Insulated plug for cable terminal connection part and cable terminal connection part

Abstract

To provide means for enabling a measurement of internal temperature of a cable terminal connection part.SOLUTION: In a cable terminal connection part including at least a connection part for connecting a power cable to an electric power apparatus and a voltage applying part, a temperature sensor is provided in an insulated plug which can be inserted into the voltage applying part. As the temperature sensor, a sensor (FBG (Fiber Bragg Grating) sensor or the like) using an optical fiber can be used. Further, in order to prevent a breakdown of the optical fiber by external force occurring after attaching the insulated plug, an excess length of the optical fiber can be secured, and / or the optical fiber can be spirally arranged within a body part.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an insulating plug for a cable terminal connection part and a cable terminal connection part.

Background Art

[0002] Cable terminal connection parts for connecting power cables to power equipment come in various shapes and structures. Among them, in cable terminal connection parts having a charging port, as a so-called inner cone type, a T-shaped terminal connection part formed by inserting a rubber stress cone with an epoxy resin bushing as the main insulation (Patent Document 1), a cable terminal connection part in which the charging port of the T-shaped terminal connection part is formed obliquely (Patent Document 2), or, as a so-called outer cone type, a device direct connection type (form) cable connection part (also called a T-shaped connector) having a structure in which a convex epoxy bushing connected to a device is covered with a rubber T-shaped insulating cylinder as the main insulation (Patent Document 3), etc. are available. These cable terminal connection parts have a device connection part, a cable connection part for connecting a power cable, and a charging part that is usually closed by attaching an insulating plug during normal use (during charging). The device connection part is used to connect to power equipment such as a switching device, the cable connection part (also called a line connection port) is used to connect a power cable, and the charging part (also called a charging port) is used for applications such as connecting a charging cable during a withstand voltage test or for temporarily transmitting power by connecting a power cable as an alternative to the cable connection part.

[0003] Also, as inventions related to cable terminal connection parts, there are those provided with a sensor capable of measuring the internal voltage (Patent Document 4), those provided with a voltage detection terminal on an insulating plug attached to the charging part (Patent Document 5), etc.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

[0005] However, none of the inventions related to the above-described prior art disclose or suggest any idea of measuring the temperature inside the cable terminal connection part.

[0006] Therefore, one of the objects of the present invention is to provide a means for making it possible to measure the temperature inside the cable terminal connection part. [Means for Solving the Problems]

[0007] In the cable terminal connection part including at least a cable connection part and a power supply part for connecting a power cable to an electric power device, the present invention made to solve the above problems is an insulating plug that can be inserted into the power supply part, and a temperature sensor capable of measuring the temperature inside the cable terminal connection part is provided on the insulating plug. In addition, in the present invention, a sensor using an optical fiber can be used as the temperature sensor. In addition, in the present invention, the optical fiber can be arranged so as to have an extra length inside the insulating plug. In addition, in the present invention, the optical fiber can be arranged in a spiral shape inside the insulating plug. Further, the invention of the present application can be configured such that the optical fiber is arranged between the insulating plug and a back cover provided at the rear end portion of the insulating plug via a spring so as to secure an extra length. Further, the invention of the present application can be configured such that the optical fiber is arranged to secure an extra length inside the insulating plug and between the insulating plug and a back cover provided at the rear end portion of the insulating plug via a spring.

Advantages of the Invention

[0008] According to the present invention, at least one of the following effects can be achieved. (1) The temperature sensor provided on the insulating plug can directly measure the temperature inside the cable terminal connection portion, and the temperature can be obtained more accurately. As a result, this also leads to setting the allowable current value based on the measured value and improving the detection accuracy of abnormal monitoring. (2) When maintenance of the temperature sensor is required, it is only necessary to stop the line and remove the insulating plug, and it is not necessary to perform operations such as removing the entire cable terminal connection portion. (3) By using a temperature sensor using an optical fiber, it becomes possible to arrange the optical fiber in a form buried inside the insulating plug. (4) By arranging the optical fiber provided on the insulating plug so as to provide an extra length, such as arranging it in a spiral shape, it is possible to prevent the optical fiber from being damaged when tensile force or compressive force is generated in the optical fiber. (5) By providing the temperature sensor with a connecting portion that can be connected to a connected portion provided at an arbitrary position inside the cable terminal connection portion, it is possible to always measure the temperature at the same measurement position.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Mode for Carrying Out the Invention

