JPH05273255A - Optical ct - Google Patents

Abstract

PURPOSE:To secure insulation of a coil case and at the same time obtain an optical CT with a coil part which can be mounted easily. CONSTITUTION:A ring-shaped coil part 4 surrounding the periphery of a conductor L is provided. The coil part 4 is formed in ring shaped by interlocking two cases 20a and 20b in semidivided shape housing a coil iron core 21. The cases 20a and 20b form an opening over the entire length of an innerperiphery surface as a housing port for housing the coil iron core 21. Also, the opening is clad with an insulation plate, thus preventing induced current from occurring in a coil case 20.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical CT which is suspended from a conductor to detect a fault current in a power transmission / distribution line, and more particularly to a coil portion which generates an induced current by a current flowing in the conductor.

[0002]

2. Description of the Related Art When an accident such as a ground fault or a short circuit occurs in a transmission line or substation, a fault current is detected by an optical CT installed on an aerial conductor in order to quickly isolate and repair the fault location. The applicant of the present invention has disclosed a technique for quickly finding a failure point by optically transmitting to a monitoring station.
It is proposed in Japanese Patent No. 5180.

[0003]

This optical CT is installed in a substation or the like under the open air, and under this condition, for example, 25
It is necessary to exhibit stable performance over a long period of time, such as demanding durability for more than a year. Further, the coil case needs to be divided into two halves in order to be attached to the existing conductor L, and thus it is difficult to make the inside of the coil case a water resistant structure. In addition, an induced current is also generated in the coil case itself, which causes an error. Therefore, it is necessary to insulate the coil case from the electric circuit. Therefore, in a conventionally known coil case, an opening 72 that serves as an entrance for housing the coil iron core 71 is provided on one side surface of the case 70 that is cut in half as shown in FIG. A metallic cover 73 is insulated with an insulating sheet 74 of synthetic resin interposed, and then attached with a fixing screw 75.

However, when the cover 73 is attached, it is necessary to interpose the insulating sheet 74 and then fix the cover 73 over substantially the entire circumference of the outer peripheral edge 77 in addition to the inner peripheral edge 76, which makes the mounting cumbersome. There was a problem.

Therefore, an object of the present invention is to provide an optical CT having a coil portion which is easy to mount while ensuring insulation of the coil case.

[0006]

In order to achieve this object, in the present invention, the coil portion is formed into a ring shape by connecting two half-split cases, and each case is opened over the entire length of the inner peripheral surface. And an opening is covered with an insulating plate.

[0007]

In the present invention, since the opening is formed on the inner peripheral surface of the case over the entire length, the coil core is accommodated through this opening. Then, if an insulating plate is attached, this opening can be closed. At this time, since the opening is formed only on the inner peripheral surface of the case, the number of mounting points is small and the mounting can be easily performed.

Further, since it is insulated by the insulating plate, the induction current generated in the coil case is prevented.

[0009]

According to the present invention, the coil portion is formed into a ring shape by connecting two half-split cases, and each case is formed with an opening over the entire length of the inner peripheral surface and the opening is formed by an insulating plate. Since it is covered, insulation of the coil case can be secured, and the optical CT can be provided with a coil portion that can be easily attached.

[0010]

The following is a detailed description of an embodiment in which the present invention is applied to a single-conductor optical CT directly attached to a conductor L installed in a substation.

As shown in FIG. 1, an optical CT is attached to a conductor L, and a transmission line 2 drawn from this optical CT is laid on the top of an optical fiber built-in insulator (not shown). And
The transmission line 2 is connected to a monitoring station on the ground by the transmission line 2 arranged on the central axis portion of the insulator with built-in optical fiber so that the fault current detected by the optical CT can be detected at the monitoring station.

The light CT has a coil portion 4 for generating an induced current by a current flowing through the conductor L, and a case body 6 for housing a sensor head 5 for converting the induced current into an optical signal.
The transmission line 2 for transmitting the optical signal is roughly formed by a transmission line mounting portion 7 for fixing the transmission line 2 to the case body 6 and a conductor gripping portion 8 for mounting and fixing the case body 6 on the conductor L.

The sensor head 5 accommodated in the case body 6 is accommodated in a cylindrical case, the connector 11 is provided at the right end, and the connection line 1 from the coil portion 4 which will be described later is provided.
2 is connected to transmit the induced current generated in the coil portion 4 to the sensor head 5. A solenoid coil 13 connected to the connection line 12 is housed and arranged in the sensor head 5, and an optical magnetic field sensor 14 composed of a Faraday element is housed in the center of the solenoid coil 13 and induced by the solenoid coil 13. The detected magnetic field is converted into an optical modulation signal. The optical modulation signal is transmitted to the transmission line 2 (optical fiber core wire 2a) connected to the optical connector 15 at the left end.

