JP2005261178A - Sheath current suppressing device for underground cable - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sheath current suppressing device for an underground cable, capable of preventing the occurrence of power accidents, by protecting a suppressing device and by making accident current to flow smoothly into the ground, even during ground fault and thunderstroke infiltration, even though the device is manufactured compactly, and that can realize cost reduction and that can be easily installed. <P>SOLUTION: The sheath current suppressing device is composed so that a reactor, in which a coil is wound around the surrounding part of an iron core many times, is connected and installed to a sheath line of a feeder line. The device is provided with a fuse, which is connected and installed, in series with the input side of the reactor, and a lightning arrester connected in parallel with the reactor. Normally, power loss is reduced by suppressing the sheath current. The occurrence of power accidents can be prevented, by protecting the suppressing device and by making the infiltrated current to flow smoothly into the ground during the thunderstroke infiltration and the ground fault. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a sheath current suppressing device for underground power transmission lines. More specifically, the sheath current is usually suppressed to reduce power loss, and in the event of a lightning strike or ground fault, the suppressor is protected and the invaded current flows smoothly to the ground to prevent the occurrence of a power accident. The present invention relates to a sheath current suppressing device for underground cables.

  Generally, the transmission system of the power system is an overhead line in the suburbs of cities or agricultural and fishing village areas, and in large city centers and new cities, power is supplied through cables buried in the ground. . In addition, such a transmission line is grounded to the ground through a sheath wire at certain intervals for safety, and in the case of an underground transmission line, a cable is used to prevent the potential of the sheath line from rising due to a system fault or the like. It is operated by a collective grounding method in which the sheath wire is grounded collectively for each connection section. Therefore, in such a collective grounding system, when a current flows through the transmission line, a voltage is also induced in the metal sheath installed around the transmission line and flows to the ground through the sheath line.

  However, if a current flows through the sheath wire in this way, unnecessary power loss occurs in the transmission line. Such power loss becomes worse when the load of each phase is unbalanced, disturbing stable power transmission, raising the temperature inside the transmission line and inducing deterioration of the transmission line There are various problems such as. In addition, in spite of such power loss, since the load current and circulating current appear on the meter (hook on Am-meter) when measuring the load current, the loss of the transmission line due to the circulating current can be accurately grasped. There are some problems that are not.

  Therefore, recently, a reactor in which a coil is wound many times around an iron core core is connected to a sheath wire, and usually serves to stably supply power without generating a circulating current in the sheath wire. A sheath current suppression device has been developed that can suppress the occurrence of abnormal voltage in the transmission line by limiting the rise in the potential of the sheath line when an abnormal voltage occurs, such as during an electrical connection. It is disclosed in detail in the current and abnormal voltage suppression device and method (patent document 1, publication date 2003.3.8).

However, such a sheath current suppression device may cause a larger power accident when the ground fault accident occurs, because the suppression device is damaged by an overcurrent and the accident current cannot flow. Even when a lightning strike enters, there is a problem that the insulation of the control device is broken and a power accident is induced. In addition, in order to manufacture the suppression device to withstand a certain amount of excessive current, the size and weight are so large that it is difficult to use in an actual power system. There is.
Korean Patent Publication No. 2003-20145

  The present invention has been devised to solve the above problems. The purpose of the present invention is to reduce the cost by making it compact and easy to install, but also protects the suppressor in the event of a ground fault or lightning strike, and allows the accident current to flow smoothly to the ground, thereby preventing power accidents An object of the present invention is to provide a sheath current suppressing device for an underground cable that can prevent the occurrence of the above.

  In order to achieve the above object, the present invention provides a sheath current suppressing apparatus in which a reactor having a coil wound around an iron core is connected to a sheath line of a transmission line, and is connected in series to the input side of the reactor. And a lightning arrester connected in parallel to the reactor.

  The fuse has a capacity of 5 kA to 20 kA.

  The reactor, the fuse, and the lightning arrester are housed and installed in an outer case.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. In addition, this embodiment does not limit the scope of rights of the present invention, but is merely provided as an example, and the same reference numerals and names are used for parts that are the same as in the conventional configuration.

