CN203812718U - Three-phase integrated current transformer - Google Patents

Abstract

The utility model relates to the technical field of electrical apparatus elements, in particular to a three-phase integrated current transformer. The three-phase integrated current transformer comprises a housing, an annular zero-sequence iron core, a zero-sequence winding, phase-sequence winding channels and an epoxy resin filling block. The annular zero-sequence iron core sleeves the phase-sequence winding channels and comprises microcrystalline iron core and a silicon steel iron core which are stacked up together. A composite iron core is formed by the silicon steel iron core and the microcrystalline iron core. The three-phase integrated current transformer has following beneficial effects: in the case of high saturation current of the zero-sequence winding, the saturation point of primary current of the zero-sequence winding is effectively enhanced due to high magnetic induction intensity of the silicon steel iron core so that secondary induced current is increased proportionally as primary current is above rated current, resulting in improved saturation performance of the transformer and supply of accurate date to a next-stage measuring and protecting device in order to enhance accuracy and safety of an electric system; and measurement accuracy of the transformer is ensured due to high magnetic conductivity of the microcrystalline iron core.

Description

A three-phase integrated current transformer

technical field

The utility model relates to the technical field of electrical components, in particular to a three-phase integrated current transformer.

Background technique

In recent years, with the implementation of the smart grid, the miniaturization trend of the entire power system has become more and more obvious. The three-phase integrated current transformer in the ring network switchgear and the column switchgear has also been vigorously developed. This three-phase integrated current transformer usually has three phase-sequence winding channels (phase-sequence winding channels are used to place phase-sequence windings) in the shell, and the zero-sequence iron core is sleeved on the three phase-sequence winding channels , and then pour insulating material into the shell to form, so that the measurement and protection of the three-phase current and zero-sequence current are integrated into a single transformer to meet the miniaturization requirements of the three-phase integrated current transformer.

However, in the traditional three-phase integrated transformer, the material of the zero-sequence iron core is generally a single microcrystalline iron core. Due to the limitation of the overall structure size, the height of the zero-sequence iron core is also subject to certain restrictions. Although the sequence iron core design method can guarantee the measurement accuracy and precision, its saturation performance is low, and it can only meet the conventional protection level and requirements. When the zero-sequence winding in the current transformer is required to have a higher saturation current (such as the primary saturation current) in the power system, this design method cannot meet the requirements, thus causing hidden dangers to the stability and safety of the power system.

Therefore, aiming at the above deficiencies, the utility model provides a three-phase integrated current transformer.

Utility model content

(1) Technical problems to be solved

The purpose of the utility model is to provide a three-phase integrated current transformer to ensure its measurement accuracy and improve the primary saturation current of the zero-sequence winding in the current transformer.

(2) Technical solutions

In order to solve the above technical problems, the utility model provides a three-phase integrated current transformer, which includes a shell, an annular zero-sequence iron core, a zero-sequence winding, a phase-sequence winding channel and an epoxy resin filling block, and the phase-sequence The winding channel passes through the casing, the annular zero-sequence iron core is sleeved on the phase-sequence winding channel, the zero-sequence winding is wound on the zero-sequence iron core, and epoxy resin is poured into the casing to form an epoxy resin filling block to The ring-shaped zero-sequence iron core is sealed in the casing, and the ring-shaped zero-sequence iron core includes a silicon steel core and a microcrystalline iron core stacked together, and an insulating layer is arranged between the silicon steel core and the microcrystalline iron core.

Wherein, the ring-shaped zero-sequence iron core includes two semicircular segments at both ends and a straight connecting segment connecting the two semicircular segments.

Wherein, the height of the housing is less than or equal to 85mm.

Wherein, the height of the silicon steel core is 20-25mm.

Wherein, the microcrystalline iron core has a height of 20-25 mm.

Wherein, the height of the insulating layer is 3-6 mm.

Wherein, the silicon steel core is pasted on the bottom of the shell.

Wherein, the outer surface of the housing is provided with mounting bolts.

(3) Beneficial effects

The above-mentioned technical solution of the utility model has the following advantages: in the three-phase integrated current transformer provided by the utility model, the ring-shaped zero-sequence iron core is sleeved on the phase-sequence winding channel, and the ring-shaped zero-sequence iron core includes A microcrystalline iron core and a silicon steel core together, an insulating layer is set between the microcrystalline iron core and the silicon steel core, and the silicon steel core and the microcrystalline iron core form a composite core. When the zero-sequence winding has a high saturation current, Due to the high magnetic induction intensity of the silicon steel core, it can effectively increase the saturation point of the primary current of the zero-sequence winding, so that when the primary current is higher than the rated current, the secondary induced current can still increase proportionally, thereby improving the saturation performance of the transformer. Provide accurate data for lower-level measurement and protection devices, improve the accuracy and safety of the power system, and at the same time, due to the high magnetic permeability of the microcrystalline iron core, the measurement accuracy of the transformer can be guaranteed.

