KR101192609B1 - Mof for reliability improvement - Google Patents

Abstract

PURPOSE: A metering outfit for improving reliability is provided to reliably measure power by including an independent iron core at a coil of each phase. CONSTITUTION: A transformer(130) is arranged in an enclosure(110) and includes a primary coil, a secondary coil, and an iron core. The secondary coil passes through the primary coil. The iron core passes through the secondary coil. A bushing is located on the upper side of the enclosure.

Description

Transformer current transformer for instrument improvement {ＭＯＦ for reliability improvement}

The present invention relates to a transformer current transformer (MOF) for the inflow instrument, in particular to have a magnetically independent structure so that the magnetic flux generated in each phase of the transformer (PT) in the transformer current transformer (MOF) does not overlap each other. It relates to a transformer transformer current transformer for improving the reliability by allowing the discharge characteristics to be improved.

Typically, metering out transformers (MOFs) for power supply and supply use high voltages and currents in transmission and distribution lines for use in combination with power supply meters, reactive power meters (VARHM), or maximum demand meters (DM). It is an electric device that denatures precisely (within 5% of error) with low voltage and current. This is a necessary equipment for the accurate calculation and collection of electricity bills based on the measurement of the amount of power used by industrial consumers, that is, relatively large consumers, such as factories and buildings.

On the other hand, the transformer transformer current transformer (MOF) is provided with a potential transformer (PT) for converting a high voltage to a low voltage, and a current transformer (Current Transformer (CT)) for precisely transforming a high current to a low current. In particular, in the three-phase four-wire transformer transformer (MOF) is composed of three current transformers (CT) and three transformers (PT), it is mainly used as a transformer when measuring the amount of power used in combination with an integrated power meter.

In addition, the instrument transformer PT is usually used for the use of a transformer having a secondary side of 100 V because it is dangerous to measure a high voltage directly with a voltmeter and is very uneconomical in view of the insulation of the voltmeter. The types of instrument transformers used in this way can be roughly classified into dry, inflow and gas.

In addition, the instrument current transformer CT refers to an instrument transformer for modifying a certain current value to a current value proportional thereto. Generally, the rated input current of the ordinary instrument, protective relay, etc. is 5A. However, the rated input current of the digital relay, which has been developed and spreading in recent years, is made to be 1A, and the large current of the primary side Since it can not be measured directly, it is a transformer that makes it possible to measure the instrument by lowering the current at a certain rate.

An example of such a conventional transformer current transformer (MOF) is described with reference to FIG.

Figure 1 (a) to (c) shows the internal structure of the front, side and back of the conventional three-phase four-wire flow transformer (MOF).

1 (a) to (c), the upper portion of the transformer transformer current transformer (MOF) is composed of three porcelain (1, 2, 3) bushing (1), and one ground bushing (4).

The lower part of the transformer transformer current transformer (MOF) is the same number of current transformers 20 windings and transformer 10 windings as the number of insulator bushings formed in the upper portion of the enclosure 5 made of steel tanks.

Instrument transformer (PT) (10) winding body is installed with the primary coil 11 and the secondary coil 12 in the inside and the core 13 is passed through the center thereof.

The current transformer (CT) 20 winding body has a primary coil 21 and a secondary coil 22 according to the current flow ratio, and a core 23 made of silicon steel passes through the center thereof. It is installed.

The transformer transformer current transformer (MOF) having such a structure is provided with three transformer (PT) winding bodies and current transformer (CT) winding bodies spaced apart from each other in the enclosure (5). At this time, three transformer (PT) windings are fixed using one channel 14. By installing three transformer (PT) 10 windings in one channel 14, material and process costs are reduced, and the outer size due to the reduction of the winding volume is reduced.

Figure 2 is a state of arrangement of a plurality of instrument current transformers (CT) and transformer (PT) built in the conventional transformer transformer current transformer (MOF) of Figure 1, wherein the three current transformers (CT) (20) windings are coils of each phase and The iron cores are arranged in separate structures that are electrically and magnetically independent. On the other hand, the three transformer (PT) (10) winding body is installed in one channel 14, the coil of each phase is made of a structure using a triangular iron core that is independently or magnetically coupled.

