Clamp ammeter and current measurement method

Abstract

To provide a clamp ammeter and a current measurement method that are excellent in workability in a narrow space.SOLUTION: A clamp ammeter includes a clamp portion and a slim grip portion connected to the clamp portion. The clamp portion has a base integral with the grip portion, and a movable portion movable relative to the base. The clamp portion operates, by the movement of the movable portion, between a closed state in which the clamp portion forms a slim loop shape in front view and an open state in which the clamp portion forms a non-loop shape in the front view. In the front view, a longitudinal direction of the clamp portion in the closed state forms an angle of greater than 45° and equal to or less than a right angle with respect to a longitudinal direction of the grip portion. The base extends from the grip portion to a distal end portion of the clamp portion in a lateral direction of the clamp portion in the closed state. The movable portion extends from the grip portion to the distal end portion of the clamp portion, and makes the clamp portion from the closed state to the open state by the movement to a proximal side.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a clamp-on ammeter and a current measurement method. [Background technology]

[0002] BACKGROUND ART Clamp-type ammeters having a clamp portion and a long, thin grip portion connected to the clamp portion are known (see, for example, Patent Documents 1 to 3). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Design Registration No. 1434290 [Patent Document 2] Japanese Patent Publication No. 2020-8567 [Non-patent literature]

[0004] [Non-Patent Document 1] Clamp Meter DCM600DR (Sanwa Electric Instruments) Catalog (https: / / www.sanwa-meter.co.jp / japan / products / clamp / dcm600dr.html) Summary of the Invention [Problem to be solved by the invention]

[0005] An object of the present disclosure is to provide a clamp-on ammeter and a current measurement method that are easy to use in narrow spaces. [Means for solving the problem]

[0006] One aspect of the present disclosure is as follows.

[0007] [1] A clamp portion and a thin and long grip portion connected to the clamp portion are included. the clamping portion has a base portion integral with the gripping portion and a movable portion movable relative to the base portion, and the clamping portion operates between a closed state in which the clamping portion forms an elongated loop shape in a front view and an open state in which the clamping portion forms a non-loop shape in a front view by the movement of the movable portion; When viewed from the front, the longitudinal direction of the clamp portion in the closed state forms an angle of more than 45° and less than a right angle with respect to the longitudinal direction of the grip portion, The base portion extends from the grip portion to a hand-side end of the clamp portion in a short direction of the clamp portion in the closed state, The movable part extends from the grip part to the hand end of the clamp part, and the movement towards the hand changes the clamp part from the closed state to the open state.

[0008] [2] The clamp-type ammeter according to [1], wherein, in the front view, the angle formed by the longitudinal direction of the clamp portion in the closed state and the longitudinal direction of the grip portion is a right angle.

[0009] [3] The clamp portion has a pair of straight portions that face each other in the short-side direction of the clamp portion and each extend linearly in the longitudinal direction of the clamp portion, and a pair of curved portions that face each other in the longitudinal direction of the clamp portion and each curve so as to protrude radially outward of the clamp portion. [1] A clamp-type ammeter as described in [2] or [3].

[0010] [4] The clamp-on ammeter according to [3], wherein each of the curved portions is curved in a semicircular arc shape.

[0011] [5] the base of the clamping portion is integrally connected to the gripping portion and extends from a gripping portion-side end located at a gripping portion-side boundary between one of the curved portions and one of the straight portions to a non-gripping portion-side end located at a non-gripping portion-side boundary between the other of the curved portions and the other straight portion; the movable portion of the clamping portion extends from a non-opening / closing side end portion located at the gripping portion side boundary portion to an opening / closing side end portion located at the non-gripping portion side boundary portion, and is connected to the gripping portion so as to be able to rotate as the movement relative to the base portion in the front view, The clamp-type ammeter according to [3] or [4], wherein the clamp portion allows a measurement object to be passed between the non-gripping portion side end of the base and the opening / closing side end of the movable portion in the open state.

[0012] [6] The clamp-type ammeter according to [5], further comprising a trigger that causes the rotation of the movable part of the clamp part by gripping and pushing the grip part.

[0013] [7] The clamp-on ammeter according to any one of [1] to [6], wherein the clamp accommodates three wires to be measured aligned in the longitudinal direction of the clamp in the closed state.

[0014] [8] The clamp-on ammeter according to any one of [1] to [7], wherein the clamp portion has an outer diameter in the short side direction of 64 mm or less.

[0015] [9] The clamp-on ammeter according to any one of [1] to [8], which measures leakage current in AC power supply equipment.

