JP2019045192A - One-line ground fault current sensor and switch gear - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an improved one-line ground fault current sensor. A one-line ground fault current sensor according to an embodiment is, for example, a one-line ground fault current sensor that is attached to a wall and detects a one-line ground fault current transmitted through the wall. And a section. Each of the plurality of electrodes has a contact portion that contacts the surface of the wall with the one-line ground fault current sensor attached to the wall. The insulating portion insulates the plurality of electrodes from each other. The detection unit detects a potential difference between two electrodes included in the plurality of electrodes. [Selection diagram] Figure 2

Description

  Embodiments relate to a single-wire ground fault current sensor and a switch gear.

  DESCRIPTION OF RELATED ART Conventionally, the metal closed type switchgear in which electric devices, such as a circuit breaker unit, were accommodated in the metal housing | casing is known.

JP, 2016-96693, A

  In equipment such as metal closed switchgears, it would be beneficial if an improved single-wire ground fault current sensor could be obtained, eg having a simpler construction.

  The single-wire ground fault current sensor according to the embodiment is, for example, a single-wire ground fault current sensor attached to a wall and detecting a single-wire ground fault current transmitted through the wall, and includes a plurality of electrodes, an insulator, and a detector. Prepare. The plurality of electrodes each have a contact portion that comes in contact with the surface of the wall when the one-wire ground fault current sensor is attached to the wall. The insulator insulates the plurality of electrodes from one another. The detection unit detects a potential difference between two electrodes included in the plurality of electrodes.

FIG. 1 is a schematic and exemplary perspective view of a switchgear to which a one-wire ground fault current sensor according to the embodiment is attached. FIG. 2 is a schematic and exemplary perspective view of a one-wire ground fault current sensor according to the embodiment. FIG. 3 is a schematic and exemplary side view of the one-wire ground fault current sensor according to the embodiment mounted to a panel of a switch gear. FIG. 4 is a schematic and exemplary block diagram of a one-wire ground fault current sensor according to the embodiment. FIG. 5 is a schematic view showing an example of the arrangement of a plurality of electrodes of the one-wire ground fault current sensor of the embodiment as viewed from the direction intersecting the outer surface of the panel. FIG. 6 is a schematic and exemplary side view of a one-wire ground fault current sensor according to a modification of the embodiment, mounted to a panel of a switch gear.

  In the following, exemplary embodiments and variants of the invention are disclosed. Configurations and controls (technical features) of the embodiments and modifications described below, and operations and results (effects) provided by the configurations and controls are examples. In addition, the same components are included in a plurality of embodiments and modifications described below. Therefore, in the following embodiments and modifications, similar operations and effects based on similar components can be obtained. In addition, below, the common code | symbol is provided to the same component, and the overlapping description is abbreviate | omitted.

[Embodiment]
FIG. 1 is a perspective view of a switchgear. As illustrated in FIG. 1, the switch gear 10 includes a metal housing 20. The switch gear 10 is a so-called metal closed switch gear in which an electric device is housed in a housing 20. For example, the electric device accommodated in the housing 20 includes a circuit breaker, a power receiving board mainly receiving power by having a transformer for an instrument, a feeder board from which a cable for load supply is drawn out, a main bus bar There is a bus contact board etc. which separates each circuit by circuit breaker. The housing 2 may also be referred to as a panel, a closed box, or the like. The switch gear 10 is installed, for example, in an electrical room of a building.

  The housing 20 has a metal frame (not shown) and a metal panel 21 fixed to the frame. The panel 21 constitutes a bottom wall (not shown) of the housing 20, a side wall 21a, a top wall 21b, and the like. The opening 20 a of the housing 20 is covered by a door 22 so as to be openable and closable. The door 22 is rotatably supported by the fixed frame of the housing 20. The door 22 also includes a frame and a panel 21. The panel 21 of the door 22 also constitutes a side wall 21a of the housing 20 when the door 22 is closed. The bottom wall, the side wall 21a, the top wall 21b, and the like are examples of the wall.

  In the housing 20, three-phase high piezoelectric paths (not shown) insulated from each other are provided. In such a case 20, when an internal arc accident or the like occurs due to any cause, a single phase ground fault current (single phase ground current) may flow through the panel 21 of the case 20. In order to detect such a one-phase ground fault current, a sensor 30 is attached to the outer surface 21c of the panel 21 in the present embodiment. The sensor 30 is an example of a single-wire ground fault current sensor. The sensor 30 may be attached to the inner surface 21d (FIG. 3) of the panel 21 in the housing 20, or may be attached to both the outer surface 21c and the inner surface 21d. The outer surface 21c and the inner surface 21d are examples of surfaces.

