In a large-scale thermal power plant, the electricity generated by a generator is boosted by a transformer, and the electric energy is transmitted over a long distance and transmitted to each user in the social power network. In this paper, the construction method and process of the installation and commissioning of a large-scale transformer in a thermal power plant are described, and the installation and commissioning techniques of the power transformer are preliminarily discussed.
1, the preparation of the transformer before installation
In the power plant construction, when the power transformer is installed in place, due to the large size of the transformer, when checking the dimensions, the center position and the direction of the entrance and exit lines must be confirmed accurately. When the design requirements are met, the transformer can be fixed on the basis of the transformer. on. The electrical installation regulations stipulate that the transformer equipped with the gas relay shall have a gradient of 1% to 1.5% in the airflow direction of the gas relay. The purpose of the transformer is to facilitate the flow of gas into the fuel tank to flow into the relay to form a protective action. . When the transformer is in place, it should be confirmed that the impact value of the transformer impact recorder should be less than 5g of the gravitational acceleration. If it is greater than the time, the manufacturer should be contacted for processing advice. Inject nitrogen moisture protection: If the transformer is not installed in time, in order to prevent the internal body of the transformer from damp, 99.99% of high-purity nitrogen gas should be injected into the box. The nitrogen pressure is 0.01-0.03 MPa. After the injection, the nitrogen gas traces on time. Monitor and make appropriate written records. When the pressure value is lower than 0.01MPa, nitrogen should be added in time.
2, transformer body inspection
2.1 transformer body inspection procedures and methods. Exhaust nitrogen. In nitrogen-filled transformers, during inspection of the body, clear, airless, and air-dry weather should be selected. Manhole doors should be opened and the pressure of nitrogen in the fuel tank should be relieved. After being ventilated for 30 minutes, personnel should wear unfastened fasteners. Work clothes and boots are taken from the manhole into the tank for inspection. Body check content. When the transformer is installed, the body is exposed to air for no more than 16 hours. The tools and tools used must have special personnel to look after them, register them and make good records. The main contents of the body examination: The transport support and body parts should be free from movement and deformation. The internal bolts should be well-fastened. The cores, clamps, iron yoke and other components should be well insulated; the internal insulation is tightly tied and there is no damage; the lead wire insulation distance is qualified. No excitation voltage regulator switching device, each tap and the indicator point the same position, good contact conductivity. The rotating plate should be flexible and sealed. Check the bottom of the tank for grease, debris and water. 2.2 transformer body test. After the inspection, conduct tests: iron core insulation measurement; measure winding high and low voltage side and insulation resistance to ground; measure winding DC resistance; measure the change of transformer, its error should be less than 0.5%.
3, body attachment installation
The exposed mounting accessories shall meet the following requirements: The relative humidity of the environment shall be less than 75%. During the installation process, dry air with a dew point of less than -40Â°C shall be continuously added to the cabinet. The opening area is covered with a plastic film and the continuous exposure time should not exceed 8 hours. After the work is done every day, a vacuum is added to supplement dry air 0.01-0.03 MPa.
Sealing: All flange connections are well-applied and well-sealed.
Installation of cooling device: The cooling device shall be filled with 99.99% high-purity nitrogen gas of 0.03 MPa before installation. No leakage shall occur for 30 min. And use qualified insulating oil to flush the interior and drain the residual oil. The fan motor and blades should be firmly installed and the rotation should be flexible. The valves in the pipeline should be flexible and correct, and the connections should be well sealed. External oil lines should be cleaned. Sealed oil pump, good oil flow relay, correct steering, no abnormal noise and overheating.
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