Generator maintenance method Daquan

1. Minor repair of generator

    In addition to completing the routine maintenance work, the added content is as follows.

    I. Open the window cover, if there is dust accumulated in the generator , it should be eliminated. Use dry and clean compressed air to blow off the dust in all parts of the generator. Note that the pressure should not exceed 2 atmospheres. The surfaces of each winding and the inside of the fan should also be thoroughly cleaned to maintain effective ventilation and heat dissipation.

    II. Clean the surface of the collector ring or commutator, as well as the brush and brush holder, etc., can be wiped with a soft and dry cloth dipped in a little gasoline (alcohol, kerosene, etc.), and then wipe the surface with other clean cloth, And check the wear of the brush and its contact with the collector ring (or commutator), repair or adjust if necessary, and check the size of the brush pressure at the same time, if it is not suitable, it should be adjusted.

    III. Disassemble the small end cover of the motor bearing (the one at the extension end of the shaft does not need to be removed), check the consumption and cleaning of the lubricating oil, if the oil is found to be insufficient, it should be added appropriately, and it is found that the color is uneven, hardened or contains other Metal impurities should be cleaned and replaced with lubricating oil. The method of disassembling and assembling the generator will be introduced below. The operator should master the essentials carefully to avoid damage to the generator. 

     IV. Carefully check the electrical and mechanical connections everywhere, clean and connect if necessary.

     V. The excitation and voltage regulation device of the generator shall be carried out with reference to the relevant requirements and the above-mentioned contents.

    Second, the generator repair

    In addition to completing all the contents of the minor repair, the following contents are also added.

    A. Comprehensively check the condition of the slip ring (or commutator) and the brush device, and perform necessary cleaning, trimming and measurement.

    KM cleaning job. The contacting conductive surfaces of the collector rings or commutators, brushes and brush holders should be free of oil, scale, carbon dust, bright and in good contact. When wiping, use a soft, dry, clean, lint-free cloth with a little gasoline (or alcohol). Pay particular attention to cleaning inside the brush holder and the root of the slip ring or commutator (below the shoulder of the wire head) and the mica groove.

    B. Polishing and rounding. The outer surface of the collector ring and commutator should be very smooth and generally dark brown. If burn marks, blackening or minor mechanical scratches are found, they should be polished. The method is: use a piece of No. 00 fine glass sandpaper (or emery cloth), and then find a hard board with a suitable width, use the board to press the sandpaper on the collector ring or the outer surface of the commutator, and then rotate the generator at a low speed. The rotor is ground until the outer surface is smooth, and finally the serious cleaning work is carried out.

    During the polishing operation, pay attention to cutting off the circuits of the stator and rotor windings to avoid electric shock or live operation.

    If the outer surface of the collector ring or the commutator is seriously burnt, or out of round (when it is not a normal cylindrical shape and the swing is serious), the rotor should be taken out, and the outer surface of the lathe should be turned on the lathe – repaired, and the surface roughness is not required. Below 1.6, the rounded commutator should be engraved with mica chips, and finally cleaned.

    C. Lower engraved mica sheet. The height of the mica sheet between the commutator sheets should be 0.51.2nim lower than the commutator sheet under normal conditions, otherwise the next engraving should be considered. The method is as follows: under the conditions of the site, a small-toothed hand saw hacksaw blade can be used to make a small knife with a hook at the front end, and gradually engrave along the mica groove until the height meets the requirements. The knife should be sharp at the next moment, the force should be even and steady, and it should be polished and cleaned after the next moment.

    D. Adjustment of the brush device. The brush is made of graphite as the main material. It has good electrical conductivity and wear resistance, but the texture is brittle and cannot withstand heavy pressure or impact. The brush is placed in the brush holder, and it is required to move freely and smoothly up and down. There should be no obvious shaking phenomenon on the left and right sides. The contact area between the lower end face and the collector ring or commutator is not less than 3/4, and it is smooth and flat. When there is no jumping, the wear amount should not exceed 2/3 of the original total height of the brush. Otherwise, the brushes should be adjusted, ground or replaced.