[0010] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, in the device connection part A1 and the power supply part A3, in the drawings, the left side is referred to as the "tip side" and the right side is referred to as the "rear end side", and in the cable connection part A2, in the drawings, the upper side is referred to as the "tip side" and the lower side is referred to as the "rear end side". That is, the direction in which the member is attached is referred to as the "tip side", and the opposite side is referred to as the "rear end side". Also, the end face on the tip side may be referred to as the "tip face", and the end face on the rear end side may be referred to as the "rear end face". Also, in each drawing, from the viewpoint of ensuring the visibility of the drawing, the hatching showing the cross section of each part may be omitted.

Embodiment

[0011] [1] Cable terminal connection part (Fig. 1) The cable terminal connection part A according to the present invention is a part for connecting a power cable to an electric power device. In the present invention, the shape, structure, etc. of the cable terminal connection part A and each part constituting the cable terminal connection part A are not particularly limited, and any aspect can be selected from known shapes and structures typified by the examples described in the background art section mentioned above.

[0012] <1> Overall configuration (Fig. 1) As an example of the cable terminal connection part A according to the present invention, Fig. 1 shows the internal structure of a T-shaped terminal connection part. The T-shaped terminal connection part is a member mainly used for connection with electric power devices such as switching devices and transformers, and is used as a cable terminal connection part having a power supply port (power supply part A3 described later) as an auxiliary connection part.

[0013] <1.1> Configuration for each area (Fig. 1) When the cable terminal connection part A shown in Fig. 1 is divided by area, the cable terminal connection part A can be divided into a device connection part A1, a cable connection part A2, and a voltage application part A3. Specifically, the cable terminal connection part A shown in Fig. 1 has a device connection part A1 to which an electric power device is connected at one end (the left side in Fig. 1) (the illustration of the end part side is omitted), a voltage application part A3 to which a voltage application cable (not shown) is connected during a withstand voltage test and an insulating plug 40 is normally attached at the other end (the right side in Fig. 1), and a cable connection part A2 that branches orthogonally to the device connection part A1 and the voltage application part A3 and to which a cable terminal part is attached.

[0014] <1.2> Configuration of Each Member (Fig. 1) When the cable terminal connection part A shown in Fig. 1 is divided by member, the cable terminal connection part A has at least a bushing 10, a connection conductor 20 mounted inside the bushing 10, a device-side fixing flange 30 provided on the device connection part A1 side, a cable terminal part (not shown) mounted on the cable connection part A2, and an insulating plug 40 mounted on the voltage application part A3.

[0015] Hereinafter, the details of each part divided by member and area will be described.

[0016] <2> Bushing (Fig. 1) The bushing 10 is a member that constitutes the main part of the main body material of the cable terminal connection part A. In this embodiment, the bushing 10 has at least an insulating cylinder 11, a device-side electrode 12, a cable-side electrode 13, and a shielding layer 14. The insulating cylinder 11, the device-side electrode 12, and the cable-side electrode 13 that constitute the bushing 10 can also be integrally formed by, for example, mold molding.

[0017] <2.1> Insulating Cylinder (Fig. 1) The insulating cylinder 11 is a member for insulating the internal conductors (the device-side electrode 12 and the cable-side electrode 13 in this embodiment) provided inside the bushing 10. The insulating cylinder 11 can be formed of a hard plastic resin material with high mechanical strength (for example, epoxy resin, fiber reinforced plastic (FRP: Fiber Reinforced Plastics), etc.).