  FIG. 2 is a perspective view of the sensor 30. FIG. FIG. 3 is a side view of the sensor 30 in a state of being attached to the panel 21 (wall). As illustrated in FIG. 2, the sensor 30 includes an electrode 31, an insulator 32, a housing 34, and a cable 35.

  The sensor 30 has a plurality of electrodes 31. Although the number of the electrodes 31 is four in the present embodiment, it is not limited thereto, and may be two or more. The electrode 31 is made of, for example, a metal material having a relatively high electric conductivity such as oxygen free copper. The electrical conductivity of the electrode 31 is higher than the electrical conductivity of the wall of the housing 20.

  Each of the electrodes 31 has a contact portion 31 a with the outer surface 21 c of the panel 21. The shape of the contact portion 31a is, for example, a substantially circular planar shape. The plurality of electrodes 31 are arranged such that their contact portions 31a are arranged in one plane. With such a configuration, the plurality of contact portions 31a and the outer surface 21c can be in contact with each other, and the contact area between the contact portion 31a and the outer surface 21c can be further increased. The contact portion 31a may also be referred to as an end surface or a contact surface. In addition, the contact part 31a may have a convex curved surface.

  The insulating portion 32 surrounds the periphery of the electrode 31 and is interposed between the plurality of electrodes 31 to suppress short circuit of the electrode 31. The insulating portion 32 is also referred to as a ladder, and is made of, for example, an insulating material such as porcelain, glass, or insulating synthetic resin.

  The insulating portion 32 has an exposed flat end face 32a. The electrode 31 protrudes from the end face 32a. The contact portion 31 a of the electrode 31 and the end face 32 a of the insulating portion 32 are substantially parallel.

  Further, at the central portion of the end face 32a of the insulating portion 32, a female screw hole 33 used for mounting (coupling) of the sensor 30 to the panel 21 is provided. The female screw hole 33 is an example of the connecting portion.

  As illustrated in FIG. 3, the panel 21 is provided with a through hole 21 e. An externally threaded portion 40a of a bolt 40 penetrating through the through hole 21e from the inner surface 21d of the panel 21 facing the inside of the housing 20 is inserted into the internally threaded hole 33 and coupled. Thus, the sensor 30 is attached to the panel 21 in a state where the contact portions 31 a of the plurality of electrodes 31 are in contact with the outer surface 21 c of the panel 21. The surface pressure between the contact portion 31 a and the outer surface 21 c of the panel 21 can be adjusted by the tightening torque of the bolt 40. A washer such as a spring washer may be interposed between the head portion of the bolt 40 and the panel 21. Further, the connection portion is not limited to the female screw hole 33, and may be an external thread portion, or may be a connection portion different from a screw mechanism, such as a rivet. The bolt 40 may also be referred to as a fastener.

  The plurality of electrodes 31 are disposed so as to surround the circumference of the female screw hole 33, as illustrated in FIG. In other words, the female screw hole 33 is disposed between the plurality of electrodes 31.

  The plurality of electrodes 31 and the insulating portion 32 are accommodated in the housing 34. The shape of the housing 34 is, for example, cylindrical, but is not limited thereto.

  A cable 35 projects from the housing 34 on the opposite side of the contact portion 31 a of the electrode 31. The cable 35 includes a signal line (not shown) and a coating 35 a covering the signal line.

  FIG. 4 is a block diagram of the sensor 30. As shown in FIG. The sensor 30 has a plurality of electrodes 31 and a detection unit 36. The detection unit 36 can detect the potential difference between the two electrodes 31 with respect to at least one combination (for example, all combinations) of the two electrodes 31 included in the plurality of electrodes 31. In the present embodiment, since the sensor 30 has four electrodes 31, the detection unit 36 includes all combinations of two of the four electrodes 31 (31A to 31D), that is, the electrodes 31A and 31A. A pair with the electrode 31B, a pair with the electrode 31A and the electrode 31C, a pair with the electrode 31A and the electrode 31D, a pair with the electrode 31B and the electrode 31C, a pair with the electrode 31B and the electrode 31D, and a pair with the electrode 31C and the electrode 31D The potential difference between the two electrodes 31 can be detected for each of a total of six combinations of sets. In the sensor 30 (in the detection unit 36), a resistor (not shown) is interposed between the two electrodes 31. Therefore, the magnitude of the current flowing between the two electrodes 31 can be detected by the potential difference between the two electrodes 31. In the detection unit 36, it is not essential to detect the potential difference for all combinations of two electrodes 31 among the plurality of electrodes 31.

