JP2548959Y2 - Surge protection device - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surge protection device, and more specifically, to prevent a reverse flash from occurring from a ground side to various communication devices and control devices due to a rise in ground potential caused by a lightning surge current. Related to security equipment.

[0002]

2. Description of the Related Art In recent years, due to the congestion of information transmission paths, the power system strong electric ground and the ground of weak electric equipment such as communication equipment and control equipment have been increasing in many cases. If the strong ground and the weak ground are close to each other, the ground potential rises due to lightning surge current flowing into the ground due to direct lightning or induced lightning, etc., and the ground potential rises from the weak ground to the substation. Reverse flashover occurs on the communication cable and control cable side of the system. For this reason, there is a possibility that these cables, communication devices, control devices, and the like may be destroyed, or a danger may be given to an operator or an operator.

On the other hand, in a communication cable, a security device for preventing a flashback is installed at an entrance of a substation or the like in order to protect the communication cable and communication equipment from abnormal voltage caused by a rise in ground potential due to a commercial ground fault. ing. FIGS. 2 to 4 are circuit diagrams of this kind of security device.
L ₁ and L ₂ are input terminals (line side terminals), T ₁ and T ₂ are output terminals (in-house equipment side terminals), and A _{1 to} A ₄ absorb abnormal voltages invading from the input terminals L ₁ and L _2. arrester, NT neutralization transformer, IT insulating transformer, E _f is distant ground terminal, E _n is house ground terminal, F is the terminal L _1, T ₁ and between L ₂ for,
Shows T ₂ between the inserted fuse, respectively.

[0004] According to the configuration of FIG. 2 and FIG. 4, when the ground potential rises by clear distinction ground fault or the like of the transmission line, the abnormal voltage inversely flashover from house ground terminal E _n is the arrester A ₁ to A ₄ Discharge. The discharge starting voltage of the surge arrester A ₁ to A ₄ are virtually equal, then it is discharged substantially simultaneously. The abnormal voltage surge current due to the surge arrester A _3, neutralizing coils NT, path arrester A _1, and, arrester A _4, neutralizing coils NT, to ground via a distant ground terminal E _f through path arrester A ₂ Flows. At this time, house a ground terminal E _n, both the output terminals T _1, T ₂ becomes the same potential, between _{E n -T 1, E n -T} 2
Since there is no potential difference between the output terminals T ₁ ,
It can be protected communication cable of the communication equipment and plant connected to the T _2. Also, due to variations in characteristics, but if arrester A _3, when the arrester when A ₁ is discharger A _4, A ₂ is not discharged in a potential difference is generated between E _n -T _2,
The discharge starting voltage of the lightning arrester is several hundred volts, and the discharge starts in a few ms after a voltage higher than the discharge starting voltage is applied, while the communication device such as a communication device connected to the output terminals T ₁ and T ₂ . breakdown voltage because the withstand about 1 minute a 1 to 2 kV, never causing damage to the communication device or the like by the potential difference between E _n -T ₂ up surge arrester a _4, a ₂ is discharged. Further, for example, in FIG. 2, if both windings of the neutralizing transformer NT are wound around the same iron core with the same number of turns, the lightning arresters A ₃ and A ₁
Both ends of the discharge when a surge current flows to ground through the winding and far ground terminal E _f between the terminals T _1, L ₁ from house ground terminal E _n, the windings between the terminals T _2, L ₂ substantially the same voltage as the voltage across the winding between the terminals T _1, L ₁ is generated, since the voltage of the terminal T _1, T _2, E _n are substantially equal to each other, damage the communication equipment or the like Absent. further,
According to the configuration of FIG. 3, it is possible to protect the voltage value by the ground potential rise by the insulating transformer IT withstand voltage between the terminals _{L 1, L 2, T 1} , T 2.

[0005]

With respect to the absorption of the abnormal voltage, the abnormal voltage of the commercial frequency can effectively protect the communication device and the like from the reverse flash by the above-mentioned conventional circuit configuration. However, for an abnormal voltage accompanied by a high-frequency transient phenomenon such as a lightning surge, electric vibration and waveform deformation occur, and as a result, between the output side and the ground (terminal T ₁ ,
T between ₂ -E _n) and interline (terminal T ₁ -T ₂ between) a large voltage is generated. For this reason, an excessive voltage is applied to the communication equipment and control equipment connected to the output terminals T ₁ and T ₂ , which are destroyed, or the insulation between the core wires of the multi-pair cable as the communication cable is broken. And other problems. Further, in the circuit configuration shown in FIG. 4, when the fuse F is blown by the lightning surge current, the line is cut off, and there is a disadvantage that it takes much time to repair the line.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to use a communication cable or a communication cable based on an abnormal voltage generated between the communication line and ground and between the communication lines due to a lightning surge. An object of the present invention is to provide a surge protection device that reliably protects devices and the like.

[0007]

SUMMARY OF THE INVENTION To achieve the above object, the present invention provides a method for connecting a pair of input terminals on a communication line side, a pair of output terminals on a local equipment side, and the input terminal and the output terminal. A neutralizing transformer to be connected, a remote ground terminal on the communication line side, a local ground terminal on the local equipment side, and a surge protector including a lightning arrester connected between the input terminal and the remote ground terminal. A pair of signal windings connected between the input terminal and the output terminal,
A shield winding connected between the remote ground terminal and the in-house ground terminal is provided, and the signal winding and the shield winding are wound around the same iron core, and the number of turns of each winding is made equal.