Description of drawings

Fig. 1 is the perspective view of the three-phase integrated current transformer of the utility model embodiment;

Fig. 2 is the top view of Fig. 1;

Fig. 3 is a cross-sectional view along line A-A of Fig. 2 .

In the figure, 1: shell; 2: annular zero-sequence iron core; 3: phase-sequence winding channel; 4: epoxy resin filling block; 5: zero-sequence winding terminal; 6: bolt assembly; 201: silicon steel core ; 202: microcrystalline iron core; 203: insulating layer.

Detailed ways

The specific implementation of the present utility model will be further described in detail below in conjunction with the accompanying drawings and examples. The following examples are used to illustrate the utility model, but not to limit the scope of the utility model.

In the description of the present invention, it should be noted that the orientations or positional relationships indicated by the terms "upper", "lower", "top", "bottom", "inner" and "outer" are based on those shown in the accompanying drawings. Orientation or positional relationship is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation of the present invention.

As shown in Figure 1, Figure 2 and Figure 3, the three-phase integrated current transformer provided by the utility model includes a shell 1, an annular zero-sequence iron core 2, a zero-sequence winding, a phase-sequence winding channel 3 and a ring Oxygen resin filling block 4, the phase sequence winding channel 3 passes through the shell 1, the phase sequence winding channel 3 is pipe-shaped, which is integrally formed with the shell 1, and the annular zero-sequence iron core 2 is sleeved on the phase sequence winding channel 3 , the zero-sequence winding is wound on the zero-sequence iron core, and epoxy resin is poured into the casing 1 to form an epoxy resin filling block 4 to seal the ring-shaped zero-sequence iron core 2 in the casing 1, and the ring-shaped zero-sequence iron core The core 2 includes a microcrystalline iron core 202 and a silicon steel core 201 stacked up and down. The silicon steel core 201 is attached to the bottom of the housing 1, and an insulating layer is provided between the microcrystalline iron core 202 and the silicon steel core 201. layer 203, so as to avoid short circuit between the silicon steel core 201 and the microcrystalline iron core 202, which will affect the performance of both. Among them, the silicon steel core 201 is made of high-quality silicon steel sheet to ensure a high accuracy limit coefficient, which can effectively increase the saturation point of the primary current; Conductivity, low saturation magnetic induction and excellent stability. Wherein, the positions of the silicon steel core 201 and the microcrystalline iron core 202 are interchangeable; the zero sequence winding terminal 5 is arranged on the side of the housing 1 .

In the above technical solution, the annular zero-sequence iron core 2 is sleeved on the phase-sequence winding channel 3, and the annular zero-sequence iron core 2 includes a silicon steel core 201 and a microcrystalline iron core 202 stacked together up and down. 201 and microcrystalline iron core 202 form a composite iron core. When the zero-sequence winding has a high saturation current, due to the high magnetic induction intensity of the silicon steel core 201, it can effectively increase the saturation point of the primary current, making the primary current higher than the rated current. Under certain circumstances, the secondary induced current can still increase proportionally, providing accurate data for the lower-level measurement and protection devices, improving the accuracy and safety of the power system, and at the same time, due to the high magnetic permeability of the microcrystalline iron core 202, the transformer’s measurement accuracy.

Among them, the epoxy resin can be vacuum-cast in the flame-retardant plastic shell 1 to form the epoxy resin filling block 4, which can prevent moisture, make the performance of the transformer stable, and require no maintenance.

Specifically, the annular zero-sequence iron core 2 is in the shape of a track and field sports track, and the annular zero-sequence iron core 2 includes two semicircular segments at both ends and a straight connecting segment connecting the two semicircular segments. Among them, the length of the outer ring of the track-and-field track-shaped zero-sequence iron core is 421mm, and the length of the inner ring is 389mm; the width of the outer ring of the track-and-field track-shaped zero-sequence iron core is 151mm, and the width of the inner ring is 119mm. This structural setting of the annular zero-sequence iron core 2 can make the structure more compact under the premise of ensuring the working performance of the transformer.

