JPH0755845A - Current sensor for forward and backward current flow wire - Google Patents

Abstract

PURPOSE:To provide a current sensor for two wires, wherein individual conductor currents inside a cable such as a parallel cord containing two or more conductors can be measured in a noncontact manner or when the sensor is brought into slight contact without working the cable. CONSTITUTION:This sensor is provided with a detection sensor S which detects a magnetic flux generated by currents flowing in individual conductors for a cable 10 composed of a plurality of cores and with a variable amplifier K which, when the detection sensor S is positioned to the cable 10 by a support utensil 20 so as to correspond to the size of the cable 10 and the mutual interval between the conductors of the cable 10 is given, obtains a variable amplification degree corresponding to the interval and which outputs a measuring signal which has amplified an electric signal generated by the detection sensor S at a prescribed amplification degree corresponding to the interval.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a current sensor for a reciprocating wire for detecting a current of a multi-core cable in which a reciprocating current flows, and in particular, without disconnecting each conductor current of a cable including two or more conductors. , Those that can measure the conductor current only by approaching the cable as it is.

[0002]

2. Description of the Related Art As a conventional current sensor, a current of one conductor is surrounded by a grasping type current transformer for measurement. On the other hand, in a cable including two or more conductors, the conductors are in close contact with each other through an insulating material, and even if the whole cable is detected by a grasping type current transformer, only the combined current of each conductor can be measured. . Therefore, there was no other way to measure the conductor currents, apart from measuring them separately.

[0003]

However, not only is it difficult to measure the current by disconnecting the conductor, but in some cases, the conductor cannot be separated and measurement is impossible.

The present invention has been made in consideration of the above points, and each conductor current in a cable such as a parallel cord including two or more conductors can be contacted or lightly contacted without processing the cable. An object is to provide a current sensor for a reciprocating electric wire that can be measured.

[0005]

In order to achieve the above object, in the present invention, a magnetic flux generated by a current flowing through each conductor of a multi-core cable as described in claim 1 is detected to detect an electric signal. A sensor, a support for positioning the detection sensor with respect to the cable in accordance with the standard size of the cable, and an interval between the conductors of the cable are provided, so that a variable amplification degree according to the interval is provided, A reciprocating wire current sensor, comprising: a variable amplifier that outputs a measurement signal obtained by amplifying an electric signal generated in a detection sensor with a predetermined amplification degree according to the interval; and a reciprocating wire current sensor according to claim 1, wherein: The support is formed to generate a signal according to the size of the cable, and the variable amplifier is configured to change the amplification degree according to the signal from the support. The current sensor for reciprocating electric wire according to claim 1, and the current sensor for reciprocating electric wire according to claim 1, wherein a plurality of detection sensors are symmetrically arranged around a two-core cable through which the reciprocating electric current flows, and a rotation angle of the cable is determined. Correspondingly, a magnetic flux that changes spatially is linked to the plurality of detection sensors, and the induced output voltage signals of these detection sensors are combined to generate an electrical signal that does not significantly change depending on the position rotation angle of the two-core cable. The present invention provides a current sensor for a reciprocating wire, which is obtained.

[0006]

In the sensor according to the first aspect of the present invention, the detection sensor is positioned with respect to the cable to be measured by the support, and the magnetic flux generated by the current of each conductor of the multi-core cable is captured by the detection sensor. An output corrected by a variable amplifier that changes the amplification degree according to the size of the conductor spacing that affects the strength of the magnetic flux is formed.

In the sensor according to the second aspect of the present invention, the variable amplifier amplifies the output of the detection sensor with an amplification degree based on a signal corresponding to the size of the cable formed by the support.

Further, in the sensor according to claim 3 of the present invention, in the case of a simple cable such as a reciprocating two-core parallel cord, the fact that the reciprocating current is the same value is utilized, so that the detection sensors are made symmetrical by the support. A plurality of detection sensors are arranged around the cable so that the output signals of the detection sensors are combined.

[0009]

FIG. 1 is an explanatory view showing an embodiment of the present invention. In this figure, 10 is a parallel two-core cable 10 in which two cores are covered with an insulating coating.
0 is supported by the support tool 20 and the detection sensor S is kept at a constant distance from the cable 10 for measurement. Detection center S
As the coil, a coil, a hall sensor, a flux gate or the like can be used.

