JP2008164473A - Device for measuring conductor temperature - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technology related to a device for measuring conductor temperature that reduces the operating time and the operation labor and can acquire accurate conductor temperature on site, in measuring the conductor temperature of a cable. <P>SOLUTION: The conductor temperature measuring device measures the temperature of a conductor 31, in the cable having the conductor 31 for making current flow and an insulator 33 disposed around the conductor 31. The conductor temperature measuring device comprises a conductor current measuring section 2 for measuring the current value of the current flowing in the conductor 31; a cable temperature measuring section 4 for measuring the temperature of the cable 3 near the part of the conductor 31, where the current value is measured by the conductor current measuring unit 2; and a conductor temperature calculation section 5 for calculating the temperature of the conductor 31, based on the current value measured by the conductor current measuring unit 2, the temperature of the cable measured by the cable temperature measuring section 4, and the thermal resistance of an insulator 33. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a conductor temperature measuring device for measuring the temperature of a conductor covered with an insulator.

  In order to ensure the safety of the cable, time management of the conductor temperature of the cable is required. Conventionally, cable conductor temperature is measured by, for example, (1) acquiring the temperature of the cable at the site, and (2) the value of the current supplied to the cable from a substation that supplies electricity to the cable to be measured. And (3) calculating the conductor temperature from the cable temperature and the current value obtained from the substation.

Further, a clamp-type current measuring device is known as a technique for measuring the current of a cable to be measured (for example, see Patent Document 1).
JP 2006-308492 A

  The cable conductor temperature can be calculated based on the current value obtained from the substation and the cable temperature. However, since there is an error between the current value acquired from the substation and the actual current value at the measurement location, development of a technique capable of calculating a more accurate conductor temperature has been desired.

  According to the clamp type current measuring device, it is possible to measure the current value at the place where the conductor temperature is measured, that is, the actual current value. However, in the prior art, since the current measuring device and the temperature measuring device are separate devices, in order to calculate the conductor temperature, the two devices must be individually loaded and installed at the measurement location, Was complicated. Furthermore, the current value acquired by the current measuring device and the cable temperature acquired by the temperature measuring device have to be input again to the processing device for calculating the conductor temperature, which makes the work complicated.

  The present invention has been made in view of the above-described problems, and relates to a conductor temperature measuring apparatus that can reduce the working time and labor and can obtain a more accurate conductor temperature in the field when measuring the conductor temperature of a cable. It is an issue to provide.

  In the present invention, in order to solve the above-described problem, a single device includes a conductor current measuring unit that measures a current value of a current flowing through a cable conductor, a cable temperature measuring unit that measures a cable temperature, and a conductor current. A conductor temperature calculating means for calculating the conductor temperature of the cable based on the current value measured by the measuring means and the cable temperature measured by the cable temperature measuring means is provided.

  More specifically, the present invention is a conductor temperature measuring device for measuring the temperature of a conductor in a cable having a conductor through which a current flows and a non-conductor portion provided around the conductor, and the current flowing through the conductor A conductor current measuring means for measuring the current value of the cable, a cable temperature measuring means for measuring the temperature of the cable in the vicinity of the portion of the conductor whose current value is measured by the conductor current measuring means, and the conductor current measuring means. Conductor temperature calculation means for calculating the temperature of the conductor based on the measured current value, the cable temperature measured by the cable temperature measurement means, and the thermal resistance of the non-conductor portion.

  The present invention can be used when measuring the temperature of a conductor in a cable in which the conductor is coated with an insulator. Therefore, this invention can be used suitably, for example, when managing the conductor temperature of the cable covered like the underground power transmission line.

  The conductor temperature of the cable can be calculated based on the current value of the current flowing through the conductor, the constituent members other than the conductor constituting the cable, in other words, the thermal resistance of the non-conductor portion, and the cable temperature. A non-conductor part is an insulator etc. which coat | cover a conductor, for example. In the present invention, the current flowing through the conductor covered with the non-conductor portion such as an insulator can be measured by the conductor current measuring means. The cable temperature can be measured by cable temperature measuring means. In addition, the thermal resistance of a nonconductor part can be calculated | required based on the physical property of the member which comprises a nonconductor part.