Generally, the height of the housing 1 is less than or equal to 85mm. In this way, the requirements of the overall structure size of the transformer can be met, for example, various installation requirements of the FZW28 pole-mounted switchgear can be met. Wherein, the height of the silicon steel core 201 is preferably 20-25 mm; the height of the microcrystalline iron core 202 is preferably 20-25 mm; the height of the insulating layer 203 is preferably 3-6 mm. Such a structural setting can ensure that the transformer is in an excellent working condition, and ensure the saturation performance and detection accuracy of the transformer.

The outer surface of the housing 1 is provided with a bolt assembly 6 to facilitate the installation of the transformer of the present invention.

The three-phase integrated current transformer of the utility model is especially suitable for ring network switch cabinets and column switches, and can meet corresponding technical indicators. The transformers used in the FZW28 and ZW20 pole-mounted switches generally require that the transformers be able to make the primary current reach 3 times the rated primary current and still not be saturated. Among them, the zero-sequence winding is controlled within 50mm height; the transformer's The rated primary current is 20A, correspondingly, the rated value of the secondary current is 1A; the secondary load is 0.5Ω.

After actual tests, the current transformer with composite iron core (LSZ135-110, zero sequence 20/1) can meet the corresponding technical indicators compared with the current transformer with single iron core (LSZ135-110, zero sequence 20/1) . Specifically, for a current transformer with a single iron core, its secondary current has increased disproportionately after the primary current is 40A. After testing, the primary current is saturated when it is about 30A, which is less than 3 times the rated current of 60A. Requirements; and the use of composite iron core current transformers, the secondary current does not increase proportionally until the primary current is 80A. After testing, the primary current is saturated at about 70A, which is still unsaturated after reaching 3 times the rated current of 60A. . With the same iron core height, the primary saturation current is increased by 130% after using the composite iron core.

To sum up, in the three-phase integrated current transformer provided by the utility model, the ring-shaped zero-sequence iron core 2 is set on the phase-sequence winding channel 3, and the ring-shaped zero-sequence iron core 2 includes stacked up and down Silicon steel core 201 and microcrystalline iron core 202, silicon steel core 201 and microcrystalline iron core 202 form a composite iron core, when the zero-sequence winding has a higher saturation current, it can effectively increase the saturation point of the primary current, and further Improve the accuracy and safety of the power system. At the same time, due to the high magnetic permeability of the microcrystalline iron core 202, the measurement accuracy of the transformer can be ensured; Under the premise, the structure can be made more compact; epoxy resin can be poured into the shell 1 to form epoxy resin filling block 4, which can prevent moisture, make the performance of the transformer stable, and require no maintenance; use silicon steel core 201 and microcrystalline iron The core 202 forms a composite iron core, which can not only ensure the saturation performance of the transformer, but also meet the accuracy requirements.

The above is only a preferred embodiment of the utility model, it should be pointed out that for those of ordinary skill in the art, without departing from the technical principle of the utility model, some improvements and modifications can also be made. And modification should also be regarded as the protection scope of the present utility model.

Claims (8)

1. A three-phase integrated current transformer, characterized in that: it includes a housing, an annular zero-sequence iron core, a zero-sequence winding, a phase-sequence winding channel and an epoxy resin filling block, and the phase-sequence winding channel passes through the shell body, the ring-shaped zero-sequence iron core is sleeved on the phase-sequence winding channel, the zero-sequence winding is wound on the ring-shaped zero-sequence iron core, and epoxy resin is poured into the shell to form an epoxy resin filling block, so that the ring-shaped zero-sequence The sequence iron core is sealed in the casing, and the ring-shaped zero-sequence iron core includes a silicon steel core and a microcrystalline iron core stacked together, and an insulating layer is arranged between the silicon steel core and the microcrystalline iron core. 2 . The three-phase integrated current transformer according to claim 1 , wherein the annular zero-sequence iron core includes two semicircular sections at both ends and a straight connecting section connecting the two semicircular sections. 3. The three-phase integrated current transformer according to claim 1, characterized in that: the height of the housing is less than or equal to 85mm. 4. The three-phase integrated current transformer according to claim 1, characterized in that: the silicon steel core has a height of 20-25mm. 5. The three-phase integrated current transformer according to claim 1, characterized in that: the microcrystalline iron core has a height of 20-25mm. 6. The three-phase integrated current transformer according to claim 1, characterized in that: the height of the insulating layer is 3-6 mm. 7. The three-phase integrated current transformer according to claim 1, characterized in that: the silicon steel core is attached to the bottom of the housing. 8. The three-phase integrated current transformer according to claim 1, characterized in that: the outer surface of the housing is provided with mounting bolts.