JPS6318927Y2 - - Google Patents

Description

[Detailed description of the invention] This invention relates to a clamp sensor used in a clamp-type ammeter.

A clamp-type ammeter encloses a clamp sensor consisting of a magnetic core and a magneto-electric transducer that can be opened and closed around a live wire to be measured, and converts the magnetic flux induced in the magnetic core into an electrical signal via the magneto-electric transducer. Converted,
The measured current is displayed on a display on the main body side that is combined with the clamp sensor, and magnetoelectric transducers for clamp sensors that use semiconductors, such as Hall elements, are known. In this case, the Hall element is usually installed on the opening/closing end face of the magnetic core, but when the magnetic core is wrapped around the wire to be measured and closed, the impact may cause cracks in the Hall element substrate, making measurement impossible. Ta.

This invention was made to eliminate such drawbacks, and its purpose is to provide a clamp sensor in which the Hall element can sufficiently withstand the impact when the magnetic core is closed.

Hereinafter, this invention will be explained in detail with reference to embodiments shown in the accompanying drawings.

Referring to FIG. 1, this clamp sensor:
It includes a pair of holders 1 and 2 that can be opened and closed. In this case, the holders 1 and 2 are formed symmetrically from an electrically insulating material such as a plastic molded product, and their base portions 3 and 4 are connected to each other by a shaft 5 so as to be openable and closable. The magnetic cores 6 and 7 are stacked, for example, a plurality of high magnetic permeability laminates punched out with the same size and shape, and are each integrally caulked with rivets (not shown) and then attached to the holders 1 and 2. inserted. And this holder 1, 2
It is fixed by, for example, an epoxy-based hardening resin 8, 9 filled therein. magnetic core 6,7
is fixed in this way, but the curable resin 8,
Instead of 9, rivets (not shown) or the like may be used to fix the magnetic cores 6, 7 from the outside of the holders 1, 2, or the rivets and hardening resins 8, 9 may be used together. . Note that the holders 1 and 2 may be formed by being divided into two parts in the thickness direction, that is, in a direction parallel to the paper surface, and the two parts may be butted together during final assembly. Inside the holders 1 and 2, magnetic gaps 10 and 11 of a predetermined length are formed by the magnetic cores 6 and 7.
In the magnetic gaps 10 and 11, Hall elements 12 and 13 are provided, for example, one Hall element 1.
If 2 is on the holder 1 side, the other Hall element 13 is placed on the holder 2 side, and is fixed with the same hardening resins 8 and 9 as described above. The lead wires (not shown) of the Hall elements 12 and 13 are connected in series and led to the main body (not shown) which is combined with the clamp sensor of this invention. The arrangement of the magnetic cores 6, 7, magnetic gaps 10, 11, and Hall elements 12, 13 in the holders 1, 2 is as described above.
For example, if the holders 1 and 2 are circular as in this embodiment, it is desirable that the arrangement be symmetrical with respect to the center of the circle.

Recesses 14 and 15 are provided on the opening and closing end surfaces of the holders 1 and 2, respectively. FIG. 2 shows an example of a recess 14 provided at the upper open end on the side of the holder 2, and the depth of the recess 14 is determined in consideration of the degree of wear of the holder. Further, the direction may be, for example, perpendicular to the illustration, that is, if the illustration is horizontal, it may be provided in the vertical direction, or as shown in FIG. It may be stopped at a position corresponding to the depth. Further, when the opposing holder and magnetic core are engaged with each other as shown in FIG. 4, a gap 16 is provided inside as shown in the figure. In this embodiment, the recesses 14 and 15 are provided on both sides of the opening and closing end surfaces of the holders 1 and 2, but they may be provided only on one end surface, and in some cases, the recesses 14 and 15 may be provided to prevent impact force. It is also possible to provide the recess 15 on the large upper opening/closing end face and omitting the recess 15 on the base opening/closing end face.

Next, the operation of the clamp sensor configured in this way will be explained. When the holders 1 and 2 are wrapped around the electric wire to be measured and listened to, an impact force is generated on the upper opening and closing end surfaces and the base opening and closing end surfaces of the holders 1 and 2. As is well known, the magnitude of this impact force is proportional to the square of its weight and velocity, that is, the magnitude of its kinetic energy. Therefore, assuming that there is no recess on the contact surface, when the holders are closed, the kinetic energy of the opposing holders is applied as external pressure to the Hall elements 12 and 13 via the filled curable resin. The recesses 14 and 15 are connected to the Hall elements 12 and 1 by this external pressure.
3. In this state where there is no external pressure,
The impact force generated on the small and lightweight Hall elements 12 and 13 itself is small, and therefore there is almost no chance of damage. Furthermore, since the impact force on the base opening/closing end surface is naturally much smaller than the impact force on the upper opening/closing end surface, the recess 15 can be omitted if there is no risk of foreign matter getting caught.

Note that the internal structure of this clamp sensor is arranged symmetrically with respect to the center of the holder, so the disturbing magnetic flux from the outside is divided into the magnetic cores 6 and 7, and the disturbing magnetic flux from the upper direction is passed through the base. Interfering magnetic flux from the core end face and from the base direction is canceled by the upper core end face, and only the original induced magnetic flux is allowed to pass through the magnetic cores 6 and 7 in one direction. This makes it possible to almost ignore the influence of magnetic flux.

Moreover, the opposing magnetic cores 6 in the holders 1 and 2,
A magnetic gap 10 and 1 is set between
1 is provided, and when the measurement is completed, the holder 1,
2 can be opened. These magnetic gaps 10 and 11 also have the effect of alleviating the impact force when the holders 1 and 2 are attracted and abutted by the induced magnetic flux when the holders 1 and 2 are wrapped around the electric wire to be measured at the start of measurement. It is something.

As explained above in detail, the clamp sensor according to this invention does not damage the Hall element etc. due to frequent opening and closing operations of the holder during measurement, has a long lifespan, and is portable. It is suitable for clamp-type ammeters that are often used outdoors. Furthermore, there is extremely little interference from the outside, and highly reliable measurements are possible. In addition, since the holder can be opened with a light force at the end of the measurement, the degree of fatigue of the operator is small even if measurements are repeated frequently, which is particularly convenient for measuring large currents.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view showing an embodiment of the clamp sensor according to this invention, FIG. 2 is an enlarged perspective view of a recess on the upper opening/closing end surface of the holder 2 in FIG. 1, and FIG. FIG. 4 is an enlarged perspective view showing an embodiment of the present invention, and FIG. 4 is a modified example applied to an interlocking type holder, with A being a plan view and B being a front view thereof. In the figure, 1 and 2 are holders, 6 and 7 are magnetic cores, 1
2 and 13 are Hall elements, 14 and 15 are recesses, and 16
indicates a void.

Claims (1)

[Claims for Utility Model Registration] A clamp comprising a pair of holders made of non-magnetic materials that can be opened and closed, a magnetic core is embedded in each of the holders, and a magneto-electric transducer is installed in the opening and closing end surfaces of the holders. A clamp sensor, characterized in that a gap is formed between the opening and closing end surfaces for buffering an impact force acting on the magnetoelectric transducer when the holder is closed.