JP4063957B2 - Ground fault current detector - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention can quickly determine feeders having a ground fault location when a ground fault occurs at any feeder at a railway station with many stop numbers or a railway vehicle base with many train lines. The present invention relates to a ground fault current detector.
[0002]
[Prior art]
At railway stations with many bus stops and railway vehicle bases with many train lines, a large number of feeders are installed in a complicated manner. It took a lot of time and work to identify the feeder with ground fault.
[0003]
[Problems to be solved by the invention]
There is a need for a technique that can improve the defect that requires a lot of time to identify a feeder having a conventional ground fault location and can quickly detect and confirm the defect. However, a technique for detecting a ground fault of a live wire such as a feeder has not been proposed yet.
[0004]
Conventionally, as a technique for detecting and displaying a transmission line tower that has suffered a lightning strike due to a lightning strike, for example, a flashing indicator as disclosed in Japanese Utility Model Laid-Open No. 4-79268 is known. The power transmission tower is equipped with a lightning arrester to prevent breakdown of equipment from lightning surge voltage. By this lightning arrester, a lightning surge current is discharged and discharged to the ground, and when this discharge ends, the AC continuity accompanying this is quickly cut off. However, if the lightning arrester is out of order, the AC continuity is not quickly interrupted. Therefore, Japanese Utility Model Laid-Open No. 6-53980 proposes a technique for detecting and displaying this AC continuity.
[0005]
In any of the above-described flashing indicator and AC continuity detector, the lightning arrester is provided on the ground line that is grounded to the ground, and is not provided on the live line through which current flows in a normal state. . Therefore, there is a demand for a detector that is provided on a live wire such as a feeder line in which a current flows in a normal state and does not operate with a normal current but operates only with respect to a ground fault current.
[0006]
The present invention has been made in view of such circumstances, and is to provide a ground fault current detector that is provided on a live line and does not operate with a normal current, and that detects operation only with respect to the ground fault current. Objective.
[0007]
[Means for Solving the Problems]
In order to achieve such an object, a ground fault current detector according to the present invention includes a CT sensor in which a voltage is induced by a current flowing in a live line, a rectifier circuit that rectifies the voltage induced by the CT sensor, and the rectifier. the output voltage of the rectifying circuit is charged with a large switched to the resistance value and the resistance switching circuit, the output voltage of the rectifier circuit with a low when a small resistance value becomes a predetermined value or more than a predetermined value connected between the circuit output terminal A capacitor, a semiconductor switch, a control circuit for bringing the semiconductor switch into a conductive state when a terminal voltage of the capacitor reaches a predetermined voltage, a solenoid to which the terminal voltage of the capacitor is applied to the coil via the semiconductor switch, display means for displaying the detection of the ground-fault current by the operation of the solenoid, it comprises a, the resistance switching circuit, plus the rectifier circuit A resistor having a large resistance value and a resistor having a small resistance value are sequentially connected in series between the force terminal and the negative output terminal, a first transistor is connected in parallel to the resistor having a large resistance value, and the positive output terminal is connected to another resistor. A resistor and a second transistor are sequentially connected in series to the negative output terminal, a base of the first transistor is connected to a connection point of the other resistor and the second transistor, and the second transistor If the base of the transistor is further connected to a connection point between the resistor having a large resistance value and the resistor having a small resistance value via another resistor, and the output voltage of the rectifier circuit is lower than the predetermined value, the second transistor as but said a cut-off state the first transistor is rendered conductive, said second transistor is rendered conductive first transistor are cut off at the predetermined value or more It has been made.
[0008]
Further, a member other than the CT sensor is 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 line, and the detector main body. May be fixed to the live wire in a suspended state.
[0009]
Then, the display means opens the bottom plate of the detector main body by the operation of the solenoid so as to drop the display cloth supported by the bottom plate, and the display cloth is coated with fluorescent dye, fluorescent paint or fluorescent pigment. It can also comprise using the cloth which apply | coated or the cloth which consists of fluorescent fiber.
