JPH07333252A - Current sensor - Google Patents

Abstract

PURPOSE:To provide a current sensor which achieves a miniaturization thereof to remove sticking out from legs of a transmission steel tower and dispenses with a specialized mounting metal and an accessory circuit such as integration circuit. ultimately eliminating the need for designing with due consideration given to the environment. CONSTITUTION:In a current sensor 5, a coil 1 wound on a flat magnetic core 2 is covered with an insulating body 3 and mounted in contact with a transmission steel tower. The sensor is for detecting a lightening current. The number of turns of the coil 1 is preferably 1-100.

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 detecting a current flowing through a power transmission tower or the like.

[0002]

2. Description of the Related Art With the recent increase in dependence on electric power and the sophistication of consumer facilities, it has been desired to supply electric power without a power failure, and when a power failure due to an accident such as a lightning strike occurs, a failure point occurs. It is necessary to surely discover the above.

A current sensor is used to detect that a current has flowed through a transmission tower or the like due to a lightning strike or the like.
The main current sensors that have been put to practical use are CT (Curre
nt Transformer) method and Rogowski method are used.

As shown in FIG. 5, a current sensor based on the CT method has a coil 16 around a core 15 formed by winding a steel sheet material made of directional silicon or a magnetic material made of ferrite in a ring shape.
To form the current transformer 17, and the current wire 19 to be measured is passed through the central hole of the core 15. This current sensor measures the value of the through current 18 by catching the change in the magnetic flux generated by the change in the current flowing through the measured current line 19 with the current transformer 17, and measures the value of the through current 18 flowing through the measured current line 19. The current is measured in a fraction of the number of turns.

In the current sensor based on the Rogowski method, a lead wire at one end of an air-core toroidal is passed through a coil to collect an output wire at one end, and a current wire to be measured is passed through the center of the air-core toroidal. In this current sensor, a current proportional to the differential value of the through current flowing through the current line to be measured is measured, and an integrating circuit is required to obtain the through current value. In addition, since the Rogowski method current sensor does not use a magnetic material, magnetic saturation does not occur and a large current such as a lightning impulse current can be measured.

Since the above-mentioned current sensor based on the CT method or the Rogowski method has a structure surrounding the current line to be measured, if the current line to be measured becomes large like a tower leg of a power transmission tower, the current sensor itself also becomes large. Become. Further, an auxiliary circuit such as an integrating circuit for measuring the value of the shoot-through current and a power source were required.

In Japanese Patent Laid-Open No. 57-85823, a small current sensor attached to a tower leg of a power transmission tower has a coil wound in a circular shape in a direction perpendicular to a magnetic flux generated by a current flowing through the tower leg. A flash-on indicator which is built-in and which indicates that a current has flowed above a set level is disclosed.

[0008]

However, the flashover indicator must be mounted so as to project from the tower pedestal, so that a dedicated mounting bracket is required and the operating environment such as wind pressure is taken into consideration. Had to design. Moreover, the current detection sensitivity of the flashing indicator has changed depending on the mounting position of the flashing indicator.

The present invention has been made in order to solve the above-mentioned problems, and is small in size, does not protrude from the tower legs of a power transmission tower, does not require a dedicated mounting bracket, and needs to be designed in consideration of the operating environment. It is an object of the present invention to provide a current sensor which does not have the above, and in which the current detection sensitivity of the flash light indicator does not change depending on the mounting position of the flash light indicator.

[0010]

As shown in FIG. 1, a current sensor 5 of the present invention made to achieve the above object has a coil 1 wound around a flat magnetic material core 2 as an insulator. Covered with 3. The current sensor 5 is attached to the power transmission tower in contact therewith for detecting a lightning current. A current is induced in the coil 1 by a lightning current. The number of turns of the coil 1 is 1 to 10
It is preferably 0.

[0011]

Since the current sensor 5 (see FIG. 1) of the present invention has a flat plate shape, it can be closely attached to the tower leg 10 of the power transmission tower as shown in FIG. No metal fittings are needed.

Further, since the current sensor 5 of the present invention can detect a lightning impulse current or a large alternating current of several kA or more, it can be used for various kinds of current detection such as a flashing indicator or a continuous lightning indicator. Further, when the current line to be measured is a tower leg or a flat plate, the detection sensitivity does not change by using the magnetic material core 2 having the same width as the tower leg or the flat plate.

[0013]

EXAMPLES Examples of the present invention will be described in detail below.

FIG. 1 is a sectional view and a longitudinal sectional view of an essential part showing an embodiment of a current sensor to which the present invention is applied.

