Balancing characteristic test device for zero-phase current transformer

Abstract

A balance characteristic test device for a zero-phase current transformer, which can perform a balance characteristic test using a small output current source. The device includes: an electric wire (1) disposed so as to penetrate a through-hole of a zero-phase current transformer (100) in a plurality of round trips; a current source (2) that causes a direct current to flow through the electric wire (1); and an ammeter (3) that measures the magnitude of a secondary current of the zero-phase current transformer (100).

Description

Technical Field

[0001] This application relates to a test apparatus for the balance characteristics of a zero-phase current transformer. Background Technology

[0002] A zero-phase current transformer, used to detect the zero-phase current during a ground fault, detects the current imbalance in the conductor caused by the ground fault current and outputs a secondary current. However, if the zero-phase current transformer itself has a large imbalance component as a characteristic, a secondary current may still be generated even when a balanced current is input to the primary side of the zero-phase current transformer, leading to false detection. Therefore, a balance characteristic test is performed by applying a balance current several times the rated current to the primary side of the zero-phase current transformer to confirm that the magnitude of the secondary current is below a specified value. The balance characteristic test of the zero-phase current transformer is performed, for example, by passing a wire connected to a current source through the through-hole of the zero-phase current transformer a round trip, applying a predetermined balance current to the wire, and measuring the output of the secondary current (see, for example, Patent Document 1). Figure 4 ).

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Utility Model No. 04-021980 Summary of the Invention

[0006] The technical problem that the invention aims to solve

[0007] For the balance characteristic test of a 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, which presents a technical problem of making the current source large and expensive.

[0008] This application was made to solve the above-mentioned problems, and its purpose is to provide a balance characteristic test device for a zero-phase current transformer that can perform balance characteristic tests using a small output current source.

[0009] Technical means for solving technical problems

[0010] The balance characteristic test apparatus for a zero-phase current transformer disclosed in this application includes: wires arranged in a manner that pass through multiple through holes in the zero-phase current transformer with multiple round trips; a current source for allowing direct current to flow through the wires; and an ammeter for measuring the magnitude of the secondary current of the zero-phase current transformer.

[0011] Invention Effects

[0012] The balance characteristic test apparatus for a zero-phase current transformer disclosed in this application includes: wires arranged in such a way that multiple round trips pass through the through holes of the zero-phase current transformer; a current source that allows direct current to flow through the wires; and an ammeter for measuring the magnitude of the secondary current of the zero-phase current transformer. Therefore, the test can be performed using a small-output current source, and the test can be performed using a small and inexpensive device. Attached Figure Description

[0013] Figure 1 This is a diagram showing the structure of the balance characteristic test device for the zero-phase current transformer involved in Embodiment 1.

[0014] Figure 2 This is a diagram showing the structure of the equilibrium characteristic test apparatus for the comparative example.

[0015] Figure 3 This is a diagram showing the structure of the balance characteristic test device for the zero-phase current transformer involved in Embodiment 2.

[0016] Figure 4 This is a diagram showing the structure of the balance characteristic test device for the zero-phase current transformer involved in Embodiment 3.

[0017] Figure 5 This is a diagram illustrating an example of the direction of the current flowing through the wire in Embodiment 3. Detailed Implementation

[0018] The balance characteristic test apparatus for a zero-phase current transformer according to an embodiment of this application will now be described in detail with reference to the accompanying drawings. The same reference numerals in the drawings indicate the same or equivalent parts.

[0019] Implementation method 1.

[0020] Figure 1 This is a diagram showing the structure of the balance characteristic test apparatus for the zero-phase current transformer according to Embodiment 1. Figure 1 In this test, the zero-phase current transformer 100 is the test object, and the balance characteristic test device for the zero-phase current transformer includes a wire 1, a current source 2, and an ammeter 3. The wire 1, serving as the primary conductor of the zero-phase current transformer 100, is arranged in a manner where multiple round trips (two or more) are grouped together and pass through the through-hole only once. Figure 1 In this configuration, wire 1 is installed with two round trips through the through hole. Current source 2 is electrically connected to both ends of wire 1, and direct current flows through wire 1. Ammeter 3 is electrically connected to the secondary current output terminal of zero-phase current transformer 100 to measure the magnitude of the secondary current of zero-phase current transformer 100. Figure 1In this test, the secondary current of the zero-phase current transformer 100 is measured using ammeter 3. However, the secondary current can also 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 using a voltmeter. In the balance characteristic test, current flows from current source 2 to wire 1, causing a balance current, for example, six times the rated current, to flow through the primary side of the zero-phase current transformer 100. It is then confirmed whether the secondary current measured by ammeter 3 is below the specified value.