  It is preferable that the distance between the part for measuring the current value of the current flowing through the conductor and the part for measuring the temperature of the cable is close. This is because if these intervals are wide, if the distance between the cable temperature measuring means and the conductor current measuring means is too wide, the error in the conductor temperature calculated by the conductor temperature calculating means becomes large.

  Here, it is preferable that the temperature of the cable measured by the cable temperature measuring unit is a surface temperature of the cable. The temperature of the cable used when calculating the conductor temperature may be the temperature around the cable. However, in this case, a medium such as soil or air exists between the cable surface and the point at which the temperature is measured. In addition, when there are other cables in the vicinity, they are easily affected by the temperature of the other cables. Furthermore, when the temperature around the cable is used as the cable temperature, it is necessary to consider the thermal resistance of a medium such as soil or air. However, if the cable temperature is calculated using the thermal resistance of such a medium, there is a risk that the error in the calculated cable temperature will increase. Thus, such errors can be reduced by using the cable surface temperature as the cable temperature.

  Further, in the conductor temperature measuring device according to the present invention, the conductor temperature calculating means calculates a heat value of the conductor based on a current value measured by the conductor current measuring means, and calculates the heat value of the calculated conductor and the conductor The loss temperature lost in the non-conductor portion is calculated by calculating the product of the thermal resistance of the non-conductor portion, and the loss temperature lost in the non-conductor portion is calculated as the surface temperature of the cable measured by the cable temperature measuring means. The temperature of the conductor may be calculated by adding.

  In this way, it is possible to measure the surface temperature of the cable as an actual measurement value, and calculate the temperature of the conductor by adding the amount of heat lost in the non-conductor portion, in other words, the loss temperature, to the measured surface temperature of the cable. Become.

  Here, in the conductor temperature measuring device according to the present invention, the conductor current measuring means has a current measuring contact portion that acquires a current value of a current flowing through the conductor in contact with the cable surface, and the cable temperature The measurement means may have a temperature measurement contact portion that acquires the surface temperature of the cable by contacting the cable surface. When the current measurement contact portion in the conductor current measuring means is, for example, a clamp portion, it is easy to attach to the cable and the current value of the conductor can be measured.

In the conductor temperature measuring device according to the present invention, the cable temperature measuring means may be a thermocouple. The cable temperature measuring means is not limited to this. That is, the cable temperature measuring means may be a radiation type that can acquire the temperature in a non-contact manner. However, it is possible to reduce errors by directly acquiring the temperature of the surface of the cable than by acquiring the temperature without contact. Therefore, by using the cable temperature measuring means as a thermocouple, it is possible to obtain a more accurate temperature and, as a result, to measure a more accurate conductor temperature.

  In addition, it is preferable that the temperature measurement contact portion in the cable temperature measurement means has a small thermal resistance. This is because the temperature error can be reduced during measurement. Therefore, the temperature measurement contact section may be provided with a thermal resistance reduction section for reducing the temperature error when acquiring the cable temperature by reducing the thermal resistance of the temperature measurement contact section. The heat resistance reduction part should just be the structure which can reduce heat resistance, The shape is not specifically limited. For example, by making the mesh shape, the thermal resistance can be reduced, and as a result, the temperature error when acquiring the temperature of the cable can be reduced.

  Here, in the conductor temperature measuring device according to the present invention, the non-conductor portion includes an insulator formed around the conductor and a sheath formed around the insulator, and calculates the conductor temperature. The means may calculate the temperature of the conductor in consideration of a current value of a sheath current flowing through the sheath.

  For example, in the case of underground transmission line cables, an aluminum sheath made of aluminum is generally provided around the insulator. And in the cable provided with such an aluminum sheath, since a sheath current is generated, an error may occur in the current value acquired by the current measuring means. Therefore, in the present invention, this error can be corrected by the conductor temperature calculation means taking into account the current value of the sheath current. Therefore, a more accurate conductor temperature can be calculated.

