Maintenance process specification of the hottest t

2022-08-20
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Transformer maintenance process specification

1) the transformer is generally overhauled within 5 years after it is put into operation and every 10 years thereafter

2) if the fully sealed transformer welded along the box edge or the manufacturer has other regulations, the overhaul can be carried out only after it is determined that there is internal fault or serious leakage of the body through test and inspection combined with the operation situation

3) after bearing the outlet short circuit, the main transformer running in the power system can be overhauled in advance after comprehensive diagnosis and analysis

4) the transformer in operation should be overhauled in advance when abnormal conditions are found or internal faults are identified through tests; The transformer in normal operation is in good condition after comprehensive diagnosis and analysis, and the overhaul cycle can be appropriately extended with the approval of the chief engineer

3.1.2 transformer overhaul items

3.1.2.1 transformer overhaul items include:

1) lift the bell jar or lift out the body for maintenance

2) maintenance of coils, leads and magnetic (Electrical) shielding devices

3) maintenance of iron core, iron core fasteners (threading screw, clamp, tension belt, bandage, etc.), pressure nails, connecting pieces and grounding pieces

4) maintenance of oil tank and accessories, including casing, moisture absorber, etc

5) maintenance of cooler, oil pump, water pump, fan, valve, pipeline and other auxiliary equipment

the spot market price of imported ore stabilized; The domestic ore market is mainly stable; The billet market rose partially; The overall coke market showed a downward pattern; The overall decline of the maritime market 6) maintenance of safety protection devices

7) maintenance of oil protection device

8) calibration of temperature measuring device and gas relay

9) maintenance and test of operation control box

Researchers said that

10) maintenance of off excitation tap changer and on load tap changer

11) replacement of all sealant pads and component leakage test

12) dry the body insulation if necessary

13) transformer oil treatment or oil change

14) clean the oil tank and spray paint

15) test and trial operation after overhaul

16) technical transformation projects that can be carried out in conjunction with transformer overhaul, such as the strengthening of the mechanical strength of the oil tank, the change of the internal grounding device of the body to external grounding, the change of the safety airway to the pressure relief valve, the change of the high-speed oil pump to the low-speed oil pump, the improvement of the oil level gauge, the installation of sealing devices in the oil conservator, and the installation of bellows connectors in the gas relay

3.1.3 preparations before transformer overhaul

1) check the annual major and minor repair report and insulation preventive test report (including oil test and chromatographic analysis report) to understand the insulation condition

2) consult the operation files to understand the defects and abnormalities, the number of accidents and outlet short circuits, and the load of the transformer

3) according to the status of the transformer, prepare the overhaul technology, organization measures, and determine the maintenance items and maintenance plan

4) transformer overhaul should be arranged in the maintenance room. When there is no maintenance room on the construction site, it is necessary to take rain proof, moisture-proof, dust-proof and fire-fighting measures, clean the site and other preparations

5) conduct electrical test before overhaul, measure DC resistance, dielectric loss, insulation resistance and oil test

6) prepare spare parts and sealant pads for replacement

7) prepare oil filtering equipment and oil storage tank

3.1.4 overhaul site conditions and process requirements

1) the bell jar (or body) should generally be carried out indoors to keep the body clean; If it is carried out in the open air, it should be carried out on a sunny day; The exposure time of the body to the air shall be as follows: when the relative humidity of the air is not greater than 65%, it shall not exceed 16h; Not more than 12h when the relative humidity of the air is not more than 75%; The exposure time is calculated from the time when the transformer discharges oil until the vacuum pumping starts

2) in order to prevent condensation on the body, the body temperature should not be lower than the ambient temperature, otherwise the vacuum oil filter should be used to heat the oil circularly and heat the transformer to make the body temperature more than 5 ℃ higher than the ambient temperature

3) the inspection of the machine body should be carried out by a specially assigned person, and the clothes should comply with the regulations. Safety voltage shall be adopted for lighting. It is not allowed to put the ladder against the ring or lead, and the operators are not allowed to step on the coil and lead

4) the tools used for body inspection should be kept by a specially assigned person and numbered and registered to prevent them from being left in the oil tank or on the body; Ventilation should be considered when working in the box

5) the disassembled parts should be cleaned and kept properly by classification. If they are damaged, they should be repaired or replaced

6) disassembly sequence: first dismantle small instruments and casings, and then dismantle large components; Assemble in reverse order

7) after the cooler, pressure relief valve 1g=9.8m/s2 (or safety airway), oil purifier, oil conservator and other components are removed, they should be sealed with cover plates, and the lifting seat with current transformer should be filled with qualified transformer oil (or other moisture-proof sealing measures should be taken)

8) casing, oil level gauge, thermometer and other vulnerable parts should be properly kept after removal to prevent damage and moisture; Capacitive bushing should be placed vertically

9) after assembly, check the cooler, oil purifier and gas relay valves, and open or close them as required

10) exhaust the upper vent holes of casing riser, upper pipe hole cover, cooler and oil purifier for many times until they are exhausted, and reseal them and wipe oil stains

11) when disassembling the operating lever of the off excitation tap changer, the position of the tap changer shall be recorded and marked; When disassembling the on load tap changer, the tap position shall be in the middle position (or according to the regulations of the manufacturer)

12) all parts of the assembled transformer shall be intact

3.1.5 precautions for on-site lifting

1) the lifting work should be clearly divided, commanded by a specially assigned person and have a unified signal. The lifting equipment should be selected according to the weight of the transformer bell cover (or body) and supervised by a specially assigned person

2) remove various connectors that affect the lifting work before lifting

3) when lifting the iron core or bell jar (body), the steel wire rope should be hung on the special lifting point, and the included angle of the steel wire rope should not be greater than 60 ℃. Otherwise, the sling should be used or the steel wire rope sleeve should be adjusted. When the lifting is about 100mm above the ground, it should be suspended, and the lifting situation should be checked, and the lifting can be continued after it is confirmed to be reliable

4) the lifting or landing speed should be uniform, the center of gravity should be well controlled, and the cable should be tied at the four corners, supported by a specially assigned person to make it take off and land smoothly. There should be a certain gap between the high and low voltage side leads, the tap changer support and the box wall to avoid hurting the body. Bell jar (body

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