CN116529842A

CN116529842A - Balance characteristic test device of zero-phase current transformer

Info

Publication number: CN116529842A
Application number: CN202080107685.3A
Authority: CN
Inventors: 米田仁; 宫内俊彦; 大野勇治
Original assignee: Mitsubishi Electric Corp
Current assignee: Mitsubishi Electric Corp
Priority date: 2020-12-15
Filing date: 2020-12-15
Publication date: 2023-08-01
Also published as: JPWO2022130481A1; WO2022130481A1; KR20230021742A; JP7378644B2

Abstract

A balance characteristic test device of a zero-phase current transformer can use a small-output current source to perform a balance characteristic test. Comprising the following steps: an electric wire (1), wherein the electric wire (1) is arranged in a manner that a plurality of round trip amounts penetrate through a through hole of the zero-phase current transformer (100); a current source (2), wherein the current source (2) causes a direct current to flow through the electric wire (1); and an ammeter (3), wherein the ammeter (3) measures the secondary current of the zero-phase current transformer (100).

Description

Balance characteristic test device of zero-phase current transformer

Technical Field

The application relates to a balance characteristic test device of a zero-phase current transformer.

Background

The zero-phase current transformer that detects zero-phase current when a ground fault occurs detects unbalance in current of the through conductor caused by the ground fault current, and outputs a secondary current. However, when the zero-phase current transformer itself has a large unbalanced component as a characteristic, even when a balanced current is input to the primary side of the zero-phase current transformer, a secondary current is generated, which causes erroneous detection. Therefore, a balance characteristic test for confirming that the magnitude of the secondary current is equal to or less than a predetermined value is performed by applying a balance current several times the rated current to the primary side of the zero-phase current transformer. The balance characteristic test of the zero-phase current transformer is performed, for example, by passing a wire connected to a current source through a through hole of the zero-phase current transformer by a single round trip amount, applying a predetermined balance current to the wire, and measuring the output of the secondary current (see, for example, fig. 4 of patent document 1).

Prior art literature

Patent literature

Patent document 1: japanese patent laid-open No. 04-021980

Disclosure of Invention

Technical problem to be solved by the invention

For the balance characteristic test of the zero-phase current transformer with a large rated current corresponding to a large current, a large balance current needs to be generated. In order to generate a large balance current, a large output current source is required, and there is a problem in that the current source becomes large and expensive.

The present invention has been made to solve the above-described problems, and an object thereof is to provide a balance characteristic test device for a zero-phase current transformer capable of performing a balance characteristic test using a small-output current source.

Technical means for solving the technical problems

The application discloses a zero-phase current transformer's balance characteristic test device includes: a plurality of wires which are arranged in a way of penetrating through the through holes of the zero-phase current transformer in a round trip amount; a current source for flowing a direct current through the wire; and an ammeter for measuring the secondary current of the zero-phase current transformer.

Effects of the invention

The application discloses a zero-phase current transformer's balance characteristic test device includes: a plurality of wires which are arranged in a way of penetrating through the through holes of the zero-phase current transformer in a round trip amount; a current source for flowing a direct current through the wire; and an ammeter for measuring the magnitude of the secondary current of the zero-phase current transformer, so that the test can be performed using a small-output current source, and the test can be performed using a small and inexpensive device.

Drawings

Fig. 1 is a diagram showing a configuration of a balance characteristic test apparatus for a zero-phase current transformer according to embodiment 1.

Fig. 2 is a diagram showing the structure of the balance characteristic test apparatus of the comparative example.

Fig. 3 is a diagram showing a configuration of a balance characteristic test apparatus for a zero-phase current transformer according to embodiment 2.

Fig. 4 is a diagram showing a configuration of a balance characteristic test apparatus for a zero-phase current transformer according to embodiment 3.

Fig. 5 is a diagram showing an example of the direction of current flowing through the electric wire in embodiment 3.