[0018] <2.2>Device-side electrode and cable-side electrode (Fig. 1) In this embodiment, the internal conductor provided inside the bushing 10 is composed of two electrodes: a device-side electrode 12 and a cable-side electrode 13. Normally, the device-side electrode 12 and the cable-side electrode 13 are electrically connected by a connection conductor 20 described later. The device-side electrode 12 is a part disposed at the device connection portion A1 to which the power device is connected. The tip surface of the device-side electrode 12 is exposed from the insulating cylinder 11 at the device connection portion A1 (not shown). Also, an opening into which the tip portion of the connection conductor 20 described later can be inserted is provided on the rear end side of the device-side electrode 12. The cable-side electrode 13 is a part disposed on the cable connection portion A2 side to which the power cable is connected. The cable-side electrode 13 has a first conductor connection portion 131 communicating with the receiving port of the charging portion A3 and a second conductor connection portion 132 connected to the cable conductor (not shown) of the power cable inserted into the cable connection portion A2. The first conductor connection portion 131 is formed in a substantially cylindrical shape and has a hollow portion 133 inside. Also, the first conductor connection portion 131 is continuously provided orthogonally to the second conductor connection portion 132 formed in a substantially cylindrical shape. The hollow portion 133 communicates with the inner surface of the bushing 10 formed between the device-side electrode 12 and the cable-side electrode 13, the opening on the rear end side of the device-side electrode 12, and the connection hole A31 on the inner surface of the charging portion A3 of the bushing 10 described later. In a state where the insulating plug 40 is attached to the charging portion A3, the conductor on the tip side of the insulating plug 40 is electrically connected to the first conductor connection portion 131. The device-side electrode 12 and the cable-side electrode 13 can be formed of a conductive material suitable for energization, such as copper, aluminum, copper alloy, or aluminum alloy, for example. The machine-side electrode 12 and the cable-side electrode 13 may be formed of the same conductive material, or may be formed of different conductive materials respectively.

[0019] <2.3> Shielding layer (Figure 1) The shielding layer 14 is a member for performing functions as a shielding part for preventing external leakage and as an electric field relaxation part for relaxing the electric field within the bushing 10. The shielding layer 14 can be formed by a conductive paint applied to the outer peripheral surface of the insulating cylinder 11. In the cable terminal connection part A shown in Figure 1, the shielding layer 14 is formed over the entire outer peripheral surface of the insulating cylinder 11 from the device connection part A1 side to the power supply part A3 side, and is partially formed on the outer peripheral surface of the insulating cylinder 11 from the device connection part side A1 to the cable connection part A2 side. The portion where the shielding layer 14 is not formed on the cable connection part A2 side constitutes a cut-off part for insulating the grounding structure on the device side and the grounding structure of the power cable. With this structure, the shielding layer 14 is electrically connected between the device-side fixed flange 30 and the back cover 70 to be described later, and is electrically connected to and grounded to the device case B of the power device via the device-side fixed flange 30.

[0020] <3> Connection conductor (Figure 1) The connection conductor 20 is a member disposed inside the bushing 10 to enable current conduction between the machine-side electrode 12 and the cable-side electrode 13. The connection conductor 20 can be formed of a conductive material suitable for current conduction, such as copper, aluminum, a copper alloy, or an aluminum alloy. In this embodiment, the connection conductor 20 has a truncated cone shape with the head on the side facing the machine-side electrode 12, and is configured to be freely mounted from the power supply part A3 side into the inside of the bushing 10. Specifically, the connection conductor 20 is inserted through the connection hole A31 from the power supply part A3 side of the bushing 10, and by mounting the tip side on the inner surface of the opening at the rear end side of the machine-side electrode 12, the rear end side is mounted closer to the machine side (closer to the left side in Figure 1) of the cavity 133. That is, in a state where the connection conductor 20 is attached to the bushing 10, the connection conductor 20 is disposed across the opening on the rear end side of the device-side electrode 12, the internal space of the bushing 10 formed between the device-side electrode 12 and the cable-side electrode 13, and the device-side side of the cavity 133. Conductor contacts (not shown) are provided on the outer circumference of the front end side and the outer circumference of the rear end side of the connection conductor 20, respectively. By attaching the connection conductor 20 inside the bushing 10, the conductor contact on the front end side of the connection conductor 20 contacts the inner surface of the opening on the rear end side of the device-side electrode 12, and the conductor contact on the rear end side of the connection conductor 20 contacts the inner surface of the opening of the cable-side electrode 13. Thereby, the device-side electrode 12 and the cable-side electrode 13 can be electrically connected via the connection conductor 20.