3A shows magnetic flux density when a three-phase power is applied to a conventional instrument transformer (PT) 10 having such a triangular iron core structure. Referring to FIG. 3A, since the coils of each phase have a structure perpendicular to the ground and share iron cores, the magnetic fluxes of the adjacent phases are greatly affected. Therefore, the magnetic flux density of each phase becomes unbalanced, causing a change in the magnitude of the electromotive force.

In addition, an induced voltage is generated in the phase formed by the coils adjacent to each other that share the core in the phase formation of one phase, thereby causing an error in the power measurement value, thereby lowering the reliability of the power measurement value. Figure 3b shows the magnetic flux density in the S phase image formation. Referring to FIG. 3B, since an induced voltage is generated by a coil in an adjacent phase even in an open phase, an open phase relay installed in order to prevent the open phase has a high possibility of malfunction. It can be increased and a separate special equipment for phase detection will be required.

In addition, it is difficult to insulate the design by increasing the area where the electric field is applied, corresponding to the current transformer (CT) and transformer (PT) primary coils that are subject to high voltage during operation of the transformer transformer current transformer (MOF), and the grounded enclosure and iron core. It is difficult to identify the cause of an accident due to the structure that is closely electromagnetically coupled to each other when an accident occurs.

Accordingly, an object of the present invention has been devised in view of the above-mentioned point, and the coils of adjacent phases are constructed by constructing the instrument transformer PT with a structure having an independent iron core for each coil so that magnetic fluxes generated in each phase do not overlap each other. To provide a transformer transformer current transformer for improving the reliability of the power measurement is not affected by the magnetic flux induced by the.

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The transformer transformer current transformer for improving the reliability of the present invention for achieving the above object, in the three-phase (R, S, T) four-wire or three-phase three-wire flow transformer for transformers, the winding of each phase is iron core Instrument transformer (PT) is formed in a structure having a magnetic core independent of each other without sharing them.

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The transformer transformer current transformer for improving the reliability of the present invention, using three current transformers (CT) and transformer (PT) each having independent windings and coils for improving the reliability of the power measurement, the efficiency of the insulation design It has the effect that it can be placed under optimum conditions through electric field analysis in the enclosure filled with.

In addition, it has the effect of improving the long-term reliability of the product, including the winding structure of the transformer (PT) that can improve the field relaxation and partial discharge characteristics and the field relaxation conditions of the bushing and the enclosure.

1 (a) to (c) is a view showing the internal structure in the front, side and rear of the conventional three-phase four-wire flow transformer (MOF), respectively,
2 is a view showing a current transformer (CT) and a transformer (PT) arrangement state in the conventional enclosure;
3A and 3B are diagrams illustrating magnetic flux densities at the time of applying a three-phase power supply of a transformer (PT) having a conventional triangular core structure and when forming an S phase;
4 (a) to (c) is a view showing the internal structure of the front, side and rear of the transformer transformer current transformer (MOF) applied to the transformer of the single-phase iron core structure according to an embodiment of the present invention, respectively ,
5a-5b is a view showing the structure of the instrument transformer (PT) of the single-phase iron core,
6A and 6B are views showing a structure in which three phases of the instrument transformer PT of the single phase iron core structure of FIGS. 5A and 5B are combined;
7A and 7B are diagrams illustrating magnetic flux densities at the time of applying a three-phase transformer (PT) power supply and a phase S phase of a single phase iron core structure according to the present invention;
8 is a view showing the internal structure in the front of the transformer transformer current transformer (MOF) applied to the transformer (PT) of the four-core iron core structure according to another embodiment of the present invention,
9 is a view showing the internal structure in the front of the transformer transformer current transformer (MOF) applied to the transformer (PT) of the five-core iron core structure according to another embodiment of the present invention,
10A and 10B are diagrams illustrating magnetic flux densities at the time of applying a three-phase transformer (PT) power supply and a phase S phase of the quadrilateral core structure of FIG. 8, respectively.
11A and 11B are diagrams illustrating magnetic flux densities at the time of applying a three-phase transformer (PT) power of the pentagonal iron core structure of FIG.
FIG. 12 is a diagram illustrating an existing arrangement of a transformer PT and a current transformer CT of an instrument transformer current transformer (MOF) and an electric field concentration part according to the arrangement of the present invention;
13 is a view for explaining a method of arranging the inside of the enclosure for improved reliability;
14 is a view showing the structure of the connection portion of the enclosure and insulator for improving partial discharge characteristics.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

4 (a) to (c) shows the internal structure of the front, side and rear of the transformer transformer current transformer (MOF) to which the transformer (PT) of the single-phase iron structure according to an embodiment of the present invention is applied, respectively.

