CN209673982U - Balanced windings for secondary circuits of standard current transformers - Google Patents

Abstract

The utility model discloses a balance winding for a secondary circuit of a standard current transformer, which is composed of two sections of winding symmetrically arranged on the circumference of an iron core. Each section of winding is connected in series with reverse polarity, and each winding occupies 1/4 of the circumference of the iron core, with the same number of turns. The reverse polarity connection of the balance winding, the electromotive force induced by the main magnetic flux in it is zero, and has no effect on the secondary winding, but it balances the magnetic flux from phase A entering the iron core from point a to point b flowing out, achieving a balanced external magnetic field common purpose. Add a balance winding to the secondary circuit of each standard current transformer, so that the magnetic flux generated by the current of the adjacent phase standard current transformer will generate two electromotive forces with opposite polarities in this phase, and the two electromotive forces will cancel each other out, further eliminating Interference between phase magnetic field and primary circuit electromagnetic field.

Description

Balanced windings for secondary circuits of standard current transformers

technical field

The utility model relates to a secondary circuit and a balance winding of a standard current transformer, in particular to a balance winding used for the secondary circuit of a standard current transformer.

Background technique

At present, three-phase combined transformers are widely used in distribution network power metering devices with a voltage level of 3kV to 35kV. They have the characteristics of large quantity, wide application, and great influence. To the safe operation and economic benefits of the power sector, the good operation quality and good error characteristics of the three-phase combined transformer are of great significance to ensure the safe and stable operation of the power grid and the accuracy and fairness of power trade.

D/L 448-2016 "Technical Management Regulations for Electric Energy Metering Devices" stipulates that current transformers and voltage transformers in operation should be inspected regularly on site. Therefore, on-site inspections must also be carried out regularly for operating three-phase combined transformers. Relevant standards such as the machinery industry standard JB/T10432-2016 "Three-phase combined transformer" stipulate that the three-phase method should be used to carry out the error detection of the three-phase combined transformer, that is, the error test of the three-phase combined transformer should be performed after applying three-phase carried out in the case of voltage and three-phase current.

When using the three-phase method to carry out on-site error detection for three-phase combined transformers, three (three-phase) high-voltage standard current transformers are required. Due to the limited field test site, in order to reduce the area of test equipment, three The error detection of the phase combination transformer increases the versatility of the test equipment, so the three-phase common box-type standard current transformer is particularly necessary.

The three-phase common box-type high-voltage standard current transformer can be applied to the accurate detection of the current transformer error in the three-phase combined transformer, and the influence of the magnetic field generated by the adjacent phase standard current transformer on the standard current transformer error must be solved. question. The researchers analyzed the influence of external current and magnetic field on the error of the current transformer, and pointed out that the external current and magnetic field will significantly affect the transmission characteristics of the current transformer. Since the distance between each phase of the three-phase common box-type high-voltage standard current transformer is relatively close, and the accuracy level of the standard current transformer is high, it is necessary to solve the influence of the magnetic field on the error of the standard current transformer.

Utility model content

In order to solve the influence of the magnetic field in the prior art on the error of the standard current transformer, the utility model provides a balance winding and installs it on each standard current transformer, so that the magnetic field lines generated by the current of the adjacent phase standard current transformer are generated in this phase Two electromotive forces with opposite polarities, and the two electromotive forces cancel each other, further eliminating the interference of the interphase magnetic field and the primary circuit electromagnetic field.

The utility model is realized through the following technical solutions:

The balance winding used for the secondary circuit of the standard current transformer includes an iron core arranged in the secondary circuit of the standard current transformer, on which two sections of winding are arranged symmetrically, and the two sections of winding are connected in series with opposite polarities, each The segment winding occupies 1/4 of the circumference of the iron core.

The utility model installs a balance winding on the secondary circuit of each standard current transformer, so that the magnetic flux generated by the current of the adjacent phase standard current transformer generates two electromotive forces with opposite polarities in this phase, and the two electromotive forces cancel each other , to further eliminate the interference of the interphase magnetic field and the primary circuit electromagnetic field.

Further, in order to achieve a better effect of balancing the magnetic flux, the number of turns of the two sections of windings is the same to balance the magnetic field on the iron core, so that the electromagnetic field interference passes through the iron core evenly.

Further, on the balance winding arranged on the edge, the number of turns of the two windings is different, and when the three phases are charged at the same time, when the outermost phase uses the balance winding, the magnetic field density will be different, It is better to use two winding sections with different numbers of turns.

Further, the shape of the iron core is a ring, and the two windings are arranged in the horizontal direction of the ring.

Further, the radius of the inner circle of the annular iron core is 1/2 of the radius of the outer circle.

Further, the shape of the iron core is a rectangular ring, and the two windings are respectively arranged on two mutually parallel sides of the rectangular ring.

