JPH0738000B2 - Hot wire current measuring device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention is applicable to high voltage such as on a transmission tower.
The present invention relates to a live-line current measuring device that measures a current flowing through a conductor such as a transmission line.

[Conventional technology]

Generally, what is called a clamp tester is used to easily measure the current of a conductor. In addition, there is a clamp tester that is used by attaching it to the tip of an insulating rod in order to measure the current of a conductor at a high place. Has been done.

[Problems to be Solved by the Invention]

The conventional clamp tester cannot measure current under high voltage, and the operation of the opening / closing mechanism of the clamp part is complicated. Further, conventionally, the current of the transmission line can be confirmed at the substation, but in the case of multiconductors, only the total current can be confirmed. As described above, conventionally, there has been no measuring instrument capable of safely and easily measuring a current flowing through a conductor under high voltage in real time and at any place such as on a transmission tower.

It is an object of the present invention to provide a live-line current measuring instrument that can safely measure the current of a single conductor at a high place or any other place under a high voltage by a simple operation. is there.

[Means for Solving the Problems]

The live-current measuring device according to the present invention is provided with a conductor guide means for opening and closing the clamp core by simply pressing the annular clamp core against the conductor, and a switch interlocking with the opening and closing operation of the clamp core. Is provided, the current of the conductor clamped in the clamp core is measured in a predetermined time according to the operation of the switch, and the measured current value is held.

[Action]

In the live-current measuring device according to the present invention, the conductor is clamped by the conductor guide means to the clamp core by a simple operation, and the current is automatically measured at a predetermined time,
The current value is held.

〔Example〕

 An embodiment according to the present invention will be described below with reference to the drawings.

FIG. 1 shows an opening / closing mechanism of the clamp core 1. The clamp core 1 is formed in an annular shape by two core members 1a and 1b. One end of each of the core members 1a and 1b is rotatably connected to one end of a connecting rod 4 by a common shaft 3. A compression spring 7 is interposed between the flange portion 5 provided on the connecting rod 4 and the fixing member 6. The connecting rod 4 penetrates the fixing member 6, and its end face is in contact with the switch 8. Conductor guide means 9a, 9b are provided at the tips of the core members 1a, 1b. As the conductor guide means 9a, 9b, in this embodiment, semicircular guide members 9a, 9b are used.
Further, 10a indicated by an imaginary line shows a conductor to be measured before being clamped, and 10b shows the conductor clamped to the clamp core 1. The clamp core 1 is provided with a detection coil described later, but the illustration is omitted here.

In the above configuration, when the guide members 9a and 9b are pressed against the side surface of the conductor 10a as shown in the drawing, when the clamp core 1 is pressed against the compression spring 7 in the direction of the arrow, the dotted line in the figure As shown, the guide members 9a and 9b are rotated together with the core members 1a and 1b with the shaft 3 as a fulcrum, and the clamp core 1 is opened. When the clamp core 1 is still pressed, the conductor 10a is taken inside the clamp core 1. At this time, the core members 1a, 1
b is returned by the bias of the compression spring 7, and the clamp core 1
Closes again and conductor 10b is clamped. With the opening and closing of the clamp core 1, when the connecting rod 4 first moves in the direction of arrow a and leaves the switch 8, the switch 8 is turned on, and when the clamp core 1 is closed next, the switch 8 is pushed again. Turns off. If the clamp core 1 is pulled from the clamped state in the direction opposite to the arrow a, the guide members 9a, 9a
b is opened and the conductor 10b is released from the clamp.

FIG. 2 and FIG. 3 show the appearance of a live-line current measuring instrument provided with the above-mentioned clamp core 1 and its opening / closing mechanism.