As shown in Figure 4 (a) to (c), the transformer transformer current transformer (MOF) 100 of the present invention has the same structure as the conventional transformer transformer transformer shown in Figure 1 (a) to (c) of the present invention. It is configured, but the transformer (PT) 130 is disposed inside the enclosure 110 is configured to have a magnetically independent structure. The structure of the transformer (PT) 130 winding body will be described in more detail with reference to FIGS. 5A to 7B.

Figures 5a and 5b is a single phase iron core instrument transformer (PT) 130 structure, Figure 5a is a case in which the winding body is perpendicular to the floor and composed of a plurality of disks, Figure 5b is the winding body is parallel to the floor and one disk Each case is shown.

5A and 5B, the transformer (PT) 130 mounted in the enclosure 110 of the transformer transformer current transformer (MOF) 100 includes a primary coil 131, a secondary coil 133, and an iron core 135. It is configured to include). The primary coil 131 is uniformly wound in accordance with the voltage ratio on the primary bobbin in the form of a disk of FRP (glass fiber reinforced plastic) or insulator, and then dried in a drying furnace. As shown in FIG. 5A, the primary coil 131 is wound in a multistage structure composed of a plurality of disks, or as shown in FIG. 5B, in a single structure composed of one disk.

The secondary coil 133 is uniformly wound on the secondary bobbin in accordance with the voltage ratio, and then dried in a drying furnace. The size of the secondary bobbin is selected by determining the number of layers and insulation distance of the winding compared to the size of the inner diameter of the primary bobbin. The secondary coil 133 is installed to penetrate the primary coil 131 to transmit electric power by an electromagnetic induction action (the action of generating electricity under the influence of a magnetic field) in the primary coil 131 to which AC power is supplied. .

Here, the iron core 135 is formed to penetrate the secondary coil 133, the iron core 135 is either a hematite like (A) of Fig. 5b or a cut-core type such as (B). You can do it.

In the case of the hematite core is generally used for triangular iron core as shown in FIG. Insert the dog and tighten it to the frame after finishing work.

As in the present invention, in the instrument transformer (PT) 130 having a single-phase iron core structure, the coil is finished to the core after inserting a coil into a portion of the iron core leg as shown in FIG. If the core 35 is cut-core, it is assembled to the support plate 137 by assembling the band 139 as shown in (b) of FIG. 5B.

Transformer (PT) 130 of the single-phase iron core structure manufactured as described above is 90 degrees perpendicular to the floor as shown in Figure 5a or parallel to the floor as shown in Figure 5b.

When the transformer (PT) 130 winding body having a single iron core as shown in FIGS. 5A and 5B is a three-phase combination as shown in FIGS. 6A and 6B, an independent iron core for each coil is used so that magnetic flux generated in each phase does not overlap each other. By having it, it becomes a structure which is not affected by the magnetic flux induced by the coil of an adjacent phase. 7A shows the magnetic flux density when a three-phase power is applied to a transformer PT having such a single-phase iron core structure. Referring to FIG. 7A, the coils of the phases have a structure in a direction parallel to the ground and have independent iron cores, and thus are not affected by the magnetic flux of the adjacent phases. Therefore, the magnetic flux density of each phase is balanced so as not to cause a change in magnitude of the electromotive force.

Therefore, even if one phase is missing, an induced voltage does not occur in the phase formed by the coils of adjacent phases having independent iron cores, so that there is no error in the power meter or very little, thereby improving the reliability of the power meter. Fig. 7B shows the magnetic flux density at the time of S phase imaging. Referring to FIG. 7B, it can be seen that no induced voltage is generated by the coil of the adjacent phase in the formed phase.

