Zero-sequence current transformer and manufacturing method thereof

Abstract

The invention provides a zero sequence current transformer and a manufacturing method thereof. The zero sequence current transformer comprises an annular casing, a current transformer coil and a mounting base. The manufacturing method includes following steps: selecting a soft cold-rolled sheet and punching the same into the casing; selecting a cold-rolled selenium steel sheet and punching and shearing the same into a strip material and winding the strip materials into an annular iron core, and then carrying high-temperature process and paint immersion process to the iron core; uniformly wrapping the annular iron core with a polyimide adhesive tape; winding the annular iron core of above specification with an enamelled wire by using a winding machine so as to obtain a zero sequence current transformer coil; assembling the wound zero sequence current transformer coil in the casing to obtain the zero sequence current transformer; and testing the assembled zero sequence current transformer. The zero sequence current transformer manufactured by manufacturing process is more perfect in various technical performances, so that the zero sequence current transformer has the advantages of high sensitivity, fine balance feature, high safety, low manufacturing cost, long service life and high practicability, and safe operation of aftercurrent action protection products is well guaranteed.

Description

technical field [0001] The invention relates to a current transformer, in particular to a zero-sequence current transformer and a manufacturing method thereof. Background technique [0002] In the low-voltage lines of distribution transformers used in the vast rural areas of our country, the residual current operating protector has been widely used. However, due to the difference in the manufacturing process of the key detection component of the residual current operating protector, the zero-sequence current transformer makes this Such products can not receive good protection effect. For example: the zero-sequence current transformer made of high magnetic permeability magnetic material has high cost. Although the sensitivity and balance characteristics are good, the magnetic coercive force is poor. When a high-current metallic short circuit occurs in a low-voltage three-phase four-wire line When it is grounded, it will inevitably form a large current closed loop in the zero...

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Problems solved by technology

[0002] In the low-voltage lines of distribution transformers used in the vast rural areas of our country, the residual current operating protector has been widely used. However, due to the difference in the manufacturing process of the key detection component of the residual current operating protector, the zero-sequence current transformer makes this Such products can not receive good protection effect

For example: the zero-sequence current transformer made of high magnetic permeability magnetic material has high cost. Although the sensitivity and balance characteristics are good, the magnetic coercive force is poor. When a high-current metallic short circuit occurs in a low-voltage three-phase four-wire line When it is grounded, it will inevitably form a large current closed loop in the zero-sequence current transformer circuit, which will easily cause magnetic saturation of the iron core in the zero-sequence current transformer, resulting in the refusal of the residual current action protector; it is made of ordinary silicon steel sheet magnetic material Zero-sequence current transformers are low in cost, but have poor sensitivity and balance characteristics. When a large unbalanced current occurs in a low-voltage three-phase four-wire line, the residual current action protection will be caused due to the poor balance characteristics of the zero-sequence current transformer. frequent malfunction

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