JPH11326432A - Earth current detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To quickly determine an electric wire having an earthing portion when an earth accident is generated in a railway station having many platforms or in a base for a rolling stock having many electric lines. SOLUTION: A CT sensor 12 is provided in a feeder 10, an induced voltage is rectified by a rectifying circuit 16, and a resistance switching circuit 52 switched to a small resistance value when an output voltage is under a prescribed value and to a large resistance value when the output is the prescribed value or more is connected between output terminals. A capacitor 22 charged by the output voltage of the rectifying circuit 16 is provided, a thyristor 38 is conducted by a control circuit 54 when a terminal voltage reaches to a prescribed voltage, and a charged voltage of the capacitor 22 is discharged via the thyristor 38 and a coil of a solenoid 36. A display means drops display cloth for display by operation of the solenoid 36. The CT sensor 12 and a detector main body are integrally connectedly fixed. The CT sensor 12 is insertedly fixed into the feeder 10, and the detector main body is suspendedly fixed to the feeder 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for providing a ground fault when a ground fault occurs on any of the feeder lines at a railway station with many stop lines or a railway depot with many railway tracks. The present invention relates to a ground fault current detector for quickly determining an electric wire.

[0002]

2. Description of the Related Art At railway stations with many stop lines and railway depots with many railway tracks, a large number of feeder lines are run in a complicated manner. Must check each feeder wire and go around,
A lot of time and work was required to identify the feeder with a ground fault.

[0003]

SUMMARY OF THE INVENTION There is a need for a technique that can improve the conventional problem that requires a lot of time to specify a feeder line having a ground fault, and that can quickly detect and determine it. However, technology to detect ground faults on live lines such as feeders has
Not yet proposed.

Conventionally, as a technique for detecting and displaying a transmission line tower that has suffered a flashover in response to a lightning strike, for example,
2. Description of the Related Art A flash indicator is disclosed in Japanese Utility Model Laid-Open No. 4-79268. Also, lightning arresters are installed on transmission line towers to prevent insulation breakdown of equipment from lightning surge voltage. The surge arrester discharges the lightning surge current and discharges it to the ground. When the discharge is completed, the AC continuity accompanying the discharge is immediately cut off. However,
If the lightning arrester is out of order, the AC follow-up current will not be cut off immediately. Therefore, in Japanese Utility Model Laid-Open No. 6-53980, this AC
A technique for detecting and displaying a continuation flow has been proposed.

[0005] In either of the flashing indicator and the AC follow-current detector described above, the lightning arrester is provided on the ground line that grounds the lightning arrestor to the ground, and is provided on a live line through which current flows in a normal state. Not something. Therefore, there is a demand for a detector which is provided on a live line such as a feeder line through which current flows in a normal state and does not operate with a normal current but operates only with a ground fault current.

The present invention has been made in view of such circumstances, and provides a ground fault current detector which is provided on a live line and does not operate with a normal current but detects operation only with respect to a ground fault current. The purpose is to do.

[0007]

In order to achieve the above object, a ground fault current detector according to the present invention comprises a CT sensor in which a voltage is induced by a current flowing through a live line, and a voltage induced by the CT sensor. A rectifier circuit connected between the output terminals of the rectifier circuit, a resistance switching circuit that is switched to a small resistance value when the output voltage of the rectification circuit is lower than a predetermined value, and to a large resistance value when the output voltage is equal to or higher than a predetermined value; A capacitor charged with an output voltage of the rectifier circuit, a semiconductor switch,
A control circuit for turning on the semiconductor switch when the terminal voltage of the capacitor reaches a predetermined voltage; a solenoid for supplying the terminal voltage of the capacitor to the coil via the semiconductor switch; and a ground fault current caused by the operation of the solenoid. And a display means for displaying that the detection has been performed.

[0008] Further, members other than the CT sensor are housed in the detector main body, the detector main body and the CT sensor are integrally connected and fixed, and the CT sensor is fitted and fixed to the live wire. The detector main body may be configured to be fixed to the live line in a suspended state.