FIG. 8 is an internal structure in front of a transformer transformer current transformer (MOF) in which a four-core iron core transformer PT is applied according to another embodiment of the present invention, and FIG. 9 is a transformer of a five-core iron core structure. The internal structure in the front of the applied transformer current transformer (MOF) is shown, respectively.

As shown in Figure 8 and 9, the transformer transformer current transformer (MOF) 100 of the present invention is configured of the same structure as the transformer transformer current transformer shown in Figure 4, the transformer is disposed inside the enclosure ( PT) (130) The winding body has a magnetically independent structure is composed of a four-core and a five-core iron core structure instead of the single-phase iron core structure of FIG.

Referring to FIG. 8, the phases share the iron core 135, but the directions of the coils are arranged parallel to the floor to minimize the influence of the coils adjacent to each other, and the cross-sectional areas b of the iron cores 135 sharing with each other penetrate each coil. This structure is larger than the cross-sectional area (a), and is hardly affected by the magnetic flux induced by the coils in the adjacent phase.

9, the phases share the iron core 135 and the direction of the coil is perpendicular to the ground, but by additionally placing the iron core outside the R phase and S phase to form an independent magnetic flux path for each phase to the adjacent phase coil It is a structure that can minimize the influence of the magnetic flux induced by.

10A illustrates magnetic flux density when a three-phase power is applied to a transformer PT having a four-core iron core structure of FIG. 8. Referring to FIG. 10A, since the cores share the cores but have a wide cross-sectional area, the coils of each phase have a structure parallel to the ground, so that the magnetic flux density of the conventional triangular core structure (see FIG. You can see that you receive less.

Therefore, even if one phase is missing, the induced voltage hardly occurs in the phase formed by the coils of the adjacent phases, so that there is no error in the power meter or very little, thereby improving the reliability of the power meter. 10B shows the magnetic flux density at the time of S phase imaging. Referring to FIG. 10B, it can be seen that almost no induced voltage is generated by the coil of the adjacent phase in the formed phase.

FIG. 11A illustrates magnetic flux density when a three-phase power is applied to a transformer PT having a five-core iron core structure of FIG. 9. 11A, the magnetic flux density of the conventional triangular iron core structure is shared since the cores share the cores and the coils of the phases are perpendicular to the ground but the cores are additionally disposed outwards of the R and T phases (see FIG. 3A). ), It is less affected by the magnetic flux of the adjacent phase.

Therefore, even if one phase is missing, the induced voltage hardly occurs in the phase formed by the coils in the adjacent phase. Fig. 11B shows the magnetic flux density at the time of S phase imaging. Referring to FIG. 11B, it can be seen that the induced voltage generated by the coil of the adjacent phase hardly occurs in the formed phase.

On the other hand, the three-phase transformer (PT) 130 winding body according to the present invention having a magnetically independent structure can be some kind of structural arrangement for the electric field relaxation of the enclosure 110 and the current transformer (CT) 140, etc. Do.

FIG. 12 is a diagram illustrating an existing arrangement of a transformer PT and a transformer CT of an instrument transformer current transformer (MOF) and an electric field concentration part according to the arrangement of the present invention.

Looking at the existing transformer transformer current transformer (MOF) of Figure 12 is a voltage between the high-voltage winding and the ground, the electric field is concentrated 10 points while the present invention arranged in combination with a single-phase current transformer (CT) and a transformer (PT) There are six areas where the concentration is smaller than that of the existing ones. From this, the structure using the single-phase iron core of the transformer (PT) winding body according to the present invention can be appropriately arranged and arranged as shown in Figure 13 through the electric field analysis of the enclosure and the current transformer (CT), according to the arrangement and arrangement method Coils can be arranged in a shape that forms 90 degrees perpendicular to the ground or 180 degrees parallel to the ground, giving conditions to alleviate the concentration of the electric field. In the field relaxation conditions, a number of methods may be proposed, such as shielding on the winding part, installation of an insulating partition, and rounding of the sharp part.

Referring to FIG. 13, the transformer, PT and current transformer (CT) are located at 7, 13, 11, 6, 10, 8, and the like where the field relaxation conditions should be given, that is, "┃". It can be seen that it depends on the arrangement and arrangement.

