JP2002372552A - Current measuring device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small-sized, easily-mountable and highly-precise current measuring device capable of reducing a current measurement error caused by variations of the winding density or variations of an interlinkage sectional area, and suppressing temperature rise. SOLUTION: This device is equipped with a measuring coil 2 having a circular core 2a comprising an insulator enclosing a bus bar 1 to be measured, and a secondary winding 2b wound on the core 2a, for measuring a current flowing in the bus bar 1 to be measured, and with a magnetic material structure 4 having a circular magnetic material 4a having roughly the same diameter as the measuring coil 2, enclosing the bus bar 1 to be measured around the center coincident with that of the measuring coil 2, and adjoining the measuring coil 2, and a short circuit winding 4b wound on the magnetic material 4a over the whole circumference so as to be interlinked with a magnetic flux passing through the magnetic material 4a, and having electrically short-circuited both ends.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a current measuring device, that is, a current measuring device for measuring a current flowing through a primary conductor.

[0002]

2. Description of the Related Art FIG. 21 is a front view partially showing a Rogowski coil, which is a conventional current measuring device disclosed in Japanese Patent Application Laid-Open No. 3-91214, for example. FIG.
It is arrow sectional drawing which follows the XXIII-XXIII line. FIG. 23 is a front view showing the winding state of the measurement winding.

In FIGS. 21 to 23, reference numeral 1 denotes a primary conductor. Reference numeral 2 denotes a current measuring device, which includes a winding core 2a and a measurement winding 2b wound around the winding core 2a. The core 2a is made of an annular insulator provided so as to penetrate the primary conductor 1, and is arranged around the primary conductor 1. On the other hand, the winding 2b is wound around the core 2a as shown in FIG. The winding 2b has an extraction unit 2c for extracting the output terminals p and q.

[0004] The conventional current measuring device 2 configured as described above.
, The current I flowing through the primary conductor 1 causes the core 2
A magnetic field H is generated in the portion a. The relationship between the magnetic field H and the current I is expressed by the following equation (1) according to the amperage revolution integral theorem.

[0005]

(Equation 1)

The current I flowing through the primary conductor (1) is a sinusoidal alternating current having an angular frequency ω, the minute length in the circumferential direction of the core (2a) is Δl, the winding density therebetween is n, and the magnetic flux interception. Assuming that the area is S, the magnetic flux is φ, and the induced voltage of the measurement winding 2b is e, the current I
Is given by the following equations (2) and (3).

[0007]

(Equation 2)

Assuming that the total number of turns of the measurement winding 2b is N and the induced voltage at the terminal p-terminal q of the winding 2b is E,

[0009]

(Equation 3)

And the induced voltage of the measurement winding 2b gives
The current I can be measured.

[0011]

The conventional current measuring device 2 having such a configuration is configured as described above. However, the winding density n and the flux cross-sectional area S of the measuring winding 2b are changed. Will change in the circumferential direction due to the fabrication of the current measuring device 2. For this reason, the magnetic flux generated by the current flowing through the other-phase bus 3 installed near the current measuring device 2 causes the measurement winding 2 b
An induced voltage is generated between the terminal p and the terminal q, causing an error in the current measurement. If a shield is provided to reduce this current measurement error, a large shield is required, which is a problem.

The measurement winding 2b has a winding take-out section 2c.
In order to ensure the insulation, there is a non-winding portion where no winding is wound, which causes a problem that the winding density differs greatly and the current measurement error increases.

Further, when the conventional current measuring device 2 having such a configuration is applied to a gas insulated switchgear of a power system, a surge electromagnetic wave generated by a switching operation of a circuit breaker or the like invades the measurement winding 2b. This is a problem because the current measurement error increases.

SUMMARY OF THE INVENTION The present invention has been made to solve these problems, and it is possible to reduce a current measurement error due to a variation in winding density and a variation in a cross-sectional area in manufacturing a current measuring device, and to make the device compact and easy to mount. It is another object of the present invention to provide a highly accurate current measuring device capable of further suppressing a rise in temperature.

[0015]

SUMMARY OF THE INVENTION A current measuring device according to the present invention comprises an annular core made of an insulator surrounding a bus to be measured and a secondary winding which is wound around the core and measures a current flowing through the bus to be measured. A measuring coil having a winding, a ring-shaped magnetic body which is substantially the same diameter as the measuring coil, surrounds the measured bus with the center being coincident with the measuring coil and is close to the measuring coil, and a magnetic flux and a chain passing through the magnetic body through the magnetic body. And a magnetic body structure having a short-circuited winding wound around the entire circumference so as to intersect and electrically short-circuited at both ends.

Further, a heat insulating material is further provided between the magnetic body structure and the measuring coil.

[0017] Further, an annular magnetic body which has a diameter substantially the same as that of the measurement coil, is centered on the measurement coil, surrounds the bus to be measured, and is adjacent to the magnetic body structure of the measurement coil on the opposite side and a magnetic body. And a second magnetic body structure having a short-circuited winding wound around the entire circumference so as to interlink with the magnetic flux passing through the coil and having both ends electrically short-circuited.

Further, an annular core and a winding made of an insulator which has a diameter substantially equal to that of the measuring coil, is centered on the measuring coil, surrounds the bus to be measured, and is located on the opposite side of the magnetic structure from the measuring coil. There is further provided a second measurement coil having a secondary winding wound around the core and measuring a current flowing through the bus to be measured.