A magnetic field H at a predetermined point P (x, y) generated by a reciprocating current flowing through the conductors 11 and 12 of the cable 10 has magnetic field vectors H1 and H2 in the circumferential direction according to the law formula of ampere circular integration. At Here, r1 and r2 are the lengths of lines connecting the centers of the conductors 11 and 12 to the predetermined point P (x, y). Expressed as

However, Is.

In this case, if the angles between the lines r1 and r2 and the x axis are θ1 and θ2, Hx of the x and y direction components Hx and Hy of the vector composite magnetic field H with the magnetic field vectors H1 and H2 is Hx.
Is H _x = H ₁ sin θ ₁ −H ₂ sin θ ₂ Is.

[0013] Similarly Hy _{is, H y = -H 1 cos θ} 1 -H 2 cos θ 2 ∴H = H _x i + H _y j (5)

As a result, the magnetic flux φ along the equal magnetic field lines in FIG.
Occurs as indicated by the dotted line. When the detection sensor S is arranged near the conductor 12 so as to interlink with the magnetic flux φ, if the current I2 flowing through the conductor 12 is an alternating current, the output e of the detection sensor S becomes Is obtained. In the simple parallel code, the currents I1 and I2 flowing through the conductors 11 and 12 are I1 = -I2.

The output voltage e of the detection sensor S is amplified by the variable amplifier K, and its output e0 or e0 'is obtained as an output signal of the sensor. In this case, k is composed of an operational amplifier A1 and feedback resistors R1 and R2, as shown in the figure,
The output e0 is Becomes

At the same time, the resistance value R1 is changed corresponding to the distance d between the conductors 11 and 12, and the amplification factor (R1 + R2) / R1 is changed. Further, the distance d between the conductors 11 and 12 can be measured when the detection sensor supporter 20 brings the detection sensor S close to the cable 10. By providing this distance d to the variable amplifier K, the resistance value R1 can be determined according to the distance d. Change it manually or automatically.

As a result, the distance d is provided at the output end of the variable amplifier.
The output of the size corrected by is obtained. The output of the variable amplifier is given to a phase shift circuit composed of an operational amplifier A2, resistors R3, R4, R5 and capacitors C1, C2, and the output is 90 °.
It becomes a phase-shifted signal.

In FIG. 2A, the detection sensor S is connected to the conductor 11,
This is an example in which a parallel cord having 12 is closely attached in parallel. In this case, since the magnetic fluxes φ1 and φ2 of the currents I1 and I2 flowing through the conductors 11 and 12 are simultaneously and evenly captured, when the cord is closely attached to a pole or the like, it is easy to press it from one side only. Can be measured.

Further, if the detection sensor S is made large in size, even if the detection sensor S is slightly displaced, the position shown in FIG.
As shown in the experimental result of (b), the output e hardly changes. For this reason, in the case of a coil, it is wound in a square shape. In the case of a hall sensor, the detection operation surface is rectangular.

FIG. 3 shows another embodiment of the present invention in which the conductors 11 and 12 are sandwiched between two detection sensors S1 and S2. In this case, the cable 10 and the detection sensor S1
, S2, and the output voltage e combines the outputs of the two sensors S1 and S2, the detection output hardly changes even if the position of the cable 10 changes slightly between the two sensors S1 and S2. .

FIG. 4 shows four detection sensors S1 to S4,
This is an example in which the conductors 11 and 12 are symmetrically arranged by a support tool (not shown). In this case, even if the orientations of the conductors 11 and 12 are not parallel to the detection sensor, in the state where the conductors are slightly rotated around the axial direction of the conductors as shown in the figure, the detection sensor is compared to when the conductors are in the horizontal state, for example. S1, S2, S3
, S4 changes, but the combined value of these outputs is constant.

FIG. 5 shows an example in which the number of detection sensors is increased to S1 to S8, and a grasping structure is provided by a non-magnetic material arm 30 with a lever as a supporting tool for opening and closing with a point P as a fulcrum. Thereby, the accuracy is improved corresponding to the increase in the number of the detection sensors S.