[0021] Figure 2 This is a diagram showing the structure of a comparative example of a balance characteristic test apparatus used to illustrate the operation of a balance characteristic test apparatus for a zero-phase current transformer, corresponding to Patent Document 1 shown in prior art documents. Figure 4 . Figure 2 The comparative example of the equilibrium characteristic test apparatus shown is the same as... Figure 1 Compared to the balance characteristic test apparatus of Embodiment 1, the wire 1 becomes wire 1a, and the current source 2 becomes current source 2a. The other structures of the balance characteristic test apparatus in the comparative example are the same as those in Embodiment 1. Figure 1 In the balance characteristic test apparatus of Embodiment 1 shown, the wire 1 is arranged such that it passes through the through hole in two round trips. In contrast, in... Figure 2 In the comparative example shown, the balance characteristic test apparatus is arranged such that the wire 1a passes through the through hole in one round trip.

[0022] Next, the operation of the balance characteristic test apparatus for the zero-phase current transformer according to Embodiment 1 will be explained while comparing it with the operation of the balance characteristic test apparatus of the comparative example. In the balance characteristic test of the zero-phase current transformer, a balance current, for example, six 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 undergoing 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. Figure 2 In the comparative example of the balance characteristic test apparatus shown, for example, when a current of I[A] flows from the current source 2a in the direction of the arrow shown in the wire 1a, since the wire 1a is arranged to pass through the through hole in one round trip, the current of I[A] flows through the through hole in one step. Figure 2 The current flows towards the depths in front of it, and the current of I[A] flows from... Figure 2 The current flows from the depth towards the front. Thus, the balancing current of I[A] is supplied to the primary side of the zero-phase current transformer 100. Therefore, for example, when it is desired to supply a balancing current of 600A to the primary side of the zero-phase current transformer, 600A can flow through it as a current source 2a.

[0023] On the other hand, Figure 1 In the balance characteristic test apparatus for the zero-phase current transformer according to Embodiment 1 shown, for example, when a current of I[A] flows from the current source 2 along the direction of the arrow shown in the wire 1, since the wire 1 is arranged to pass through the through hole in two round trips, the current of I[A] in two amounts flows through the through hole. Figure 1 The current flows towards the depths in front of it, and the current of I[A] in two quantities flows from... Figure 1 The current flows from the depth towards the front. Thus, a balancing current of I*2[A] is supplied to the primary side of the zero-phase current transformer 100. Therefore, for example, when it is desired to supply a 600A balancing current to the primary side of the zero-phase current transformer, a current source 2 can supply 300A. In conducting a balancing characteristic test with a 600A balancing current supplied to the primary side of the zero-phase current transformer, a current source 2a that generates 600A of current is required in the balancing characteristic test apparatus of the comparative example. However, in the balancing characteristic test apparatus according to Embodiment 1, a small-output current source 2 that generates half the current of the comparative example (300A) is sufficient. Since the size of the current source depends on the size of the output current, the current source 2 of Embodiment 1 can be a smaller current source than the current source 2a of the comparative example. Furthermore, at the same time, the current source 2 of Embodiment 1 can be a cheaper current source than the current source 2a of the comparative example.

[0024] Furthermore, in the balance characteristic test apparatus according to Embodiment 1, since the multiple round trips of the wire 1 are arranged as a group and only pass through the through hole of the zero-phase current transformer 100 once, the operation of passing the wire 1 through the through hole before the balance characteristic test and the operation of pulling the wire 1 out of the through hole after the test are as simple as the balance characteristic test apparatus of the comparative example.

[0025] In addition, Figure 1 In the description, wire 1 is installed with two round trips through the through hole. However, since wire 1 is the conductor on the primary side of the zero-phase current transformer 100, it is sufficient to install it with multiple round trips (two or more). For example, if wire 1 is installed with three round trips through the through hole, then when a current of I[A] flows from the current source 2, a balancing current of I*3[A] is energized on the primary side of the zero-phase current transformer 100, thus allowing the use of a current source with a smaller output.

