Test method for assessing transformer oil surface breakdown voltage

Abstract

The invention discloses a test method for assessing transformer oil surface breakdown voltage, and belongs to the technical field of power insulated oil insulation performance assessment. Parts of an electrode cup are cleaned, dried and assembled, a sample plate is placed on the bottom plate of the electrode cup, and vacuum drying processing needs to be carried out on the sample plate; a sampler measures the processed transformer oil, the transformer oil, is injected in the electrode cup body, the injection amount needs to be enough so as to ensure overall electrode rods and electrode heads to be fully immersed in the oil sample, and during the injection process, bubbles on the upper surface and the lower surface of the sample plate need to be removed; the electrode cup is placed in an oil tank of a test electrode box, a hemispherical electrode head is connected with a low-voltage conductive rod of the oil tank, the low-voltage conductive rod is connected with a ground line, a semi-conic electrode head is connected with a high-voltage conductive rod of the oil tank, the high-voltage conductive rod is connected with a high-voltage generator via a voltage divider and a guarantee resistor; insulated liquid is injected in the oil tank, the overall electrode cup is fully immersed for external insulation for the electrode cup, and after an oil tank cover is covered, surface breakdown test is carried out.

Description

technical field [0001] The invention relates to a test method for evaluating the surface breakdown voltage of transformer oil, and belongs to the technical field of insulation performance evaluation of electric insulating oil. Background technique [0002] Whether it is in a power transformer or a high-voltage pulse generator, in the design of high-voltage insulation, the interface where liquid-solid insulating materials are used together is the weak link of the insulation, and flashover along the surface is prone to occur, also known as surface breakdown. The surface breakdown voltage of transformer oil is much smaller than its corresponding bulk breakdown voltage. Therefore, in the equipment using transformer oil as the insulating medium, the surface breakdown of the interface between the oil and the solid insulating support is the main cause of insulation accidents, and has become the main factor restricting the development of high-voltage equipment towards UHV miniaturiz...

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Problems solved by technology

The disadvantage of these three types of electrode models is that when adjusting the electrode gap, it is necessary to process insulating samples of different thicknesses, which is not suitable for tests under large gaps, and the operation is inconvenient. The electrode is an integrated structure. If there is damage, the repeatability of the measurement results will be poor; the plate electrode model and the needle / rod-plate electrode model are not suitable for optical measurement due to the uncertain breakdown position; the plate electrode model and the hemispherical electrode model, in the test The two ends of the surface of the product, the regional field strength distribution between the two poles is a slightly uniform electric field, and the uniform electric field cannot reflect the influence of the difference in the composition of the transformer oil on its breakdown voltage along the surface, and the polarity effect of the transformer oil

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