  Further, the conductor temperature measuring device according to the present invention includes an allowable temperature determining means for determining whether or not the conductor temperature calculated by the conductor temperature calculating means exceeds a predetermined allowable temperature, and the allowable temperature determining means. Cumulative time calculation means for calculating a cumulative time when it is determined that the temperature of the conductor exceeds a predetermined allowable temperature, and whether the cumulative time calculated by the cumulative time calculation means exceeds a predetermined time And a notifying means for notifying the determination when the accumulated time is determined to exceed a predetermined time by the accumulated time determining means.

  According to the present invention, it is possible to perform conductor temperature management by including the above-described allowable temperature determination means, accumulated time calculation means, accumulated time determination means, and notification means. In addition, this apparatus, such as the current value measured by the conductor current measuring means, the cable temperature measured by the cable temperature measuring means, the conductor temperature calculated by the conductor temperature calculating means, and the accumulated time calculated by the accumulated time calculating means Display means may be provided for displaying data measured by the method and results calculated by the apparatus. As a result, the user of the conductor temperature measuring device can easily check the temperature of the conductor at the site. The notification by the notification means is not limited to the notification by the display unit. Notification by sound may be used. That is, any means that can transmit information to a person may be used, and the notification method is not limited.

In the conductor temperature measurement device according to the present invention, the non-conductor portion includes an insulator covering the conductor, a sheath provided around the insulator, and an exterior provided around the sheath. Then, the conductor temperature calculating means calculates the heat generation amount Wc of the conductor according to the equation 1 expressed by Wc = (n · Rac) · (I1 / ηo) ² , and expressed as RTh = R1 + (1 + P) · R2. The total thermal resistance RTh of the non-conductor portion is calculated by the following formula 2, and the loss temperature Td due to the dielectric loss in the non-conductor is calculated by the formula 3 represented by Td = Wd (R1 / 2 + R2), You may calculate the temperature T1 of the said conductor by Formula 4 represented by T1 = Wc * RTh + Td + T0. By using the above formulas 1 to 4, the current value of the current flowing through the conductor can be calculated more accurately.

  In Equations 1 to 4, n is the number of core wires of the cable, Rac is an effective thermal resistance of the AC conductor at the always allowable temperature of the conductor, I1 is a current value measured by the conductor current measuring means, and ηo is large. Reduction rate in the case of a constant, R1 is the thermal resistance of the insulator constituting the non-conductor portion, P is the ratio of the loss generated in the sheath to the loss generated in the conductor (heat generation amount Wc of the cable), R2 is the above The thermal resistance of the exterior, Wc is the amount of heat generated by the conductor calculated from Equation 1, RTh is the total thermal resistance of the nonconductor portion calculated from Equation 2, and Td is the dielectric in the nonconductor portion calculated from Equation 3. The loss temperature due to body loss, T0, is the surface temperature of the cable measured by the cable temperature measuring means. The always allowable temperature means an allowable conductor temperature. Further, the number of core wires of the cable is, for example, n = 3 when the cable is a pipe-type cable, and n = 1 when the cable is a single core / triple.

  The conductor temperature measuring device according to the present invention may be provided with a battery unit for operating current measuring means, temperature measuring means, display means and the like. Thereby, the freedom degree of the usage place of a conductor temperature measuring apparatus can be raised.

  In addition, a plurality of conductor temperature measuring devices according to the present invention are provided, the devices are electrically connected to each other, and information such as a current value, a temperature acquired by the conductor temperature measuring device, or a calculated conductor temperature is collectively displayed. A server that can be managed may be provided, and the server and the plurality of conductor temperature measuring devices may be electrically connected. Thereby, collective management of each information acquired by the conductor temperature measuring apparatus is attained. The electrical connection may be either wired or wireless.

  ADVANTAGE OF THE INVENTION According to this invention, when measuring the conductor temperature of a cable, the technique regarding the conductor temperature measuring apparatus which can acquire more exact conductor temperature on-site while reducing work time and work effort can be provided.

  Next, an embodiment of a conductor temperature measuring apparatus according to the present invention will be described with reference to the drawings. In the following description, a conductor temperature measuring device that can be suitably used for time management when performing an overload operation of an ultrahigh voltage underground transmission line (cable) will be described as an example. The overload operation is a provisional overload operation performed in conjunction with provisional circumstances such as repair work of another electric wire route. In the provisional overload operation, when the overload operation is performed exceeding the constantly allowable temperature (90 ° C. or less) of the cable conductor, it is required to perform the time management of the cable conductor short time allowable temperature.