[0026] As described above, the balance characteristic test apparatus for the zero-phase current transformer according to Embodiment 1 includes: a wire 1 provided in such a way that multiple round trips pass through the through hole of the zero-phase current transformer 100; a current source 2 for allowing direct current to flow through the wire 1; and an ammeter 3 for measuring the magnitude of the secondary current of the zero-phase current transformer 100. Therefore, a balance characteristic test can be performed using a small-output current source, and a small and inexpensive current source can be used.

[0027] Implementation method 2.

[0028] Figure 3 This is a diagram showing the structure of the balance characteristic test apparatus for the zero-phase current transformer involved in Embodiment 2. Figure 3 The balance characteristic test apparatus for the zero-phase current transformer involved in Embodiment 2 shown is... Figure 1 When comparing the balance characteristic test apparatus for the zero-phase current transformer according to Embodiment 1, multiple round-trip wires 1 are grouped together and covered by a covering 4 to form a single conductor on the primary side. For example, multiple round-trip wires 1 and an insulating material such as resin are integrally formed to create the wires 1 covered by the covering 4. The other structures of the balance characteristic test apparatus for the zero-phase current transformer according to Embodiment 2 are the same as those of the balance characteristic test apparatus according to Embodiment 1.

[0029] exist Figure 3 In the balance characteristic test apparatus for the zero-phase current transformer according to Embodiment 2, when a current of I[A] flows from the current source 2 along the direction of the arrow shown on the wire 1, a balance current of I*2[A] is energized on the primary side of the zero-phase current transformer 100, which is the same as the balance characteristic test apparatus for the zero-phase current transformer according to Embodiment 1. Therefore, in the balance characteristic test apparatus for the zero-phase current transformer according to Embodiment 2, the same effect as that in the balance characteristic test apparatus for the zero-phase current transformer according to Embodiment 1 can be obtained. Furthermore, in Figure 3 In the balance characteristic test apparatus for the zero-phase current transformer according to Embodiment 2 shown, since the multiple round-trip wires 1 are grouped together and covered by the cover 4 to form a whole, the handling of the wires 1 becomes easy. The operation of passing the multiple round-trip wires 1 through the through hole before the balance characteristic test and the operation of pulling out the multiple round-trip wires 1 from the through hole after the balance characteristic test become easy.

[0030] In addition, Figure 3In the balance characteristic test device of the zero-phase current transformer involved in Embodiment 2 shown, multiple round-trip wires 1 are grouped together and covered by a covering 4 to form a whole. However, it is sufficient for multiple round-trip wires 1 to form a whole. For example, multiple round-trip wires 1 can also be fixed together by clips or adhesives.

[0031] Alternatively, the wire 1, which will be integrated into one piece, can be formed into a rigid and straight rod shape and pass through the through hole. In this case, it becomes easier to pass the wire 1 through the through hole with multiple reciprocating motions before the balance characteristic test, and to pull the wire 1 with multiple reciprocating motions out of the through hole after the balance characteristic test.

[0032] As described above, the balance characteristic test apparatus for the zero-phase current transformer according to Embodiment 2 includes: a wire 1 arranged in such a way that multiple round trips pass through a through hole of the zero-phase current transformer 100; a current source 2 for allowing direct current to flow through the wire 1; and an ammeter 3 for measuring the magnitude of the secondary current of the zero-phase current transformer 100. Since the multiple round trips of the wire 1 are integrated, a small-output current source can be used to perform the balance characteristic test, and a small current source can be used. Furthermore, the operations of passing the multiple round trips of the wire 1 through the through hole before the balance characteristic test and the operations of pulling the multiple round trips of the wire 1 out of the through hole after the balance characteristic test are simplified.

[0033] Implementation method 3.

[0034] Figure 4 This is a diagram showing the structure of the balance characteristic test apparatus for the zero-phase current transformer involved in Embodiment 3. Figure 4 The balance characteristic test apparatus for the zero-phase current transformer involved in Embodiment 3 shown is... Figure 1 When comparing the balance characteristic test apparatus of the zero-phase current transformer according to Embodiment 1, a first wiring switch 5 is provided at the bend of the wire near the current source 2, and a second wiring switch 6 is provided at the bend of the wire away from the current source 2. Additionally, a switching indicator 7 is provided, which indicates the switching of the internal wiring of the first wiring switch 5 and the second wiring switch 6 via a switching signal line 8.

