JPH088574A - Device for preventing electromagnetic induction - Google Patents

Abstract

PURPOSE:To improve the operability of a crane and to improve the safety of workers by preventing the occurrence of electromagnetic induction faults. CONSTITUTION:A device for preventing electromagnetic induction is provided with at least one of a loss generating section composed of ferrite cores 1 and 4 for converting high-frequency energy induced in an induction wire 3 into heat, and an energy blocking section provided with a parallel resonance circuit 2 which resonates in parallel with the high frequency induced in the wire 3 and increases the impedance of the induction wire 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to prevention of electromagnetic induction damage, and more particularly to a device for preventing damage to a human body due to high frequency energy induced in a large crane in a strong electric field.

[0002]

2. Description of the Related Art For example, in a strong electric field near a medium-wave high-power transmission facility, large high-frequency energy due to electromagnetic induction may be induced in a wire of a large crane, and a worker may come in contact with the high-frequency energy to cause electric shock. . As countermeasures against such electromagnetic interference, conventionally, the hook of a crane has been grounded, or an operator wears insulating rubber gloves to prevent electric shock due to induced energy.

[0003]

The conventional method as described above impairs workability. Therefore, the present invention provides an electromagnetic induction prevention device capable of significantly improving the operability of a crane and sufficiently ensuring the safety of workers by not using a ground wire or insulating rubber gloves. To aim.

[0004]

In order to achieve the above-mentioned object, an electromagnetic induction prevention device according to the present invention comprises a loss generating part made of a ferrite core for converting high frequency energy induced in an induction wire into heat. With an energy blocking unit having a parallel resonance circuit for parallelizing the high frequency induced in the induction wire to make the induction wire high impedance.
It is characterized by having at least one.

Here, it is preferable that the loss generating portion and the energy blocking portion are connected in series, and the induction wire can pass through the ferrite core. Further, it is preferable that the induction wire and the parallel resonance circuit are electromagnetically coupled via the second ferrite core.

[0006]

In the present invention, the high-frequency energy induced in a large crane or the like is converted into heat by the loss tangent of the ferrite core, or the impedance of the induction circuit (induction line) is increased by the parallel resonance circuit, or a combination thereof. Can be attenuated by

[0007]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 shows the construction of an embodiment of an electromagnetic induction prevention device according to the present invention. The present embodiment has a loss generating section A composed of a ring-shaped ferrite core 1 in which unit ferrite cores 1A are laminated, and an energy blocking section B composed of a parallel resonant circuit 2 in which a variable inductance 2A and a capacitor 2B are connected in parallel. are doing. The induction wire 3 penetrates the ferrite core 1, and further, the second ferrite core 4 in which unit ferrite cores 4A are laminated in order to couple the induction wire 3 and the parallel resonance circuit 2 is used as a transformer, and the energy blocking unit B is used. Is formed. The guide wire 3 corresponds to a wire in the case of a large crane. By attaching a device to the upper part of the guide wire terminal 3A (corresponding to a hook suspended on a wire in the case of a large crane), the induced high frequency energy is reduced to a value that does not affect the human body at the guide wire terminal. Can be attenuated up to.

The loss generating section A uses a ferrite core having a sufficient resistance loss (loss tangent) at the frequency of the induced high frequency to convert the high frequency energy into heat and attenuate it. For example, as shown in FIG. 2, in a strong electric field on the premises of a medium-wave high-power broadcasting station, an insulation-coated induction wire with a total length of about 55 m to the experimental building 13 via the pole 12 about 45 m away from the management building 11. In the experiment in which 3 was stretched and the high-frequency current was measured by the ammeter 14, the outer diameter was 28 mm, the inner diameter was 16 mm, and the thickness was 1 mm.
3mm ring-shaped ferrite core (H of TDK Corporation
When the loss generating part A in which 30 pieces of 5A material) were laminated was used, about 150 W was converted into heat.

The ferrite core depends on its material and shape.
It has its own impedance component, and the increase in the number used
Increase resistance and reactance. In general, the guide line is sufficiently short and capacitive as compared with the medium wavelength, so that it may be tuned to the guide frequency depending on the number due to the increase of the core, that is, the increase of the guide component. FIG. 3 shows a change in short-circuit current due to a change in the number of cores used in the experiment conducted in the experimental facility shown in FIG. In FIG. 3, curves D, E, and F are the product H6F (loss factor tan of TDK Corporation, respectively.
<13 × 10 ^-6 , 1MH at δ / μiac of 0.5MHz
z <17 × 10 ^-6 ), H5A (loss factor is 10 kHz
<2.5 × 10 ⁻⁶ , <10 × 1 at 100 kHz
0 ^-6 ), and H5C2 (loss factor <10 kHz <
This is the case where 7.0 × 10 ⁻⁶ ) is used as the core. When the core is not used (the number is 0), the short circuit current value is 980m
In A, the value of the short-circuit current changes depending on the material and shape of the core used. In this case, the shapes were the same. As shown in the figure, the short-circuit current increases with the number of cores up to 10 when the H5A material is used as the core and up to 30 when the H6F material is used, and thereafter decreases. This increase in the short circuit current value is due to tuning to the induction frequency. On the other hand, in the case of the H5C2 material, the short-circuit current monotonously decreases with the number of cores, but when the tuning is performed similarly, the short-circuit current increases. For this reason, the number of cores to be used must be 30 or more so as not to tune to the induction frequency, for example, when using H5A material.

