JP7378644B2 - Zero-phase current transformer equilibrium characteristics test equipment - Google Patents

Description

The present application relates to a zero-phase current transformer balance characteristic testing device.

A zero-sequence current transformer that detects a zero-sequence current when a ground fault occurs detects an unbalance of current in a through conductor caused by the ground fault current, and outputs a secondary current. However, if the zero-phase current transformer itself has a large unbalanced component, a secondary current will be generated even if a balanced current is input to the primary side of the zero-phase current transformer. , causing false positives. Therefore, a balance characteristic test is performed in which a balance current several times the rated current is passed through the primary side of a zero-phase current transformer to confirm that the magnitude of the secondary current is below a specified value. A balance characteristic test of a zero-phase current transformer can be performed, for example, by passing a wire connected to a current source through the through hole of a zero-phase current transformer for one round trip, passing a predetermined balance current through the wire, and then This is performed by measuring the output of the following current (see, for example, FIG. 4 of Patent Document 1).

Utility Model Publication No. 04-021980

In order to test the balanced characteristics of a zero-phase current transformer with a large rated current that corresponds to a large current, it is necessary to generate a large balanced current. In order to generate a large balanced current, a current source with a large output is required, which poses the problem that the current source becomes large and expensive.

The present application was made in order to solve the above-mentioned problems, and its purpose is to provide a zero-phase current transformer balance characteristic test device that can perform a balance characteristic test using a current source with a small output. do.

The zero-phase current transformer balance characteristic testing device disclosed in the present application includes: an electric wire installed so that a plurality of reciprocating portions pass through a through hole of a zero-phase current transformer; a current source that sends a DC current through the electric wire; and an ammeter that measures the magnitude of the secondary current of the zero-phase current transformer.

The zero-phase current transformer balance characteristic testing device disclosed in the present application includes: an electric wire installed so that a plurality of reciprocating portions pass through a through hole of a zero-phase current transformer; a current source that sends a DC current through the electric wire; Since it is equipped with an ammeter that measures the magnitude of the secondary current of a zero-phase current transformer, tests can be performed using a current source with a small output, making it possible to perform tests with small and inexpensive equipment. can.

1 is a diagram showing the configuration of a zero-phase current transformer balance characteristic testing device according to Embodiment 1. FIG. FIG. 2 is a diagram showing the configuration of an equilibrium characteristic testing device of a comparative example. FIG. 3 is a diagram showing the configuration of a zero-phase current transformer balance characteristic testing device according to a second embodiment. FIG. 7 is a diagram showing the configuration of a zero-phase current transformer balance characteristic testing device according to Embodiment 3; 7 is a diagram illustrating an example of the direction of current flowing through electric wires in Embodiment 3. FIG.

DESCRIPTION OF THE PREFERRED EMBODIMENTS A zero-phase current transformer balance characteristic testing device according to an embodiment of the present invention will be described in detail below with reference to the drawings. In each figure, the same reference numerals indicate the same or corresponding parts.

Embodiment 1.
FIG. 1 is a diagram showing the configuration of a zero-phase current transformer equilibrium characteristic testing device according to the first embodiment. In FIG. 1, a zero-phase current transformer 100 is a test object, and a zero-phase current transformer balance characteristic testing device includes an electric wire 1, a current source 2, and an ammeter 3. The electric wire 1 is installed as a primary-side conducting wire of the zero-phase current transformer 100 so that a plurality of reciprocations of two or more reciprocations form a set and pass through the through hole only once. In FIG. 1, the electric wire 1 is installed so that it passes through the through hole twice in two round trips. The current source 2 is electrically connected to both ends of the electric wire 1 and causes a direct current to flow 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 using the ammeter 3, but it is also possible to connect a load such as a resistor to the secondary current output terminal of the zero-phase current transformer 100 The magnitude of the secondary current of the zero-phase current transformer 100 may be measured by measuring the voltage across the load using a voltmeter or the like. In the balanced characteristic test, a current is caused to flow from the current source 2 to the electric wire 1 so that a balanced current of, for example, six times the rated current flows through the primary side of the zero-phase current transformer 100. It is checked whether the secondary current measured by the ammeter 3 at this time is below a specified value.