In FIG. 2 and FIG. 3, the clamp core 1 and its opening / closing mechanism, and a current measuring and display circuit described later are provided in a case 11 shielded by an aluminum plate or the like. The case 11 is provided with a display portion 12 having a display lid 12a, a battery lid 13 and the like, and a power switch and the like (not shown) as appropriate. The case 11 is attached to the tip of an insulating pipe 14 which is made expandable and contractible. This insulating pipe 14 is adjusted by adjusting the adjusting screw parts 15 and 16.
Its length can be adjusted freely. A grip portion 17 is provided at the rear of the insulating pipe 14. The total length from the rear end of the grip portion 17 to the tips of the guide members 9a and 9b can be adjusted to, for example, about 3.16 to 1.7 m by adjusting the length of the insulating pipe 14.

According to the above configuration, after adjusting the insulating pipe 14 to an appropriate length, by holding the grip portion 17 by hand, and pressing the guide portion 9a, 9b against the conductor to be measured by pressing the insulating pipe 14 The conductor can be clamped to the clamp core 1 as described above. The clamp can be easily released by pulling the insulating pipe 14 toward you.

Next, an embodiment of the electric circuit will be described with reference to FIG.

In FIG. 4, an inner shield 18 made of copper foil or the like is provided inside the case 11, and a current measuring / display circuit 19 and a control circuit 20 are provided inside the inner shield 18. A detection coil 21 is wound around the clamp core 1. The current flowing through the detection coil 21 is measured by the current measurement and display circuit 19, and the measured value is held by the current value holding circuit 22, It is configured to be displayed on the display unit 12.

In the control circuit 20, the input level of the inverter 23 applied via the resistor R ₁ is changed by turning on / off the switch 8. The capacitor C ₁ is provided to smooth noise caused by chattering of the switch 8. The inverter 23 also has a Schmitt circuit configuration as a noise countermeasure. In the mono-multi 24, the time constant of the resistor R ₂ and the capacitor C ₂ is selected to be, for example, 6 seconds, and the transistor Tr ₁ is controlled by the output of Q ₁ thereof, and the mono-multi 25 falls at that time.
Are triggered and the oscillator 26 is operated. In the monomulti 25, the time constant of the resistor R ₃ and the capacitor C ₃ is selected to be, for example, 15 seconds, and the transistor Tr ₂ is controlled by the output Q ₂ thereof. The oscillator 26 is configured as a multivibrator by NAND gates 27 and 28, a capacitor C ₄ , resistors R ₄ and R _{5, and the} like, and outputs an output pulse of, for example, 3 KHz to a transistor Tr ₃
I am trying to add it to.

The transistor Tr ₁ is connected in series with the transistor Tr _2, and a relay 29 having a relay switch 29a is connected to its collector. The relay 29 controls the current measuring and displaying circuit 19. The speaker 30 to the collector of the transistor Tr ₃ is is connected. The battery 31 is configured to supply the + B power supply voltage to a predetermined circuit through the power switch 32.

Next, the operation of the above configuration will be described with reference to FIG.

In the state where the clamp core 1 does not clamp the conductor to be measured, the switch 8 is off, so that the input of the inverter 23 is "H" (high level) and the output is "L".
(Low level). Also at this time Mono Multi 25
Q ₂ output is “H”, and the transistor Tr ₂ is on. In this state, the above-described clamping operation of the clamp core 1 is performed, and when the clamp core 1 is opened and closed to clamp the conductor 10b, after the switch 8 is once turned on,
Turns off. When the switch 8 is turned on, the inverter
The input of 23 becomes "L" and the output rises to "H". This rise triggers the monomulti 24, and its Q ₁ output becomes “H” for 6 seconds. This turns on the transistor Tr _{1 and} drives the oscillator 26.

When the transistor Tr ₁ is turned on, the relay 29 is energized and the relay switch 29a is turned on, whereby the current measurement and display circuit 19 is operated and the current flowing through the detection coil 21 is measured for 6 seconds. A current corresponding to the current flowing through the conductor 10b is induced in the detection coil 21 via the clamp core 1. On the other hand, the oscillator 26
The transistor Tr ₃ is controlled by the oscillation output pulse of and the speaker 30 is driven.
3KHz signal sound is emitted.