  FIG. 1 is a configuration diagram of a sheath current suppressing device according to an embodiment of the present invention. As shown in the figure, in the sheath current suppressing device, a reactor 7 that suppresses a sheath current by magnetization characteristics is connected to a sheath line of a transmission line (not shown), and the reactor 7 protects the reactor against overcurrent on the input side of the reactor 7. The fuses 4 to be connected are connected in series, and the lightning arrester 2 is connected in parallel with the reactor 7. By making the fault current flow smoothly to the ground through the lightning arrester 2, the power system accident can be prevented.

  The reactor 7 suppresses the circulating current by utilizing the magnetization characteristics of the coil 5 and the iron core 6, and is connected between a sheath wire (not shown) and a ground wire. The iron core 6 is insulated and impregnated with a varnish for electrical insulation, and is installed inside the outer case 3 so that moisture penetration can be prevented. The coil 5 is wound around the periphery of the iron core 6 many times. The input terminal 1 is connected to a sheath wire on the power transmission line side, and the output terminal 1 'is connected to a ground wire grounded to the ground.

  The fuse 4 is connected in series to the input terminal 1 of the reactor 7 to protect the suppressor by blocking the accident current from flowing into the reactor 7 even if a ground fault occurs. It is preferable to use the one of 5 kA to 20 kA, and the reactor can be safely protected without being easily disconnected.

  The lightning arrester 2 is connected in parallel to the reactor 7 so that an accident current flows to the ground through the lightning arrester 2 in the event of a ground fault or a lightning strike, thereby preventing a power accident from occurring on the transmission line. Is.

  Such a lightning arrester 2 has a high resistance so that current does not flow in a normal voltage state, but when lightning or the like enters, it becomes a conductive circuit and the resistance becomes very small, causing an accident current. It flows smoothly and returns to high resistance when it returns to normal, and it is used in many places such as power plants, substations, and power distribution lines.

The operation of the embodiment of the present invention having the above configuration will be described below.
The sheath current suppressing device is configured such that the reactor 7 is connected to the sheath wire, and the sheath current is normally suppressed by the impedance of the reactor 7 to reduce the power loss of the transmission line, thereby stabilizing the power. To be able to send.

  In the event of a ground fault or lightning strike, if an accident current exceeding the capacity of the reactor 7 flows through the sheath wire, the fuse 4 connected in series to the input terminal 1 of the reactor 7 is disconnected and the reactor is disconnected. It is possible to prevent the control device from being damaged by interrupting the flow of the accident current into 7.

  At this time, the accident current that has entered the sheath wire smoothly flows to the ground through the lightning arrester 2 connected in parallel to the reactor 7 to prevent a power accident from occurring on the transmission line.

  Therefore, since such an overcurrent does not flow into the reactor 7, such a sheath current suppressing device can be used safely even if its size and capacity are significantly reduced as compared with the prior art. It is very easy to install a restraining device, and maintenance and repair are convenient.

  In the present invention as described above, even if an overcurrent exceeding the capacity of the reactor is induced in the sheath wire, the fuse connected in series on the input side can be disconnected to prevent the suppression device from being damaged due to the overcurrent. Since the invaded overcurrent flows smoothly to the ground through a lightning arrester connected in parallel with the reactor, it is possible to prevent a power accident from occurring on the transmission line.

  In addition, the sheath current suppressing device can be used safely even if its capacity and size are significantly smaller than the conventional one, and it is very easy to install on the underground power transmission line, and has the advantages of convenient maintenance and repair. is there.

It is a block diagram of the sheath current suppression apparatus by the Example of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Input terminal, 1 '... Output terminal, 2 ... Lightning arrester, 3 ... Outer case, 4 ... Fuse, 5 ... Coil, 6 ... Iron core, 7 ... reactor

Claims (3)

In a sheath current suppressing device that connects and installs a reactor in which a coil is wound many times around an iron core to a sheath wire of a transmission line,
A fuse connected in series to the input side of the reactor;
A sheath current suppressing device for underground cables, comprising a lightning arrester connected in parallel to the reactor.   The sheath current suppressing device for an underground cable according to claim 1, wherein the fuse has a capacity of 5 kA to 20 kA.   The sheath current suppressing device for an underground cable according to claim 1, wherein the reactor, the fuse, and the lightning arrester are housed and installed inside an outer case.

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