[0010]
Furthermore, the live line may be a stop line or a feeder line or a feeder jumper line.
[0011]
In addition, the CT sensor induces an output voltage without being saturated with a ground fault current flowing through the live wire, and does not induce an output voltage with being saturated with a lightning surge current. It may be set to be configured.
[0012]
Further, a discharging resistor can be connected in parallel with the capacitor.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a circuit diagram of an embodiment of the ground fault current detector of 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. 3A and 3B are external views of the ground fault current detector of the present invention disposed on a live wire, where FIG. 3A is a front view and FIG. 3B is a side view. FIG. 4 is a view showing an example in which the ground fault current detector of the present invention is arranged on the feeder.
[0014]
First, the circuit configuration will be described with reference to FIG. A CT sensor 12 is disposed on a feeder 10 that is a live wire. The CT sensor 12 is not saturated with a ground fault current of about 6000 A at the commercial frequency flowing through the feeder 10, and an output voltage is induced by an electromagnetic induction phenomenon, and an output current is induced by saturation with respect to a lightning surge current. Rather, it is selected that has low power even when induced. A surge absorber 14 such as a varistor is interposed between the output terminals of the CT sensor 12 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.
[0015]
The positive output terminal of the rectifier circuit 16 is connected to one end of a capacitor 22 via a forward diode 18 and a current limiting resistor 20 in series. Further, the negative output end of the rectifier circuit 16 is connected to the other end of the capacitor 22. A discharging resistor 24 is connected in parallel with the capacitor 22. Furthermore, one end of the capacitor 22 is connected to the other end of the capacitor 22 through 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 other end of the capacitor 22 through a Zener diode 30 and a resistor 32 in series. 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 through a coil of the solenoid 36 and a thyristor 38 as a semiconductor switch in series. A connection point between the Zener diode 30 and the resistor 32 is connected to the gate of the thyristor 38.
[0016]
Further, the positive output terminal of the rectifier circuit 16 is sequentially connected to the negative output terminal of the rectifier circuit 16 via a resistor 40 having a large resistance value and a resistor 42 having a small resistance value in series. A first transistor 44 is connected in parallel with the resistor 40. The positive output terminal of the rectifier circuit 16 is connected to the negative output terminal of the rectifier circuit 16 through another resistor 46 and the second transistor 48 sequentially 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 to the connection point between the resistors 40 and 42 via another resistor 50.
[0017]
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 very small, and the potential difference across the resistor 42 is the turn-on voltage of the transistor 48. The voltage is 6 V or less, and the transistor 48 is in a cut-off state. The resistors 40 and 42 are set to 3.75 and 0.2 ohms as an example. 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. Therefore, the capacitor 22 is hardly charged. However, when a ground fault occurs in the feeder 10, the ground fault current of 3000 to 6000A flows, and when the output voltage of the rectifier circuit 16 suddenly rises above a predetermined value, the current flowing through the resistor 42 also increases. The potential difference between both ends becomes equal to or higher than the turn-on voltage, and the transistor 48 becomes conductive. As a result, the transistor 44 is turned off. Therefore, the output voltage of the rectifier circuit 16 flows to a large resistance value in which the resistors 40 and 42 are connected in series. Note that the resistor 46 is set to be extremely large compared to the resistors 40 and 42, which is 1 kilohm. As described above, the resistors 40, 42, 46, and 50 and the transistors 44 and 48 have a small resistance value when the output voltage of the rectifier circuit 16 is lower than a predetermined value, and the resistors 40 and 42 are connected in series when the output voltage is higher than the predetermined value. A resistance switching circuit 52 that can be switched to a large resistance value is formed.