Detailed Description

Next, a balance characteristic test apparatus for a zero-phase current transformer according to an embodiment of the present application will be described in detail with reference to the drawings. Like reference numerals designate like or corresponding parts throughout the several views.

Embodiment 1

Fig. 1 is a diagram showing a configuration of a balance characteristic test apparatus for a zero-phase current transformer according to embodiment 1. In fig. 1, a zero-phase current transformer 100 is a test object, and a balance characteristic test device of the zero-phase current transformer includes an electric wire 1, a current source 2, and an ammeter 3. The electric wire 1 is provided as a primary-side wire of the zero-phase current transformer 100 so that a plurality of round-trip amounts equal to or more than two round-trip amounts are combined and penetrates through the through-hole only once. In fig. 1, the electric wire 1 is provided so as to penetrate the through hole by two reciprocating amounts. The current source 2 is electrically connected to both ends of the electric wire 1, and a direct current flows through the electric wire 1. The ammeter 3 is electrically connected to the secondary current output terminal of the zero-phase current transformer 100, and measures the magnitude of the secondary current of the zero-phase current transformer 100. In fig. 1, the magnitude of the secondary current of the zero-phase current transformer 100 is measured by the ammeter 3, but the magnitude of the secondary current of the zero-phase current transformer 100 may be measured by connecting a load such as a resistor to the secondary current output terminal of the zero-phase current transformer 100 and measuring the voltage across the load by a voltmeter or the like. In the balance characteristic test, a current flows from the current source 2 to the electric wire 1 so that a balance current, for example, 6 times the rated current flows through the primary side of the zero-phase current transformer 100. It was checked whether the secondary current measured by ammeter 3 was equal to or less than a predetermined value.

Fig. 2 is a diagram showing the configuration of a balance characteristic test apparatus of a comparative example for explaining the operation of the balance characteristic test apparatus of the zero-phase current transformer, and corresponds to fig. 4 of patent document 1 shown in the prior art document. In the balance characteristic test apparatus of the comparative example shown in fig. 2, the electric wire 1 is the electric wire 1a, and the current source 2 is the current source 2a, as compared with the balance characteristic test apparatus according to embodiment 1 shown in fig. 1. Other configurations of the balance characteristic test apparatus of the comparative example are the same as those of the balance characteristic test apparatus according to embodiment 1. In contrast to the balance characteristic test apparatus according to embodiment 1 shown in fig. 1, which is provided so that two round-trip amounts of the electric wire 1 pass through the through-hole, the balance characteristic test apparatus according to the comparative example shown in fig. 2 is provided so that one round-trip amount of the electric wire 1a passes through the through-hole.

Next, the operation of the balance characteristic test device for a zero-phase current transformer according to embodiment 1 will be described in comparison with the operation of the balance characteristic test device of the comparative example. In the balance characteristic test of the zero-phase current transformer, a balance current of, for example, 6 times the rated current needs to be applied to the primary side of the zero-phase current transformer. When the rated current of the zero-phase current transformer subjected to the balance characteristic test is 100A, a balance current of 600A needs to be applied to the primary side of the zero-phase current transformer. In the balance characteristic test apparatus of the comparative example shown in fig. 2, for example, when a current of ia flows from the current source 2a in the arrow direction shown by the electric wire 1a, since the current is provided so that 1 round trip of the electric wire 1a penetrates the through hole, a current of ia flows from the front side to the rear side in fig. 2 and a current of ia flows from the rear side to the front side in fig. 2 in the through hole. Thus, the balance current of IA is energized to the primary side of zero-phase current transformer 100. Therefore, for example, when it is desired to supply the balance current of 600A to the primary side of the zero-phase current transformer, the balance current may flow through 600A as the current source 2a.

