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Routine Maintenance, Inspection Items And Requirements For Hydro Generators

July 17, 2020

Routine maintenance, inspection items and requirements for hydro-generators
1. Maintenance of generator stator:
During the overhaul of the unit, all parts of the stator should be fully inspected to deal with the problems that threaten the safe and stable operation of the unit in a timely and thorough manner. Problems such as the cold vibration of the stator core and the replacement of wire rods can generally be done in the machine pit.
The general maintenance items and precautions of generator stator are as follows:
1. Inspection of stator core lining and positioning ribs. Check the stator iron core lining, the positioning ribs should be free of loose and open welding, the tightening bolts are not loose, and there is no open welding at the spot welding place. If the stator core is loose, tighten the tightening bolts.
2. Inspection of tooth pressure plate. Check that the bolts of the tooth pressure plate should not be loose. If there is a gap between the pressure finger of the individual tooth pressure plate and the iron core, the fastening top wire can be adjusted, and if there is a gap between the individual pressure finger and the iron core, it can be locally cushioned and spot welded.
3. Inspection of the stator core combination joint. The gap between the stator core and the base is measured and checked. The base seam combined seam can not pass the inspection request with a 0.05mm feeler gauge. Local gaps are allowed. Check with a feeler gauge of no more than 0.10mm. The depth should not exceed 1/3 of the width of the combined surface, and the total length should not exceed 20% of the circumference. There should be no gaps around. If it is unqualified, the padding of the stator iron core combination joint should be carried out. The thickness of the insulation paper pad should be 0.1 to 0.3mm larger than the actual gap. After the pad is added, the iron core combination bolts are fastened, and the iron core combination seam must not have a gap.
4. When the stator is repaired, it is strictly forbidden to drop iron chips and welding slag into the gaps of the stator core, and the end of the wire bar should be prevented from being injured during shovel welding or hammering. Check that the foundation bolts and pins of the stator are not loose and the spot welding is firm.
2. Stator withstand voltage test: complete various tests in accordance with the requirements of electrical preventive tests.
3. Rotating parts: maintenance of rotor and windshield
1. Check the spot welding and structural welds of each combination bolt of the rotor, and there is no open welding, cracks, and bolts are not loose. The wheel ring should be free of looseness, the surface of the brake ring should be free of cracks and burrs, and the rotor must be free of debris and cleaned.
2. Check whether the spot welding of the magnetic pole key, the wheel arm key and the "one" key is cracked, and if necessary, repair it in time.
3. Check whether the connecting bolts and locking pads of the air distribution plate are loose, and whether the welding seam is cracked.
4. Check the fastening of the fan's fixing bolts and locking pads, and check the fan for creases for cracks, if any, they should be dealt with in time.
5. Check whether the fixing bolts of the balance weight added to the rotor are tight.
6. Check and measure the air gap of the generator. The measurement method of the air gap of the generator is: the slope of the wooden wedge or aluminum wedge is coated with chalk gray, so that the slope is inserted into the stator core, pressed with a certain force, and then pulled out to measure the slope of the wedge with a vernier caliper The thickness at is the air gap there. Note that the measurement position should be in the middle of each pole and relative to the stator core surface. It is required that the difference between each gap and the measured average gap is not greater than ±10% of the measured average gap.

4. Rotor withstand voltage test: complete all tests in accordance with the requirements of electrical preventive tests.

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V. Inspection and maintenance of upper frame:
Check the pins and wedges on the upper frame and the foundation of the stator. All the connecting bolts are not loosened. Measure the change of the horizontal center of the upper frame, measure the distance between the inner wall of the center of the upper frame and the axis, and the measurement position can be selected in four directions of X-Y coordinates. If the horizontal center changes or does not meet the requirements, the reasons should be analyzed and adjusted, and the center deviation should not be greater than 1mm. Check that the combined bolts and pins of the frame and the foundation should not be loose, and the fixed stopper is spot welded to the fixed parts. Whether the connecting bolts and locking gaskets of the air distribution plate are tight. There should be no other abnormal phenomena such as cracks and open welding at the weld. The joint surface of the frame and the stator should be cleaned, derusted and coated with anti-rust oil.