[0008]

According to the present invention, when the potential of the ground terminal in the office rises due to a lightning surge, a shield winding connected between the ground terminal in the office and the far ground terminal, and a pair of signals coupled to the shield winding are provided. Since the number of turns with the winding is the same, the potentials of the output terminal and the in-house ground terminal, which are the in-house equipment terminals, are all equal, and the voltage between the output terminal and the ground and the voltage between the output terminals are all substantially zero. . In addition, if the signal winding and the shield winding are arranged on the same line with respect to the same iron core, the stray capacitance can be suppressed, and an abnormal voltage accompanying electric vibration and waveform fluctuation does not occur at the output terminal. For this reason, there is no fear that an excessive voltage is applied to the communication cable, the communication device, and the like connected to the output terminal, and there is no risk of causing harm to the workers and the like.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a circuit diagram of the security device according to the present invention,
As described above, L ₁ and L ₂ are input terminals (line side terminals), T ₁ ,
T ₂ are output terminals (house equipment side terminal), E _f is distant ground terminal, E _n is the house ground terminal, surge arrester A ₁ between the input terminal L _1, L ₂ and far ground terminal E _f, A ₂ are connected respectively. A varistor _Var is connected between the output terminals T ₁ and T ₂ . Here, since the voltage between the output terminals T ₁ and T ₂ is basically 0 as described later, the varistor _Var is not indispensable for the present invention.

[0010] In the present embodiment, neutralization transformer NT is, the signal winding N ₁ which is connected between terminals L _1, T _1, the terminal L _2, T ₂
A signal winding N ₂ connected between, is composed of a shielding winding N ₀ Metropolitan connected between distant ground terminal E _f and house a ground terminal E _n, each winding N _1, N _2, N ₀ Is a single layer wound around the same iron core, and the winding ratio is 1: 1: 1. The signal windings N ₁ and N ₂ are connected to terminals L ₁ , T ₁ and L ₂ ,
They are respectively connected to the communication cable of the line side and the plant (not shown) via the T _2.

The operation of this embodiment will be described below. First, when an abnormal voltage enters the line-side communication cable due to a lightning surge, the lightning arrester A ₁ connected to the input terminals L ₁ and L ₂ ,
A ₂ is operated, surge current to the earth through a distant ground terminal E _f. On the other hand, it increases the ground potential of the plant by a lightning surge current, when the potential of the plant ground terminal E _n increases, neutralized trans abnormal voltage by the breakdown voltage of the NT input terminals L _1,
Acting from the L ₂ side so as not to reverse flashover to the communication cable side of the house, house communication cables and communications equipment, the application of an abnormal voltage to the control device or the like to prevent. Also, since the number of turns of the shield winding N ₀ and the number of turns of the signal windings N ₁ and N ₂ wound on the same iron core are all equal, the voltages at both ends of each winding are equal, in other words, the output terminals T ₁ , T ₂ and voltage-plant ground terminal E _n is also equal. Thus between the output terminals T _1, T _2, and the output terminal T _1,
T ₂ and the potential difference between the house ground terminal E _n becomes almost zero both, there is no risk of damaging the communication device and a user or the like which is connected to the output terminal T _1, T _2. The impedance of the shield winding N ₀ is to prevent the outflow of current from the house ground terminal E _n to the distant ground terminal E _f side, it is possible to prevent an increase in distant ground potential.

Further, if the signal windings N ₁ and N ₂ and the shielding winding N ₀ are arranged on the same line with respect to the same iron core, the stray capacitance can be suppressed, and the output terminal is accompanied by electric vibration and waveform fluctuation. No abnormal voltage is generated. In addition,
If it is desired to further eliminate electric vibrations due to a decrease in stray capacitance, this can be realized by increasing the thickness of the winding coating. Also, neutralizing transformer N
If the current capacity of each of the windings N ₁ , N ₂ , and N ₀ constituting T is insufficient, windings having the same configuration may be separately connected in parallel.

[0013]

[Effects of the Invention] As described above, according to the present invention, it is possible to suppress occurrence of an abnormal voltage between a signal winding and ground and between signal windings due to a lightning surge. This has the effect of preventing damage to communication equipment, control equipment, workers and operators connected thereto. Further, unlike the conventional case, there is no problem such as a delay in repair due to the blowing of a fuse or the like. Further, the configuration is extremely simple, and it can be provided at low cost.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of a security device showing one embodiment of the present invention.

FIG. 2 is a circuit diagram of a security device showing a first conventional example.

FIG. 3 is a circuit diagram of a security device showing a second conventional example.

FIG. 4 is a circuit diagram of a security device showing a third conventional example.

[Explanation of symbols]

L ₁ , L ₂ input terminal (line side terminal) T ₁ , T ₂ output terminal (station equipment side terminal) A ₁ , A ₂ surge arrester _Var varistor NT neutralizing transformer N ₁ signal winding N ₂ signal winding N ₀ Shield winding

Claims (1)

(57) [Scope of request for utility model registration] 1. A pair of input terminals on the communication line side, a pair of output terminals on the local equipment side, a neutralizing transformer connected between the input terminal and the output terminal, and a remote ground terminal on the communication line side. And a surge protective device comprising: an in-house ground terminal on the in-house device side; and an arrester connected between the input terminal and the far-ground terminal, wherein the neutralizing transformer has a structure in which the input terminal and the output terminal are connected to each other. A pair of signal windings connected therebetween, and a shield winding connected between the remote ground terminal and the in-house ground terminal, and these signal windings and the shield winding are wound around the same iron core. And a surge protection device characterized in that the number of turns of each winding is equal.