[0021] <3.1> Presence or absence of connection conductor Note that the cable terminal connection portion A according to the present invention does not necessarily have the connection conductor 20 as an essential structure. For example, inside the cable terminal connection portion A, a structure may be provided that enables current to flow between the device-side electrode 12 and the cable-side electrode 13 without passing through the connection conductor 20. Specifically, an internal conductor in which the device-side electrode 12 and the cable-side electrode 13 are integrally formed may be used (see the connection conductor in Patent Document 6). <4> Insulating plug (FIG. 1) The insulating plug 40 is a member for closing the charging portion A3 provided in the cable terminal connection portion A. Details of the insulating plug 40 according to the present invention will be described later.

[0022] <5> Device connection portion (FIG. 1) The device connection portion A1 is a portion that serves as a connection portion with an electric power device. The device-side electrode 12 is located in the device connection portion A1, and enables current to flow to the cable connection portion A2 side and the charging portion A3 side via the connection conductor 20 disposed inside the bushing 10.

[0023] <6> Cable connection portion (FIG. 1) The cable connection portion A2 is a portion that serves as a connection portion for a power cable. The cable-side electrode 13 is located at the cable connection part A2, and it enables energization with the device connection part A1 side through the connection conductor 20 arranged inside the bushing 10. Further, the cable-side electrode 13 has a branched structure having a first conductor connection part 131 and a second conductor connection part 132. Since the second conductor connection part 132 on the cable connection part A2 side is continuously provided with the first conductor connection part 131 on the charging part A3 side, the cable connection part A2 can also be energized with the charging part A3 side through the cable-side electrode 13.

[0024] <7>Charging part (Fig. 1) The charging part A3 is a part used for connecting a charging cable (not shown) during a withstand voltage test or for connecting a power cable (not shown) as an alternative to the cable connection part A2 for performing temporary power transmission. The charging part A3 has a structure capable of being energized with the cable-side electrode 12 provided at the cable connection part A2, and during normal use of the cable terminal connection part A according to the present invention, the insulating plug 40 is attached and maintained in a closed state.

[0025] [2]Insulating plug (Figs. 1 to 4) Next, details of the insulating plug 40 for closing the charging part A3 will be described.

[0026] <1>Basic configuration (Figs. 1, 2) The insulating plug 40 is a member for closing the charging part A3 provided in the cable terminal connection part A. In the present invention, the insulating plug 40 may have a shape and structure that can be inserted and fitted into the connection hole A31 provided in the charging part A3. The connection hole A31 is the internal space of the bushing 10 provided in the charging part A3. An example of the insulating plug according to the present invention will be described with reference to Fig. 2. The insulating plug 40 according to this embodiment has a main body part 41, a high-voltage side electrode 42, and a shielding side electrode 43. Note that the main body part 41, the high-voltage side electrode 42, and the shielding side electrode 43 may be integrally formed by, for example, mold molding. On the rear end side of the insulating plug 40, a back cover 70 that can be fixed to the bushing 10 is separately provided in a manner such that a spring 60 is interposed between it and the shielding side electrode 43. With this structure, the insulating plug 40 fitted into the connection hole A31 of the power supply unit A3 is acted upon so as to be pressed in the insertion direction by the elastic force of the spring 60 that is compressed between the back cover 70 and the insulating plug 40.

[0027] <2>Main body part (Figure 2) The main body part 41 is the main member for insulating the power supply unit A3. The main body part 41 is made of an elastic insulating material such as rubber and has a shape that adheres to the inner wall surface of the connection hole A31. It is preferable to use an insulating material with excellent insulation properties during high-voltage power supply, such as ethylene propylene rubber (EP rubber) or silicone rubber, as the rubber used for the main body part 41. On the rear end side of the main body part 41, a member that can be gripped by a tool or the like may be separately provided in order to prepare for removal from the connection hole A31 (not shown).

