6.2　General Items

6.2.1　Inspection of concrete foundation:The concrete foundation shall meet the requirements of the current national standard GB 50204 Code for Acceptance of Constructional Quality of Concrete Structures，prior to the installation.The strength of concrete foundation shall reach 75% and above，and the foundation settlement shall be stable.The elevation，center line and others shall be clearly marked，and the deviation shall be within the allowable range，and meet the requirements of the working drawing.

6.2.2　The installation of motor shall be in accordance with the following requirements:

1　The deviation of vertical and horizontal center lines of foundation plate shall be less than 1mm.

2　The elevation error of foundation plate shall be less than 1mm.

3　The horizontal error of foundation plate shall not be more than 0.15mm per meter and the bolts shall have 2-5 pitches of thread exposed after the foundation bolts are tightened.

4　The shim plate shall be placed at the load-centralized position，generally，250mm away from both sides of the anchor bolts，and 400-700mm from other parts.The contact surface between the shim plate and the equipment shall not be less than 70% of shim plate area.The total number of shim plate in each group shall not exceed 5.The shim plates should be 70-100mm in total thickness，and shall be stably placed，tightly pressed，and welded together by spot welding.The anchor bolt shall be perpendicular to the anchor plate which shall closely contact with the foundation surface.

5　The bearing block shall be placed at a proper position and tightly fixed to the foundation plate.The insulation resistance of the insulated bearing block shall not be less than 1MΩ.

6　The joint section of the two stators shall meet the manufacturer's specification.

6.2.3　The inspection of detachable motor stators and rotors shall be in accordance with the following requirements:

1　The inside of motor shall be kept clean，and the air hole shall be unblocked.

2　The winding connection and welding shall be correct and in good condition.

3　The slot wedge shall not stick out nor be broken or loosened，and its end shall be securely fastened.

4　The insulating layers of coil shall be intact and free of scratches and the winding wires shall not be loosened.

5　The magnetic pole，iron yoke and excitation coil shall be securely fastened.

6　The iron core，shaft journal，slip ring and commutator of rotor shall be clean and free of scratches and rust.The air holes shall be unblocked.

7　The counterweight and balancing bolt of rotor shall be securely locked.The direction of fan shall be correct and the fan blades are free of crack.

8　The conducting bar and end ring of the rotor of squirrel-cage motor shall be well welded and free of crack.

9　The magnetic pole center line of DC motor shall be consistent with the geometrical center line.

10　The electrical brush shall be in good contact with the commutator and the collector ring.

6.2.4　The alignment of motor shall be in accordance with the following requirements:

1　The alignment of motor shall be in accordance with those specified in Table 6.2.4.

2　For alignment of single-bearing rotor，generally an opening of 0.02 to 0.04mm should be kept.

3　For alignment of multiple couplings，the effect of self-weight of rotor shall be taken into consideration.

6.2.5　The installation of couplings shall be in accordance with the following requirements:

1　The coupling shall be assembled correctly after it is heated until its inner diameter is expanded to 0.5-1.0mm larger than the shaft diameter.

2　For flexible coupling，the rubber stopper shall be capable of being smoothly inserted into the hole of coupling，and not affect the axial end-play of shaft.

3　For rigid coupling，all the bolt holes for interconnected couplings shall be the same，and fit precisely with the connecting bolt.The nut shall be equipped with a locking device.

4　For gear coupling，the clearance of gear engagement shall not exceed 0.10-0.30mm where the distance between the shaft centers is 50-100mm.The contact part of tooth shall not exceed two thirds of tooth width.

5　The allowable runout for end face of coupling shall be in general:0.02-0.03mm for rigid coupling，and 0.04-0.05mm for semi-rigid coupling.

6.2.6　Air gap and unevenness:the air gap of the driving side and non-driving side of motor shall be measured respectively at 4 points with even interval and the unevenness of each side shall not exceed 10%.

6.2.7　The fitting between the sliding bearing and shaft journal shall be in accordance with the following requirements:

1　The top and side clearances of bearing bush shall meet the manufacturer's requirements，and shall be in accordance with the following requirements if there are no such requirements available:

1）The top clearance between the shaft journal and the bearing bush:1.5-2.0‰ of the diameter of shaft journal.

2）The side clearance between the shaft journal and the bearing bush:0.75-1.0‰ of the diameter of shaft journal.

