This technological instruction for the repair of main, tap-off, backup transformers, power plant autotransformer and main transformers (hereinafter referred to as transformers) describes the individual operations and the process of current repair of transformers as a whole, indicating the types of equipment and technological equipment that can be used during operations and is intended for the repair personnel of the power plant during the organization and conduct of current repairs of transformers. For the transformers repair these are the information that you need.
The list of documents on the basis of which the instruction is made
To make sure that the lifting mechanism and its brakes are working properly, the active part is raised 100-200 mm from the bottom of the tank, kept on weight for several minutes and lowered. Then, during factory repair, the active part is completely removed from the tank, installed on the oil drain grate in the oil pan of the washing section and washed with a stream of warm dry transformer oil. When repairing under non-stationary conditions, the active part is removed to a position convenient for washing it above the tank. Before washing, they inspect it, paying attention to the places of sediment deposition and contamination in the windings, on the core and in the channels.
Washing of the active part is carried out from top to bottom. Thoroughly flush the channels of the windings and the magnetic system, as well as other parts of the transformer available for flushing. After washing and draining the oil, the active part is transported to a pre-prepared platform and is usually lowered onto wooden blocks placed in a baking sheet so that it occupies a stable vertical position. Next, the slings are released and the repair of the active part, cover, tank, radiators and other parts of the transformer is started. As a rule, the active part and the tank are repaired at the same time so as not to delay its installation in the tank and filling it with oil, minimizing the time spent in the air.
Repair Of Windings
With an average repair, they check the quality of the winding compaction, the absence or presence of their deformation or displacement with respect to the normal position, the serviceability of the rations and assess the condition of the coil insulation; integrity, mechanical strength and color. Weakening of the compact is easy to detect if the insulating gaskets and parts of the end insulation are tried to be moved by hand: if the compact is weak, they will move. For transformers of dimensions I and II, the windings are pressed with yoke beams by temporarily loosening the upper yoke retention pins and tightening the nuts 2 of the vertical pressing pins 4, tightening the upper yoke beams with the lower ones.
With significant drying of the insulation, unequal axial dimensions of the HV and LV windings and poor pressing of the internal windings, additional insulation in the form of rings and gaskets is laid in them and pressed with vertical studs.
The windings of transformers of old releases that do not have special pressing devices are pressed in by the wedging method. It lies in the fact that in the upper part of the windings between the equalizing and yoke insulation, additional insulating gaskets wedges made of previously dried pressed electric cardboard or getinaks are driven in. One row of gaskets is wedged alternately after another, evenly bypassing the windings but the entire circumference.