[0018]
In this way, when the output voltage of the rectifier circuit 16 becomes equal to or higher than a 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 in the capacitor 22. Then, the capacitor 28 is charged via the diode 26 with the terminal voltage of the capacitor 22. When the charging voltage of the capacitor 28 exceeds the Zener voltage of the Zener diode 30, the capacitor 34 is charged. When the charging voltage of the capacitor 34 reaches the turn-on voltage of the thyristor 38, the thyristor 38 becomes conductive. Due to 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.
[0019]
Even if a lightning surge current flows through the feeder 10, the rectifier circuit 16 does not generate a large output voltage due to saturation of the CT sensor 12, and even if it occurs, the capacitors 22, 28, and 34 are charged with respect to the instantaneous lightning surge current. The thyristor 38 is not conducted due to the charging delay due to the time constant. Even if the capacitor 22 is charged due to such factors, the resistor 24 connected in parallel is discharged, and the state in which the capacitor 22 is unnecessarily charged is quickly eliminated except when the ground fault current is detected. Is done.
[0020]
Next, an example of display means for displaying that the ground fault current has been detected by the operation of the solenoid 36 will be described with reference to FIG. In the detector main body 60, the circuit board 62 on which the above-described circuit configuration excluding the CT sensor 12 is mounted, the solenoid 36, and the display cloth 64 are housed. The display cloth 64 has an upper end fixed in the detector main body 60 and a bobbin-shaped weight fixed to the lower end, and is normally supported by a bottom plate 68 that is opened and closed with a shaft 66 as a swing shaft. The bottom plate 68 is held in a closed state by the elasticity of the leaf spring 70 that engages with the recess 68a. Therefore, 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 the bottom plate 68 is opened against the elasticity of the leaf spring 70, The display cloth 64 falls (indicated by a one-dot chain line in FIG. 2). Here, the display cloth 64 is configured using a red cloth so as to have high visibility, but a cloth coated with a fluorescent paint, a fluorescent dye, or a fluorescent pigment is used, and a cloth made of fluorescent fibers is used. If used, confirmation is easy even at night.
[0021]
Therefore, when the ground fault current is detected and the solenoid 36 is operated and the bottom plate 68 is opened, the display cloth 64 is dropped and displayed. Then, after the ground fault is restored, the display cloth 64 is rewound again and accommodated in the detector body 60, and the bottom plate 68 is closed and engaged with the leaf spring 70 to thereby hold the ground fault current of the present invention. The detector can be used repeatedly.
[0022]
Furthermore, in the ground fault current detector of the present invention, as shown in FIG. 3, the CT sensor 12 and the detector body 60 in which members other than the CT sensor 12 are housed are integrally connected and fixed. The CT sensor 12 includes a rectangular ferrite core 12a that can be divided into two vertically and a detection coil 12b wound around the ferrite core 12a. The output end of the detection coil 12b is appropriately connected to a circuit board 62 housed in the detector body 60. Further, the mounting bracket 72 to which the lower half of the ferrite core 12a is fixed is fixed to the detector body 60. Further, the ferrite upper fixing bracket 74 with the upper half of the ferrite core 12a fixed can be separated and fixed to the mounting bracket 72 by bolts and nuts, and the feeder 10 is held between the CT sensor 12 and the feeder 10. It is configured so that it can be inserted and fixed. Further, the mounting bracket 72 protrudes from the detector body 60 in the longitudinal direction of the feeder 10, and the clamping fixtures 78 and 78 are attached to the mounting bracket 72 by bolts and nuts via the conductive rubber materials 76 and 76. The feeder 10 is configured to be separable and fixed so that the feeder 10 can be clamped and fixed. Further, the main body drop prevention fitting 84 is fixed to the mounting fitting 72 by being fastened together with the clamping fixtures 78 and 78, and the main body drop prevention fitting 84 appropriately surrounds and supports the outer periphery of the detector main body 60. Yes.