Further, the apparatus further comprises a shield winding for winding the measurement coil and the magnetic body structure together.

The shield winding is composed of a plurality of divided coils, each of which has the same number of turns and the same poles are connected.

In addition, a shield member made of a nonmagnetic material and a good conductor is provided to surround the magnetic material structure and the measuring coil together.

Also, a metal tank for storing a plurality of sets of the bus to be measured, the measurement coil, the magnetic material structure and the shield member, and a support provided inside the metal tank for supporting each set of shield members from the metal tank. And a plate.

The shield member has a groove and a hole formed in the support plate around the measured bus, the measured bus passes through the hole, and the measurement coil is housed in the groove.

The measurement coil is provided on the bottom side of the groove, and the magnetic material structure is provided so as to close the groove.

The shield member comprises an inner cylinder, an outer cylinder, and a bottom plate, and has a U-shaped cross section.

Further, the magnetic body structure is provided on the opening side of the U-shaped section of the shield member, and the measurement coil is provided on the inner side of the U-shaped section.

In addition, a cover made of a non-magnetic material and a good conductor is provided in the opening of the shield member.
The slit portion is provided so that the outer peripheral portion or the inner peripheral portion of the lid is not electrically connected.

Further, the magnetic body structure is installed on the same plane perpendicular to the measured bus.

[0029]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 FIG. 1 is a front view showing a current measuring device according to Embodiment 1 of the present invention in a partial cross section. FIG. 2 is a sectional view taken along the line II-II in FIG. FIG. 3 is a front view showing a winding state of a short-circuit winding of an iron core structure (magnetic material structure).

In FIGS. 1 to 3, a measurement coil 2 is manufactured by winding a measurement winding 2b as a secondary winding around an annular core 2a made of an insulating material as shown in FIG. An insulated short-circuit winding 4b is wound around an annular iron core 4a formed by laminating magnetic materials such as silicon steel plates so as to interlink with a magnetic flux passing through the iron core 4a as shown in FIG. Are electrically short-circuited to produce an iron core structure 4 as a magnetic structure. The iron core structure 4 is manufactured so as to have substantially the same diameter as the measurement coil 2, and is disposed closely to the side surface of the measurement coil 2. Then, the primary conductor 1 as a bus to be measured
Are arranged on the central axis of both. That is, the measurement coil 2 and the iron core structure 4 having substantially the same diameter are connected to the primary conductor 1.
Are arranged side by side so as to be in close contact with each other on the same plane perpendicular to the axis.

In the current measuring device having such a configuration,
Since the iron core 4 a is provided on the outer periphery of the primary conductor 1, a magnetic flux due to the main circuit current flowing through the primary conductor 1 flows through the iron core 4 a. Since both ends of the short-circuit winding 4b are short-circuited, an induced current for canceling the magnetic flux flows through the short-circuit winding 4b. However, the excitation voltage is low, so
Iron core 4 generated by main circuit current flowing through primary conductor 1
The magnetic flux in a is small.

The magnetic flux generated by the main circuit current flowing through the other phase bus 3 is concentrated on the iron core 4a. And iron core structure 4
In the space in the vicinity of the outer peripheral portion, the magnetic flux density becomes larger than when no iron core structure 4 is provided. On the other hand, the magnetic flux density near both side surfaces of the iron core structure 4 is reduced by the magnetic flux being concentrated on the iron core 4a, and is reduced as compared with the case where the iron core structure 4 is not provided.

That is, the current measuring device having such a configuration measures an annular core 2a made of an insulating material surrounding the bus 1 to be measured and a current 2 wound around the core 2a and flowing through the bus 1 to be measured. A measurement coil 2 having a secondary winding 2b, an annular magnetic body 4a and a magnetic body having substantially the same diameter as the measurement coil 2 and surrounding the measured bus 1 with the center coincident with the measurement coil 2 and close to the measurement coil 2 4a, a magnetic structure 4 having a short-circuit winding 4b wound around the entire circumference so as to interlink with the magnetic flux passing through the magnetic material 4a and having both ends electrically short-circuited. By providing the measuring coil 2 having a diameter substantially the same as that of the magnetic material structure 4 in close contact with the magnetic body structure 4, the magnetic flux density of the core 2 a of the measuring coil 2 can be reduced, and the variation in the winding density and the variation in the cross-sectional area of the linkage. Can reduce the current measurement error due to Kill.

In the method of surrounding the iron core 4a with a conductor having a large area instead of the short-circuit winding 4b, an eddy current due to the main circuit current of the other-phase bus 3 flows through this conductor, and a magnetic flux due to the eddy current affects the measuring coil. However, the current measurement error cannot be reduced.

Embodiment 2 FIG. 4 is a side view, partly in section, showing a current measuring device according to Embodiment 2 of the present invention.
In the present embodiment, the iron core structure 4 and the measurement coil 2
And a thin plate-shaped heat insulating material 15 that is difficult to conduct heat. Other configurations are the same as those of the first embodiment.

