Oil-immersed transformer coil

Abstract

The invention discloses an oil-immersed transformer coil provided therein with a plurality of lateral oil passages, wherein each oil passage comprises two insulating struts arranged in parallel; a plurality of equally-spaced longitudinal support strips are arranged vertically in parallel over and between the insulating struts; a plurality of equally-spaced lateral support strips are arranged vertically in parallel over and along the longitudinal support strips; the sides of the lateral support strips facing the inflow of cooling oil are provided with sloped surfaces inclined to the bottom. Thecooling oil longitudinally flows in the bottom layer and converges laterally in the upper layer to form an integral body. When a high temperature exists at a certain point, the temperature of the cooling oil at the certain point of the oil passage can be laterally diffused to the surrounding oil passages to achieve rapid and uniform cooling. The cooling oil flows down along the sloped surfaces and merges with the laminar flow at the bottom layer of the oil passages to form a torrent, thereby destroying the liquid surface stability of the bottom oil film, avoiding the formation of a static oilfilm, and increasing a temperature difference between the cooling oil and the coil so as to improve the heat transfer efficiency.

Description

technical field [0001] The invention relates to the technical field of power transformers, in particular to an oil-immersed transformer coil. Background technique [0002] With the increase of single transformer capacity, the loss increases, so the heating and cooling of the transformer has become a more prominent problem. The total loss of the transformer is proportional to the 0.75th power of the capacity, while the surface area of ​​the transformer for heat dissipation is only proportional to the 0.5th power of the capacity. In this way, the increase in the heat generation of the transformer is greater than the increase in the heat dissipation surface. Therefore, large-capacity transformers need to form thicker oil passages between the coils to effectively cool, but the temperature of each part of the coil is different, and there will be sudden high points in some parts, and the existing oil passages are all It uses multiple parallel support bars to support between the ...

AI Technical Summary

Problems solved by technology

Therefore, large-capacity transformers need to form thicker oil passages between the coils to effectively cool, but the temperature of each part of the coil is different, and there will be sudden high points in some parts, and the existing oil passages are all It uses multiple parallel support bars to support between the coils to form several parallel gaps (that is, oil channels). As the thickness of the support bars increases, each oil channel is actually a separate channel. When a certain There is a sudden high temperature point in the position of the oil passage, and the heat can only be transferred along the direction of the oil passage, but cannot be spread laterally to the surrounding area. As a result, the temperature of the cooling oil in some oil passages is high, but the surrounding oil passages do not fully perform cooling. Phenomenon of action

Due to the friction factor between the cooled surface and the cooling medium, and the slow flow rate of the transformer oil, the flow rate of the transformer oil at the cooled surface is zero. Although the non-moving transformer oil film is very thin, the heating element and the cooling The temperature difference between the media mainly appears in this layer, so that the upper layer of transformer oil and the cooled surface cannot directly exchange heat. The existence of the static oil film will cause the temperature to show two gradient changes, thereby reducing the temperature difference. Low temperature will affect the efficiency of heat transfer. If the immobile layer is destroyed, the temperature difference will increase sharply, so this immobile layer is also a main reason for the low cooling efficiency of the coil.

Images