The display means is arranged so that the bottom plate of the detector body is opened by the operation of the solenoid and the display cloth supported by the bottom plate is dropped, and the display cloth is made of a fluorescent dye or a fluorescent paint or It is also possible to use a cloth coated with a fluorescent pigment or a cloth made of fluorescent fibers.

[0010] Further, the live line may be a feeder line or a feeder jumper line of a stop number line or an electrical terminal line.

Further, the CT sensor induces an output voltage without being saturated by a ground fault current flowing through the hot wire, and does not induce an output voltage by being saturated by a lightning surge current. May be set and configured.

Further, a discharge resistor may be connected in parallel with the capacitor.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a circuit diagram of one embodiment of a ground fault current detector according to the present invention. FIG. 2 is a diagram showing an example of the mechanism of the display means used in the ground fault current detector of the present invention. FIG. 3 is an external view of a state in which the ground fault current detector of the present invention is disposed on a live line, where (a) is a front view,
(B) is a side view. FIG. 4 is a diagram showing an example in which the ground fault current detector of the present invention is disposed on a feeder line.

First, the circuit configuration will be described with reference to FIG. A CT sensor 12 is provided on an electric wire 10 which is a live wire. In the CT sensor 12, an output voltage is induced by an electromagnetic induction phenomenon without being saturated by a ground fault current of about 6000 A at a commercial frequency flowing through the feeder line 10, and is saturated with a lightning surge current to induce an output current. Instead, those that are low in power even if induced are selected. This CT sensor 1
2 between output terminals, surge absorber 1 such as varistor
4 is interposed to limit high voltage output such as surge. The output terminal of the CT sensor 12 is connected to the rectifier circuit 16.
And the voltage limited by the surge absorber 14 is rectified and output.

The positive output terminal of the rectifier circuit 16 is connected to one end of a capacitor 22 through a forward diode 18 and a current limiting resistor 20 in series. Further, the negative output terminal of the rectifier circuit 16 is connected to the other end of the capacitor 22. Then, a discharging resistor 24 is connected in parallel with the capacitor 22. Further, one end of the capacitor 22 is connected to the other end of the capacitor 22 via a forward diode 26 and a capacitor 28 in series. A connection point between the diode 26 and the capacitor 28 is connected to the capacitor 22 via a zener diode 30 and a resistor 32 in series.
Is connected to the other end. Further, a capacitor 34 is connected in parallel with the resistor 32. One end of the capacitor 22 is connected to the other end of the capacitor 22 via a coil of a solenoid 36 and a thyristor 38 as a semiconductor switch in series. The connection point between the Zener diode 30 and the resistor 32 is connected to the gate of the thyristor 38.

Further, the plus output terminal of the rectifier circuit 16
It is connected to the minus output terminal of the rectifier circuit 16 via the resistors 40 and 42 in series. A transistor 44 is connected in parallel with the resistor 40. Further, the plus output terminal of the rectifier circuit 16 is connected to the minus output terminal of the rectifier circuit 16 via the resistor 46 and the transistor 48 in series. The base of the transistor 44 is connected to the connection point between the resistor 46 and the transistor 48, and the base of the transistor 48 is connected via the resistor 50 to the connection point between the resistors 40 and 42.

In such a circuit configuration, when 100 to 400 A, which is a normal current, flows through the feeder line 10, the voltage output from the rectifier circuit 16 is slight, and the potential difference between both ends of the resistor 42 is the turn-on voltage of the transistor 48. For example, the voltage is 0.6 V or less, and the transistor 48 is off. The resistors 40 and 42 are, for example, 3.
It is set to 75 and 0.2 ohms. Therefore, the transistor 44 is in a conductive state, and the output voltage of the rectifier circuit 16 flows through the transistor 44 to the resistor 42 having a small resistance value. Thus, the capacitor 22 is hardly charged. However, when a ground fault occurs in the feeder line 10 and a ground fault current of 3000 to 6000 A flows and the output voltage of the rectifier circuit 16 rapidly rises to a predetermined value or more, the current flowing to the resistor 42 also increases. When the potential difference between both ends becomes higher than the turn-on voltage, the transistor 48
Becomes conductive. Accordingly, the transistor 44 is turned off. Therefore, the output voltage of the rectifier circuit 16 flows through a large resistance value in which the resistors 40 and 42 are connected in series. The resistance 46 is 1 kΩ and the resistance 40
It is set to be extremely large as compared with the values 42 and 42. Thus, the resistors 40, 42, 46, 50 and the transistor 4
4 and 48, a resistance switching circuit 52 is formed in which when the output voltage of the rectifier circuit 16 is lower than a predetermined value, the resistance of the resistor 42 is small, and when the output voltage is higher than the predetermined value, the resistance is switched to a large resistance of the series connection of the resistors 40 and 42. Have been.