Since the same ampere-turn current as the main circuit current flowing through the primary conductor 1 flows through the short-circuit winding 4b of the iron core structure 4, the short-circuit winding 4b generates heat. On the other hand, since the measurement coil 2 measures the main circuit current flowing through the primary conductor 1 by the induced voltage, the induced current hardly flows and there is no temperature rise. However, the heat generated by the short-circuit winding 4b causes the temperature of the core 2a to rise, causing a change in the cross-sectional area of the core 2a, thereby increasing the current measurement error.

In the current measuring device according to the present embodiment, by providing a heat insulating material 15 made of a refractory material between the iron core structure 4 and the measuring coil 2, it is possible to reduce a current measurement error due to the main circuit current. .

Embodiment 3 FIG. 5 is a side view, partly in section, showing a current measuring device according to Embodiment 3 of the present invention.
In the present embodiment, an iron core structure 16 as a second magnetic structure having the same structure as the iron core structure 4 is provided. The iron core structure 16 is manufactured by winding an annular iron core 16a made of a magnetic material such as a silicon steel plate with a short-circuit winding 16b and electrically short-circuiting both ends thereof. The iron core structure 4, the iron core structure 16, and the measuring coil 2 have substantially the same diameter. The measurement coil 2 is provided between the iron core structure 4 and the iron core structure 16 and attached to the outer periphery of the primary conductor 1.

In the current measuring device having such a configuration,
An annular magnetic body 16a and a magnetic body 16a which have a diameter substantially the same as that of the measurement coil 2 and are centered on the measurement coil 2 and surround the bus 1 to be measured and are adjacent to the magnetic body structure 4 of the measurement coil 2 on the opposite side. Since the second magnetic body structure 16 having the short-circuited winding 16b wound around the entire circumference so as to interlink with the magnetic flux passing through the magnetic body 16a and having both ends electrically short-circuited, the measurement coil 2 The magnetic flux density of the core 2a is further reduced as compared with the first embodiment, and the current measurement error due to the variation in the winding density and the variation in the cross-sectional area can be further reduced.

Embodiment 4 FIG. FIG. 6 is a partial cross-sectional side view showing a current measuring device according to Embodiment 4 of the present invention.
In the present embodiment, the measurement coils 2 and 22 having substantially the same diameter as the magnetic material structure 4 are provided on both sides of the magnetic material structure 4 in close contact with each other.

In such a current measuring device,
An annular core 22a and a core 22a having substantially the same diameter as the measuring coil 2 and having the center coincident with the measuring coil 2 and surrounding the bus 1 to be measured and adjacent to the magnetic material structure 4 on the opposite side to the measuring coil 2 are provided. Since the second measurement coil 22 having the secondary winding 22b for measuring the current flowing through the bus 1 to be measured is provided, and if two measurement coils 2 and 22 are required, the magnetic material structure By providing measurement coils on both side surfaces of the magnetic material structure 4, the two measurement coils 2 and 22 can be brought into close contact with the magnetic material structure 4, and the magnetic flux due to the main circuit current flowing through the bus 1 to be measured is transferred to the magnetic material structure 4. 4 and the magnetic flux density of the two measurement coils 2 and 22 can be reduced, and two measurement coils 2 and 22 can be installed without providing a plurality of magnetic material structures 4. Miniaturization can be achieved .

Embodiment 5 FIG. FIG. 7 is a side view, partly in section, showing a current measuring device according to Embodiment 5 of the present invention.
FIG. 8 is a front view showing a winding state of the shield winding. In the present embodiment, the core structure 4 and the measurement coil 2 are collectively wound and fixed by the shield winding 17. The shield winding 17 includes a plurality of split coils 17a to 17f, and the same poles are connected by connection wires 17g and 17h.

Since the short-circuit winding 4b of the iron core structure 4 is wound around the iron core 4a and both ends are short-circuited, an induced current flows through the short-circuit winding 4b so as to cancel the magnetic flux due to the main circuit current. Therefore, the magnetic flux density generated in the iron core 4a by the main circuit current is small.

The split coil 17 of the shield winding 17
Since only the same poles a to 17f are connected, the induced voltages of the split coils 17a to 17f due to the main circuit current cancel each other out, and the induced current generated in the shield winding 17 by the magnetic flux due to the main circuit current does not flow. There is no effect on the measurement of the measured current.

On the other hand, the magnetic flux generated by the main circuit current flowing through the other-phase bus 3 is concentrated on the portion P1 closest to the other-phase bus 3 and the portion P2 farthest from the other core 3 of the iron core 4a.
8 is opposite to the circumferential direction of the iron core 4a as shown in FIG.
An induced current flows through 17f so as to cancel this magnetic flux.

Since the measurement coil 2 is disposed in the shield winding 17, the magnetic flux density of the measurement coil 2 is determined by the induced current flowing through the shield winding 17 and the main circuit current flowing through the other phase bus 3. To cancel the magnetic flux, the other phase bus 3
The magnetic flux density due to the main circuit current flowing through the power supply is greatly reduced. Therefore, it is possible to greatly reduce a current measurement error due to a variation in the winding density of the measurement coil 2 and a variation in the cross-sectional area of the linkage.