FIG. 2 is a diagram showing the configuration of a comparative example of an equilibrium characteristic testing device for explaining the operation of the zero-phase current transformer equilibrium characteristic testing device. It corresponds to this. When comparing the equilibrium characteristic testing apparatus of the comparative example shown in FIG. 2 with the equilibrium characteristic testing apparatus according to the first embodiment shown in FIG. 1, the electric wire 1 is replaced with an electric wire 1a, and the current source 2 is replaced with a current source 2a. The other configuration of the equilibrium characteristic testing device of the comparative example is the same as the configuration of the equilibrium characteristic testing device according to the first embodiment. In the equilibrium characteristic test device according to the first embodiment shown in FIG. 1, the electric wire 1 is installed so that two round trips pass through the through hole, whereas the equilibrium characteristic test device according to the comparative example shown in FIG. In this case, the electric wire 1a is installed so that one round trip passes through the through hole.

Next, the operation of the zero-phase current transformer equilibrium characteristic testing apparatus according to the first embodiment will be described while comparing it with the operation of the equilibrium characteristic testing apparatus of the comparative example. In a balanced characteristic test of a zero-phase current transformer, it is necessary to supply a balanced current of, for example, six times the rated current to the primary side of the zero-phase current transformer. If the rated current of a zero-phase current transformer that performs a balanced characteristic test is 100 A, it is necessary to supply a balanced current of 600 A to the primary side of the zero-phase current transformer. In the equilibrium characteristic test device of the comparative example shown in FIG. 2, for example, when a current of I [A] is passed from the current source 2a in the direction of the arrow shown along the electric wire 1a, one round trip of the electric wire 1a penetrates. Since it is installed to penetrate the hole, one current of I[A] flows through the through hole from the front to the back in Fig. 2, and one current of I [A] flows from the back to the front in Fig. 2. A current of I[A] flows. As a result, a balanced current of I[A] is applied to the primary side of the zero-phase current transformer 100. Therefore, for example, if it is desired to supply a balanced current of 600 A to the primary side of a zero-phase current transformer, it is sufficient to supply 600 A as the current source 2a.

On the other hand, in the zero-phase current transformer balance characteristic testing device according to the first embodiment shown in FIG. In this case, the electric wire 1 is installed so that two round trips pass through the through hole, so a current of I [A] for two times flows through the through hole from the front to the back in Fig. 1. A current of I[A] flows twice from the back to the front. As a result, a balanced current of I*2 [A] is applied to the primary side of the zero-phase current transformer 100. Therefore, for example, if it is desired to supply a balanced current of 600 A to the primary side of a zero-phase current transformer, 300 A may be supplied as the current source 2. When conducting a balanced characteristic test in which a balanced current of 600 A is applied to the primary side of a zero-phase current transformer, the balanced characteristic test device of the comparative example requires a current source 2a that generates a current of 600 A. In the balanced characteristic test device according to No. 1, it is sufficient to have a current source 2 with a small output that generates a current of 300 A, which is half that of the comparative example. Since the size of the current source depends on the amount of current that can be output, the current source 2 according to the first embodiment can be smaller than the current source 2a according to the comparative example. Further, in accordance with this, the current source 2 according to the first embodiment can be cheaper than the current source 2a according to the comparative example.

In addition, in the equilibrium characteristic test device according to the first embodiment, the electric wires 1 for multiple reciprocations are installed as a set so as to pass through the through hole of the zero-phase current transformer 100 only once. The work of passing the electric wire 1 through the through-hole before the test and the work of removing the electric wire 1 from the through-hole after the test are very simple as in the equilibrium characteristic test device of the comparative example.

In the explanation with reference to FIG. 1, it was assumed that the electric wire 1 was installed so as to pass through the through hole twice in two round trips. It suffices if it is installed so that it can be penetrated by more than one round trip. For example, if the electric wire 1 is installed so that three round trips pass through the through hole, when a current of I [A] flows from the current source 2, a current of I*3 [A] is applied to the primary side of the zero-phase current transformer 100. This means that a balanced current of 1 is applied, and a current source with a smaller output may be used.