As described above, when the output voltage of the rectifier circuit 16 becomes equal to or higher than the predetermined value and the resistance switching circuit 52 is switched to a large resistance value, the output voltage of the rectifier circuit 16 is charged to the capacitor 22. Then, the capacitor 28 is charged by the terminal voltage of the capacitor 22 via the diode 26. When the charging voltage of the capacitor 28 exceeds the Zener voltage of the Zener diode 30, the capacitor 34 is charged, and the charging voltage of the capacitor 34 is
When the turn-on voltage reaches 8, the thyristor 38 becomes conductive. By the conduction state of the thyristor 38, the charging voltage of the capacitor 22 is discharged through the coil of the solenoid 36 and the thyristor 38, and the solenoid 36 is operated. Therefore, when the terminal voltage of the capacitor 22 reaches a predetermined voltage, the thyristor 38 is turned on.
The zener diode 30, the resistor 32, and the capacitor 34 form a control circuit 54 that makes the thyristor 38 conductive.

Even if a lightning surge current flows through the feeder line 10, the rectifier circuit 16 does not generate a large output voltage due to the saturation of the CT sensor 12, and even if it does, the capacitors 22, 28, The thyristor 38 does not conduct due to the charging delay due to the charging time constant of 34. And even if the capacitor 22 is charged due to such a factor, the capacitor 24 is discharged by the resistor 24 connected in parallel, and the state where the capacitor 22 is unnecessarily charged other than at the time of detecting the ground fault current is quickly eliminated. Is done.

Next, with reference to FIG. 2, an example of display means for displaying that a ground fault current has been detected by the operation of the solenoid 36 will be described. In the detector main body 60, a circuit board 62 on which the above-described circuit configuration excluding the CT sensor 12 is mounted, the solenoid 36, and a display cloth 64 are housed.
The display cloth 64 has an upper end fixed in the detector main body 60 and a lower end fixed with a bobbin-shaped weight, and is normally supported by a bottom plate 68 that is opened and closed with a shaft 66 as a swing axis. The closed state of the bottom plate 68 is held by the elastic force of the leaf spring 70 engaging with the concave portion 68a. Then, when a current flows through the coil of the solenoid 36 and the lines of magnetic force of the permanent magnet holding the plunger 36a are canceled, the plunger 36a momentarily protrudes due to the spring pressure and opens the bottom plate 68 against the elasticity of the leaf spring 70, The display cloth 64 falls (indicated by a dashed line in FIG. 2). Here, the display cloth 64 is formed using a red cloth to increase visibility, but a cloth coated with a fluorescent paint or a fluorescent dye or a fluorescent pigment is used. If used, confirmation is easy even at night.

Then, when a ground fault current is detected and the solenoid 36 is operated and the bottom plate 68 is opened, the display cloth 64 falls to display this. After the ground fault is restored, the display cloth 64 is rewound and stored in the detector main body 60, and the bottom plate 68 is closed to be engaged with and held by the leaf spring 70. The detector can be used repeatedly.