  The detection unit 36 outputs an abnormality detection signal to the control panel 23 provided in the housing 20 when the potential difference of at least one of the combinations of the two electrodes 31 is equal to or more than a predetermined threshold.

  When the control panel 23 receives an abnormality detection signal, for example, it controls an audio output unit such as a speaker (not shown) so as to output an audio (alarm sound) indicating a warning or displays such as a lamp so as to emit light. It is possible to control the output unit or to control the display output unit such as a display to output characters or images indicating a warning. The control panel 23 is an example of an output control unit, and may be referred to as a control device or a processing device.

  Further, in the present embodiment, in the detection unit 36, the portion that detects the potential difference and the portion that outputs the abnormality detection signal are insulated from each other. That is, the detection unit 36 and the control panel 23 are insulated so that the current flowing to the detection unit 36 via the electrode 31 does not reach the control panel 23. The detection signal transmitted from the detection unit 36 to the control board 23 may be an optical signal in order to ensure insulation between them. In this case, the detection unit 36 is provided with a conversion unit (not shown) for converting an electric signal into an optical signal, the cable 35 is an optical fiber cable, and an optical fiber is provided in the cable 35 as a signal line.

  FIG. 5 is a schematic view showing the arrangement of the four electrodes 31 of the sensor 30 as viewed from the direction intersecting the outer surface 21c of the panel 21. As shown in FIG. As illustrated in FIG. 5, the sensor 30 has four electrodes 31 not aligned in a straight line. Therefore, regardless of the directions of the currents Ia to Id flowing along the panel 21, a potential difference occurs between the at least two electrodes 31. The currents Ia to Id are examples of single-line ground fault currents.

  Specifically, when current Ia or a current in the opposite direction is generated, between the two electrodes 31 arranged offset along the flowing direction of the current Ia, that is, the electrode 31A or the electrode 31D and the electrode 31B Or, a potential difference occurs between the electrode 31C and the electrode 31C.

  Also, for example, when the current Ib or the current in the opposite direction is generated, any one of the electrode 31A and the electrodes 31B to 31D is disposed between the two electrodes 31 arranged to be shifted along the flowing direction of the current Ib. A potential difference is generated between the electrode 31B and the electrode 31C, and between the electrode 31C and the electrode 31D.

  Also, for example, when a current Ic or a current in the opposite direction is generated, between the two electrodes 31 arranged to be shifted along the flowing direction of the current Ic, that is, the electrode 31A or 31B and the electrode 31C or A potential difference occurs between the electrode 31D and the electrode 31D.

  Also, for example, when a current Id or a current in the opposite direction is generated, between the two electrodes 31 arranged to be shifted along the flowing direction of the current Id, that is, the electrode 31B and the electrodes 31A, 31C, 31D A potential difference occurs between the electrode 31C and the electrode 31D, and between the electrode 31D and the electrode 31A.

  In addition to the currents Ia to Id, even when current flows in other directions, the four electrodes 31 not aligned on a straight line have two potential differences with respect to current in any direction. The electrode 31 will always be included.

  The plurality of electrodes 31 is not limited to the four electrodes 31. Specifically, three or more electrodes 31 not aligned in a straight line necessarily include two electrodes 31 in which a potential difference is generated with respect to a current in any direction. Three or more electrodes 31 which do not line up on the line may be included. When the sensor 30 has three electrodes 31, the three electrodes 31 may be disposed at a position overlapping with the apex of the triangle.

  Further, even in the sensor 30 having only two electrodes 31, it is possible to detect the current flowing in the direction intersecting with the direction in which the two electrodes 31 are arranged. Therefore, by arranging the two sensors 30 on the panel 21 so that the directions in which the two electrodes 31 are arranged cross each other, the sensor 30 having the four electrodes 31A to 31D as described above, and the three electrodes 31 A similar detection result can be obtained as with the sensor 30 (not shown).

  As described above, the sensor 30 according to the present embodiment mutually insulates the plurality of electrodes 31 and the plurality of electrodes 31 each having the contact portion 31a in contact with the outer surface 21c (surface) of the panel 21 (wall). The detection unit 36 detects the potential difference between the insulating unit 32 and the combination of the two electrodes 31 included in the plurality of electrodes 31. According to such a configuration, for example, the detection unit 36 can detect a single-wire ground fault current flowing along the panel 21. And according to such a configuration, for example, the sensor 30 capable of detecting the one-wire ground fault current can be realized by a relatively simple configuration.