As described above, the zero-phase current transformer equilibrium characteristic testing device according to the first embodiment is capable of testing the electric wire 1 installed so that multiple reciprocations pass through the through hole of the zero-phase current transformer 100, and the electric wire 1 Since it is equipped with a current source 2 that flows a direct current and an ammeter 3 that measures the magnitude of the secondary current of the zero-phase current transformer 100, it is possible to perform a balanced characteristic test using a current source with a small output. Therefore, a small and inexpensive current source can be used.

Embodiment 2.
FIG. 3 is a diagram showing the configuration of a zero-phase current transformer equilibrium characteristic testing device according to the second embodiment. Comparing the zero-phase current transformer balance characteristic test device according to the second embodiment shown in FIG. 3 with the zero-phase current transformer balance characteristic test device according to the first embodiment shown in FIG. A set of wires is covered with a covering 4 and integrated to form one primary conductor. For example, the electric wire 1 covered with the covering 4 is formed by integrally molding the electric wire 1 for multiple round trips and an insulating material such as resin. The other configuration of the zero-phase current transformer balance characteristic testing device according to the second embodiment is the same as the configuration of the balance characteristic testing device according to the first embodiment.

In the zero-phase current transformer balance characteristic testing device according to the second embodiment shown in FIG. The fact that a balance current of I*2 [A] is applied to the primary side of the current transformer 100 is the same as in the zero-phase current transformer balance characteristic testing device according to the first embodiment. Therefore, the zero-phase current transformer equilibrium characteristic testing device according to the second embodiment can provide the same effects as the zero-phase current transformer equilibrium characteristic testing device according to the first embodiment. Furthermore, in the zero-phase current transformer balance characteristic testing device according to the second embodiment shown in FIG. It becomes easier to handle, and it becomes easier to pass the electric wire 1 for multiple round trips through the through hole before the equilibrium characteristic test, and to pull out the electric wire 1 for multiple round trips from the through hole after the equilibrium characteristic test. .

In addition, in the zero-phase current transformer balance characteristic test device according to the second embodiment shown in FIG. 3, it is assumed that the electric wires 1 for multiple reciprocations form a set and are covered with the covering 4 and are integrated. It is sufficient that the electric wires 1 for a plurality of reciprocations are integrated. For example, the electric wires 1 for a plurality of reciprocations may be fixed with a clip or adhesive to be integrated.

Alternatively, the integrated electric wire 1 may be formed into a hard, straight rod shape and installed so as to pass through the through hole. In this case, it becomes easier to pass the electric wire 1 for a plurality of reciprocations through the through hole before the equilibrium characteristic test, and to extract the electric wire 1 for a plurality of reciprocations from the through hole after the equilibrium characteristic test.

As described above, the zero-phase current transformer equilibrium characteristic testing device according to the second embodiment is capable of testing the electric wire 1 installed so that a plurality of reciprocating portions pass through the through hole of the zero-phase current transformer 100, and the electric wire 1. It is equipped with a current source 2 that sends a direct current and an ammeter 3 that measures the magnitude of the secondary current of the zero-phase current transformer 100, and since the electric wire 1 for multiple round trips is integrated, the output is small current. Balance characteristic tests can be performed using a current source, and a small current source can be used. Furthermore, it becomes easier to pass the electric wire 1 for a plurality of reciprocations through the through hole before the equilibrium characteristic test, and to pull out the electric wire 1 for a plurality of reciprocations from the through hole after the equilibrium characteristic test.

Embodiment 3.
FIG. 4 is a diagram showing the configuration of a zero-phase current transformer equilibrium characteristic testing device according to the third embodiment. Comparing the zero-phase current transformer balance characteristic test device according to the third embodiment shown in FIG. 4 with the zero-phase current transformer balance characteristic test device according to the first embodiment shown in FIG. A first wiring switch 5 is provided at the folded part, and a second wiring switch 6 is provided at the folded part of the wire far from the current source 2. It also includes a switching indicator 7 that instructs the first wiring switching device 5 and the second wiring switching device 6 to switch internal wiring through 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 wiring of the first wiring switch 5, and after the through wire 10a passes through the through hole of the zero-phase current transformer, the second wire is connected to the current source wire 9a connected to the current source 2. The through wire 10b is connected to the through wire 10b through the internal wiring of the switch 6, and 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 wiring of the first wiring switch 5. 10c passes through the through hole of the zero-phase current transformer and then connects to the through wire 10d through the internal wiring of the second wiring switch 6, and after the through wire 10d passes through the through hole of the zero phase current transformer, it connects to the first through wire 10d. The current source wire 9b is connected to the current source 2 through the internal wiring of the wiring switch 5. The current source wire 9b is connected to the current source 2. As a result, the current source wires 9a, 9b, the first wiring switch 5, the through wires 10a, 10b, 10c, 10d, and the second wiring switch 6 are inserted into the through hole of the zero-phase current transformer two times back and forth. It consists of electric wires that are installed so that they pass through the area. The other configuration of the zero-phase current transformer balance characteristic testing device according to the third embodiment is the same as the configuration of the balance characteristic testing device according to the first embodiment.