Further, the ground fault current detector according to the present invention is shown in FIG.
As shown in the figure, the CT sensor 12 and the CT sensor 12
The detector main body 60 in which other members are stored is integrally connected and fixed. The CT sensor 12 includes a square-shaped ferrite core 12a that can be divided vertically into two parts, and a detection coil 12b wound around the ferrite core 12a. The output end of the detection coil 12b is connected to the detector body 6
It is appropriately connected to a circuit board 62 housed in the housing. Further, the mounting bracket 72 to which the lower half of the ferrite core 12a is fixed is fixed to the detector main body 60. Further, the ferrite upper fixing bracket 74 to which the upper half of the ferrite core 12a is fixed can be separated and fixed to the mounting bracket 72 by bolts and nuts.
It is configured such that the T sensor 12 can be inserted and fixed to the feeder wire 10. Further, the mounting bracket 72 protrudes from the detector main body 60 in the longitudinal direction of the feeder wire 10, and the holding fixtures 78, 78 are connected to the mounting bracket 72 by bolts and nuts via conductive rubber materials 76, 76. It is configured to be separable and fixable so that the feeder wire 10 can be clamped and fixed. Furthermore, the main body fall prevention bracket 84 is fixed to the mounting bracket 72 by being fastened and fixed together with the holding fixtures 78, 78, and the main body fall prevention bracket 84 appropriately surrounds and supports the outer periphery of the detector main body 60. I have.

As described above, since the CT sensor 12 and the detector main body 60 are integrally fixed and both are fixed to the feeder wire 10, their attachment is easy. Then, like a conventional flash indicator or an AC follow-current detector, the CT sensor 12
Apart from this, there is no need to fix the detector main body 60 to a steel tower or the like, and no mounting member is required. In addition, feeder wire 1
Because it is fixed at three points in the longitudinal direction with respect to 0,
The detector main body 60 fixed in the suspended state is firmly fixed to the feeder wire 10 and does not vibrate. If a more rigid fixation is required, the size of the fitting 72 protruding in the longitudinal direction of the feeder wire 10 may be further increased. Further, since the detector main body 60 is supported by the main body drop prevention metal fittings 84 fixed together with the mounting metal fittings 72,
Even if the detector main body 60 is separated from the mounting bracket 72 by vibration or the like, it is possible to prevent the detector main body 60 from dropping and prevent a serious accident caused by the drop. It can be reliably prevented.

A ground fault current detector 90 having such a configuration
For example, as shown in FIG.
0 is provided on the feeder wire 10 near a place where the feeder jumper wire 82 is connected. Here, the feeder jumper wire 82 may be provided. According to the performance test, the ground fault current detector 90 of the present invention
It does not operate continuously at 0 A, and at 1400 A, it has a performance of operating in three cycles. Moreover, it does not operate with a lightning surge current of 40 KA.

In the above embodiment, the thyristor 38 is used as a semiconductor switch. However, the present invention is not limited to this, and another semiconductor switch such as a power transistor may be used. The circuit configurations of the resistance switching circuit 52 and the control circuit 54 are not limited to those described above. A circuit configuration may be employed. Further, the display means is not limited to the one shown in FIG.
What is necessary is just a mechanism which can be observed from the outside. And furthermore,
The ground fault current detector of the present invention is not limited to the feeder line 10 but may be provided to any live line. Here, it goes without saying that the constants of the above circuit configuration are appropriately adjusted according to the normal current and the ground fault current flowing in the live line.

[0026]

As described above, since the ground fault current detector according to the present invention is constituted, the following special effects can be obtained.

In the ground fault current detector according to the first aspect, the capacitor is not charged and does not operate for the normal current of the live wire, and the resistance switching circuit of the resistance switching circuit does not operate for the ground fault current. As a result, the capacitor is charged and operates, so that the live line where the ground fault has occurred can be quickly identified.

Further, in the ground fault current detector according to the second aspect, since the CT sensor and the main body of the detector are integrated and fixed to the live line, the conventional flash display and AC follow-current detection are performed. Unlike a CT device, there is no need to fix the detector main body to a steel tower or the like separately from the CT sensor, and the installation work is easy, and furthermore, it is possible to install the detector at an arbitrary position on a live line.

In the ground fault current detector according to the third aspect, since a fluorescent paint or a fluorescent fiber or the like is used for the display cloth of the display means, it is easy to confirm even at night.

Further, in the ground fault current detector according to the fourth aspect, since the ground fault current detector is disposed on a feeder line or a feeder jumper line, it is used in a railway station having many stop number lines or a railway vehicle base having many railway lines. In the event of a ground fault, it is possible to quickly identify the electric wire that caused the accident.

