Due to the different construction, materials, loads and working conditions of diesel generator parts, assemblies, assemblies and assemblies, the diesel generator maintenance can be divided into minor repair, medium repair and major repair according to the working time. Today, I will share with you the medium repair of diesel generator. The diesel generator needs to be maintained and repaired in a planned way after it has been operated for about half a year or its cumulative working time has reached 1000h. In addition to completing the minor repair of diesel generator, there are also the following contents.
1、 Check the slip ring and brush device: check the condition of the slip ring (or commutator) and brush device, and carry out necessary cleaning, trimming and measurement.
① Cleaning work: the contact conductive surfaces of the collector ring or commutator, brush and brush holder shall be free of oil, dirt, carbon dust, bright and in good contact. When wiping, use a soft, dry, clean cloth without hair, which can be dipped in a little gasoline (or alcohol). Pay special attention to the cleaning of the brush holder and the root of the collector ring or commutator (under the shoulder of the wire head) and the mica groove.
② Polishing and rounding: the outer surface of collector ring and commutator should be very smooth, generally dark brown. If burn marks, blackening or slight mechanical scratches are found, polish them. The method is to use a piece of No.00 fine glass abrasive paper (or emery cloth), then find a piece of hardwood with proper width, press the abrasive paper on the outer circular surface of the collector ring or commutator with a wooden board, and then turn the motor rotor at low speed until the outer circular surface is smooth, and finally carry out serious cleaning work.
③ The height of the mica plate between the commutator plates shall be 0.5~1.2mm lower than that of the commutator plate under normal conditions, otherwise, the lower engraving shall be considered. The method is as follows: under site conditions, a small knife with a hook at the front end can be made by using a section of a fine-tooth hand saw hacksaw blade, and gradually cut down along the mica chip groove until the height meets the requirements. The knife should be sharp, the force should be even and stable, and the polishing and cleaning should be carried out after the next carving.
④ The adjusting brush of the brush device is pressed and formed with graphite as the main material. It has good conductivity and wear resistance, but it is fragile and not resistant to heavy pressure or impact. The brush is placed in the brush holder, and it is required to move up and down freely and smoothly. There should be no obvious shaking on the left and right. The contact area between the lower end face and the collector ring or commutator should not be less than 3/4, and it should be smooth and flat. There should be no jumping during operation. The wear amount should not exceed 2/3 of the original total height of the brush. Otherwise, adjust, grind or replace the brush.
⑤ Grinding of electric brush The new electric brush or the electric brush whose contact surface has been ablated must be grinded to make it fit well with the collector ring or commutator before use. The method of grinding the contact surface is: use a piece of No.00 abrasive paper, let the sanded side face the brush, put the sand-free side on (preferably stick to) the outer circle of the collector ring or commutator, and let the brush spring press the brush tightly, and turn the rotor counterclockwise in the direction of normal operation of the motor until more than 80% of the lower end face of the brush is in close contact with the outer circle of the collector ring. After the brush is grinded, its installation direction or brush holder should not be changed. Before formal use, it shall undergo 2~3min no-load running-in, and then gradually increase the electrical load.
2、Overall inspection and cleaning of bearings: the rotors of small and medium-sized motors generally use rolling bearings, which are lubricated with grease. Generally, ZGN-3 calcium base grease is used for ordinary motors, and ZL-3 lithium base bearing grease is used for damp and hot motors. Generally, when the motor runs continuously for about 1500h, the lubricating grease should be replaced to ensure the normal operation of the motor.
The working quality of the bearing directly affects the operation reliability of the motor. Therefore, attention should be paid to maintenance.
For intact bearings, use a feeler gauge to measure the fit clearance between the inner and outer circles of the bearing and the ball (column) under the site conditions. No shaking is detected. All parts shall be in good appearance, without damage, corrosion and crack, and the rolling contact surface roundness and surface roughness shall be good. When the inner ring is held and the outer ring is pulled, it shall rotate flexibly and quickly, and the sound shall be uniform and free of noise.
3、 Check the insulation of the motor and each winding: comprehensively check the insulation of the motor and each winding, and check the electrical and mechanical connections.
After maintenance and repair, recheck whether the electrical connection and mechanical installation of the motor are correct and firm, and use dry compressed air to blow all parts inside the motor. Finally, according to the normal startup and operation requirements, carry out no-load and load tests to determine whether it is intact.
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