[0028] <3>High-voltage side electrode (Figure 2, Figure 1) The high-voltage side electrode 42 is a member provided on the front end side of the main body part 41. In this embodiment, the shape of the high-voltage side electrode 42 is such that the front end side is flat and the rear end side is dome-shaped. With this structure, when the insulating plug 40 is attached to the connection hole A31, the front end side of the high-voltage side electrode 42 is in contact with the cable side electrode 12 that is the internal conductor (Figure 1). Also, since the rear end side of the high-voltage side electrode 42 is formed in a dome shape, the electric field applied to the insulating plug 40 is alleviated during power supply to the cable terminal connection part A. Also, a hole through which the optical fiber constituting the temperature sensor 50 described later can be inserted is provided in the high-voltage side electrode 42.

[0029] <4>Shielding side electrode (Figure 2, Figure 1) The shielding side electrode 43 is a member provided on the rear end side of the main body part 41. As shown in Figure 2, in this embodiment, the shape of the shielding side electrode 43 is such that the front end side is dome-shaped and the rear end side is flat. Further, a plurality of recesses 431 are arranged on the circumferential side of the rear end of the shielding-side electrode 43, one end of each spring 60 is housed in each of these recesses 431, and the other end of the spring 60 is configured to contact the back cover 70 fixed to the bushing 10. In the embodiment, a plurality of springs 60 are used, and one end of each spring 60 is housed in each of the plurality of recesses 431. However, in the present invention, the number of springs 60 is not limited. For example, when the elastic force for pressing the insulating plug 40 against the bushing 10 can be ensured, one end of a spring having a large outer diameter may be housed in a groove-shaped recess formed in a circumferential shape.

[0030] With this structure, when the insulating plug 40 is attached to the connection hole A31, the insulating plug 40 is pressed in the insertion direction by the elastic force of the spring 60 compressed between the back cover 70 and the shielding-side electrode 43 (Fig. 1). In addition, since the tip side of the shielding-side electrode 43 is formed in a dome shape, the electric field applied to the insulating plug 40 is relaxed when the cable terminal connection portion A is energized. Thereby, when the cable terminal connection portion A is energized, the insulation performance of the interface between the insulating cylinder 11 and the main body portion 41 of the insulating plug 40 can be maintained.

[0031] A hole through which an optical fiber constituting a temperature sensor described later can be inserted is also provided in the shielding-side electrode 43. A member that can be gripped with a tool or the like may be separately provided on the rear end side of the shielding-side electrode 43 to facilitate removal from the connection hole A31 (not shown).

[0032] <5> Arrangement of Temperature Sensor (Figs. 1, 2) In the present invention, a temperature sensor 50 is provided on the insulating plug 40, and in a state where the insulating plug 40 is attached to the energizing portion A3, the measuring portion of the temperature sensor 50 is configured to be arranged inside the cable terminal connection portion A.

[0033] <5.1> Temperature Sensor (Fig. 1) The temperature sensor 50 is a sensor for measuring the temperature inside the cable end connection part A. In the present invention, the type of the temperature sensor 50 is not particularly limited, and various sensors can be used. In this embodiment, as the temperature sensor 50, a sensor composed of a combination of an optical fiber 51 having an FBG part 511, which is called an FBG (Fiber Bragg Grating) sensor, and a measuring device 52 (interrogator) equipped with a light source and a light receiving part is used. Hereinafter, details of each part constituting the FBG sensor will be described.

[0034] <5.2>FBG part (Figure 2) The FBG part 511 is a part that functions as a temperature measurement part. In the present invention, the FBG part 511 is formed by forming a diffraction grating with a different refractive index in the core of the optical fiber 51. This FBG part 511 is exposed from the tip of the insulating plug 40 and arranged at an arbitrary position inside the cable end connection part A. By detecting the wavelength change of the reflected light accompanying the temperature change in the FBG part 511, the temperature around the FBG part 511 can be measured.