Embodiment 6 FIG. FIG. 9 is a side view, partly in section, showing a current measuring device according to Embodiment 6 of the present invention.
In the present embodiment, the measuring coils 2 and 22 having substantially the same diameter as the magnetic material structure 4 are provided on both sides of the magnetic material structure 4 in close contact with each other, and the measurement coils 2 and 22 are collectively assembled.
And fix by winding. That is, the measurement coils 2 and 22 are closely provided on both sides of the magnetic body structure 4, and the shield winding 17 is provided so as to include the magnetic body structure 4 and the two measurement coils 2 and 22.

In this configuration, when two measurement coils are required, the measurement coils 2 and 2 are provided on both sides of the magnetic material structure 4.
By providing the measurement coil 22, the measurement coils 2 and 22 can be brought into close contact with the magnetic body structure 4, and the magnetic flux due to the main circuit current flowing through the other-phase bus 3 can be concentrated on the magnetic body structure 4. Since the induced current flowing through the shield winding 7 cancels out the magnetic flux due to the main circuit current, the magnetic flux densities of the two measurement coils 2 and 22 can be greatly reduced.
It is possible to reduce the size in the case where the measuring coils 2 and 22 are installed.

Embodiment 7 FIG. FIG. 10 is a front view showing a partial cross section of a current measuring device according to Embodiment 7 of the present invention. FIG.
1 is a sectional view taken along the line XI-XI in FIG.

10 and 11, reference numeral 5 denotes a non-magnetic good conductor such as aluminum, which is formed by welding a cylindrical inner cylinder 5a and an outer cylinder 5b and a disc-shaped bottom plate 5c, and having a U-shaped cross section. The shield member 5. The measuring coil 2 and the magnetic body structure 4 of the present embodiment
It is stored inside. When the measurement coil 2 and the magnetic body structure 4 are housed in the shield member 5, the measurement coil 2 is shielded on the bottom side of the shield member 5 in the right direction in FIG. It is arranged on the opening side of the member 5. The terminal p-terminal q of the measurement winding 2b extends from a through hole provided in the outer cylinder 5b. Other configurations are the same as those of the first embodiment.

In the current measuring device having such a configuration,
Since the measuring coil 2 is attached to the outer periphery of the primary conductor 1, the magnetic flux generated by the main circuit current of the primary conductor 1 and the measuring coil 2
The main circuit current flowing through the primary conductor 1 can be measured by the induced voltage at the terminal p-terminal q.

Since the iron core 4a is provided on the outer periphery of the primary conductor 1, magnetic flux due to the main circuit current flowing in the primary conductor 1 flows. However, since both ends of the short-circuit winding 4b are short-circuited,
An induction current for canceling the magnetic flux flows through the short-circuit winding 4b.
Also, the excitation voltage is small, and therefore, the magnetic flux generated by the main circuit current in the iron core 4a is small.

The magnetic flux generated by the main circuit current of the other-phase bus 3 is concentrated on the iron core 4a, and the magnetic coupling between the shield member 5 and the other-phase bus 3 is improved. The induced current flows more than in the case where no shield coil 5 is provided, and the magnetic flux density due to the main circuit current of the other phase bus 3 of the measuring coil 2 disposed inside the shield member 5 is greatly reduced.

Further, since the measuring coil 2 is in close contact with the magnetic structure 4 having substantially the same diameter, the magnetic flux due to the main circuit current of the other-phase bus 3 concentrates on the magnetic structure 4 and the magnetic flux density of the measuring coil 2 portion To reduce. Therefore, in the vicinity of the core in the measurement coil 2, the magnetic flux can be greatly reduced due to the magnetic flux concentration effect and the superposition effect due to the increase in the induced current.

Further, the magnetic flux concentrated on the iron core 4a is reduced,
The magnetic saturation of the iron core 4a is reduced. Therefore, a current measurement error can be reduced even in a large current region.

Further, the magnetic material structure 4 is made of a shield member 5
Is provided in the opening, the magnetic flux penetrating from the opening can be shielded by the magnetic material structure 4, and the magnetic flux density due to the other phase bus 3 of the core 2a of the measuring coil 2 can be reduced. Thus, it is possible to reduce the current measurement error due to the variation in the winding density and the variation in the cross-sectional area.

Further, by providing the magnetic body structure 4 in the opening, the electromagnetic wave can be shielded, and the current measurement error due to the electromagnetic wave can be reduced.

Further, since the same ampere turn as the main circuit current flows through the short-circuit winding 4b of the magnetic body structure 4, a temperature rise occurs. On the other hand, since the measurement winding 2b of the measurement coil 2 measures the induced voltage, almost no induced current flows.
Then, the magnetic material structure 4 whose temperature rises is
Is provided on the side of the opening, so that heat dissipation is good and a rise in temperature can be suppressed.

The magnetic material structure 4 and the measuring coil 2 having the same diameter as the opening can be easily housed in the shield member 5.

When the magnetic structure 4 is provided inside the shield member 5 and the measurement coil 2 is provided at the opening side of the electromagnetic shield member 5, the magnetic coupling between the shield member 5 and the other-phase bus 3 is further improved. Although good, the magnetic flux due to the main circuit current flowing through the other-phase bus 3 easily enters the measuring coil 2, and the current measurement error is significantly larger than when the shield member 5 is provided in the opening. Further, since the magnetic structure 4 through which a current flows is provided inside, the temperature rise is greater than when the magnetic structure 4 is provided in the opening.