<First embodiment>
(Constitution)
1 and 2 show a schematic configuration of a conductor temperature measuring apparatus according to the present embodiment. The conductor temperature measuring device 1 according to the present embodiment includes a conductor current measuring unit 2 (corresponding to the conductor current measuring means of the present invention) that measures the current value of the current flowing through the conductor 31 of the cable 3, and the surface of the cable 3. A cable temperature measuring section 4 (corresponding to the cable temperature measuring means of the present invention) for measuring temperature, and an arithmetic processing section 5 (corresponding to the conductor temperature calculating means of the present invention) capable of calculating the temperature of the conductor 31. Is provided.

The current measurement unit 2 according to the present embodiment is formed by an annular clamp unit 21 (corresponding to a current measurement contact unit of the present invention) having a hollow portion 23 in a closed state. The clamp portion 21 can be opened and closed (see FIG. 2). The cable 3 is inserted into the hollow part 23 from the opening 22 with the clamp part 21 open, and the clamp part 21 comes into contact with the cable 3 by closing the opening 22 after the cable 3 is inserted. 2 is fixed to the cable 3. Then, the current measurement unit 2 acquires the current value of the current flowing through the conductor 3 via the clamp unit 21. The conductor current measuring unit 2 and the arithmetic processing unit 5 are electrically connected inside the conductor temperature measuring device 1, and the current value acquired by the conductor current measuring unit 2 is transmitted to the arithmetic processing unit 5.

  The cable temperature measuring unit 4 is provided on a part of the inside of the clamp unit 21. The cable temperature measurement unit 4 is provided with a temperature measurement contact unit 41, and the cable temperature measurement unit 4 acquires the surface temperature of the cable 3 through the temperature measurement contact unit 41. The cable temperature measuring unit 4 and the arithmetic processing unit 5 are electrically connected inside the conductor temperature measuring device 1, and the surface temperature of the cable 3 acquired by the cable temperature measuring unit 4 is transmitted to the arithmetic processing unit 5. Is done.

  Note that the temperature measurement contact portion 41 in the present embodiment is formed of a mesh-like thin film. FIG. 3 is a plan view showing the temperature measurement contact portion 41. By making the mesh shape, the thermal resistance of the temperature measurement contact portion 41 can be reduced, and as a result, the accurate surface temperature of the cable 3 can be acquired.

  Next, the arithmetic processing unit 5 will be described. FIG. 4 is a functional block diagram of the arithmetic processing unit 5. The arithmetic processing unit 5 is provided with a central processing unit (hereinafter referred to as CPU) 51 and a memory 52. As shown in the figure, to the CPU 51, the current value of the conductor measured by the conductor current measuring unit 2 and the surface temperature of the cable 3 measured by the cable temperature measuring unit 4 are transmitted, and data for acquiring these data An acquisition unit 53 is provided. In addition, the CPU 51 is provided with a conductor temperature calculation unit 54 that calculates the temperature of the conductor 31 by processing the data acquired by the data acquisition unit 53 based on a predetermined program. A predetermined program for executing the calculation of the temperature of the conductor 31 in the conductor temperature calculation unit 54 can be stored in the memory 52.

  Further, the CPU 51 determines whether or not the temperature of the conductor 31 calculated by the conductor temperature calculation unit 54 always exceeds the allowable temperature (corresponding to the allowable temperature determination means of the present invention). A cumulative time calculation unit 56 (corresponding to the cumulative time calculation means of the present invention) that calculates the total time when it is determined by the allowable temperature determination unit 55 that the temperature of the conductor 31 always exceeds the allowable temperature. An accumulated time determination unit 57 (corresponding to the accumulated time determination unit of the present invention) is provided for determining whether or not the accumulated time exceeds a predetermined time.

  Further, the CPU 51 is provided with a notification unit 58 that notifies the determination when the accumulated time determination unit 57 determines that the accumulated time exceeds a predetermined time. The notification unit 58 notifies a user or the like through video or sound.