[0016]

[10] A current measurement method using a clamp-on ammeter according to any one of [1] to [9], A current measurement method in which, in a distribution board in which main wiring and branch wiring are arranged, the main wiring to be measured is placed within the clamp portion of the clamp-type ammeter to measure the current.

[0017]

[11] The current measurement method according to

[10] , wherein the main wiring is three wires corresponding to a three-phase power supply facility or a single-phase power supply facility. [Effects of the Invention]

[0018] According to the present disclosure, it is possible to provide a clamp-type ammeter and a current measurement method that are excellent in workability in narrow spaces. [Brief explanation of the drawings]

[0019] [Figure 1] 1A and 1B are front views illustrating a closed state and an open state of a clamp portion of a clamp-type ammeter according to an embodiment of the present disclosure. [Figure 2] 2 is a front view showing a state in which three wires are housed in a clamp portion of the clamp-on ammeter shown in FIG. 1. FIG. [Figure 3] 2 is an explanatory diagram for explaining current measurement by the clamp-on ammeter shown in FIG. 1 in a distribution board in which main wiring and branch wiring are arranged. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0020] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings.

[0021] As shown in FIG. 1, a clamp-type ammeter 1 according to one embodiment of the present disclosure has a clamp portion 2 and an elongated holding portion 3 connected to the clamp portion 2. The clamp portion 2 has a base 2a integral with the holding portion 3 and a movable portion 2b that can move relative to the base 2a. The movement of the movable portion 2b causes the clamp portion 2 to move between a closed state in which it forms an elongated loop when viewed from the front and an open state in which it forms a non-loop when viewed from the front. When viewed from the front, the longitudinal direction D21 of the clamp portion 2 in the closed state forms an angle θ (a right angle in this embodiment) that is greater than 45° and less than a right angle with respect to the longitudinal direction D1 of the holding portion 3. The base 2a extends from the holding portion 3 to the hand-side end 2c of the clamp portion 2 in the short-side direction D22 of the clamp portion 2 in the closed state. The movable portion 2b extends from the holding portion 3 to the hand-side end 2c of the clamp portion 2. The movement toward the front changes the clamp portion 2 from the closed state to the open state. The hand side means the hand side when the user grips the grip portion 3, and the near side means the opposite side. The angle θ that the longitudinal direction D21 of the clamp portion 2 in the closed state makes with the longitudinal direction D1 of the grip portion 3 means the angle θ that the central axis O2 extending in the longitudinal direction D21 of the clamp portion 2 in the closed state makes with the central axis O1 extending in the longitudinal direction D1 of the grip portion 3.

[0022] The clamp portion 2 has a pair of straight portions 4 that face each other in the short direction D22 of the clamp portion 2 and each extend linearly in the longitudinal direction D21 of the clamp portion 2, and a pair of curved portions 5 that face each other in the longitudinal direction D21 of the clamp portion 2 and each curve (in a semicircular arc shape in this embodiment) so as to protrude radially outward from the clamp portion 2.

[0023] The base 2a of the clamp unit 2 is connected integrally to the gripping unit 3 and extends from a gripping unit side end 2a1 located at the gripping unit side boundary 6 between one curved portion 5 and one straight portion 4 to a non-gripping unit side end 2a2 located at the non-gripping unit side boundary 7 between the other curved portion 5 and the other straight portion 4, and the movable portion 2b of the clamp unit 2 extends from a non-opening / closing side end 2b2 located at the gripping unit side boundary 6 to an opening / closing side end 2b1 located at the non-gripping unit side boundary 7, and is connected to the gripping unit 3 so as to be able to rotate about the rotation axis P as the above-mentioned movement relative to the base 2a when viewed from the front, and when the clamp unit 2 is in the open state, as shown in Figure 2, the object to be measured 8 can be passed between the non-gripping unit side end 2a2 of the base 2a and the opening / closing side end 2b1 of the movable portion 2b. In this embodiment, the measurement object 8 is three wires 8a, and when the clamp portion 2 is in the open state, each of the wires 8a can be passed between the non-gripping portion side end 2a2 of the base portion 2a and the opening / closing side end 2b1 of the movable portion 2b.

[0024] The clamp-type ammeter 1 has a trigger 9 that causes the movable part 2b of the clamp part 2 to rotate as the above-mentioned movement when the grip part 3 is grasped and pressed. When the trigger 9 is pressed, the clamp part 2 is in an open state, and when the pressing operation is released, the clamp part 2 is in a closed state.