The conductor gripping part 8 is composed of two clamps provided on the upper part of the case body 6, and the conductor L is gripped by one side of the coil part 4 by the conductor gripping part 8.

In the coil portion 4, a ring-shaped coil case 20 surrounding the conductor L is provided on one side of the case body 6, and a coil iron core 21 is provided in each of the coil cases 20.
Are arranged. This coil case 20 is divided into a lower case 20a that can be attached to the conductor L.
And an upper case 20b.

As shown in FIG. 2, the upper and lower cases 20 are
A flange 23 of the lower case 20a and a flange 24 of the upper case 20b are formed outside the mating surface 22 of a and 20b. A planting bolt 25 is provided on the flange 23, and is inserted into an attachment hole 26 formed in the flange 24 to be fixed by a tightening nut 27. A positioning pin 28 is erected on the flange 23 of the lower case 20a and is fitted in a pin hole (not shown) of the flange 24 so that the two cases 20a and 20b are assembled correctly.

Both the upper and lower cases 20a, 20b are made of metal such as aluminum and have a substantially U-shaped cross section whose inner peripheral surface is opened by an opening 29. Since the upper and lower cases 20a and 20b have almost the same configuration, the lower case 20a will be described below.

As shown in FIGS. 2 and 3, the lower case 20a
Left and right rims 31, 32 are formed on the center side of the mating surface 22 of, and an insulating epoxy resin is formed between the left and right rims 31, 32.
An insulating plate 33 made of Teflon, Bakelite or the like is attached. Therefore, the insulating plate 33 is the inner peripheral surface of the through hole 34 that penetrates the conductor L. In this way, since the lower case 20a is insulated by the insulating plate 33,
The induced current is prevented from circulating in the lower case 20a by the alternating current flowing through the conductor L.

A concave groove 30a is formed between the right edge 31 and the mounting bar 30, and the right end portion of the insulating plate 33 is fitted in the concave groove 30a. The lip 32 on the left side is the lip 31.
It has a larger diameter and three screw holes 36 are formed in the rim 32. Then, the insulating plate 33 is attached with a mounting bracket 37 sandwiching the left end portion. Since the mounting member 37 has an L-shaped cross section as shown in FIG. 4, a space for accommodating the left end portion of the insulating plate 33 has a rim 3
2 is formed between the mounting bracket 37 and the mounting bracket 37 so that the left end portion of the insulating plate 33 can be mounted without being strongly pressed when mounted on the rim 32. In addition, the mounting bracket 37 is formed with a recessed portion 38 having screw holes 38a at three locations.
The head of 5 is attached to the through hole 34 without protruding.

A coil unit 21a, which will be described later, is housed in the lower case 20a, and a mounting resin plate 39 is mounted on the mounting bar 30.
Is fixed. Mounting resin plate 39 mounted at this time
As a result, the entire mating surface 22 is made smooth, and the upper and lower cases 20a and 20b are in close contact with each other and can be joined.

A box piece 41 forming the terminal box 40 is formed on the side surface of the lower case 20a when the upper case 20b and the lower case 20a are joined together. The ends of the coil wires 46 in 20b are connected to each other and the connection wires 12 are connected to each other so that a magnetic field is generated in the solenoid coil 13 by the induced current generated in the coil core 21.

As shown in FIG. 5, both upper and lower cases 20a,
The coil iron core 21 housed in 20b is a coil wire 4 in which the periphery of a rod-shaped iron core 44 having a rectangular cross section is insulation-coated.
6 is wound on the forward and return paths by the required number of turns so that a sufficient induced current is generated by the fault current flowing through the conductor L. The mounting resin plates 43 are attached to both ends of the coil unit 21a, and the outer periphery of the coil unit 21a is covered with a moisture resistant layer 48 made of a resin having a low water absorption rate such as EPDM.

As shown in FIG. 6, the coil unit 21a is housed in both upper and lower cases 20a and 20b, and a mounting resin plate 43 is fixed to the mounting bar 30. Further, a water resistant mold layer 49 formed by dipping a resin having a low water absorption rate, such as an epoxy resin or a silicone resin, is formed on the outer periphery of the coil unit 21a by both cases 20a, 20b.
The inside is filled so that water does not collect in the case 20.