The distance between the conductors 11 and 12 can be known from the standard of the cable 10, but, for example, the lever 4 provided on the arm 30.
It can be measured as an opening angle of 1, 42. Then, which standard the cable to be measured corresponds to may be detected based on the opening angle, and the amplification degree of the variable amplifier may be automatically set according to the detected value.

In the present invention, the measuring method of the conductor spacing in the cable 10 or the judging method based on the standard is not particularly limited, and in addition to the mechanical method using the support, the so-called electrostatic method and high-frequency vortex are used. Various methods such as a current method and a line potential detection method can be used.

In each of the above embodiments, an air core is used, but it is obvious that an iron core may be inserted to concentrate the magnetic flux.

[0026]

According to the sensor of claim 1 of the present invention, the support sensor positions the detection sensor with respect to the cable to be measured, and the magnetic flux generated by the current of each conductor of the multi-core cable is detected by the detection sensor. By capturing and compensating with a variable amplifier that changes the amplification degree according to the size of the conductor interval that affects the strength of the generated magnetic flux, the cable current can be easily made without contacting or simply approaching without separating the cable. Can be measured.

Further, according to the sensor of the second aspect of the present invention, since the amplification degree of the variable amplifier is automatically determined based on the signal given by the supporting tool, only the cable to be measured is set on the supporting tool. Allows accurate measurement according to the cable dimensions.

Further, according to the sensor of claim 3 of the present invention, in the case of a simple cable such as a reciprocating two-core parallel cord, the fact that the reciprocating current is the same value is utilized to make the detection sensors symmetrical. By arranging a plurality of detection sensors around the cable with a support and combining the output signals of each detection sensor, it is possible to have the same detection capability as a single wire grasping current transformer. . As a result, accurate measurement can be performed without making the positional relationship between the parallel cord and the detection sensor particularly accurate. As a method of combining the output signals of the respective detection sensors, various methods including digital processing can be adopted.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of an embodiment of the present invention.

2 (a) is an explanatory view showing another measuring method according to the embodiment of FIG. 1 in which a detection sensor is closely contacted in parallel with a parallel cord from a side surface, and FIG. 2 (b) is the same drawing (a). 4) is an explanatory view showing an experimental result of an error change due to the position shift of the detection sensor in FIG.

FIG. 3 shows another embodiment of the present invention, and is an explanatory view of a parallel cord in which two detection sensors are arranged in proximity to each other.

FIG. 4 shows still another embodiment of the present invention, in which 4
Explanatory drawing of what arranged one detection sensor symmetrically around the parallel code.

FIG. 5 shows still another embodiment of the present invention.
Explanatory drawing of what arrange | positions each detection sensor around a parallel code, makes a detection sensor support tool a grasping type, and measures a conductor space | interval.

[Explanation of symbols]

 10 Cables 11 and 12 Conductors 20 Supports 30 Arms 41 and 42 Lever d Distance between conductors H Magnetic field I Current S Detection sensor

Claims (3)

[Claims] 1. A detection sensor for detecting a magnetic flux generated by a current flowing through each conductor of a multi-core cable to generate an electric signal, and a support for positioning the detection sensor with respect to the cable in accordance with the size of the cable. The tool and the conductors of the cable have a variable amplification degree according to the distance, and an electric signal generated in the detection sensor is amplified by a predetermined amplification degree according to the distance to output a measurement signal. A current sensor for a reciprocating wire that has a variable amplifier. 2. The sensor according to claim 1, wherein the support member is configured to generate a signal according to a dimension of the cable, and the variable amplifier has an amplification factor according to a signal from the support device. Current sensor for reciprocating electric wire, which is configured to change the voltage. 3. The reciprocating wire current sensor according to claim 1, wherein a plurality of detection sensors are symmetrically arranged around a two-core cable through which a reciprocating current flows, and spatially corresponding to a rotation angle of the cable. It is characterized in that the changing magnetic flux is interlinked with each of the plurality of detection sensors, and the induced output voltage signals of these detection sensors are combined to obtain an electric signal that does not largely change depending on the position rotation angle of the two-core cable. Current sensor for reciprocating electric wire.