  The memory 52 stores a program for the conductor temperature calculation unit 54 to calculate the conductor temperature based on the data acquired by the data acquisition unit 53. The memory 52 can store the temperature history of the conductor 31 calculated by the conductor temperature calculation unit 54. Further, the memory 52 stores information related to the time during overload operation. The accumulated time calculation unit 56 can calculate the accumulated time by adding the times stored in the memory 52.

  The conductor temperature measuring device 1 according to the present embodiment includes a display unit 6 capable of displaying the temperature of the conductor 31 in addition to the conductor current measuring unit 2, the cable temperature measuring unit 4, and the arithmetic processing unit 5 described above, And a battery unit 7.

  The display unit 6 includes a current value of the conductor 31 measured by the conductor current measuring unit 2, a surface temperature of the cable 3 measured by the cable temperature measuring unit 4, a temperature of the conductor 31 calculated by the conductor temperature calculating unit 54, The accumulated time calculated by the accumulated time calculating unit 56 and the result of the determination determined by the accumulated time determining unit 57 are displayed. By displaying these pieces of information on the display unit 6, the user of the conductor temperature measuring device 1 can check the state of the cable 3 and the like on site.

  The battery unit 7 operates the conductor current measuring unit 2, the cable temperature measuring unit 4, the arithmetic processing unit 5 and the like described above. By providing the battery unit 7, the conductor temperature measuring device 1 according to the present embodiment is portable. As a result, the degree of freedom of the place of use of the conductor temperature measuring device 1 according to this embodiment can be expanded.

  The conductor temperature measuring device 1 may be provided with a timer so that the temperature of the conductor 31 is automatically measured periodically. In addition, a plurality of conductor temperature measuring devices 1 are installed at a predetermined location and a server capable of collectively managing the conductor temperatures is provided, and the conductor temperature measuring device 1 and the server are electrically connected to manage the conductor temperature. It is possible to perform time management and the like at the time of performing load operation collectively.

(processing)
Next, the process performed by CPU51 of the conductor temperature measuring apparatus 1 which concerns on this embodiment is demonstrated. FIG. 5 shows a processing flow executed by the CPU 51.

  In step S <b> 01, the data acquisition unit 53 acquires the current value of the conductor 31, the surface temperature of the cable 3, the thermal resistance of the constituent members constituting the cable 3, and the like. When the acquisition of all data necessary for calculating the temperature of the conductor 31 is completed, the process proceeds to step S02.

  In step S02, the conductor temperature calculator 54 calculates the temperature of the conductor 31. Specifically, the calculation unit 54 calculates the temperature T1 of the conductor 31 of the cable 3 by Expression 4 represented by T1 = Wc · RTh + Td + T0. Wc is the amount of heat generated by the conductor 31 (W / cm), RTh is the total thermal resistance (° C. · cm / W) of the cable 3, Td is the temperature rise (° C.) due to dielectric loss in the cable 3, and T0 is the cable. It is the base temperature or ambient temperature of the cable measured by the temperature measuring means. Here, Equation 4 is expanded as follows.

T1 = Wc · RTh + Td + T0
= Wc {R1 + (1 + P) (R2 + R3)} + Wd (R1 / 2 + R2 + R3) + T0
= Wc {R1 + R2 (1 + P)} + Wd (R1 / 2 + R2 + R3) + [R3 {(1+
P) Wc + Wd} + T0] / Cable surface temperature

  The conductor temperature calculation unit 54 individually calculates a value required by Equation 4 such as the heat generation amount (W / cm) of the conductor 31, and processes this according to Equation 4 to finally determine the temperature of the conductor 31. calculate. In the present embodiment, the surface temperature of the cable 3 is used for T0. Therefore, the temperature T1 of the conductor 31 can be calculated from the actually measured value, and the temperature error can be reduced. Hereinafter, the calculation procedure of each value processed by Expression 4 will be described.