When the current measurement is performed for 6 seconds, the Q ₁ output falls to “L”, the transistor Tr ₁ is turned off, the oscillator 26 stops oscillating, and the monomulti 25 is triggered. Therefore, the relay switch 29a is turned off and the sound emission of the speaker 30 is stopped. As a result, the current measurement and display circuit 19 stops the measurement, and the measured current value is held by the current hold circuit 22. The display unit 12 displays the held current value as the current of the conductor 10b.

Also, the mono-multi circuit 25 makes the Q ₂ output "L" for 15 seconds after being triggered. As a result, the held current value is not released for the above 15 seconds. Therefore, when the conductor 10b to be measured is removed from the clamp core 1, the switch 8 turns on. However, if the switch 8 turns on within 9 seconds after the mono-multi circuit 25 is triggered, the held current value is Holds and does not change until the switch 8 is turned on again, and does not affect the current value displayed on the display unit 12. If the switch 8 is turned on for more than 9 seconds after the mono-multi circuit 25 is triggered,
After 15 seconds, the relay 29 is turned on again to release the hold, clear the current value shown on the display unit 12, and emit a sound to inform that the hold has been released.

FIG. 6 is a block diagram conceptually showing the circuit of FIG.

In FIG. 6, the switch 8 is operated in conjunction with the opening / closing operation of the clamp core 1, whereby the control circuit 20 operates the current measurement / display circuit 19 and the oscillation circuit 26. As a result, the current is measured for 6 seconds, and the alarm sound is emitted from the speaker 30 during this time. When the measurement for 6 seconds is completed, the speaker 30 stops emitting sound and the current measurement and display circuit
The current value measured by 19 is displayed. Therefore, the conductor
You can read the displayed current value after unclamping 10b.

〔The invention's effect〕

According to the present invention, the clamp core is provided with the conductor guide means such as the guide members 9a and 9b, and the current value is automatically held.Therefore, the conductor is clamped without remote control by hand. It can be performed by a simple operation of simply pressing the clamp core onto the conductor. Further, by attaching the clamp core to the tip of the insulating pipe or the like as in the embodiment, it is possible to perform the measurement work safely and easily under a high voltage in any place such as on the transmission tower.

[Brief description of drawings]

FIG. 1 is a side view showing an opening / closing mechanism of a clamp core in a live-current measuring device according to an embodiment of the present invention, FIG. 2 is a side view showing an appearance of the measuring device, and FIG. 4 is a plan view showing the external appearance of the unit, FIG. 4 is a circuit diagram showing an embodiment of an electric circuit, FIG. 5 is a timing chart showing the operation of the electric circuit, and FIG. 6 is a block diagram conceptually showing the electric circuit. is there. Reference numeral 1 is a clamp core, 8 is a switch, 9a and 9b are guide members, 19 is a current measurement and display circuit, 20 is a control circuit, 21 is a detection coil, and 22 is a current value hold circuit. In the drawings, the same reference numerals indicate the same or the same parts.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-56-51672 (JP, A) SAIKAI Sho 60-154871 (JP, U) SUNKO 51-33950 (JP, Y1) SUNKO 15- 10881 (JP, Y1)

Claims (1)

[Claims] 1. A clamp core having an annular shape, a part of which is openable and closable, a detection coil provided on the clamp core, and a conductor to be measured provided on an open / close portion of the clamp core. The conductor guide means for opening the clamp core to take in the conductor to be measured into the clamp core, the switch controlled in conjunction with the opening / closing operation of the clamp core, and the conductor to be measured are The current measuring circuit for measuring the current flowing through the conductor to be measured in the state inside the clamp core through the clamp core and the detection coil, and the operation of the current measuring circuit according to the operation of the switch are predetermined. A live line current measuring instrument comprising a control circuit for controlling the time and a current value holding circuit for holding the current value measured at the predetermined time.