On the other hand, in the balance characteristic test device for a zero-phase current transformer according to embodiment 1 shown in fig. 1, for example, when a current of ia flows from the current source 2 in the arrow direction shown by the electric wire 1, since the current of ia is provided so that two round trip amounts of the electric wire 1 pass through the through hole, a current of ia flows from the front side to the rear side of fig. 1 and a current of ia flows from the rear side to the front side of fig. 1. Thus, the balance current of i× 2[A is energized to the primary side of the zero-phase current transformer 100. Therefore, for example, when it is desired to supply a balance current of 600A to the primary side of the zero-phase current transformer, 300A may be supplied as the current source 2. In the case of performing the balance characteristic test of the balance current of 600A supplied to the primary side of the zero-phase current transformer, the current source 2a generating the current of 600A is required in the balance characteristic test apparatus of the comparative example, but the balance characteristic test apparatus according to embodiment 1 may be provided with the current source 2 generating the small output of 300A which is half of the current of the comparative example. Since the size of the current source depends on the size of the current that can be output, the current source 2 of embodiment 1 can use a smaller current source than the current source 2a of the comparative example. In addition, the current source 2 of embodiment 1 may be a cheaper current source than the current source 2a of the comparative example.

In the balance characteristic test apparatus according to embodiment 1, since a plurality of electric wires 1 are provided in a group and are inserted only once into the through-hole of the zero-phase current transformer 100, the operation of inserting the electric wires 1 into the through-hole before the test of the balance characteristic test and the operation of extracting the electric wires 1 from the through-hole after the test are very simple as in the balance characteristic test apparatus of the comparative example.

In the description of fig. 1, the electric wire 1 is provided so that two round-trip amounts penetrate through the through-hole, but the electric wire 1 may be provided as a wire on the primary side of the zero-phase current transformer 100 so that a plurality of round-trip amounts of two or more penetrate through the through-hole. For example, if the three round-trip amounts of the electric wire 1 are set so as to penetrate through the through-hole, when the current of ia flows from the current source 2, the balance current of i× 3[A is supplied to the primary side of the zero-phase current transformer 100, and a smaller output current source may be used.

As described above, the zero-phase current transformer balance characteristic test device according to embodiment 1 includes: an electric wire 1 provided so as to penetrate through the through hole of the zero-phase current transformer 100 by a plurality of back and forth amounts; a current source 2 for flowing a direct current through the electric wire 1; and an ammeter 3 for measuring the magnitude of the secondary current of the zero-phase current transformer 100, the balance characteristic test can be performed using a small-output current source, and a small and inexpensive current source can be used.

Embodiment 2

Fig. 3 is a diagram showing a configuration of a balance characteristic test apparatus for a zero-phase current transformer according to embodiment 2. When comparing the balance characteristic test device for a zero-phase current transformer according to embodiment 2 shown in fig. 3 with the balance characteristic test device for a zero-phase current transformer according to embodiment 1 shown in fig. 1, a plurality of wires 1 each having a round trip amount are integrated by being covered with a cover 4, and thus become one primary-side wire. For example, the electric wire 1 covered with the cover 4 is formed by integrally molding a plurality of electric wires 1 of the round trip amount and an insulator such as resin. Other configurations of the balance characteristic test apparatus for a zero-phase current transformer according to embodiment 2 are the same as those of the balance characteristic test apparatus according to embodiment 1.

In the balance characteristic test device for a zero-phase current transformer according to embodiment 2 shown in fig. 3, when a current of ia flows from the current source 2 in the arrow direction shown by the electric wire 1, a balance current of i× 2[A is supplied to the primary side of the zero-phase current transformer 100, which is the same as the balance characteristic test device for a zero-phase current transformer according to embodiment 1. Therefore, the balance characteristic test device for a zero-phase current transformer according to embodiment 2 can obtain the same effects as the balance characteristic test device for a zero-phase current transformer according to embodiment 1. Further, in the balance characteristic test apparatus for a zero-phase current transformer according to embodiment 2 shown in fig. 3, since a plurality of round-trip wires 1 are integrated by being covered with a cover 4, the handling of the wires 1 is easy, and the operation of penetrating the plurality of round-trip wires 1 through the through-hole before the balance characteristic test and the operation of extracting the plurality of round-trip wires 1 from the through-hole after the balance characteristic test are easy.