As shown in the figure, in the current sensor 5, a coil 1 is vertically wound around a magnetic material core 2, and the whole is covered with an insulator 3 for waterproofing and insulation. Further, as shown in FIG. 2, in the current sensor 6, the coil 1 may be wound around the magnetic material core 2 in the lateral direction. The material and size of the magnetic material core 2, the diameter of the coil 1, the number of turns, and the winding direction are selected according to the measured current value.

As shown in FIG. 3, the current sensor 5 is wound around a tower leg 10 of a power transmission tower with a belt 8 and a coil 1 inside the current sensor 5 is attached in a direction to cut a magnetic flux generated by a current 9 at a right angle. .

The sensitivity test of the current sensor 5 was conducted by constructing the simulated lightning impulse test circuit shown in FIG.

The simulated lightning impulse test circuit shown in FIG.
When the switch 22 is closed, current flows from the power source 21 to charge the capacitors 23 and 24, and then the discharge switch 25.
When is short-circuited, the simulated lightning impulse current is transmitted to the shunt resistor 26, and the current-voltage change appears on the oscilloscope 27. The output line of the resistor 28 and the input line of the shunt resistor 26 were connected to the tower 10, and the output line of the current sensor 5 was connected to the oscilloscope 27.

With respect to the current sensor 5 having two and four coil turns, a lightning impulse current having a waveform of 8 × 20 μs is passed, the current value of the lightning impulse current and the output voltage of the current sensor 5 are measured, and the result is shown. Shown in 1.

[0020]

[Table 1]

As shown in Table 1, the sensitivity of the current sensor 5 to the lightning impulse current was good.

Next, in the simulated lightning impulse test circuit shown in FIG. 4, the current sensor 5 having three coil turns was attached, and the current sensor 5 was connected to the flash unit display section instead of the oscilloscope 27. 8k20μs waveform of 1kA
When a lightning impulse current was applied to the display unit for the flashover indicator worked normally.

Further, in the simulated lightning impulse test circuit shown in FIG. 4, a current sensor 5 having three coil turns was attached, and the current sensor 5 was connected to a continuous lightning stroke display device display section in place of the oscilloscope 27.

With respect to the display section for the continuous lightning stroke display device for 5 consecutive shots and 3 consecutive shots, a lightning impulse current having a waveform of 8 × 20 μs was passed, and the current value of the lightning impulse current was measured. The operation state was observed, and the results for 5 consecutive shots are shown in Table 2 and the results for 3 consecutive shots are shown in Table 3.

[0025]

[Table 2]

[0026]

[Table 3]

As shown in Tables 2 and 3, both of the 5-repeating and 3-repeating continuous lightning stroke display device display sections operated normally with respect to the lightning impulse current.

[0028]

As described above in detail, the current sensor of the present invention is small in size, does not protrude from the tower leg of the power transmission tower, and does not require a dedicated mounting bracket or an auxiliary circuit such as an integrating circuit. It is not necessary to design considering the usage environment. Moreover, the current detection sensitivity of the flashing indicator does not change depending on the mounting position of the flashing indicator. Furthermore, the simple structure makes the manufacturing cost low and the maintenance easy.

[Brief description of drawings]

1A and 1B are a sectional view and a longitudinal sectional view of an essential part showing an embodiment of a current sensor to which the present invention is applied.

FIG. 2 is a sectional view of an essential part showing an embodiment of a current sensor to which the present invention is applied.

FIG. 3 is a diagram showing a mounting example of a current sensor to which the present invention is applied.

FIG. 4 is a simulated lightning impulse current generation circuit used in a sensitivity experiment of a current sensor to which the present invention is applied.

FIG. 5 is an external view showing an example of a conventional current sensor.

[Explanation of Codes] 1.16 is a coil, 2 is a magnetic material core, 3 is an insulator, 4 is an end portion, 5 and 6 are current sensors, 8 is a belt, 9 and 18 are current, 10 is a tower of a transmission tower Legs, 15 core, 17 current transformer, 19 current wire to be measured, 21 variable DC power supply, 22 switches, 23 and 24 capacitors, 25 discharge switch, 26 shunt resistor, 27 oscilloscope, Two
8 is a resistor.

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Claims (3)

[Claims] 1. A current sensor, wherein a coil wound around a flat plate-shaped magnetic material core is covered with an insulator. 2. A current sensor for detecting a lightning current, characterized in that a coil wound around a flat plate-shaped magnetic material core is covered with an insulator and is attached in contact with a power transmission tower. 3. The current sensor according to claim 2, wherein the number of turns of the coil is 1 to 100.