[0035] <5.3>Measuring device (Figure 1) The measuring device 52 (interrogator) is a device for projecting light onto the optical fiber 51 and receiving the reflected light from the optical fiber 51. In the present invention, the mounting mode of the measuring device 52 is not particularly limited. In Figure 1, the measuring device 52 in a state where the optical fiber 51 exposed from the rear end of the insulating plug 40 is connected is fixed to the back cover 70. The measured temperature value recorded by the measuring device 52 may be configured to be acquirable by various methods such as transfer by wireless communication or collection via a recording medium.

[0036] <6>Arrangement mode of temperature sensor (Figure 1, Figure 3) In the present invention, the arrangement mode of the temperature sensor 50 with respect to the insulating plug 40 is not particularly limited. For example, when a part of the optical fiber 51 that constitutes the temperature sensor 50 is embedded inside the main body 41 that constitutes the insulating plug 40, the following configurations can be considered.

[0037] <6.1> Arrangement Example 1 (Fig. 1) For example, the optical fiber 51 can be arranged and embedded linearly in the front - rear direction of the insulating plug 40. In the embodiment of Fig. 1, the insulating plug 40 is configured such that the optical fiber 51 penetrates in the longitudinal direction of the insulating plug 40. According to this configuration, by making the length of the optical fiber 51 to be used as short as possible, the manufacturing cost can be suppressed.

[0038] <6.2> Arrangement Example 2 (Fig. 3(a)) For example, a configuration can be adopted in which an extra length is provided for the optical fiber 51 located between the insulating plug 40 and the back cover 70 (ensuring the extra - length part 512). As shown in Fig. 3(a), the extra - length part 512 may be formed by slackening the optical fiber 51 or formed in a spiral shape, and the forming method is not particularly limited. According to this configuration, when the insulating plug 40 is attached to the energizing part A3, the insulating plug 40 is pushed in the insertion direction by the spring 60, and when the back cover 70 is separated from the insulating plug 40 by the restoring force of the spring 60, the tensile force generated between the part of the optical fiber 51 embedded in the main body 41 and the part connected to the measuring device 52 (interrogator) provided on the back cover 70 can reduce the risk of the optical fiber 51 being damaged.

[0039] <6.3> Arrangement Example 3 (Fig. 3(b)) For example, a configuration can be adopted in which an extra length is provided for the optical fiber 51 inside the main body 41 that constitutes the insulating plug 40 (ensuring the extra - length part 512). In Fig. 3(b), as an example of ensuring the extra - length part 512, the optical fiber 51 is arranged in a spiral (coil) shape. According to this configuration, after attaching the insulating plug 40 to the power supply unit A3, when the insulating plug 40 is pushed in the insertion direction by the spring 60 and the main body portion 41 is in a compressed state, or when the main body portion 41 expands and contracts due to temperature changes, it simply acts so that the spiral pitch of the optical fiber 51 changes, and an external force that could lead to damage to the optical fiber 51 located inside the main body portion 41 is not applied. Therefore, the risk of damage to the optical fiber 51 can be reduced. Regarding the spiral (coil-shaped) configuration, as shown in FIG. 3(b), it may be formed in a single-wound state or in a multi-wound state, and there are no particular limitations on the diameter of the wound portion, the number of turns, the pitch of the spiral portion, etc.

[0040] <6.4>Others (not shown in the figure) In the present invention, each of the above-described configurations can also be appropriately combined and used within a range where there is no structural contradiction. Also, in the present invention, the aspect of the slack portion 512 is not particularly limited. For example, it includes a trajectory in which the optical fiber 51 circulates in a circular shape, a trajectory in which the optical fiber 51 is folded back or circulates in a plurality of straight lines, a folded-back length, a trajectory with different lengths of the circulation diameter, etc. Also, the number of turns or the number of fold-backs of the optical fiber 51 is not particularly limited.

[0041] <7>Measurement aspect of temperature (FIG. 1, FIG. 4) In the present invention, the temperature measurement location by the temperature sensor 50 can be any location inside the cable end connection portion A. Various methods can be adopted for the method of positioning the temperature sensor 50 at the measurement location. For example, a method of providing and locking claws, holes, etc. that can position the temperature sensor 50 at the measurement location, a method of adhering the temperature sensor 50 to the measurement location, a method of providing a connection structure (connection portion and connected portion) between the measurement location and the temperature sensor 50, etc. can be adopted. Next, an example of the measurement location will be described.

