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The reliability of oil-immersed transformers is determined by their health status, not only depends on design and manufacturing, structural materials, but also closely related to overhaul and maintenance. Discuss the improvement of the short-circuit withstand capability of the transformer in the power system.

The oil-immersed transformer is mainly realized by power electronic technology. The basic principle is to convert the power frequency signal into a high frequency signal through the power electronic circuit on the original side, that is, up-frequency, and then couple to the secondary side through the intermediate high frequency isolation transformer. Revert to a power frequency signal, that is, frequency reduction. By adopting an appropriate control scheme to control the work of the power electronic device, the electric energy of one frequency, voltage, and waveform is transformed into the electric energy of another frequency, voltage, and waveform. Since the volume of the intermediate isolation transformer depends on the saturation magnetic flux density of the iron core material and the larger allowable temperature rise of the iron core and windings, and the saturation magnetic flux density is inversely proportional to the operating frequency, increasing its operating frequency can increase the iron core’s Utilization, thereby reducing the volume of the transformer and improving its overall efficiency.

Measures to improve the short-circuit resistance of oil-immersed transformers

The safe, economical and reliable operation and output of the transformer depend on its own manufacturing quality, operating environment and overhaul quality. This chapter tries to answer the measures to effectively prevent the sudden failure of the transformer during the operation and maintenance of the transformer.

(1) Standard design, attach importance to the axial compression process of coil manufacturing. When designing, the manufacturer should consider not only reducing the loss of the transformer and increasing the insulation level, but also the improvement of the transformer’s mechanical strength and the ability to withstand short-circuit faults. In terms of manufacturing process, since many transformers use insulating press plates, and the high and low voltage coils share a press plate, this structure requires a high level of manufacturing technology. The spacers should be densified, and after the coils are processed, Dry a single coil at a constant pressure, and measure the height of the coil after compression; each coil of the same pressure plate is processed by the above process, and then adjusted to the same height, and the oil pressure device is used to apply the specified pressure to the coil during the final assembly. The height of design and process requirements. In the general assembly, in addition to paying attention to the compression of the high-voltage coil, special attention should be paid to the control of the compression of the low-voltage coil.

(2) Conduct a short-circuit test on the transformer to prevent trouble before it happens. The operational reliability of large transformers firstly depends on its structure and manufacturing process level, and secondly, various tests are carried out on the equipment during operation to grasp the working conditions of the equipment in time. To understand the mechanical stability of the transformer, it can be improved through the short-circuit test to ensure that the structural strength of the transformer is well known.

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Post time: Nov-30-2021