  Further, in the present embodiment, the plurality of electrodes 31 are three or more electrodes 31 in which the contact portions 31 a are not aligned in a straight line. According to such a configuration, for example, in at least one of the combinations of two electrodes 31 included in three or more electrodes 31, it is possible to detect the potential difference caused by the current in any direction flowing through panel 21. .

  In particular, when the number of the electrodes 31 is three, the outer surface 21 c of the panel 21 supports (the contact portion 31 a of) the sensor 30 at three points. Therefore, according to such a configuration, a situation in which any one of the plurality of contact portions 31a is separated from the outer surface 21c can be avoided, and the three contact portions 31a and the outer surface 21c are more reliable. There is also an advantage that a contact state can be obtained.

  Further, in the present embodiment, the female screw hole 33 (coupling portion) is provided between the plurality of electrodes 31. Moreover, when the sensor 30 has three or more electrodes 31, the some electrode 31 is arrange | positioned around the internal thread hole 33 (joining part). Therefore, according to such a configuration, the required contact surface pressure between the contact portions 31a of the plurality of electrodes 31 and the outer surface 21c of the panel 21 can be easily obtained by the relatively simple configuration. In other words, the variation in the contact surface pressure at the plurality of contact portions 31a can be easily set smaller.

  As mentioned above, although the embodiment of the present invention was illustrated, the above-mentioned embodiment is an example, and limiting the scope of the invention is not intended. The above embodiment can be implemented in other various forms, and various omissions, replacements, combinations, and changes can be made without departing from the scope of the invention. These embodiments are included in the scope and the gist of the invention, and included in the invention described in the claims and the equivalents thereof. In addition, the specifications (structure, type, direction, shape, size, length, width, thickness, height, number, placement, position, material, etc.) of each configuration or shape are appropriately changed and implemented. can do.

  For example, the position where the single-wire ground fault current sensor is attached to the switch gear, the number thereof, the arrangement in the case of attaching a plurality of single-wire ground fault current sensors, and the like can be set variously.

[Modification]
Also, for example, FIG. 6 is a side view of the sensor 30A according to the modification of the embodiment attached to the panel 21. However, as exemplified in FIG. The electrode 31 of 30A is configured as a plate spring, and has an elastically deformable portion 31b (bent portion) that can be elastically bent and deformed. The elastic deformation portion 31 b elastically deforms in a state where the sensor 30 A is attached to the panel 21, and applies an elastic force to the outer surface 21 c of the panel 21. With such a configuration, a required contact surface pressure can be easily obtained between the contact portion 31 a and the outer surface 21 c of the panel 21. Also, the variation in the contact pressure with the outer surface 21c of the plurality of contact portions 31a is likely to be reduced. The elastically deformable portion 31b may be provided at a position away from the contact portion 31a. Also, the elastically deformable portion may be a coil spring. In other words, the electrode 31 may have a coil spring.

  DESCRIPTION OF SYMBOLS 10 Switch gear 20 housing 21 panel (wall) 21c outer surface (surface) 21d inner surface (surface) 30, 30A sensor 31, 31A to 31D electrode 31a contact 31b: elastic deformation portion 32: insulation portion 33: female screw hole (joint portion) 36: detection portion

Claims (5)

A single-wire ground fault current sensor mounted on a wall and detecting a single-wire ground fault current transmitted through the wall,
A plurality of electrodes each having a contact portion that comes in contact with the surface of the wall when the one-wire ground fault current sensor is attached to the wall;
An insulating portion in which the plurality of electrodes are mutually insulated;
A detection unit that detects a potential difference between two electrodes included in the plurality of electrodes;
, Single-wire ground fault current sensor.   The single-wire ground fault current sensor according to claim 1, wherein the plurality of electrodes are three or more electrodes in which the respective contact portions are not aligned in a straight line.   The single-wire ground fault current sensor according to claim 2, wherein the electrode has an elastically deformable portion which elastically deforms in an attached state and applies an elastic force to the wall.   The single-wire ground fault current sensor according to any one of claims 1 to 3, further comprising a joint portion with the wall positioned between the plurality of electrodes. The one-wire ground fault current sensor according to any one of claims 1 to 4;
A housing having a wall to which the single-wire ground fault current sensor is coupled and containing an electric device;
With a switch gear.

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