[0023]
Thus, since the CT sensor 12 and the detector main body 60 are fixed integrally and fixed together to the feeder 10, the attachment thereof is easy. And unlike the conventional flash indicator and AC continuous current detector, it is not necessary to fix the detector main body 60 to a steel tower or the like separately from the CT sensor 12, and the attachment member is not required. Moreover, since it is fixed to the feeder 10 at three points in the longitudinal direction, the detector body 60 fixed in a suspended state may be firmly fixed to the feeder 10 and vibrate. Absent. If further robust fixing is required, the dimension of the mounting bracket 72 protruding in the longitudinal direction of the feeder wire 10 may be further increased. In addition, since the detector main body 60 is supported by the main body drop prevention metal fitting 84 that is fastened and fixed to the attachment metal fitting 72, the detector main body 60 may be separated from the attachment metal fitting 72 by vibration or the like. However, it is possible to prevent the detector main body 60 from falling, and it is possible to reliably prevent the occurrence of a serious accident associated with the dropping.
[0024]
For example, as shown in FIG. 4, the ground fault current detector 90 having such a configuration is disposed on the feeder 10 near the place where the feeder 10 is connected by the feeder jumper wire 82 via the disconnector 80. . Here, the feeder jumper wire 82 may be disposed. According to the performance test, the ground fault current detector 90 of the present invention does not operate continuously at a commercial frequency of 1000 A, and at 1400 A, the performance of operating in 3 cycles is obtained. Moreover, it does not operate with a lightning surge current of 40 KA.
[0025]
In the above embodiment, the thyristor 38 is used as the semiconductor switch, but the present invention is not limited to this, and another semiconductor switch such as a power transistor may be used. Further, control circuit configuration of the control circuit 54 is not limited to those described above, as long as it has an equivalent function in light of the above embodiment and its purpose, any circuit configuration employed in accordance with such a structure of the semiconductor switch May be. Furthermore, the display means is not limited to the one shown in FIG. 2, and any mechanism that can observe the operation of the solenoid 36 from the outside may be used. Furthermore, the ground fault current detector of the present invention is not limited to the feeder 10, and may be disposed on any live wire. Here, as a matter of course, the constants of the circuit configuration are appropriately adjusted according to the normal current and the ground fault current flowing through the live wire.
[0026]
【The invention's effect】
As described above, since the ground fault current detector of the present invention is configured, the following special effects can be obtained.
[0027]
In the ground fault current detector according to claim 1 , the resistance switching circuit has a small resistance value for a normal current of a live wire, and the capacitor is not charged and does not operate. Thus , when the output voltage of the rectifier circuit exceeds a predetermined value, the conduction state and the cutoff state of the first and second transistors of the resistance switching circuit are switched , and the resistance switching circuit is immediately switched to a large resistance value. Since the capacitor is rapidly charged by the output voltage of the capacitor and the control circuit operates quickly and reliably by the high voltage of the capacitor, it is possible to quickly identify the live line in which the ground fault has occurred. Moreover, the configuration of the resistance switching circuit is relatively simple.
[0028]
Further, in the ground fault current detector according to claim 2, since the CT sensor and the detector main body are integrated and fixed to the live line, like a conventional flash indicator or AC continuity detector. In addition, it is not necessary to fix the detector main body to a steel tower or the like separately from the CT sensor, the arrangement work is easy, and it is possible to arrange the detector body at an arbitrary place on the live wire.
[0029]
In the ground fault current detector according to claim 3, since the fluorescent cloth or the fluorescent fiber is used for the display cloth of the display means, the confirmation is easy even at night.
[0030]
Further, in the ground fault current detector according to claim 4, since the ground fault current detector is disposed on the feeder line or feeder jumper line, a ground fault accident at a railway station with many stop numbers or a railway vehicle base with many train lines On the other hand, it is possible to quickly identify the wire that caused the accident.
[0031]
In the ground fault current detector according to claim 5, since the CT sensor is selected not to be saturated with the ground fault current but to be saturated with the lightning surge current, the lightning surge current is erroneously detected. There is nothing.