On the other hand, the transformer transformer current transformer 100 is formed to fix the plurality of bushings 120 to the upper portion of the enclosure 110 formed of an iron tank, a transformer disposed in the interior of the enclosure 110 for the high voltage large current to be drawn 130 and the current transformer 140 is put into the winding. At this time, in the process of applying the high voltage coil to the high voltage coil in the steel enclosure 110, an electric field is concentrated between the upper plate of the enclosure and the high-voltage conductor in the bushing may cause partial discharge.

Accordingly, the present invention has proposed a structure as shown in FIG. 14 to prevent partial discharge occurring at the connection portion of the enclosure and insulator.

Referring to FIG. 14, the bushing 120 formed on the upper portion of the enclosure 110 of the transformer transformer current transformer 100 is an insulator 121 having an empty inside in the axial direction, and at the inner diameter thereof, air (air) is used to maintain insulation. filled with air or gas. The upper portion of the insulator 121 is assembled with a high pressure conductor (primary enclosed) 123 so that the high pressure conductor 123 and the inner wall of the insulator 121 are electrically in-phase. A high pressure shield 127 is inserted into the lower end of the insulator 121 to mitigate corona discharge at the end of the high voltage conductor 123. The insulating packing 129 is coupled between the lower end of the insulator 121 and the high pressure shield 127.

The insulator 121 having such a configuration is fixed to the insulator 110 of the transformer current transformer 100 for an oil insulated instrument, and then fixed through the insulator fixing bracket 125 and bolted together. After fixing the insulator 121 to the upper portion of the enclosure 110, the insulating oil 150 is injected into the inside. When the high voltage power is applied to the inner winding through the enclosure 110, the concentration of the electric field occurs at the connection portion between the enclosure 110 and the insulator 121, the hole of the upper plate of the enclosure 110 is mounted Burring (111) processing the site to mitigate the field concentration phenomenon on the hole surface. Buring refers to a process in which a hole is bent in a flat plate and the end of the hole is bent by pushing a punch having a diameter larger than the hole.

In addition, by using an insulator such as FRP, which has a higher mechanical strength than steel, the insulator fixing bracket 125 has an effect of increasing the low pressure and high pressure distance of the insulator fixing portion, thereby substantially reducing the strength of the electric field. It is possible to improve the partial discharge characteristics by obtaining the effect.

Meanwhile, in the detailed description of the present invention, specific embodiments have been described, but various modifications may be made without departing from the scope of the present invention. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be defined not only by the claims below but also by the equivalents of the claims.

100: transformer transformer current transformer 110: enclosure
111: Burring 120: Bushing
121: insulator 123: high-voltage conductor
125: insulator fixing bracket 127: high pressure shield
129: insulation packing 130: instrument transformer
131: primary coil 133: secondary coil
135: iron core 137: support plate
140: current transformer for instrument 150: insulating oil

Claims (8)

In the transformer current transformer for three-phase (R, S, T) 4-wire or 3-phase 3-wire inflow instrument,
Instrument transformer comprising a transformer transformer (PT) is formed in a structure in which the winding body of each phase does not share the iron core with each other and has a magnetically independent iron core. According to claim 1, wherein the instrument transformer (PT)
A primary coil made of one disk (bobbin) or wound in a multistage structure according to an arrangement structure with a current transformer CT for the instrument;
A secondary coil installed through the primary coil; And
The transformer transformer current transformer is formed so as to penetrate the secondary coil, characterized in that it has an iron core made of a single-phase hematite core or cut core. The transformer transformer current transformer of claim 2, wherein the winding of the instrument transformer (PT) is formed at an angle of 90 degrees or 180 degrees with respect to the installation bottom surface. delete delete The method according to any one of claims 1 to 3, wherein the electric field concentration phenomenon can be efficiently controlled according to the arrangement and arrangement of the transformer CT and the transformer PT in the enclosure of the transformer transformer current transformer. A transformer transformer for electric transformers having electric field relaxation conditions including shielding, insulating bulkhead, and round processing of sharp parts. delete delete

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