[0035] The current source wire 9a, connected to the current source 2, is connected to the through wire 10a via the internal wiring of the first wiring switch 5. The through wire 10a passes through the through hole of the zero-phase current transformer and then connects to the through wire 10b via the internal wiring of the second wiring switch 6. The through wire 10b passes through the through hole of the zero-phase current transformer and then connects to the through wire 10c via the internal wiring of the first wiring switch 5. The through wire 10c passes through the through hole of the zero-phase current transformer and then connects to the through wire 10d via the internal wiring of the second wiring switch 6. The through wire 10d passes through the through hole of the zero-phase current transformer and then connects to the current source wire 9b via the internal wiring of the first wiring switch 5. 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 a wiring configuration in which two reciprocating currents pass through the through hole of the zero-phase current transformer. The other structures of the balance characteristic test device for the zero-phase current transformer involved in Embodiment 3 are the same as those of the balance characteristic test device involved in Embodiment 1.

[0036] Figure 5 This is a diagram illustrating an example of the configuration of the through wires 10a, 10b, 10c, and 10d in the balance characteristic test apparatus of the zero-phase current transformer according to Embodiment 3, showing four states with different directions of current flow. Figure 5 The diagram shown is an observation from side 2 of the current source. Figure 4 A cross-sectional view of the portions of the through wires 10a, 10b, 10c, and 10d passing through the through hole of the zero-phase current transformer 100, wherein the through wires 10a, 10b, 10c, and 10d are configured to be square in the portions passing through the through hole of the zero-phase current transformer 100. Figure 5 The upper left figure shows the internal wiring of the first wiring switch 5 and the second wiring switch 6 respectively. Figure 4 The dashed lines indicate the direction of current flowing through through-wires 10a, 10b, 10c, and 10d. Through-wires 10a and 10c carry current from... Figure 5 The direction from the front to the depths, that is, in Figure 4 The current flowing away from current source 2 passes through wires 10b and 10d from... Figure 5 The direction from the depths of the middle to the front, that is, in Figure 4 The current in the direction closer to current source 2.

[0037] The first wiring switch 5 and the second wiring switch 6 change the connection of their internal wiring according to the indication from the switching indicator 7, in order to switch to... Figure 5This represents any one of four states where the current flows in different directions. For example, when the switching indicator 7 receives a wiring switching indication via the switching signal line 8, the first wiring switch 5 and the second wiring switch 6 change the connection of their internal wiring to switch clockwise. Figure 5 The four states are shown. When Figure 5 The state of the top left becomes Figure 5 When in the upper right state, the balanced current flowing through the through wires 10a, 10b, 10c, and 10d becomes a state where it has rotated 90 degrees clockwise within the through hole. When according to... Figure 5 When the order of "top left", "top right", "bottom right" and "bottom left" is switched to change the direction of the current flowing through the through wires 10a, 10b, 10c and 10d, the balanced current flowing through the through wires 10a, 10b, 10c and 10d rotates 90 degrees clockwise in the through hole each time.

[0038] In the balance characteristic test, even if the magnitude of the balancing 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 will change depending on the position of the balancing 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 the wire flowing through the through hole of the zero-phase current transformer 100 is rotated, or the secondary current is measured while the zero-phase current transformer itself is rotated, and the maximum value of the measured secondary current is taken as the final measured value of the secondary current.

[0039] In the balance characteristic test apparatus for the zero-phase current transformer according to Embodiment 3, the test is conducted according to the indication from the switching indicator 7. Figure 5 The secondary current is measured in four states: "top left," "top right," "bottom right," and "bottom left." The largest of the four secondary currents is taken as the final measured value. Furthermore, during the measurement of the secondary current, the current does not flow through the switching signal line 8. Thus, since the direction of the current through the through-hole of the zero-phase current transformer 100 can be changed according to the indication from the switching indicator 7, the position of the balancing current can be changed to measure the secondary current without physically moving the balance characteristic test apparatus or the zero-phase current transformer 100. Therefore, compared to rotating the wire through the through-hole of the zero-phase current transformer 100 or rotating the zero-phase current transformer itself, the balance characteristic test can be performed in a shorter time.