Embodiment 8 FIG. FIG. 12 is a front view showing a current measuring device according to the eighth embodiment of the present invention in a partial cross section. FIG.
3 is a sectional view taken along the line XIV-XIV in FIG. In the present embodiment, a lid 6 b is provided on a container 6 a that houses the magnetic body structure 4 and the measurement coil 2 to form a shield member 6.

A magnetic material structure 4 and a measuring coil 2 having substantially the same diameter are provided in close contact with each other, and a container 6a made of a nonmagnetic material and a good conductor having an opening on the side surface is prepared. And the measuring coil 2 are inserted, and a lid 6b made of a non-magnetic good conductor is connected to the container 6a by bolts at the outer periphery with a slit at the opening so that the inner periphery is not electrically connected to the container 6a. Is provided.

In this configuration, since the shield member 6 is provided with a slit so as not to electrically connect the lid 6b and the inner peripheral portion of the container 6a, the magnetic flux generated by the main circuit current flowing through the primary conductor 1 is generated. And the shield member 6 has 1
Due to the main circuit current flowing through the secondary conductor 1, an induced current that disturbs the magnetic flux density of the measurement coil 2 does not flow. On the other hand, the other phase bus 3
Of the magnetic circuit 4a of the magnetic body structure 4
And the magnetic coupling between the shield member 6 and the primary conductor 1 is improved.

By providing the lid 6 a of the shield member 6, the magnetic flux from the other-phase bus 3 enters the lid 6 a, the amount of magnetic flux penetration of the induction current path increases, and the induction current path flowing through the lid 6 a and the shield member 6 is reduced. Many induced currents flow. In this induced current, a larger amount of induced current flows than in the seventh embodiment, and the magnetic flux density of the measurement coil 2 is further reduced as compared with the seventh embodiment.
Current measurement errors due to variations in winding density and variations in cross-sectional area can be further reduced. Further, due to the increase in the induced current of the shield member 6 on the other-phase bus 3 side, the magnetic flux penetrating into the shield member 6 is reduced, and the iron core 4a
Local magnetic saturation can be alleviated.

Since the temperature of the magnetic body structure 4 rises, a vent 6c is provided in the lid 6a to dissipate the heat, thereby suppressing the temperature rise of the magnetic body structure 4. Also,
By providing the lid 6b of a good conductor, it becomes difficult for the electromagnetic wave to reach the measurement coil 2 and the current measurement error is reduced.

Even when the magnetic material structure 4 is provided inside the container 6a and the measurement coil 2 is provided at the opening of the container 6a, the current measurement error is slightly increased due to the electromagnetic shielding effect of the lid 6b. As in the above configuration, it is possible to reduce a current measurement error due to a variation in winding density and a variation in cross-sectional area.

Embodiment 9 FIG. 14 is a front view of a three-phase collective bus in a gas insulated switchgear of a power system illustrating a current measuring device according to a ninth embodiment of the present invention. FIG. 15 is a sectional view taken along the line XVI-XVI in FIG.

In FIG. 14, reference numerals 1a, 1b, and 1c denote primary conductors through which a three-phase main circuit current flows. Reference numeral 7 denotes three primary conductor through holes each having a predetermined diameter for penetrating the three primary conductors, and three circular grooves formed concentrically around each of the primary conductor through holes. This is a support plate made of a non-magnetic and good conductor such as aluminum having 7a, 7b, and 7c.

In FIG. 15, 8a and 8b are primary conductors 1
a, 1b, and 1c are metal tanks in which a support plate 7 is disposed. The measuring coil 2 has grooves 7a, 7
b, 7c, the magnetic material structure 4 has grooves 7a, 7b,
7c are provided on the opening side. Each terminal p-terminal q of the measurement coil 2 extends from a guide hole provided in the support plate 7 and is introduced into the signal processing device 9.

In the present embodiment, one support plate 7
Can support a three-phase (three) current measuring device and can be downsized. Further, the support plate 7 includes the primary conductor 1.
a, 1b, 1c, and the magnetic flux generated by the main circuit current of the primary conductor is orthogonal to the primary conductor, so that all the magnetic flux in the support plate 7 passes through the support plate 7,
The induced current induced in the support plate 7 increases. For this reason,
The magnetic flux density of the measurement coil 2 is reduced.

The magnetic flux generated by the main circuit current of the primary conductor 1c is generated by the iron core 4a inserted in the grooves 7a and 7c on the same plane.
Therefore, the magnetic flux concentrates more on the iron core 4a than when there is a single iron core. Therefore, the magnetic coupling with the support plate 7 is improved, and the induced current flowing through the support plate 7 increases. Further, in the measurement coil 2 portion which is in close contact with the iron core 4a, since the magnetic flux concentrates on the iron core 4a, the magnetic flux density decreases, and the current measurement error can be reduced.

Embodiment 10 FIG. FIG. 16 is a sectional view of the current measuring device according to the tenth embodiment of the present invention. In the present embodiment, a lid 10 is provided in addition to the configuration of the ninth embodiment. That is, the non-magnetic good conductor lid 10 which is concentric with the primary conductors 1a, 1b, 1c is provided in the openings of the grooves 7a, 7b, 7c of the support plate 7. The lid 10 has an L-shaped cross section and covers up to the outer periphery of the primary conductor through hole of the support plate 7. The lid 10 is electrically connected to the outer periphery of the opening of the support plate 7.