FIG. 5 is a diagram showing an example of the arrangement of the through wires 10a, 10b, 10c, and 10d in the zero-phase current transformer balance characteristic testing device according to the third embodiment, and shows four states in which the current flows in different directions. ing. The diagram shown in FIG. 5 is a cross-sectional view of the portion where the through-holes 10a, 10b, 10c, and 10d pass through the through-holes of the zero-phase current transformer 100 in FIG. 4, as seen from the current source 2 side. The through wires 10a, 10b, 10c, and 10d are arranged so as to form a square in the portion where they pass through the through hole of the zero-phase current transformer 100. The upper left diagram in FIG. 5 shows the through wires 10a, 10b, 10c, 10d shows the direction of the current flowing through 10d. Current flows through the through wires 10a and 10c from the front to the back in FIG. 5, that is, in the direction away from the current source 2 in FIG. 4, and through the through wires 10b and 10d, from the back to the front in FIG. A current flows in the direction shown in FIG. 4, that is, in the direction approaching the current source 2 in FIG.

The first wiring switch 5 and the second wiring switch 6 are configured to switch to one of four states in which the current flows as shown in FIG. 5 in accordance with instructions from the switching indicator 7. The internal wiring connections of the first wiring switch 5 and the second wiring switch 6 are changed. For example, when a wiring switching instruction is transmitted from the switching indicator 7 through the switching signal line 8, the first wiring switching device 5 and the second wiring switching device 6 switch between the four states shown in FIG. The connections of the internal wiring of the first wiring switch 5 and the second wiring switch 6 are changed so as to switch. When the upper left state of FIG. 5 changes to the upper right state of FIG. 5, the balanced currents flowing through the through wires 10a, 10b, 10c, and 10d will be in a state as if they were rotated 90 degrees clockwise within the through hole. When the direction of the current flowing through the through wires 10a, 10b, 10c, and 10d is switched in the order of "upper left," "upper right," "lower right," and "lower left" in FIG. rotates 90 degrees clockwise within the through hole.

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 position of the balance current passing through the through-hole of the zero-phase current transformer 100 determines whether the zero-phase current transformer The magnitude of the 100 secondary currents may vary. Therefore, in a balanced characteristic test, for example, the secondary current is measured while rotating the electric 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. However, the largest value among the measured secondary currents was taken as the final measured value of the secondary current.

In the zero-phase current transformer balance characteristic testing device according to the third embodiment, each of the four states shown in "upper left", "upper right", "lower right", and "lower left" in FIG. The secondary current is measured, and the largest value among the four obtained secondary currents is taken as the final measured value of the secondary current. Note that when measuring the secondary current, no current is allowed to flow through the switching signal line 8. In this way, since the direction of the current passing through the through hole of the zero-phase current transformer 100 can be changed by the instruction from the switching indicator 7, it is not necessary to physically move the balance characteristic test device or the zero-phase current transformer 100. The secondary current can be measured without changing the position of the equilibrium current. Thereby, the balance characteristic test can be performed in a shorter time than when rotating the electric wire passing through the through hole of the zero-phase current transformer 100 or when rotating the zero-phase current transformer itself.