Compared with the prior art, the utility model has the following advantages and beneficial effects:

1. The utility model is used in the balance winding of the secondary circuit of the standard current transformer to effectively avoid the influence of the error of the standard current transformer when the adjacent phase standard current transformer flows through the current;

2. The utility model is used in the balance winding of the secondary circuit of the standard current transformer, which is safe, reliable and low in cost;

3. The utility model is used for the balance winding of the secondary circuit of the standard current transformer and is easy to install.

Description of drawings

The drawings described here are used to provide a further understanding of the embodiments of the utility model, constitute a part of the application, and do not constitute a limitation to the embodiments of the utility model. In the attached picture:

Figure 1 is a pair of windings used to balance the A-phase current;

Figure 2 is a front view of the layout of a three-phase common box-type standard current transformer;

Figure 3 is a side view of the layout of a three-phase common box-type standard current transformer.

Marks and corresponding parts names in the attached drawings:

1-current booster, 2-standard current transformer.

Detailed ways

In order to make the purpose, technical solutions and advantages of the utility model clearer, the utility model will be further described in detail below in conjunction with the examples and accompanying drawings. The schematic implementation of the utility model and its description are only used to explain the utility model Novelty, not as a limitation to the utility model.

Example 1

As shown in Figures 1 and 3, the balanced winding is composed of two sections of windings arranged symmetrically on the circumference of the iron core. Each section of winding is connected in series with opposite polarity. Each winding occupies 1/4 of the circumference of the iron core and has the same number of turns. The balance winding is connected in reverse polarity, the electromotive force induced by the main magnetic flux is zero, and has no effect on the secondary winding, but it balances the magnetic flux from phase A entering the iron core from point a to point b flowing out, achieving a balanced external magnetic field common purpose. Add a balance winding to the secondary circuit of each standard current transformer, so that the magnetic flux generated by the current of the adjacent phase standard current transformer will generate two electromotive forces with opposite polarities in this phase, and the two electromotive forces will cancel each other out, further eliminating Interference between phase magnetic field and primary circuit electromagnetic field.

In order to make the effect of balancing the magnetic flux better, the number of turns of the two sections of windings is the same, the shape of the iron core is a ring, and the two windings are arranged in the horizontal direction of the ring to balance the windings on the iron core. Magnetic field, so that electromagnetic field interference passes through the iron core evenly

The radius of the inner circle of the annular iron core is 1/2 of the radius of the outer circle.

Example 2

The two-stage windings are set with different numbers of turns, which is used when the three phases are charged at the same time. When the outermost phase uses a balanced winding, the magnetic field density will be different, and the effect of using two-stage windings with different turns is better. it is good.

Example 3

The shape of the iron core is a rectangular ring, and the two windings are arranged on two parallel sides of the rectangular ring respectively, which is convenient for installation and use in the transformer.

Example 4

As shown in Figures 2 and 3, Figure 2 is the front view of the layout of the high-voltage standard current transformer, and Figure 3 is the side view of the layout of the high-voltage standard current transformer. Transformer) includes A phase, B phase, and C phase three phases, each phase is provided with a current booster 1 and a standard current transformer 2, the balance winding is arranged on the standard current transformer 2, and the balance winding is specifically installed On the secondary circuit of the standard current transformer 2, the magnetic field lines generated by the current of the adjacent phase standard current transformer generate two electromotive forces with opposite polarities in this phase, and the two electromotive forces cancel each other out, further eliminating the interphase magnetic field and the primary circuit Electromagnetic field interference.

The specific embodiments described above have further described the purpose, technical solutions and beneficial effects of the present utility model in detail. Within the protection scope of the utility model, any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the utility model shall be included in the protection scope of the utility model.

Claims (6)

1. being used for the balance winding of standard current transformer secondary circuit, which is characterized in that including being arranged in normalized current mutual inductance The iron core of device secondary circuit is symmetrically arranged with two sections of windings, two sections of windings in series, and two sections of winding polarity phases on the iron core Instead, every section of winding accounts for the 1/4 of iron core perimeter.

2. the balance winding according to claim 1 for standard current transformer secondary circuit, which is characterized in that described The number of turns of two sections of windings is identical.

3. the balance winding according to claim 1 for standard current transformer secondary circuit, which is characterized in that described The number of turns of two sections of windings is different.

4. the balance winding according to claim 1 for standard current transformer secondary circuit, which is characterized in that described The shape of iron core is annulus, and described two windings are respectively provided with the horizontal direction of annulus.

5. the balance winding according to claim 4 for standard current transformer secondary circuit, which is characterized in that described The radius of the iron core inner circle of circular ring shape is the 1/2 of the radius of outer circle.

6. the balance winding according to claim 1 for standard current transformer secondary circuit, which is characterized in that described The shape of iron core is straight-flanked ring, and described two windings are respectively set on two sides being parallel to each other of straight-flanked ring.