The calorific value Wc of the conductor 31 is calculated by Formula 1 represented by Wc = (n · Rac) · (I1 / ηo) ² . n is the number of core wires of the cable 3, Rac is the effective resistance of the AC conductor (Ω / cm) at a constant allowable temperature, I1 is the current value (A) measured by the conductor current measuring unit 2, and ηo is the reduction rate in the case of multiple constants It is. The constantly allowable temperature refers to 90 ° C. or lower in the present embodiment. Further, the number of core wires of the cable is n = 3 when the cable 3 is a pipe type cable, and n = 1 when the cable 3 is a single core / triple.

The total thermal resistance RTh of the cable 3 is calculated by Expression 2 represented by RTh = R1 + (1 + P) · R2. Here, FIG. 6 shows the relationship between the configuration of the cable 3 and the thermal resistance. R 1 is the thermal resistance of the insulator (° C. · cm / W), R 2 is the thermal resistance of the cable sheath 34 (° C. · cm / W), P is the loss generated in the sheath and the loss generated in the conductor 31 (heat generation of the cable) The ratio of the quantity Wc). That is, the total thermal resistance RTh of the cable 3 corresponds to the total thermal resistance of the non-conductor portion of the present invention.
For example, the thermal resistance of the anticorrosion layer of the cable may be used for R2. When the temperature around the cable 3 is used as the temperature of the cable 3, the thermal resistance R3 (° C. · cm / W) of the medium (air, soil, etc.) further interposed between the cable surface and the temperature measurement point Need to be considered. In the present embodiment, the surface temperature of the cable 3 is used as the temperature of the cable 3. Therefore, there is no need to consider the thermal resistance R3, and the temperature error can be reduced accordingly.

  By calculating the product of the calorific value Wc of the calculated conductor 31 and the total thermal resistance RTh of the cable 3, the loss temperature lost in the cable 3 insulator 33 and the exterior 34 is calculated. Further, the loss temperature Td due to the dielectric loss of the cable 3 is calculated by Expression 3 represented by Td = Wd (R1 / 2 + R2).

  Thus, the calculation of the respective values (for example, the heat generation amount (W / cm) of the conductor 31) for calculating the temperature of the conductor 31 by Expression 4 (T1 = Wc · RTh + Td + T0) is completed. Then, each calculated value is processed according to Equation 4, so that the temperature of the conductor 31 is finally calculated. When the temperature of the conductor 31 is calculated, the process proceeds to step S03.

  In step S03, the allowable temperature determination unit 55 determines whether or not the temperature of the conductor 31 calculated by the conductor temperature calculation unit 54 always exceeds the allowable temperature. When it is determined that the calculated temperature of the conductor 31 is always higher than the allowable temperature, the process proceeds to step S04. On the other hand, when it is determined that the calculated temperature of the conductor 31 does not always exceed the allowable temperature, the CPU 1 ends the process.

  In step S04, the accumulated time calculation unit 56 calculates the accumulated time (hereinafter referred to as time t) when the allowable temperature determination unit 55 determines that the temperature of the conductor 31 is always higher than the allowable temperature. The More specifically, the time t is stored in the memory 52 as needed, and the cumulative time calculation unit 56 calculates the cumulative time by adding the time t stored in the memory 52. When the process of step S04 ends, the process proceeds to step S05.

  In step S05, the accumulated time determination unit 57 determines whether or not the accumulated time exceeds a predetermined time. The predetermined time is, for example, an overload operation time of 120 hours per year or an overload operation accumulated time of 3000 hours. If it is determined that the accumulated time exceeds the predetermined time, the process proceeds to step S06. On the other hand, when it is determined that the accumulated time does not exceed the predetermined time, the CPU 1 ends the process.

  In step S06, the notification unit 58 notifies the user or the like of the conductor temperature measuring device 1 that the accumulated time exceeds a predetermined time. The notification may be performed via the display unit 6 or may be performed by providing a speaker and notifying by sound.

  When the processing described above is executed by the CPU 51, the temperature of the conductor 31 is calculated, the accumulated time is calculated, a notification when the accumulated time exceeds a predetermined time, and the like are appropriately performed.