In such a current measuring device,
A large amount of magnetic flux due to the main circuit current of the other-phase conductor interlinks with the lid 10, and the induced current flows through the support plate 7 and the lid 10,
The magnetic flux density of the measurement coil 2 can be further reduced.

Embodiment 11 FIG. FIG. 17 is a sectional view of a current measuring device according to Embodiment 11 of the present invention. In the present embodiment, the lid 11a and the lid 1
1b is provided. That is, the grooves 7a, 7
A lid 11a of a nonmagnetic good conductor concentric with the primary conductors 1a, 1b, 1c is provided in the openings of b and 7c. The lid 11b is connected, and only the outer periphery of the lid 11a is electrically connected to the outer periphery of the opening of the support plate 7.

In the current measuring device having such a configuration,
The magnetic flux due to the main circuit current of the other-phase conductor generates the lid 11a and the lid 11b.
Since the induced current flows more through the support plate 7, the lid 11a, and the lid 11b, the magnetic flux density of the measurement coil 2 can be further reduced.

Embodiment 12 FIG. FIG. 18 is a front view of a three-phase collective bus in a gas insulated switchgear of a power system for explaining a current measuring device according to a twelfth embodiment of the present invention. FIG.
FIG. 19 is a sectional view taken along the line XX-XX in FIG. 18. In FIGS. 18 and 19, reference numeral 12a denotes a container having a U-shaped cross section concentric with the primary conductor accommodating the measurement coil 2 and the magnetic substance structure 4, and 12b denotes a disk-shaped lid concentric with the primary conductor. . The measuring coil 2 and the magnetic structure 4
Of the shield member that accommodates the. Only the outer periphery of the lid 12b is electrically connected to the outer periphery of the container 12a.
The support plate 7 is used to fit the containers 12a.
There are three holes into which a is inserted. And the container 12
The container 12a and the support plate 7 are fastened with bolts in order to electrically connect the support plate 7a to the support plate 7.

In this configuration, the thickness of the support plate 7 can be made smaller than the thickness of the measurement coil 2 and the magnetic body structure 4.
The size and weight can be reduced.

Embodiment 13 FIG. FIG. 20 is a sectional view of a current measuring device according to Embodiment 13 of the present invention. In the present embodiment, the measuring coil 2 having an inner diameter and an outer diameter smaller than the magnetic material structure 4 is inserted into a groove provided in the support plate 7, and the magnetic material is so closed as to close the opening of the groove in which the measuring coil 2 is inserted. The structure 4 is provided, and the measurement coil 2 and the magnetic body structure 4 are brought into close contact with each other. Further, the magnetic structure 4 is surrounded by a shield member made of a nonmagnetic and good conductor inner cylinder 13a and outer cylinder 13b attached to the support plate 7. The inner cylinder 13a, the outer cylinder 13b, and the support plate 7 are electrically connected by welding.

In the current measuring device having such a configuration,
The support plate only needs to have a thickness enough to insert the measurement coil 7, and the support plate 7 can be made thinner, and the size and weight can be reduced. On the other hand, since the inner cylinder 13a and the outer cylinder 13b are attached to the support plate 7 by welding and the magnetic structure is inserted therein, the magnetic field between the other buses, the inner cylinder 13a, the outer cylinder 13b, and the support plate 7 is increased. The coupling is improved, and the induced current flows through the inner cylinder 13a, the outer cylinder 13b, and the support plate 7, so that the magnetic flux of the measurement coil 2 can be reduced. Further, since the groove is smaller than the magnetic material structure 4, the groove is closed by the magnetic material structure 4, so that it is difficult for the electromagnetic wave to penetrate, and the current measurement error is reduced.

[0080]

The current measuring device according to the present invention has an annular core made of an insulator surrounding the bus under test and a secondary winding wound around the core and measuring the current flowing through the bus under test. The measurement coil has a diameter substantially the same as that of the measurement coil. And a magnetic structure having a short-circuited winding wound around the entire circumference and electrically short-circuited at both ends. Therefore, the magnetic flux density at the core portion of the measurement coil can be reduced, and the current measurement error due to the variation in the winding density and the variation in the cross-sectional area can be reduced.

Further, a heat insulating material is further provided between the magnetic body structure and the measuring coil. Therefore, the current measurement error due to the main circuit current can be reduced.

Further, a ring-shaped magnetic body and a magnetic body which are substantially the same in diameter as the measurement coil, are centered on the measurement coil, surround the bus to be measured, and are located on the opposite side to the magnetic body structure of the measurement coil and on the opposite side. And a second magnetic body structure having a short-circuited winding wound around the entire circumference so as to interlink with the magnetic flux passing through the coil and having both ends electrically short-circuited. for that reason,
The magnetic flux density at the core of the measurement coil is further reduced, and the current measurement error due to the variation in the winding density and the variation in the cross-sectional area can be further reduced.

An annular core and a winding made of an insulating material having substantially the same diameter as the measuring coil, centered on the measuring coil, surrounding the bus to be measured, and adjacent to the magnetic structure on the side opposite to the measuring coil. There is further provided a second measurement coil having a secondary winding wound around the core and measuring a current flowing through the bus to be measured. Therefore, when two measurement coils are required, the two measurement coils can be brought into close contact with the magnetic body structure by providing the measurement coils on both side surfaces of the magnetic body structure, respectively. The magnetic flux due to the flowing main circuit current can be concentrated on the magnetic material structure, the magnetic flux density of both measurement coil sections can be reduced, and there is no need to provide a plurality of magnetic material structures. Is possible.