3）The clearance between the bearing cap and the upper bush:-0.15-0.05mm for columned bearing bush，and±0.03mm for ring-type bearing bush.

2　The contact arc and contact point of lower bush shall be in accordance with the manufacturer's requirements，if no such requirements are available the following requirements shall be met:

1）The contact arc shall be 60°-90°.The number of contact points on the contact surface shall be at least 2 per square centimeter.

2）The contact surface between the lower bush bearing pillow block and the bearing bush shall be greater than 60%.The joint face clearance between the bearing block and the bearing bush backside shall not exceed 0.05mm.

3）The thrust face clearance of bidirectional thrust bearing bush shall not exceed 0.4mm.

6.2.8　Turning inspection of small motor shall be in accordance with the following requirements:

1　The rotor rotates smoothly without abnormal sound.The mechanical connection parts are in good condition and the bolts are securely tightened.

2　The lubricating grease on the roller bearing shall be removed and replaced if it has discolored，degenerated and hardened.

6.2.9　The bearing temperature rise shall meet the manufacturer's requirements，and if no such requirements are available the following requirements shall be met:

1　For the bearing lubricated by oil ring:the maximum allowable temperature is 80°C where the maximum limit of temperature rise is 45°C.

2　For the bearing lubricated by circulating oil:its allowable temperature is 65°C where the temperature at the inlet is 35-45°C.

3　For roller bearing:the temperature rise shall not exceed 60°C.

6.2.10　The inspection and adjustment of electrical brush shall be in accordance with the following requirements:

1　In general，the null line of electrical brush shall be on at the geometrical center line of the main pole.

2　The electrical brushes of each pole shall be evenly and reasonably distributed around the circle of the commutator and the allowable deviation of polar distance is 1.0mm normally.

3　The distance between the brush box and the commutator or the surface of slip ring shall be 2.5±0.5mm.

4　The clearance between the electrical brush and the brush box shall be 0.1-0.2mm.

5　The contact face of electrical brush shall fit the arc of the commutator or the slip ring and the overlapping area shall be greater than 70%.

6　The minimum pressure of the spring of the electrical brush shall be set to such a value that the brush will not flame.Generally it ranges from 0.015-0.025MPa.

7　For an electrical brush inclined by a certain angle，the acute-angle tip shall point to the direction opposite to that of the shaft rotation.

8　The both sides of the double-angular brush shall not contact with each other，and should have a clearance of 1 to 2mm between them.

9　When the electrical brush is working on the surface of commutator，the distance between the riser and the brush box is generally 5-17mm for small and medium motors，and 35mm for large motor.

10　The electrical brushes of different brands or manufacturers shall not be used for the same motor at the same time.

11　Micro sparks under the electrical brush are allowed.

6.2.11　The axial end-play of the motor rotor shall not exceed those specified in Table 6.2.11.

6.2.12　The vibration（double amplitude）of the motor shall not exceed those specified in Table 6.2.12.

6.2.13　Secondary grouting shall be in accordance with the following requirements:

1　The burrs and oil pollution on the foundation surface and under the base plate shall be removed prior to secondary grouting.The foundation concrete shall be soaked in the water for 6-12h and the excess water shall be removed before secondary grouting.

2　Fine gravel concrete or suitable grouting compound shall be used for grouting in general.The space under the foundation plate shall be fully grouted.The grouting process shall be completed without interruption.

3　After reaching the required strength，secondary grouting shall be inspected again and alignment shall be made again.

6.2.14　The drying of motor shall be in accordance with the following requirements:

1　The temperature for drying shall be slowly raised with the rise of 5-8℃per hour for large motors，and 7-15℃per hour for small motors.

2　The maximum allowable temperature of the winding and the iron core shall be determined according to the insulation grade of the motor.It shall be 70-80℃if measured with an alcohol thermometer，and 80-90℃if measured with a resistance thermometer.

3　For the motor with rotor to be dried，the rotor shall be turned by 180° about every 2 hours after the temperature of rotor rises to 70℃.

4　Where DC motor is used as an electrical generator to run for drying by means of short-circuit，the electrical brush shall be turned by 1-2 commutators in the direction of rotation.

5　Drying can be deemed completed when the absorptance and insulation resistance meet the requirements and the insulation resistance stays unchanged for 5 hours at the same temperature after it drops and then rises.