[0025] In the closed state, the clamp unit 2 accommodates three wires 8a, which are the measurement object 8, arranged in the longitudinal direction D21 of the clamp unit 2.

[0026] The clamp-on ammeter 1 is configured with a CT (Current Transformer) that measures the current flowing through the object to be measured 8 in the closed clamp section 2 by utilizing the magnetic circuit formed by the closed clamp section 2. The clamp-on ammeter 1 may be, for example, a wire-wound type, a Hall element type, or another type.

[0027] The clamp-type ammeter 1 can easily pass one or more, particularly three, wires (wires 8a) through the clamp portion 2 even in a narrow space such as a distribution board 10 to measure the current flowing through the wires with high accuracy. In particular, as shown by the dashed-dotted arrow in Figure 3, the clamp-type ammeter 1 is suitable for measuring current, particularly leakage current of AC power supply equipment, by placing three wires 8a (in this embodiment, R-phase, S-phase, and T-phase wires corresponding to three-phase power supply equipment) corresponding to three-phase or single-phase power supply equipment as the main wiring 11, which is the measurement object 8, within the clamp portion 2 in a distribution board 10 where the main wiring 11 and branch wiring 12 are arranged.

[0028] The leakage current may be a leakage current I0 as shown by the two-dot chain arrow in FIG. 3, or an effective leakage current I 0r When measuring leakage current, it is more efficient to first measure the current in each branch wiring 12 branching off from main wiring 11, and then measure each branch wiring 12 only if a leak is detected, rather than measuring the current in each branch wiring 12 branching off from main wiring 11 from the beginning.

[0029] In the case of a three-wire main wiring 11, such as that of a three-phase power supply facility, the three wires 8a are stiffer and less mobile than the branch wiring 12, and are located a short distance from the wall 13 of the distribution board 10, making it difficult to use an ammeter with a conventional circular or square clamp. A circular clamp would prevent the three wires 8a from being placed inside the clamp because the clamp would interfere with the wall 13 of the distribution board 10. While a square clamp would allow placement, the three wires 8a would be positioned off-center, making it difficult to measure leakage current with the precision required. In this embodiment, the clamp 2 forms a long, narrow loop in the closed state, allowing the three wires 8a to be placed at the center of the clamp 2 while avoiding interference with the wall 13, as shown in FIG. 2 .

[0030] In particular, in the case of wiring that branches at a JIS-standard circuit breaker 14 (JIS C 8201-2-1 Annex JC standard circuit breaker 14 for lighting distribution panels) as shown in FIG. 3 , it is preferable to measure the main wiring 11 at a position adjacent to the circuit breaker 14 and immediately before the branch (e.g., the position indicated by the long, dotted, long circle in FIG. 3 ). However, at this point, the distance L1 from the wall surface 13 to the center of the main wiring 11 is only 32 mm. In this regard, the outer diameter L2 in the short-side direction D22 of the clamping portion 2 of this embodiment is not particularly limited, but is preferably 64 mm or less from the perspective of compatibility with the JIS-standard circuit breaker 14. Note that if a terminal block 15 connected to the main wiring 11 is present inside the distribution board 10, the measurement may be performed at a position adjacent to the terminal block 15 (e.g., the position indicated by the long, dotted, long circle in FIG. 3 ). The distribution board 10 may be configured to include the terminal block 15 instead of the circuit breaker 14. In this case, it is preferable to measure the main wiring 11 at a position adjacent to the terminal block 15 and immediately before the branch.

[0031] The three wires 8a can be placed inside the clamp unit 2 by grasping the rod-shaped gripping unit 3, moving the hand-side end 2c (straight portion 4 of the base 2a) of the clamp unit 2 in the open state as shown by the solid line in Fig. 2 toward the wires 8a along the wall surface 13, passing the three wires 8a sequentially between the non-gripping-unit end 2a2 of the base 2a and the opening / closing-unit end 2b1 of the movable unit 2b, and returning the clamp unit 2 to the closed state as shown by the two-dot chain line in Fig. 2. At this time, as shown in Fig. 1, the angle θ between the longitudinal direction D21 of the clamp unit 2 in the closed state and the longitudinal direction D1 of the gripping unit 3 is greater than 45° but less than a right angle. This means that the center of gravity of the clamp unit 2, which is large and heavy and cannot be touched directly, approaches the gripping unit 3, and the force required to perform work while holding the gripping unit 3 can be significantly reduced. Furthermore, since the gripping portion 3 is farther away from the wall surface 13 than when the angle θ is 45° or less, it becomes easier to perform the series of operations for placing the three wires 8a inside the clamping portion 2. Therefore, safe work can be achieved with good operability.