[0042] <7.1>Measurement example 1 (FIG. 1) For example, the temperature measurement location can be the cavity 133 inside the bushing 10. As shown in FIG. 1, by retaining the FBG portion 511 exposed from the tip of the insulating plug 40 as it is in the cavity portion 133, the temperature inside the cavity portion 133 can be measured.

[0043] <7.2>Measurement Example 2 (FIG. 4(a)) For example, the temperature measurement location can be the surface or inside of the connection conductor 20. As shown in FIG. 4(a), by inserting the FBG portion 511 exposed from the tip of the insulating plug 40 into a hole provided in the connection conductor 20, the internal temperature of the connection conductor 20 can be measured. In this case, it is preferable to provide some slack in the optical fiber 51 between the rear end side of the connection conductor 20 and the tip side of the insulating plug 40. The length of the slack in this case preferably ensures a distance equal to or greater than the distance from the rear end portion of the connection conductor 20 after the connection conductor 20 is attached to the rear end portion of the power supply portion A3. Thereby, the connection conductor 20 into which the FBG portion 51 is inserted can be first attached to the bushing 10, and then the insulating plug 40 provided with the optical fiber 51 can be attached to the bushing 10.

[0044] According to the configuration of FIG. 4(a), the internal temperature of the connection conductor 20 can be measured, and a temperature close to the temperature of the cable conductor of the power cable that is electrically connected to the connection conductor 20 via the connection conductor 20, the internal conductor (cable-side electrode 13), and the conductor connection terminal (not shown) attached to the cable conductor, all of which are made of metal with high thermal conductivity, can be measured. Therefore, based on this measurement, it becomes easy to set the allowable current value and to detect when there are changes or abnormalities in the temperature of the cable conductor.

[0045] <7.3>Measurement Example 3 (FIG. 4(b)) For example, the temperature measurement location can be the cable-side electrode 13. As shown in FIG. 4(b), by positioning the FBG portion 511 that constitutes the temperature sensor 50 on the surface of the cable-side electrode 13, the surface temperature of the cable-side electrode 13 can be measured. In this case, it is preferable to provide a surplus length to the optical fiber 51 exposed from the tip side of the insulating plug 40 (the insertion side into the connection hole A31). In this case, it is preferable to secure a length of the surplus length that is equal to or greater than the distance from the position of the cable-side electrode 13 (internal conductor) where the FBG portion 511 is attached to the rear end portion of the charging portion A3. Thereby, the FBG portion 511 provided at the tip of the optical fiber 51 can be attached to the cable-side electrode 13 (internal conductor), and then the insulating plug 40 provided with the optical fiber 51 can be attached to the bushing 10.

[0046] According to the configuration of FIG. 4(b), the surface temperature of the cable-side electrode 13 (internal conductor) can be measured, and the temperature close to the temperature of the cable conductor of the power cable that is electrically connected to the internal conductor (cable-side electrode 13) through the internal conductor (cable-side electrode 13) formed of metal with high thermal conductivity and the conductor connection terminal (not shown) attached to the cable conductor can be measured. Therefore, based on the measurement, it becomes easy to set the allowable current value and to detect when there is a change or abnormality in the temperature of the cable conductor.

[0047] <7.4>Measurement Example 4 (FIG. 4(c)) For example, the measurement location of the temperature can be the high-voltage side electrode 42. By positioning the FBG portion 511 constituting the temperature sensor 50 on the surface of the high-voltage side electrode 42, specifically, on the tip surface 421 of the high-voltage side electrode 42, the surface temperature of the high-voltage side electrode 42 can be measured. With this configuration, the surface temperature of the high-voltage side electrode 42 can be measured, and the temperature close to the temperature of the cable conductor of the power cable that is electrically connected through the high-voltage side electrode 42, the internal conductor (cable-side electrode 13), and the conductor connection terminal (not shown) attached to the cable conductor, all of which are formed of metal with high thermal conductivity, can be measured. Therefore, based on the measurement, it becomes easy to set the allowable current value and to detect when there is a change or abnormality in the temperature of the cable conductor.