In addition, in the explanation with reference to FIG. 4, it was assumed that the electric wire is installed so that it passes through the through hole for two round trips. As in the first embodiment, it is only necessary that the hole be installed so as to pass through a plurality of reciprocations. Therefore, in the explanation with reference to FIG. 5, it is assumed that the through wires 10a, 10b, 10c, and 10d are arranged so as to form a square in the portion where they pass through the through hole of the zero-phase current transformer 100. It is only necessary to arrange a through-wire that penetrates through multiple round trips. Furthermore, in the description of FIG. 5, if the connections of the internal wiring of the first wiring switch 5 and the second wiring switch 6 are changed so that the four states shown in FIG. 5 are switched clockwise. However, the current source wires 9a, 9b, the first wiring switch 5, four or more even-numbered through wires, and the second wiring switch 6 are connected to the through hole of the zero-phase current transformer two times back and forth. The first wiring is connected so as to form an electric wire installed so that the above-mentioned multiple round trips pass through, and the direction of the current of the through-hole electric wire passing through the through-hole of the zero-phase current transformer 100 changes. Any type of device may be used as long as the internal wiring connections of the switch 5 and the second wiring switch 6 can be changed.

Furthermore, in the explanation with reference to FIG. 4, it is assumed that the switching instruction device 7 instructs the first wiring switching device 5 and the second wiring switching device 6 to switch the internal wiring through the switching signal line 8. Any method may be used as long as it can instruct each of the wiring switching device 5 and the second wiring switching device 6 to switch the internal wiring.

As described above, the zero-phase current transformer balance characteristic testing device according to the third embodiment includes a plurality of through wires 10a, 10b, 10c, and 10d passing through the through hole of the zero-phase current transformer 100, and a current source 2. and a first wiring switch 5 connected to one end of the through wires 10a, 10b, 10c, and 10d, and a second wiring connected to the other end of the through wires 10a, 10b, 10c, and 10d. It includes a switch 6 and a switching indicator 7 that instructs the first wiring switch 5 and the second wiring switch 6 to switch the internal wiring, and at least the internal wiring of the first wiring switch 5 and the through-hole The electric wires 10a, 10b, 10c, and 10d and the internal wiring of the second wiring switch 6 constitute an electric wire installed so that a plurality of reciprocations pass through the through hole of the zero-phase current transformer 100. , the direction of the current flowing through one of the plurality of through wires 10a, 10b, 10c, and 10d passing through the through hole changes according to the instruction from the switching indicator 7. It is possible to measure the secondary current by changing the position of the equilibrium current without having to move it, and it is possible to perform an equilibrium characteristic test in a short time.

Although this application describes various exemplary embodiments, various features, aspects, and functions described in one or more embodiments may be limited to the application of particular embodiments. Rather, they are applicable to the embodiments alone or in various combinations.
Therefore, countless variations not illustrated are envisioned within the scope of the technology disclosed herein. For example, this includes cases where at least one component is modified, added, or omitted, and cases where at least one component is extracted and combined with components of other embodiments.

1, 1a electric wire, 2, 2a current source, 3 ammeter, 4 covering, 5 first wiring switch, 6 second wiring switch, 7 switching indicator, 8 switching signal line, 9a, 9b current source Electric wires, 10a, 10b, 10c, 10d Penetrating wires, 100 Zero-phase current transformer.

Claims (4)

An electric wire installed so that multiple round trips pass through the through hole of the zero-phase current transformer,
a current source that causes a direct current to flow through the electric wire;
A balance characteristic testing device for a zero-phase current transformer, comprising: an ammeter for measuring the magnitude of the secondary current of the zero-phase current transformer. The zero-phase current transformer balance characteristic testing device according to claim 1, wherein the electric wire for a plurality of reciprocations is integrated. 3. The zero-phase current transformer balance characteristic testing device according to claim 2, wherein the integrated electric wire has a straight rod shape. a plurality of through wires passing through the through hole of the zero-phase current transformer;
a first wiring switch 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;
a switching indicator that instructs the first wiring switching device and the second wiring switching device to switch internal wiring,
At least the internal wiring of the first wiring switch, the through wire, and the internal wiring of the second wiring switch pass through the through hole of the zero-phase current transformer for multiple round trips. constitutes the electric wire installed in
2. The zero-phase current transformer balance characteristic testing device according to claim 1, wherein the direction of the current flowing through any one of the plurality of through wires passing through the through hole is changed according to an instruction from the switching indicator.

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