(Sheath current cancellation method)
Next, a method for canceling the sheath current will be described. In measuring the value of the current flowing through the conductor 31 of the cable 3, it is preferable to consider the influence of the sheath current. This is because a more accurate temperature of the conductor 31 can be calculated by considering the influence of the sheath current. Hereinafter, a method for considering the sheath current, in other words, a method for canceling the sheath current will be described.

First, in order to consider the influence of the sheath current, it is necessary to determine whether the current value of the conductor 31 can be measured by the conductor current measuring unit 2 including the ground line connected to the cable 3. When the current value of the conductor 31 including the ground line can be measured, the clamp portion 21 of the conductor current measuring unit 2 is installed so that the current value of the conductor 31 including the ground line can be measured. This is because the current value of the conductor 31 in which the influence of the sheath current is considered in advance can be measured by measuring the current value of the conductor 31 by the conductor current measuring unit 2 including the ground wire.

  7 and 8 show the results of investigating the sheath current effect of the clamp type current sensor. This investigation was conducted on the A and B routes in which a current of 154 kV flows as the target cable. In order to verify the error due to the sheath current, the measurement was performed with an existing clamp-type current sensor with and without the ground wire included. The range of the clamp type current sensor was all 500A.

  As shown in FIGS. 7 and 8, when the current values of the conductors including the ground line are measured for both the route A and the route B, it can be confirmed that the error is smaller than that when the ground line is not included. This means that if the current value of the conductor including the ground line can be measured, the current value of the conductor in which the influence of the sheath current is considered in advance can be measured. Therefore, when the current value of the conductor including the ground line can be measured, it is preferable to measure the current of the conductor including the ground line.

  On the other hand, when the current value of the conductor including the ground line cannot be measured, the influence of the sheath current can be taken into consideration by the following processing.

  First, when there is a ground wire in the vicinity of the measurement location, the current value of the ground wire may be measured in advance and reflected in the current value measured by the conductor current measuring unit 2. That is, assuming that the conductor current value reflecting the current value of the ground wire measured in advance is the calculated conductor current value, the calculated conductor current value is calculated conductor current value = current value calculated by the conductor current measuring unit. (Clamp measurement value) + ground line current value / (current value calculated by the conductor current measurement unit / current value calculated by the conductor current measurement unit (at the time of installation)) . A clamp (at the time of installation) is an electric current value measured when installing a conductor temperature measuring device. The clamp measurement value is a current value obtained continuously after the conductor temperature measurement device is installed. For example, in the first actual measurement and the second actual measurement in FIG. 9, the calculated conductor current value calculated approaches the current value confirmed by the substation by reflecting the current value of the ground wire by the above formula. Can be confirmed. That is, when applied to the present embodiment, the current value measured by the conductor current measuring unit 2 can be corrected. Therefore, it is possible to obtain a more accurate temperature by calculating the temperature of the conductor 31 using the corrected current value, that is, the calculated conductor current value.

  Next, when the measurement including the grounding wire is not possible and there is no grounding wire in the vicinity, the calculated conductor current value is calculated based on the current value obtained at the substation. That is, in this case, the calculated use conductor current value is calculated by the calculation use conductor current value = current value calculated by the conductor current measurement unit + (current value acquired by the substation (when installed) −conductor current measurement unit). Current value (during installation)) · (current value calculated by conductor current measurement unit / current value calculated by conductor current measurement unit (during installation)). For example, in the first actual measurement and the second actual measurement in FIG. 10, by using the current value acquired at the substation, the calculated calculated conductor current value approaches the current value confirmed by the substation. It can be confirmed. That is, when applied to the present embodiment, the current value measured by the conductor current measuring unit 2 can be corrected.

Next, when it is not possible to measure including the grounding wire and the current value of the grounding wire cannot be measured, the calculated conductor current value is calculated using the sheath current design value obtained in advance by numerical calculation. That is, in this case, the calculated conductor current value is calculated conductor current value = current value calculated by the conductor current measuring unit + sheath current design value · (current value calculated by the conductor current measuring unit / (installed design conductor Current value−sheath current design value))) can be calculated (see FIG. 11). This makes it possible to acquire a conductor current that takes into account the influence of the sheath current.

