welding or by bolting; to stack the rotor rim according to the drawings and the erection instructions and to press it tight in sections; to drive the rim keys tight, so that the rim and the rotor frame form one body; to hang the magnetic poles; to connect the pole coils and the damper rings, where present; to assemble the rotor braking ring; to assemble the fan baffles as the design requires; to carry out the drying, the paint protection and the cleaning work as the design requires; to carry out the electrical tests and the mechanical inspection and measurement work.