In the balance characteristic test device for a zero-phase current transformer according to embodiment 2 shown in fig. 3, a plurality of round-trip wires 1 are integrated as a group and covered with a cover 4, but the round-trip wires 1 may be integrated by fixing the round-trip wires 1 with a clip, an adhesive, or the like.

The integrated electric wire 1 may be formed in a hard and straight rod shape and may be inserted into the through hole. In this case, the operation of penetrating the plurality of electric wires 1 in the round trip amount through the through-hole before the balance characteristic test and the operation of extracting the plurality of electric wires 1 in the round trip amount from the through-hole after the balance characteristic test are made easier.

As described above, the zero-phase current transformer balance characteristic test device according to embodiment 2 includes: an electric wire 1 provided so as to penetrate through the through hole of the zero-phase current transformer 100 by a plurality of back and forth amounts; a current source 2 for flowing a direct current through the electric wire 1; and an ammeter 3 for measuring the magnitude of the secondary current of the zero-phase current transformer 100, and a plurality of wires 1 for round trip are integrated, so that a balance characteristic test can be performed using a small-output current source, and a small-sized current source can be used. Further, the operation of penetrating the plurality of electric wires 1 in the round trip amount through the through-hole before the balance characteristic test and the operation of extracting the plurality of electric wires 1 in the round trip amount from the through-hole after the balance characteristic test are facilitated.

Embodiment 3

Fig. 4 is a diagram showing a configuration of a balance characteristic test apparatus for a zero-phase current transformer according to embodiment 3. When comparing the balance characteristic test device for a zero-phase current transformer according to embodiment 3 shown in fig. 4 with the balance characteristic test device for a zero-phase current transformer according to embodiment 1 shown in fig. 1, the first wiring switch 5 is provided at the folded portion of the electric wire close to the current source 2, and the second wiring switch 6 is provided at the folded portion of the electric wire distant from the current source 2. Further, a switching indicator 7 is provided, and the switching indicator 7 instructs the first wiring switcher 5 and the second wiring switcher 6 to switch the internal wiring via a switching signal line 8.

The current source wire 9a connected to the current source 2 is connected to the through wire 10a through the internal wire of the first wire switcher 5, the through wire 10a is connected to the through wire 10b through the internal wire of the second wire switcher 6 after passing through the through hole of the zero-phase current transformer, the through wire 10b is connected to the through wire 10c through the internal wire of the first wire switcher 5 after passing through the through hole of the zero-phase current transformer, the through wire 10c is connected to the through wire 10d through the internal wire of the second wire switcher 6 after passing through the through hole of the zero-phase current transformer, the through wire 10d is connected to the current source wire 9b through the internal wire of the first wire switcher 5 after passing through the through hole of the zero-phase current transformer, and the current source wire 9b is connected to the current source 2. Thus, the current source wires 9a and 9b, the first wiring switch 5, the through wires 10a, 10b, 10c, and 10d, and the second wiring switch 6 constitute wires provided so that two reciprocations pass through the through holes of the zero-phase current transformer. Other configurations of the balance characteristic test apparatus for a zero-phase current transformer according to embodiment 3 are the same as those of the balance characteristic test apparatus according to embodiment 1.