As shown in FIG. 1, the case body 6 has a cylindrical space storage box 50 in which the sensor head 5 is stored.
A fiber box 51 partitioned by a partition wall 52 is provided below the storage box 50. The storage box 50 is formed with an opening 53 that serves as an inlet when the sensor head 5 is stored, and is closed by a sealing lid 54. Further, the fiber box 51 is provided with a communication hole 52a at the left end of the partition wall 52, and the optical fiber core wire 2a pulled out to the left from the optical connector 15 is bent downward to be introduced. In addition, an opening 56, which is opened when the optical fiber core wire 2a is assembled to the fiber box 51, is formed in a substantially rectangular shape at the bottom of the fiber box 51, and is closed by a cover 57.

The optical fiber core wire 2a connected to the optical connector 15 is drawn out from the optical connector 15 to the left side, and then is bent into a U-shape into the fiber box 51 through the communication hole 52a and drawn out through the drawing hole 66. ing.

A transmission line mounting portion 7 is provided outside the lead-out hole 66, and the optical fiber cable 2c is fixedly mounted on the top of the insulator with built-in optical fiber. In the transmission line 2, the two optical fiber core wires 2a for transmitting and receiving light are inserted into the pipe 2b made of aluminum, and the outside thereof is made of an aluminum twisted wire containing copper wire. The optical fiber cable 2c is covered with an outer skin, and has weather resistance and mechanical strength. The outer end of the transmission line 2 is peeled off before mounting so that the pipe 2b is exposed.
Further, the tip thereof is an optical fiber cable 2c, and this end portion is fixed to the transmission line attaching portion 7 and is firmly attached and fixed against the tension applied to the installed optical fiber cable 2c.

Next, the light C of the embodiment having such a configuration is described.
With respect to T, this action will be described. Now, when a fault current flows through the conductor L, the conductor gripping portions 8 provided at two positions are surrounded by the coil portion 4 because they are provided on one side of the coil portion 4. The electric current flows in the conductor L without splitting, and an induced current is generated in the coil of the coil iron core 21.

At this time, since the inside of the coil case 20 is insulated by the insulating plate 33, an induced current is not generated in the coil case 20 due to the current flowing through the conductor L.
Only the induced current by the coil iron core 21 is induced. The induced current induced in the coil wire 46 is transmitted to the sensor head 5 by the connection wire 12 connected in the terminal box 42, and the secondary magnetic field is generated by the solenoid coil 13. The optical magnetic field sensor 14 arranged at the center of the solenoid coil 13
By this, the secondary magnetic field is converted into an optical modulation signal, and the optical modulation signal is transmitted to the monitoring station through the transmission line 2 (optical fiber core wire 2a / optical fiber cable 2c) via the optical fiber built-in insulator.

Further, in this embodiment, even if the mounting bracket 37 is mounted on the left rim 32, the insulating plate 33 is not strongly pressed, so that the insulating plate 33 made of resin does not creep. Therefore, since the mounting screw 35 is not loosened due to creep, stable water resistance is exhibited for a long time,
Water is prevented from entering the inside of the coil wire 46.
Further, in this embodiment, the coil wire 46 is formed by the water resistant mold layer 49 and the moisture resistant layer 48 in the upper and lower cases 20a, 20b.
Corrosion of the iron core 44 for a long period of time is prevented. Further, in cold regions, water is prevented from staying in the gap between the coil unit 21a and the coil case 20, and accidents such as freezing cracks due to accumulated water are prevented.

In this embodiment, the coil unit 21
Although a is prepared and is housed in the coil case 20, it is not always necessary to form the coil unit 21a, and a well-known coil iron core 21 is used as the coil case 20.
May be stored inside.

Further, although the example of the optical CT for one conductor is shown in this embodiment, it is applied to the optical CT for multiple conductors such as the optical CT for two conductors, which detects the fault current of the multiple conductor of three or four conductors. be able to.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing a state of being attached to a conductor.

FIG. 2 is an exploded perspective view of a coil portion.

FIG. 3 is an exploded perspective view of a lower case.

FIG. 4 is a partial cross-sectional view of a lower case.

FIG. 5 is a partially cutaway sectional view of a coil unit.

FIG. 6 is a sectional view of a coil portion.

FIG. 7 is an exploded perspective view of a conventional coil portion.

[Explanation of symbols]

 2 ... Transmission line 4 ... Coil part 5 ... Sensor head 6 ... Case body 20 ... Coil case 20a ... Lower case 20b ... Upper case 21 ... Coil iron core 29 ... Opening 33 ... Insulation plate

Claims (1)

[Claims] 1. A coil unit mounted around a conductor to generate an induced current by a current flowing through the conductor, a sensor head housed in a case body and converting the induced current into an optical modulation signal, and the optical modulation signal. In an optical CT having a transmission line for transmitting to the ground part, the coil part is formed in a ring shape by connecting two half-shaped cases, and an opening is formed in each case over the entire length of the inner peripheral surface. Optical CT that is formed and the opening is covered with an insulating plate.