[0032] Although the embodiments of the present disclosure have been described above, the present disclosure is not limited to the above-described embodiments, and the above-described embodiments can be modified in various ways without departing from the gist of the present disclosure.

[0033] For example, the clamp-on ammeter 1 may be configured to measure a current other than a leakage current. The clamp-on ammeter 1 may also be configured to measure wiring other than a three-wire type, such as a two-wire type. [Explanation of symbols]

[0034] 1. Clamp-on ammeter 2 Clamp section 2a base 2a1 Grip side end 2a2 Non-grip side end 2b Moving part 2b1 Opening and closing end 2b2 Non-opening end 2c Hand end 3 Gripping part 4 Straight section 5 Curved section 6 Grip side boundary 7 Boundary area on non-grip side 8 Measurement Object 8a wire 9 Triggers 10 Distribution board 11 Main wiring 12 Branch wiring 13 Wall 14 Circuit Breaker 15 Terminal block D1 Longitudinal direction of gripping part D21 Longitudinal direction of clamp in closed state D22 Short side of clamp when closed L1 Distance from the wall to the center of the main wiring L2: Outer diameter of clamp part in the short direction O1: Central axis extending in the longitudinal direction of the gripping part O2 The central axis of the clamp in the closed position P rotation axis θ angle

Claims

1. A clamp portion and a thin and long grip portion connected to the clamp portion are included. the clamping portion has a base portion integral with the gripping portion and a movable portion movable relative to the base portion, and the clamping portion operates between a closed state in which the clamping portion forms an elongated loop shape in a front view and an open state in which the clamping portion forms a non-loop shape in a front view by the movement of the movable portion; When viewed from the front, the longitudinal direction of the clamp portion in the closed state forms an angle of more than 45° and less than a right angle with respect to the longitudinal direction of the grip portion, The base portion extends from the grip portion to a hand-side end of the clamp portion in a short direction of the clamp portion in the closed state, The movable part extends from the grip part to the hand end of the clamp part, and the movement towards the hand changes the clamp part from the closed state to the open state.

2. 2. The clamp-on ammeter according to claim 1, wherein the angle formed by the longitudinal direction of the clamp portion in the closed state and the longitudinal direction of the grip portion is a right angle when viewed from the front.

3. 2. The clamp-type ammeter according to claim 1, wherein the clamp portion has a pair of straight portions that face each other in the short-side direction of the clamp portion and each extend linearly in the long-side direction of the clamp portion, and a pair of curved portions that face each other in the long-side direction of the clamp portion and each curve so as to protrude radially outward of the clamp portion.

4. 4. The clamp-on ammeter according to claim 3, wherein each of the curved portions is curved in a semicircular arc shape.

5. the base of the clamping portion is integrally connected to the gripping portion and extends from a gripping portion-side end located at a gripping portion-side boundary between one of the curved portions and one of the straight portions to a non-gripping portion-side end located at a non-gripping portion-side boundary between the other of the curved portions and the other straight portion; the movable portion of the clamping portion extends from a non-opening / closing side end portion located at the gripping portion side boundary portion to an opening / closing side end portion located at the non-gripping portion side boundary portion, and is connected to the gripping portion so as to be able to rotate as the movement relative to the base portion in the front view, 4. The clamp-on ammeter according to claim 3, wherein the clamp portion allows an object to be measured to pass between the non-gripping portion side end of the base portion and the opening / closing side end of the movable portion in the open state.

6. 6. The clamp-on ammeter according to claim 5, further comprising a trigger that causes the rotation of the movable part of the clamping part when the gripping part is gripped and pressed.

7. 2. The clamp-on ammeter according to claim 1, wherein the clamp portion, in the closed state, accommodates three wires to be measured, aligned in the longitudinal direction of the clamp portion.

8. 2. The clamp-on ammeter according to claim 1, wherein the clamp portion has an outer diameter in the lateral direction of 64 mm or less.

9. 2. The clamp-on ammeter according to claim 1, which measures leakage current in AC power supply equipment.

10. A current measurement method using the clamp-on ammeter according to any one of claims 1 to 9, A current measurement method in which, in a distribution board in which main wiring and branch wiring are arranged, the main wiring to be measured is placed within the clamp portion of the clamp-type ammeter to measure the current.

11. 11. The current measurement method according to claim 10, wherein the main wiring comprises three wires corresponding to a three-phase power installation or a single-phase power installation.

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