Fig. 5 is a diagram showing an example of the arrangement of the through wires 10a, 10b, 10c, and 10d in the balance characteristic test apparatus for a zero-phase current transformer according to embodiment 3, and shows four states in which the directions of current flow are different. Fig. 5 is a cross-sectional view of a portion of the through wires 10a, 10b, 10c, 10d penetrating through the through hole of the zero-phase current transformer 100 in fig. 4 as seen from the current source 2 side, and the through wires 10a, 10b, 10c, 10d are arranged to have a square shape in a portion penetrating through the through hole of the zero-phase current transformer 100. The upper left diagram of fig. 5 shows the direction of the current flowing through the through wires 10a, 10b, 10c, 10d when the internal wiring of each of the first wiring switcher 5 and the second wiring switcher 6 is in the state shown by the broken line in fig. 4. The through wires 10a and 10c flow current in a direction from the front to the rear in fig. 5, that is, in a direction away from the current source 2 in fig. 4, and the through wires 10b and 10d flow current in a direction from the rear to the front in fig. 5, that is, in a direction closer to the current source 2 in fig. 4.

The first wiring switcher 5 and the second wiring switcher 6 change the connection of the internal wirings of the first wiring switcher 5 and the second wiring switcher 6 in accordance with the instruction from the switching instruction 7 to switch to any one of four states in which the directions of the current flowing are different as shown in fig. 5. For example, when the switching instruction of the wiring is transmitted from the switching indicator 7 through the switching signal line 8, the first wiring switcher 5 and the second wiring switcher 6 change the connection of the internal wiring of the first wiring switcher 5 and the second wiring switcher 6 to switch the four states shown in fig. 5 clockwise. When the upper left state in fig. 5 is changed to the upper right state in fig. 5, the balance current flowing through the through wires 10a, 10b, 10c, 10d is rotated clockwise by 90 degrees in the through hole. When the directions of the currents flowing through the through-wires 10a, 10b, 10c, 10d are switched in the order of "upper left", "upper right", "lower left" in fig. 5, the balance currents flowing through the through-wires 10a, 10b, 10c, 10d are rotated clockwise by 90 degrees each time in the through-holes.

In the balance characteristic test, even if the magnitude of the balance current flowing through the through-hole of the zero-phase current transformer 100 is the same, the magnitude of the secondary current of the zero-phase current transformer 100 is changed according to the position of the balance current flowing through the through-hole of the zero-phase current transformer 100. Therefore, in the balance characteristic test, for example, the secondary current is measured while rotating the wire passing through the through hole of the zero-phase current transformer 100, or the secondary current is measured while rotating the zero-phase current transformer itself, and the largest value of the measured secondary currents is used as the final measurement value of the secondary current.

In the zero-phase current transformer balance characteristic test apparatus according to embodiment 3, the secondary currents are measured in four states indicated by "upper left", "upper right", "lower right", and "lower left" in fig. 5, respectively, in response to an instruction from the switching instruction 7, and the largest value among the four obtained secondary currents is used as the final measurement value of the secondary current. In addition, when the secondary current is measured, no current flows through the switching signal line 8. In this way, the direction of the current flowing through the through-hole of the zero-phase current transformer 100 can be changed in response to the instruction from the switching instruction 7, and therefore the position of the balance current can be changed to measure the secondary current without physically moving the balance characteristic test device or the zero-phase current transformer 100. Thus, the balance characteristic test can be performed in a shorter time than in the case of rotating the electric wire passing through the through hole of the zero-phase current transformer 100 or in the case of rotating the zero-phase current transformer itself.

In the description of fig. 4, the electric wire is provided so that two round-trip amounts penetrate through the through-hole, but the electric wire may be provided as a wire on the primary side of the zero-phase current transformer 100 so that a plurality of round-trip amounts of two or more penetrate through the through-hole, as in embodiment 1. Therefore, in the description of fig. 5, the through wires 10a, 10b, 10c, and 10d are arranged in a square shape at the portion penetrating the through hole of the zero-phase current transformer 100, but it is sufficient to arrange a through wire penetrating in a plurality of round-trip amounts of two or more. In the explanation of fig. 5, the connection of the internal wirings of the first wiring switcher 5 and the second wiring switcher 6 is changed so as to switch the four states shown in fig. 5 in the clockwise direction, but the connection of the internal wirings of the first wiring switcher 5 and the second wiring switcher 6 may be changed so as to change the direction of the current flowing through the through-wires of the zero-phase current transformer 100 in a state where the current source wires 9a and 9b, the first wiring switcher 5, the even number of through-wires of four or more, and the second wiring switcher 6 are connected so as to form wires provided so as to penetrate the through-holes of the zero-phase current transformer in a plurality of round-trip amounts of two or more.

