The Method of Equalizing the Field Strength Inside the Medium-Voltage Transformer

Abstract

The invention discloses an internal field intensity balancing method for medium-voltage mutual inductor. The method comprises the following steps: performing region partition according to a field intensity distribution situation between a primary winding and a secondary winding obtained through structural analysis of the mutual inductor; winding the outermost layer of the primary winding with semiconductor crinkled paper of different surface resistance values, wherein the semiconductor crinkled paper of lower surface resistance values is wound in regions with higher field intensities between the primary winding and secondary winding, and the semiconductor crinkled paper of larger surface resistance values is wound in regions with lower field intensities between the primary winding and secondary winding; and assembling the primary winding and the secondary winding, and filling the space between the primary winding and the secondary winding with a main insulator. Through adoption of the method, the field intensities between the primary winding and the secondary winding can be balanced; the partial discharge amount is reduced; the original structures of the primary winding and the secondary winding are kept constant; and the parameters of the medium-voltage mutual inductor are not reduced.

Description

technical field [0001] The invention relates to the technical field of transformers, in particular to a method for equalizing field strength inside a medium-voltage transformer. Background technique [0002] Transformer, also known as instrument transformer, is a general term for current transformer and voltage transformer. It can change high voltage into low voltage and high current into small current for measurement or protection system. Its function is mainly to convert high voltage or high current into standard low voltage or standard small current in proportion, so as to realize the standardization and miniaturization of measuring instruments, protection equipment and automatic control equipment. [0003] The medium voltage transformer refers to the primary side voltage of 3kV-35kV. The medium voltage transformer needs to assess the internal partial discharge. The smaller the partial discharge, the better, and the factor that affects the partial discharge is the balanc...

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Problems solved by technology

[0004] In order to prevent partial discharge, semiconductor shielding materials are often used to wrap the surface of the primary winding and the secondary winding, and no special treatment is performed to balance the electric field. For projects that require relatively high partial discharge, in order to reduce the partial discharge , often achieved by increasing the insulation distance between primary and secondary windings, this method will inevitably sacrifice other parameters, such as capacity, protection factor and accuracy reduction

Alternatively, adding a metal shield between the primary winding and the secondary winding is not only troublesome to operate, but also increases the chance of insulation breakdown

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