5.2　Bearing Pedestals and Bearing

5.2.1　The inspection and installation of supporting bearings and bearing pedestals for generator and excitation device shall comply with the following provisions in addition to the relevant provisions in Articles 4.4.10 and 4.4.11 and in 4.5 hereof:

1　The oil drain grooves and holes at bearing pedestals joint surfaces shall be well through.

2　The bearing pedestals elevation shall comply with the requirements for coupling centering.

3　The axial position adjustment value of bearing pedestals shall allow thermal expansion deflection of the unit；and after rotor expansion in unit operation，there shall be a gap between rotor flange and bearing pedestals.

4　The longitudinal up-rising inclination of bearing pedestals shall be close to that of journal，and the permissible transversal horizontal deviation is 0.20mm/m.

5.2.2　The bearing pedestals of generator and excitation device on floor shall be provided with insulated backing plates，which shall comply with the following provisions in making and installation:

1　Between the bearing pedestals and soleplate there shall be intact steel adjusting shims with total thickness over 5mm，each set with 2-3 shims，which shall be flat and free of burr or curling，and the contact surfaces shall be tight after being fit to place.Under special conditions，such as a lead at the bearing pedestals bottom through the soleplate，the shims can be two halves to facilitate fitting and removal，provided that the joint shall be made flat without overlapping，to ensure dense and flat packing.

2　The insulation sheet on the top shall protrude from bearing pedestals edge，the edges of a lower insulation sheet shall protrude over that above，the bolt hole dimensions of insulation sheets shall be slightly larger than the corresponding bolt hole dimensions on bearing pedestals，and the bolt hole edge shall be flat without burr.

3　A steel shim slightly smaller than the insulation sheet can be put between two insulation sheets.

4　During works the exposed part of insulation sheets shall be kept clean and dry and in good insulation，and water-proof tape may be used to cover and seal up exposed part and joint.

5　After connection of oil pipes，the insulation resistance of bearing pedestals to ground shall comply with the provisions in 5.1.11.

5.2.3　The insulation for end-cover type bearings shall comply with the following provisions:

1　Insulation sheet in a whole piece shall be used between the inner and outer pillow and end cover of generator bearing spherical seat，in homogeneous thickness and be clean and free of burr or curling on surface，and the single layer thickness and total thickness shall comply with manufacturer requirements.

2　To facilitate measuring insulation value，a whole piece of metal shim can be put between two insulation sheets，and the shim shall be laid flat.

3　The insulation sheet at the upper and lower bush horizontal split shall also meet the above provision，and the thickness on both left and right shall be identical.

4　The contact between the inner and outer pillow and insulation sheet of generator bearing spherical seat shall be tight；the tightening screws on outer circumference shall be tightened，and there shall be no gap when checked with a 0.05mm feeler gauge between the joint surfaces after the rotor is placed；at the horizontal split，the insulation sheet shall be flush with the bush spherical seat inner and outer pillows.

5　After completion of official assembling，the insulation resistance value between bush spherical seat inner and outer pillows shall comply with the provision in 5.1.11.