[0032]
Furthermore, in the ground fault current detector according to claim 6, since the resistor is connected in parallel to the capacitor that operates the solenoid when the terminal voltage reaches a predetermined voltage, the capacitor is unnecessarily caused by lightning surge current or the like. Even if the capacitor is charged, the capacitor is quickly discharged and the inappropriate charging state of the capacitor is eliminated, so that the capacitor is always maintained in a state with respect to the normal current. Therefore, the detection sensitivity does not vary 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 display means used in the ground fault current detector of the present invention.
FIGS. 3A and 3B are external views showing a state in which the ground fault current detector of the present invention is disposed on a live line, wherein FIG. 3A is a front view and FIG. 3B is a side view.
FIG. 4 is a view showing an example in which the ground fault current detector of the present invention is arranged on a feeder.
[Explanation of symbols]
10 feeder 12 CT sensor 16 rectifier circuit 22 capacitor 24 resistor 36 solenoid 38 thyristor
40, 42, 46, 50 resistance
44, 48 transistor 52 Resistance switching circuit 54 Control circuit 60 Detector body 64 Display cloth 68 Bottom plate 70 Leaf spring 72 Mounting bracket 74 Ferrite upper fixing bracket 78 Nipping fixing bracket 82 Feed jumper wire 84 Body fall prevention bracket 90 Ground fault current detection vessel

Claims (6)

A CT sensor in which a voltage is induced by a current flowing through a live line, a rectifier circuit that rectifies the voltage induced by the CT sensor, and an output voltage of the rectifier circuit connected between output terminals of the rectifier circuit and lower the smaller the resistance value is changed next to a large resistance value at a predetermined value or more resistance switching circuit, a capacitor is charged by the output voltage of the rectifier circuit, and semiconductor switches, the terminal voltage of the capacitor reaches a predetermined voltage A control circuit for bringing 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 display means for displaying that a ground fault current is detected by the operation of the solenoid; the provided, the resistance switching circuit, the large resistance and the resistance value of the resistance value between the positive output terminal and negative output terminal of said rectifier circuit A series resistor is sequentially connected in series, a first transistor is connected in parallel with the resistor having a large resistance value, and the negative output is sequentially connected to the plus output terminal through another resistor and a second transistor in series. The base of the first transistor is connected to the connection point of the other resistor and the second transistor, and the base of the second transistor is further connected to the connection point of the second transistor via another resistor. When the output voltage of the rectifier circuit is lower than the predetermined value by connecting to a connection point between a resistor and a resistor having a small resistance value, the second transistor is turned off and the first transistor is turned on, A ground fault current detector configured so that the second transistor becomes conductive when the predetermined value or more is reached, and the first transistor becomes cut-off . 2. The ground fault current detector according to claim 1, wherein a member other than the CT sensor is housed in the detector main body, the detector main body and the CT sensor are integrally connected and fixed, and the CT sensor is connected to the hot wire. A ground fault current detector, wherein the detector main body is fixed to the live wire in a suspended state while being fitted and fixed to the ground. 2. The ground fault current detector according to claim 1, wherein the display means opens the bottom plate of the detector main body by the operation of the solenoid and drops the display cloth supported by the bottom plate, and the display cloth. A ground fault current detector comprising: a cloth coated with a fluorescent dye, a fluorescent paint or a fluorescent pigment, or a cloth made of fluorescent fibers. 2. The ground fault current detector according to claim 1, wherein the live line is a stop line or a feeder line or a feeder jumper line. 2. The ground fault current detector according to claim 1, wherein the CT sensor induces an output voltage without being saturated with a ground fault current flowing through the live wire, is saturated with a lightning surge current, and does not induce an output voltage, A ground-fault current detector, which is configured to be low power even when induced. 2. The ground fault current detector according to claim 1, wherein a discharge resistor is connected in parallel with the capacitor.

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