In the description of fig. 4, the switching indicator 7 indicates the switching of the internal wiring to the first wiring switcher 5 and the second wiring switcher 6 via the switching signal line 8, but any method may be used as long as the switching of the internal wiring to the first wiring switcher 5 and the second wiring switcher 6 can be indicated.

As described above, the zero-phase current transformer balance characteristic test device according to embodiment 3 includes: a plurality of through wires 10a, 10b, 10c, 10d penetrating through the through holes of the zero-phase current transformer 100; a first wiring switcher 5 connected to the current source 2 and to one end of the through wires 10a, 10b, 10c, 10d; a second wiring switcher 6 connected to the other end portions of the through wires 10a, 10b, 10c, 10d; and a switching indicator 7 for indicating switching of the internal wiring to the first wiring switching device 5 and the second wiring switching device 6, wherein at least the internal wiring of the first wiring switching device 5, the through wires 10a, 10b, 10c, 10d, and the internal wiring of the second wiring switching device 6 constitute wires provided so as to penetrate through the through holes of the zero-phase current transformer 100 by a plurality of round trip amounts, and the direction of the current flowing through any one of the plurality of through wires 10a, 10b, 10c, 10d penetrating through the through holes is changed in accordance with the indication of the switching indicator 7, so that the position of the balance current can be changed to measure the secondary current without physically moving the balance characteristic test device or the zero-phase current transformer 100, and the balance characteristic test can be performed in a short time.

The various illustrated embodiments are described herein, but the various features, aspects, and functions described in one or more embodiments are not limited to the application of the particular embodiments, and may be applied to the embodiments alone or in various combinations.

Accordingly, numerous modifications not illustrated are considered to be included in the technical scope disclosed in the present application. For example, the case where at least one component is modified, added, or omitted, and the case where at least one component is extracted and combined with the components of other embodiments is included.

Description of the reference numerals

1. 1a wire

2. 2a current source

3 ammeter

4 covers

5 first wiring switcher

6 second wiring switcher

7 switch indicator

8 switch signal line

9a, 9b current source wire

10a, 10b, 10c, 10d through-wires

100 zero phase current transformer.

Claims

1. The utility model provides a zero-phase current transformer's balance characteristic test device which characterized in that includes:

a wire that is provided so as to penetrate through holes of the zero-phase current transformer by a plurality of round-trip amounts;

a current source that causes a direct current to flow through the electric wire; and

and the ammeter is used for measuring the secondary current of the zero-phase current transformer.

2. A balance characteristic test apparatus of a zero-phase current transformer according to claim 1, wherein,

the electric wires of a plurality of round trip amounts are integrated.

3. A balance characteristic test apparatus of a zero-phase current transformer according to claim 2, wherein,

the integrated electric wire is in a straight rod shape.

4. The balance characteristic test apparatus of a zero-phase current transformer according to claim 1, comprising:

a plurality of through wires penetrating through the through holes of the zero-phase current transformer;

a first wiring switcher connected to the current source and one end of the through wire;

a second wiring switch connected to the other end of the through wire; and

a switching indicator that indicates switching of the internal wiring to the first wiring switcher and the second wiring switcher,

at least the internal wiring of the first wiring switch, the through-wire, and the internal wiring of the second wiring switch constitute the wire provided so as to pass through the through-hole of the zero-phase current transformer in a plurality of round-trip amounts,

the direction of the current flowing through any one of the plurality of through wires penetrating through the through hole is changed in accordance with the instruction of the switching instruction.