Further, there is further provided a shield winding for winding the measurement coil and the magnetic body structure together. Therefore, it is possible to greatly reduce the current measurement error due to the variation in the winding density of the measurement coil and the variation in the cross-sectional area.

The shield winding is composed of a plurality of split coils, each split coil having the same number of turns, and the same poles connected to each other. Therefore, the induced voltage of each split coil due to the main circuit current is offset,
Since the induced current generated in the shield winding by the magnetic flux due to the main circuit current does not flow, it does not affect the measurement of the measured current.

Further, there is further provided a shield member made of a non-magnetic material and a good conductor which surrounds the magnetic material structure and the measuring coil together. Therefore, the magnetic flux concentrated on the magnetic body can be reduced, the magnetic saturation of the magnetic body can be reduced, and the effect of reducing the current measurement error even in a large current region can be obtained.

A metal tank for storing a plurality of sets of the bus to be measured, the measurement coil, the magnetic material structure and the shield member, and a support provided inside the metal tank for supporting each set of shield members from the metal tank. And a plate. Therefore, a plurality of shield members can be supported by one support plate, and downsizing can be achieved.

The shield member has a groove and a hole formed in the support plate around the measured bus, the measured bus passes through the hole, and the measuring coil is housed in the groove. Therefore, the number of components forming the shield member can be reduced, and the cost can be reduced.

The measurement coil is provided on the bottom side of the groove, and the magnetic material structure is provided so as to close the groove.
For this reason, the groove is closed by the magnetic material structure, so that it is difficult for the electromagnetic wave to enter the groove, and the current measurement error is further reduced.

The shield member has an inner cylinder, an outer cylinder and a bottom plate, and has a U-shaped cross section. Therefore, the magnetic flux concentrated on the magnetic body can be reduced, the magnetic saturation of the magnetic body can be relaxed, the current measurement error can be reduced even in a large current region, and since the cross section is U-shaped, the measuring coil and the magnetic body structure can be used. This is easy when housed inside the shield member.

The magnetic structure is provided on the opening side of the U-shaped section of the shield member, and the measurement coil is provided on the inner side of the U-shaped section. For this reason, since the magnetic material structure whose temperature rises is provided on the opening side of the shield member, heat dissipation is improved, and the temperature rise can be suppressed.

Further, a cover made of a non-magnetic material and a good conductor is provided in the opening of the shield member.
A slit portion is provided so that the outer peripheral portion or the inner peripheral portion of the lid is not electrically connected. Thus, by providing the lid on the shield member, the magnetic flux from the other-phase bus enters the lid,
The amount of magnetic flux passing through the induction current path increases, and a large amount of induction current flows through the induction current path flowing through the lid and the shield member. Therefore, the magnetic flux density of the measurement coil portion is further reduced, and the current measurement error due to the variation in the winding density and the variation in the cross-sectional area can be further reduced. Further, due to an increase in the induced current of the shield member on the other phase bus side, the magnetic flux penetrating into the shield member is reduced, and local magnetic saturation of the magnetic body can be reduced.

Further, the magnetic body structure is installed in the same plane perpendicular to the measured bus. Therefore, the magnetic flux due to the main circuit current flowing through the measured bus can be efficiently concentrated on the magnetic body structure, and the magnetic flux density of the measurement coil unit can be reduced.

[Brief description of the drawings]

FIG. 1 is a front view showing a partial cross section of a current measuring device according to a first embodiment of the present invention.

FIG. 2 is a sectional view taken along the line II-II in FIG.

FIG. 3 is a front view showing a winding state of a short-circuit winding of an iron core structure (magnetic material structure).

FIG. 4 is a side view, partly in section, showing a current measuring device according to a second embodiment of the present invention.

FIG. 5 is a side view, partly in section, showing a current measuring device according to a third embodiment of the present invention.

FIG. 6 is a side view, partly in section, showing a current measuring device according to a fourth embodiment of the present invention.

FIG. 7 is a side view partially in section showing a current measuring device according to a fifth embodiment of the present invention.

FIG. 8 is a front view showing a winding state of a shield winding.

FIG. 9 is a side view, partly in section, showing a current measuring device according to a sixth embodiment of the present invention.

FIG. 10 is a front view showing a partial cross section of a current measuring device according to a seventh embodiment of the present invention.

FIG. 11 is a sectional view taken along the line XI-XI in FIG. 10;

FIG. 12 is a front view showing a current measuring device according to an eighth embodiment of the present invention in a partial cross section.

13 is a sectional view taken along the line XIV-XIV in FIG.

FIG. 14 is a front view of a three-phase collective bus in a gas insulated switchgear of a power system for explaining a current measuring device according to a ninth embodiment of the present invention.

15 is a sectional view taken along the line XVI-XVI in FIG.

FIG. 16 is a sectional view of a current measuring device according to the tenth embodiment of the present invention.

FIG. 17 is a sectional view of a current measuring device according to Embodiment 11 of the present invention.