Further, in the ground fault current detector according to the fifth aspect, the CT sensor is selected not to be saturated by the ground fault current but to be saturated by the lightning surge current, so that the lightning surge current is erroneously detected. Nothing to do.

Further, in the ground fault current detector according to the sixth aspect, when the terminal voltage reaches a predetermined voltage, a resistor is connected in parallel to the capacitor operated by the solenoid, so that the fault is not caused by a lightning surge current or the like. Even if the capacitor is charged as needed, the capacitor is discharged quickly, and the improper state of charge of the capacitor is eliminated, so that the capacitor always maintains the state for the normal current. Accordingly, there is no variation in the detection sensitivity and there is no possibility of malfunction.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of an embodiment of a ground fault current detector according to the present invention.

FIG. 2 is a diagram showing an example of a mechanism of a display means used in the ground fault current detector of the present invention.

3A and 3B are external views of a state in which a ground fault current detector according to the present invention is disposed on a hot wire, wherein FIG. 3A is a front view and FIG. 3B is a side view.

FIG. 4 is a diagram showing an example in which the ground fault current detector of the present invention is disposed on a feeder line.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Feeder wire 12 CT sensor 16 Rectifier circuit 22 Capacitor 24 Resistance 36 Solenoid 38 Thyristor 52 Resistance switching circuit 54 Control circuit 60 Detector main body 64 Display cloth 68 Bottom plate 70 Leaf spring 72 Mounting bracket 74 Ferrite upper fixing bracket 78 Clamping fixing bracket 82 Electric jumper wire 84 Main unit fall prevention fitting 90 Ground fault current detector

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Yasushi Yamaguchi 1-3-4 Meieki Station, Nakamura-ku, Nagoya City, Aichi Prefecture Tokai Railway Company, Tokai Railway Business Headquarters (72) Inventor Shunsaku Koga Nakamura, Nagoya City, Aichi Prefecture 1-3-2 Kuname Station Tokai Railway Company Tokai Railway Business Headquarters (72) Inventor Yuzo Yamamoto 1-8-1, Hisamoto, Takatsu-ku, Kawasaki-shi, Kanagawa Prefecture

Claims (6)

[Claims] 1. A CT sensor in which a voltage is induced by a current flowing through a live line, a rectifier circuit for rectifying a voltage induced by the CT sensor, and a rectifier circuit connected between output terminals of the rectifier circuit. A resistance switching circuit that switches to a small resistance value when the output voltage is lower than a predetermined value, and a large resistance value when the output voltage is higher than the predetermined value; a capacitor charged by the output voltage of the rectifier circuit; a semiconductor switch; and a terminal voltage of the capacitor. When a predetermined voltage is reached, a control circuit that brings the semiconductor switch into a conductive state, a solenoid in which a terminal voltage of the capacitor is applied to the coil via the semiconductor switch, and that a ground fault current is detected by the operation of the solenoid. And a display means for displaying. 2. The ground fault current detector according to claim 1, wherein members other than the CT sensor are housed in a detector main body, and the detector main body and the CT sensor are integrally connected and fixed. A ground fault current detector, wherein a sensor is fitted and fixed to the hot wire and the detector main body is fixed to the hot wire in a suspended state. 3. The ground fault current detector according to claim 1, wherein the display means is configured to open a bottom plate of the detector main body by operation of the solenoid and to drop a display cloth supported by the bottom plate. In addition, a ground fault current detector characterized in that the display cloth is formed using a cloth coated with a fluorescent dye, a fluorescent paint or a fluorescent pigment, or a cloth made of fluorescent fibers. 4. The ground fault current detector according to claim 1, wherein said live line is a feeder line or a feeder jumper line of a stop number or an electric cable. 5. The ground fault current detector according to claim 1, wherein the CT sensor induces an output voltage without being saturated by a ground fault current flowing through the hot wire, and is saturated by a lightning surge current to output the output voltage. A ground-fault current detector characterized in that it is configured so as not to induce the electric current and to set the electric power to be small even when the electric current is induced. 6. The ground fault current detector according to claim 1, wherein a discharge resistor is connected in parallel with said capacitor.