[0048] As described above, from the above-described embodiment in which the insulating plug 40 is provided with the temperature sensor 50 capable of measuring the temperature inside the cable terminal connection portion A, it is possible to measure a temperature close to the temperature of the cable conductor of the power cable, and based on the measurement, it becomes easy to detect when there is a change or abnormality in the temperature of the cable conductor. Accordingly, when there is an abnormality in the temperature of the cable conductor, it is possible to detect a sign before the power cable or the cable terminal connection portion is destroyed, and it can be expected that the article will be replaced before the end of its life. Therefore, it becomes possible to contribute to Goal 11 of the Sustainable Development Goals (SDGs), which is an international goal aiming for a sustainable and better world by 2030, as described in the "2030 Agenda for Sustainable Development" adopted at the United Nations Summit in September 2015, to "achieve inclusive, safe, resilient and sustainable cities and human settlements".

[0049] As described above, the present invention has been specifically described based on the embodiments, but the present invention is not limited to the above-described embodiments. For example, in the embodiment, in the cable terminal connection portion A having the charging portion A3, in the case of a so-called inner cone type, the case of a T-shaped terminal connection portion formed by inserting a rubber stress cone with an epoxy resin bushing as the main insulation has been described, but it may be applied to a cable terminal connection portion in which the charging portion is formed obliquely as in Patent Document 2.

[0050] Further, in the embodiment, the inner cone type has been described, but as a so-called outer cone type, it may be applied to a device direct connection type (also called a T-shaped connector) having a structure in which a convex epoxy bushing connected to a device is covered with a rubber T-shaped insulating cylinder as the main insulation as in Patent Document 3. In the case of a rubber T-shaped insulating cylinder, the main body portion of the insulating plug to be mounted (the main insulating portion of the insulating plug) is preferably formed of a hard insulator such as epoxy resin, rather than rubber as in the embodiment.

Explanation of Reference Numerals

[0051] A: Cable terminal connection portion A1: Machine connection part A2: Cable connection part A3: Power supply part A31: Connection hole 10: Bushing 11: Insulating cylinder 12: Machine-side electrode 13: Cable-side electrode 131: First conductor connection part 132: Second conductor connection part 133: Hollow part 14: Shielding layer 20: Connection conductor 30: Machine-side fixing flange 40: Insulating plug 41: Body part 42: High-voltage side electrode 421: Tip surface 43: Shielding side electrode 431: Recess 50: Temperature sensor 51: Optical fiber 511: FBG part 512: Slack part 52: Measuring device 60: Spring 70: Rear cover B: Machine case

Claims

1. An insulating plug that can be inserted into a cable connection terminal that includes at least a cable connection portion and a voltage supply portion for connecting a power cable to an electric power device, a temperature sensor capable of measuring the temperature inside the cable termination connection portion is provided in the insulating plug; the temperature sensor is a sensor using an optical fiber, an excess length is provided in the optical fiber at the exposed portion from the tip of the insulating plug, Insulating plug for cable termination.

2. The length of the excess length is such that the insulating plug can be attached and detached to the voltage supply unit while the optical fiber is positioned at a predetermined measurement point of the cable termination connection part.

2. An insulating plug for a cable termination according to claim 1.

3. The optical fiber is arranged in a spiral to form the excess length.

2. An insulating plug for a cable termination according to claim 1.

4. A cable termination connection unit including at least a cable connection unit and a voltage supply unit for connecting a power cable to a power device, The cable termination connection portion is The insulating tube has at least an electrode provided therein, an insulating tube that insulates the electrode, and a shielding layer provided on the outer circumferential surface of the insulating tube, The insulating plug according to any one of claims 1 to 3 is attached to the voltage-sensing part. Cable termination connection.

5. The cable connection part is characterized in that the power cable is connected to the cable connection part.

5. The cable termination according to claim 4.

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