FIG. 18 is a front view of a three-phase collective bus in a gas insulated switchgear of a power system illustrating a current measuring device according to a twelfth embodiment of the present invention.

19 is a sectional view taken along the line XX-XX in FIG.

FIG. 20 is a sectional view of a current measuring device according to Embodiment 13 of the present invention.

FIG. 21 is a front view partially showing a Rogowski coil, which is a conventional current measurement, in a cross section.

FIG. 22 is a sectional view taken along the line XXIII-XXIII in FIG. 21;

FIG. 23 is a front view showing a winding state of a measurement winding.

[Explanation of symbols]

1, 1a, 1b, 1c Primary conductor (bus under measurement), 2
Measuring coil, 2a winding core, 2b measuring winding (secondary winding), p and q terminals, 3 other phase bus, 4 magnetic material structure (iron structure), 4a iron core (magnetic material), 4b short-circuit winding 5, shield member, 5a inner cylinder, 5b outer cylinder, 5c
Bottom plate, 6 shielding member, 6a container, 6b lid, 6
c vent, 7 support plate, 7a, 7b, 7c groove, 8
a, 8b Metal tank, 9 Signal processor, 10, 1
1a, 11b lid, 12a container (shield member), 1
2b lid (shield member), 13a inner cylinder (shield member), 13b outer cylinder (shield member), 15 heat insulating material,
16 iron core structure (second magnetic body structure), 16a iron core (magnetic body), 16b short-circuit winding, 17 shield winding, 17a to 17f split coil, 17g, 17h connection wire, 22 measurement coil (second Measuring coil), 22a
Core, 22b Measurement winding (secondary winding).

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Hiroaki Taniguchi 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Mitsui Electric Co., Ltd. (72) Inventor Yasuhiro Maeda 2-3-2 Marunouchi, Chiyoda-ku, Tokyo 3 Inside Rishi Electric Co., Ltd. (72) Inventor Naoki Ochi 2-3-2 Marunouchi, Chiyoda-ku, Tokyo F-term (reference) 2G025 AA01 AA08 AA17 AB14 2G035 AA03 AA06 AA12 AB08 AC13 AD19 5E081 AA05 DD05 DD11

Claims (14)

[Claims] 1. A measurement coil having an annular core made of an insulator surrounding a bus to be measured and a secondary winding wound around the core and measuring a current flowing through the bus to be measured, and the measurement coil And a ring-shaped magnetic body surrounding the bus to be measured and having a center substantially coincident with the measurement coil and adjacent to the measurement coil, and the entirety of the magnetic body interlinked with the magnetic flux passing through the magnetic body. And a magnetic structure having a short-circuit winding wound around the periphery and electrically short-circuited at both ends. 2. The current measuring device according to claim 1, further comprising a heat insulating material between the magnetic structure and the measuring coil. 3. An annular magnetic body having substantially the same diameter as said measuring coil, centered on said measuring coil, surrounding said bus under test and adjacent to said measuring coil on the side opposite to said magnetic body structure; The magnetic body further includes a second magnetic body structure having a short-circuited winding wound around the entire circumference so as to interlink with a magnetic flux passing through the magnetic body and having both ends electrically short-circuited. The current measuring device according to claim 1 or 2, wherein 4. An annular ring having substantially the same diameter as the measuring coil, centering on the measuring coil, surrounding the bus under test, and being in close proximity to the magnetic material structure on the side opposite to the measuring coil. 3. The current according to claim 1, further comprising a second measurement coil having a winding core and a secondary winding wound around the winding core and measuring a current flowing through the bus under measurement. Measuring instrument. 5. The current measuring device according to claim 1, further comprising a shield winding for winding the measurement coil and the magnetic structure together. 6. The shield coil according to claim 5, wherein the shield winding is composed of a plurality of split coils, each of the split coils has the same number of turns, and the same poles are connected. Current measuring instrument. 7. The current measuring device according to claim 1, further comprising a shield member made of a non-magnetic material and a good conductor, surrounding the magnetic material structure and the measuring coil collectively. 8. A metal tank for accommodating a plurality of sets of the bus under test, the measuring coil, the magnetic material structure, and the shield member, and each set of the shield members provided inside the metal tank. The current measuring device according to claim 7, further comprising a support plate that supports the metal tank. 9. The shield member has a groove and a hole formed in the support plate around the measured bus, the measured bus penetrates the hole, and the measurement coil is housed in the groove. The current measuring device according to claim 8, wherein 10. The current measuring device according to claim 9, wherein the measuring coil is provided on a bottom side of the groove, and the magnetic structure is provided so as to close the groove. . 11. The current measuring device according to claim 7, wherein the shield member comprises an inner cylinder, an outer cylinder and a bottom plate and has a U-shaped cross section. 12. The magnetic member structure is provided on the opening side of the U-shaped cross section of the shield member, and the measurement coil is provided on the inner side of the U-shaped cross section. 12. The current measuring device according to 11. 13. A cover made of a non-magnetic material and a good conductor is provided in an opening of the shield member so that the opening of the shield member is not electrically connected to an outer peripheral portion or an inner peripheral portion of the lid. 10. A slit portion is provided.
13. The current measuring device according to any one of items 1 to 12. 14. The current measuring device according to claim 1, wherein the magnetic body structure is installed in a same plane perpendicular to the bus to be measured.