[0040] In addition, Figure 4In the description, the wire is installed with two round trips through the through hole. However, since the wire is a conductor on the primary side of the zero-phase current transformer 100, it can be installed with multiple round trips (two or more) through the through hole, which is the same as in embodiment 1. Therefore, in Figure 5 In the description, the through wires 10a, 10b, 10c, and 10d are configured to be square in the portion passing through the through hole of the zero-phase current transformer 100, but it is sufficient to configure through wires with multiple round trips (two or more). Additionally, in Figure 5 The instructions state that the switch should be made in a clockwise direction. Figure 5 The four states shown involve changing the connection of the internal wiring of the first wiring switch 5 and the second wiring switch 6. However, for the current source wires 9a and 9b, the first wiring switch 5, four or more even-numbered through wires, and the second wiring switch 6, as long as the wires are connected in a manner that forms a through hole of the zero-phase current transformer with two or more round trips, changing the connection of the internal wiring of the first wiring switch 5 and the second wiring switch 6 to change the direction of the current in the through wires passing through the through hole of the zero-phase current transformer 100 can be arbitrary.

[0041] In addition, Figure 4 In the description, the switching indicator 7 indicates the switching of internal wiring to the first wiring switcher 5 and the second wiring switcher 6 through the switching signal line 8. However, any method can be used as long as it can indicate the switching of internal wiring to the first wiring switcher 5 and the second wiring switcher 6 respectively.

[0042] As described above, the balance characteristic test device for the zero-phase current transformer according to Embodiment 3 includes: a plurality of through wires 10a, 10b, 10c, and 10d passing through the through hole of the zero-phase current transformer 100; a first wiring switch 5 connected to the current source 2 and one end of the through wires 10a, 10b, 10c, and 10d; a second wiring switch 6 connected to the other end of the through wires 10a, 10b, 10c, and 10d; and a switching indicator 7 indicating the switching of internal wiring for the first wiring switch 5 and the second wiring switch 6, at least the first wiring switch... The internal wiring of the device 5, the through wires 10a, 10b, 10c, 10d, and the internal wiring of the second wiring switch 6 are configured with wires arranged in a manner that pass through the through hole of the zero-phase current transformer 100 in multiple round trips. The direction of the current flowing through any one of the multiple through wires 10a, 10b, 10c, 10d passing through the through hole changes according to the indication of the switching indicator 7. 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, and the balance characteristic test can be performed in a short time.

[0043] This application describes various exemplary embodiments, but the various features, forms and functions described in one or more embodiments are not limited to the application of a specific embodiment, and can be applied to the embodiment alone or in various combinations.

[0044] Therefore, it can be assumed that numerous variations not illustrated are also included within the scope of the technology disclosed in this application. For example, this includes cases where at least one constituent element is modified, added to, or omitted, and cases where at least one constituent element is extracted and combined with constituent elements of other embodiments.

[0045] Label Explanation

[0046] 1. 1A wire

[0047] 2. 2A current source

[0048] 3 Ammeters

[0049] 4. Covering

[0050] 5 First cabling switch

[0051] 6 Second wiring switch

[0052] 7. Switch indicator

[0053] 8. Switching signal lines

[0054] 9a, 9b current source wires

[0055] Through-wires 10a, 10b, 10c, and 10d

[0056] 100 zero-phase current transformer.

Claims

1. A device for testing the balance characteristic of a zero-phase current transformer, characterized in that comprising: an electric wire provided in a manner that it penetrates the through hole of the zero-phase current transformer in a plurality of round trips; a current source that causes a direct current to flow through the electric wire; and an ammeter that measures the magnitude of the secondary current of the zero-phase current transformer, the secondary current is measured while rotating the electric wire that penetrates the through hole of the zero-phase current transformer, or the secondary current is measured while rotating the zero-phase current transformer itself.

2. The balance characteristic testing device for a zero-phase current transformer according to claim 1, characterized in that the electric wire in a plurality of round trips is integrated.

3. The balance characteristic testing device for a zero-phase current transformer according to claim 2, characterized in that the integrated electric wire is a straight rod.

4. The balance characteristic testing device for a zero-phase current transformer according to claim 1, characterized by comprising: a plurality of through electric wires that penetrate the through hole of the zero-phase current transformer; a first wiring switcher connected to the current source and one end portion of the through electric wire; a second wiring switcher connected to the other end portion of the through electric wire; and a switch indicator that indicates the switching of the internal wiring of the first wiring switcher and the second wiring switcher, at least the internal wiring of the first wiring switcher, the through electric wire, and the internal wiring of the second wiring switcher constitute the electric wire provided in a manner that it penetrates the through hole of the zero-phase current transformer in a plurality of round trips, the direction of the current flowing through any one of the plurality of through electric wires that penetrate the through hole is changed according to the indication of the switch indicator.

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