      The brushes and brush holders are matched with the collector ring or commutator, and the brand and specification should not be changed without authorization.

      Generally, the spring pressure of carbon brushes and brushes made of carbonized graphite is 0.01 to 0.025 MPa; the spring pressure of brushes made of electrochemical graphite is 0.01 to 0.04 MPa. If it is found that the brush wears too fast during use, the pressure can be appropriately reduced; if there is a large flashover phenomenon, the pressure can be appropriately increased.

      The distance between the lower end of the brush holder and the surface of the slip ring is not less than 2 to 3 nm. The connection of the soft connecting wire of the brush should not be too tight, and should be correct and firm.

    In order to improve the commutation performance, the relative position between the brush and the magnetic pole should be adjusted, the commutation magnetic pole should be installed, and the appropriate brush characteristics should be selected.

    E. Grinding of brushes. New brushes or brushes with ablated contact surfaces must be ground to make them fit well with the collector ring or commutator before they can be used.

    The method of grinding the contact surface is: use a piece of 00-grit sandpaper, let the sandy side face the brush, put the sandless side on the outer circle of the collector ring or commutator (drum stick), and Let the brush spring press the brush, and rotate the rotor counterclockwise according to the normal operation direction of the generator 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 polished, its installation direction or brush holder should not be reversed. Before the official use, it should go through 2-3min no-load running-in, and then gradually increase the electrical load.

    II. Thoroughly inspect and clean the bearing.

    The rotors of small and medium generators generally use rolling bearings, which are lubricated with grease. Usually, the universal generator uses ZGN-3 calcium-based grease, and the moist heat generator uses ZL-3 kang-based bearing grease. Under normal circumstances, when the generator runs continuously for about 1500h, the grease should be replaced to ensure the normal operation of the generator.

    The working quality of the bearing directly affects the operation reliability of the generator, so attention should be paid to maintenance and maintenance.

    The intact bearing is measured with a thickness gauge under field conditions. The matching clearance between the inner and outer circles of the bearing and the ball (column) is appropriate, and no shaking can be detected. The appearance of each part is good: no damage, no corrosion, no cracks, good roundness and surface roughness of the rolling contact surface, when holding the inner ring to dial the outer ring, the rotation is flexible and brisk, and the sound is uniform and no noise.

    The maintenance requirements for bearings are regular cleaning, inspection and regreasing.

    The cleaning method is: first take out the old grease with bamboo (wood) pieces, and use a brush dipped in gasoline or kerosene to scrub the bearing. Field conditions. Can not be removed from the shaft for cleaning. If it is removed for cleaning, it can be washed in warm oil or diesel after taking out the old grease. After brushing, rinse the bearing once with an appropriate amount of kerosene, and then add new grease.

    Adding grease must require the specified grade and quantity (generally, the amount of grease added accounts for about 1/2-2/3 of the inner volume of the bearing). Do not mix different types of grease. Not too much, not too little. Too much, the bearing dissipates poorly, and the temperature rises: too little, lubrication is not guaranteed, and wear increases.

    In addition, attention should be paid to bearing maintenance. To remove the bearing, a bearing “puller” should be used, and a hammer should not be used to knock it hard. The inner and outer covers of the generator bearing should be kept intact, the oil seal felt ring is intact, and the screws are complete and tightened. If the felt ring is damaged, it should be made and replaced with industrial felt, and cannot be replaced with soft civilian felt. Dirty, hardened (deteriorated) greases with impurities such as sand or iron filings cannot be used.

    III. Comprehensively check the windings and insulation of the generator, and check the electrical and mechanical connections.

    IV. After maintenance and overhaul, the correctness and reliability of electrical connection and mechanical installation should be re-checked, and dry compressed air should be used to blow out all parts of the generator. Finally, carry out no-load and load tests according to normal start-up and operation requirements to determine whether it is in good condition.