Page 258 - Water Standards
P. 258

—When a DM type field discharge switch is used, the amount, arrangement,
                    shape and installation position of the arc extinction grid  s plates, shunt
                    resistor  s connection and resistance and arc extinction contact  s spacing shall be
                    checked. All of them shall meet the product and ordering requirements  
                 4) The laying and wiring of excitation system cable shall meet the following require⁃
                   ments:
                   —The lengths of the three⁃phase power cable which connects the excitation trans⁃
                    former with the power cabinet shall be equal.
                   —Cable laying and internal wiring shall meet the requirements in GB 50168 and
                    GB 50171  
           4   2   9  Horizontal hydraulic generator installation shall meet the following requirements:
               1  Bearing liner scraping shall meet the following requirements:
                 1) The bearing liner and mirror plate shall be checked according to the requirements
                   of Article 4   2   8 of this specification. The bearing liners which are required by the
                   manufacturer to be scraped on the work site shall be processed in two steps, i   e.
                   initial scraping and fine scraping. The initial scraping shall be done before putting
                   the rotor onto the stator and the fine scraping shall be conducted after centering the
                   rotor.
                 2) The scraping of the pedestal bearing liner shall meet the following requirements:
                   —The gap between the bearing liner and the shaft neck shall meet the design re⁃
                    quirements. Gaps on the two sides shall be one half of the top gap, and the
                    difference between the gaps on the two sides shall be no larger than 10% of
                    the gap.
                   —The contact angle between the bearing liner bottom and the shaft neck shall
                    meet the design requirements and shall be no larger than 60°. The bearing liner
                    shall be totally and uniformly contacted along the direction of its length. There
                    shall be 1-3 contact points per square centimeter in the contact area.
                   —For bearings which adopt pressure oil circulating lubrication systems, the oil
                    gallery size shall meet the design requirements and the head  s length on two
                    ends of the lengthways oil gallery at the joint shall be no less than 15mm  
                 3) Scraping of thrust pads shall meet the following requirements:
                   —The contact area between the thrust pad and thrust collar shall reach
                    75 % of the total area and there shall be 1 - 3 contact points per square
                    centimeter.
                   —The thickness of thrust pads without adjusting devices shall be equal. The
                    thickness difference between each thrust pad in the same group shall be no lar⁃
                    ger than 0   02mm  
               2  The allowable installation error of the bearing seat shall meet the requirements of Ta⁃
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