5.5　Stator Position Adjustment and Cover Closing

5.5.1　The generator stator and rotor magnetic centers shall be so adjusted that both can coincide under the full load state of generator，and shall comply with the following provisions:

1　The magnetic center of stator relative to rotor shall have a reserved deflection value to the exciter，and the value shall comply with manufacturer specification，or be calculated with the following formula if there is no specification from the manufacturer.

D=ΔL/2+C

Where　ΔL—thermal expansion of generator rotor in full load operation，mm；

C—max.absolute displacement of turbine rotor at generator coupling in full load operation，mm.

Notes:①ΔL can be taken as 1mm per meter of length between the two journal centerlines of rotor；

②C=0 when the generator rotor axial position is not affected by the expansion displacement of turbine rotor.

2　The permissible deviation of reserved deflection of generator magnetic center is 1.0mm，and for a hydrogen-cooled generator and end cover bearing type generator，the requirements for shaft sealing device shall also be met.

3　The relative positions of stator and rotor shall be measured at corresponding points on both ends of stator，and marks shall be made after measurement.

5.5.2　The air gap between generator stator and rotor shall be homogeneous on all sides，complying with manufacturer requirements.The air gap shall be measured at fixed four points on top，bottom，left and right at the same section selected on both ends of generator，and the permissible deviation of gap value at each measuring point from the average gap shall be 1.0mm.

It is not necessary to measure the air gap of a generator with end cover bearings if the ex-works fitting position is not changed during installation.

5.5.3　Inspection and installation of axial flow fan blades shall comply with the following requirements:

1　The blade surface shall be smooth，free of crack，burr or mechanical damage.

2　For blades assembled on-site，the position，angle and rotating direction shall comply with the numbered marks of manufacturer and requirements on drawings.

3　The joint between fan blade base and fan loop impeller can be checked with coloring method，and shall be dense without looseness.

4　Blades shall be mounted and fastened with torque spanner，to ensure uniform tightening force and locked；the tightening torque shall comply with manufacturer requirements and be recorded.

5　Blades mounted on-site or fitted in factory shall be checked by knocking with a copper bar，and for any dumb sound，the cause shall be found out and treated.

6　The minimum radial clearance of blades and fan guard shall comply with manufacturer requirements，and should be 1.5mm-2.0mm when there is no requirement from the manufacturer.

7　After completion of fan installation，the insulation resistance of rotor to ground shall be measured with a 1000V megohm meter，and it shall comply with the provision in 5.1.11.

5.5.4　Installation of generator inner cover shall comply with the following provisions:

1　The spigot between fan hood and inner cover shall be engaged，with good connection at joint surfaces；there shall be no offset at the inner circle connection of split of inner cover.

2　The joint surfaces of inner cover of a hydrogen-cooled and water-hydrogen hydrogen-cooled generator and the stator casing shall be engaged，and the installation direction shall be correct.

3　Pins shall be fitted for joint surfaces，and bolts shall be tightened and be provided with locking device.

5.5.5　The axial clearance value of generator bearing with shaft shoulder and fan with air baffle shall comply with the requirements in technical documents of manufacturer，to ensure there is gap for rotor thermal expansion under full load condition.

5.5.6　The radial single side gap of the end cover air baffle of air-cooled and dual internal water cooled generator shall comply with manufacturer requirements，should be 0.50mm-0.80mm when there is no requirement from the manufacturer.

5.5.7　The installation of the inner oil baffle in the shaft seal of a hydrogen-cooled and water-hydrogen hydrogen-cooled generator shall comply with the provision in 5.6.4.

5.5.8　The final enclosure of generator end cover shall comply with the following provisions:

1　Before enclosure of cover，the inside of generator stator must be checked，and it shall be clean and free of sundries，all parts shall be in sound condition；the fitting gaps shall comply with requirements in technical documents of manufacturer；the inspection and test items for electrical and I&C sections have been completed and inspection signatures have been made.

2　The cover flange planes shall have been cleaned and comply with provisions in 5.3.3.

3　The rubber sealing packing for hydrogen-cooled and water-hydrogen-hydrogen-cooled generator shall be filled in a method as required by manufacturer，and comply with the following provisions:

1）Sealing grooves shall be cleaned，the coating shall fill up the grooves and the bolts on vertical and horizontal joint surfaces of cover shall be tightened.

2）Packing sealing materials shall be filled with pressurizing from the hole at the bottom，when it flows out from the upper adjacent hole，block it with a plug and continue filling from the bottom with pressure，until the whole groove is filled up.

4　When rubber strips are used for sealing，the sectional dimensions of the strips shall comply with manufacturer requirements and they shall have sufficient elasticity；the overlapping technique shall comply with manufacturer requirements.

5　If packing such as cardboard is used at the joint surfaces between cover and soleplate，and between cover and casing for an air-cooled or dual internal water cooled generator，the packing shall be flat，without discontinuity or fold，and it shall be ensured that the joint surfaces are free of leakage.

6　The sealed pressure air duct on small cover shall be well through and be aligned with the pressure tuyere on large end cover.