Returning to FIG. 1, the energy blocking portion B is formed in the coupling between the parallel resonance circuit 2 and the induction wire 3 by using the second ferrite core 4 as the core of the transformer. A high impedance circuit (parallel resonance circuit 2) that is parallel-resonated to the induced frequency is electromagnetically coupled to the induction circuit (induction line 3) to make the induction line side have high impedance,
Block high frequency energy. The resonance frequency is variable.

Although it is possible to use the energy blocking unit independently, by connecting the loss generating unit and the energy blocking unit in series, the number of cores used as a whole can be increased as compared with the case where they are used individually. To reduce the size,
High frequency energy can be attenuated to the required level.

FIG. 4 shows an embodiment of the electromagnetic induction prevention device 20 in which the loss generating portion A and the energy blocking portion B are combined. Each of the half-ring-shaped core halves 21A and 22
The core halves 21 and 22 in which A is laminated and the core halves 23 and 24 in which half ring-shaped core halves 23A and 24A, respectively, are laminated are exposed at their opposite surfaces and are covered with insulators 25A and 25B. It is being appreciated. The insulators 25A and 25B may be openable / closable by, for example, a hinge, or may be separated. When the insulators 25A and 25B are closed, the core halves 21 and 22 and the core halves 23 and 24 are in close contact with each other to form a ring-shaped closed magnetic circuit. Variable inductance 26
A, a parallel resonance circuit 26 as an energy blocking unit in which a capacitor 26B is connected in parallel is embedded in an insulator 25B, and when the covered conductor 26C of the resonance circuit forms a ring-shaped closed magnetic path by the core halves 23 and 24. It fits inside the ring. The guide wire 27 (wire of the crane) is put into a ring-shaped closed magnetic circuit formed by the core halves 21 and 22 and the core halves 23 and 24 to close the insulators 25A and 25B. A heat dissipation plate may be attached to an appropriate position of the electromagnetic induction prevention device, for example, near the core or on the outer periphery of the device to dissipate the heat generated in the core.

FIG. 5 is a view showing a state where the electromagnetic induction prevention device 20 of the present invention is attached to the hook portion 32 of the crane 31, (a) is an overall view thereof, and (b) and (c) are one thereof. It is an enlarged view of a part. Insulator 2 as shown in FIG.
The wire 33 is sandwiched between 5A and 25B, and then the insulators 25A and 25B are closed as shown in FIG. (C), fixed by the fasteners 34, and the electromagnetic induction prevention device 20 is attached to the wire 33 above the hook portion 32. . The electromagnetic induction prevention device 20 is not electrically connected to the wire 33 but is electromagnetically connected. Since the outer periphery of the electromagnetic induction prevention device is covered with the insulator as described above and is not directly electrically connected to the wire, it can be easily attached and detached.

In the process of manufacturing a crane, electromagnetic induction can be prevented by, for example, directly attaching (electrically coupling) a parallel resonance circuit to the hook portion or providing a core having a large resistance loss. However, since the electric field strength is not so high that the usual place where the crane is used is problematic, it is not cost-effective to take such measures for all vehicles in the manufacturing process. The electromagnetic coupling described above is advantageous because it can be easily attached to and detached from a ready-made vehicle and the effect of preventing guidance can be obtained.

[0016]

As described above, by mounting the electromagnetic induction prevention device of the present invention on a large crane or the like, the induced energy is attenuated to a value that does not affect the human body, thus improving work efficiency and worker safety. Both can be improved.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of an exemplary embodiment of the present invention.

FIG. 2 is a diagram showing experimental equipment for measuring the effect of the present invention.

FIG. 3 is a diagram showing a change in short-circuit current depending on the number of cores used.

FIG. 4 is a diagram showing an embodiment of an electromagnetic induction prevention device of the present invention.

FIG. 5 is a diagram showing a state in which the electromagnetic induction prevention device of the present invention is attached to a crane.

[Explanation of symbols]

 A Loss generating part B Energy blocking part 1,4 Ferrite core 1A, 4A Unit ferrite core 2 Parallel resonant circuit 2A Variable inductance 2B Capacitance 3 Induction wire 11 Management building 12 Pole 13 Experimental building 14 Ammeter 20 Electromagnetic induction prevention device 21,22 , 23, 24 Core half 21A, 22A, 23A, 24A Unit core half 25A, 25B Insulator 26 Parallel resonant circuit 27 Guiding wire 31 Crane 32 Hook part 33 Wire 34 Fastener

Claims (4)

[Claims] 1. A loss generating part formed of a ferrite core for converting high frequency energy induced in the induction wire into heat, and a high frequency induced in the induction wire are parallel-resonated to increase the impedance of the induction wire. And an energy blocking unit having a parallel resonance circuit for use in the electromagnetic induction prevention device. 2. The electromagnetic induction prevention device according to claim 1, wherein the loss generating section and the energy blocking section are connected in series. 3. The electromagnetic induction prevention device according to claim 1, wherein the induction wire can pass through the ferrite core. 4. The induction wire and the parallel resonant circuit are second
4. The electromagnetic induction prevention device according to claim 1, wherein the electromagnetic induction prevention device is electromagnetically coupled through the ferrite core.