  According to the conductor temperature measuring apparatus 1 described above, the temperature of the conductor 31 can be calculated using the surface temperature of the cable 3, that is, the actually measured value. As a result, it is possible to obtain a more accurate temperature of the conductor 31 than when the temperature of the conductor is calculated using the temperature around the cable. In addition, since the conductor current measuring unit 2, the cable temperature measuring unit 4, and the arithmetic processing unit 5 are provided in one device, transportation and installation are facilitated, and work time and labor are reduced, and an accurate conductor is used on site. It becomes possible to acquire the temperature of 3.

  Furthermore, the conductor temperature measuring device 1 includes an allowable temperature determination unit 55, an accumulated time calculation unit 56, an accumulated time determination unit 57, and a notification unit 58, so that time management is easily performed when the cable 3 is overloaded. be able to.

  In the present embodiment, the conductor current measuring unit 2 and the cable temperature measuring unit 4 are integrally formed. However, the conductor temperature measuring apparatus according to the present invention is not limited to this. FIG. 12 shows a schematic configuration of a conductor temperature measuring apparatus according to another embodiment. The basic configuration of the conductor temperature measuring apparatus 1a according to the embodiment shown in FIG. 12 is the same as that of the conductor temperature measuring apparatus 1 according to the embodiment shown in FIGS. However, the conductor temperature measuring device 1a is different in that the conductor current measuring unit 2 and the cable temperature measuring unit 4 are electrically connected by cables 8 provided outside the conductor temperature measuring device 1a. Different from the device 1. The conductor temperature measuring device 1 in which the conductor current measuring unit 2 and the cable temperature measuring unit 4 are integrally formed is very easy to carry. However, when the diameter of the cable 3 is large, the size of the device itself is increased, the weight of the device itself is increased, and it may be difficult to clamp. In such a case, it becomes easy to attach to the cable 3 by adopting a configuration like the conductor current assumption device 1a. The arithmetic processing unit 5 can be installed on the ground. That is, the arithmetic processing unit 5 can be installed in a stable place.

  As mentioned above, although preferred embodiment of this invention was described, the conductor temperature measuring apparatus which concerns on this invention can include these combinations as much as possible not only in these.

The schematic structure of the conductor temperature measuring apparatus of the state which closed the clamp part is shown. The schematic structure of the conductor temperature measuring apparatus of the state which opened the clamp part is shown. It is a top view which shows the contact part for temperature measurement. It is a functional block diagram of an arithmetic processing part. The processing flow performed by CPU is shown. The relationship between the cable configuration and each resistance is shown. The sheath current influence investigation result of a clamp type current sensor is shown. The sheath current influence investigation result of a clamp type current sensor is shown. The calculation result of the current value in consideration of the influence of the sheath current is shown. The calculation result of the current value in consideration of the influence of the sheath current is shown. The calculation result of the current value in consideration of the influence of the sheath current is shown. The schematic structure of the conductor temperature measuring apparatus which concerns on other embodiment is shown.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Conductor temperature measuring device 2 ... Conductor current measuring part 3 ... Cable 4 ... Cable temperature measuring part 5 ... Arithmetic processing part 6 ... Display part 7 ... Battery part 51. ..CPU
52 ... Memory 53 ... Data acquisition unit 54 ... Conductor temperature calculation unit 55 ... Allowable temperature determination unit 56 ... Accumulated time calculation unit 57 ... Accumulated time determination unit 58 ... Notification unit

Claims (9)

A conductor temperature measuring device for measuring a temperature of the conductor in a cable having a conductor through which a current flows and a non-conductor portion provided around the conductor;
Conductor current measuring means for measuring a current value of a current flowing through the conductor;
A cable temperature measuring means for measuring the temperature of the cable in the vicinity of the portion of the conductor whose current value is measured by the conductor current measuring means;
Conductor temperature calculating means for calculating the temperature of the conductor based on the current value measured by the conductor current measuring means, the cable temperature measured by the cable temperature measuring means, and the thermal resistance of the non-conductor portion. When,
A conductor temperature measuring device comprising:   The conductor temperature measuring device according to claim 1, wherein the cable temperature measured by the cable temperature measuring means is a surface temperature of the cable. The conductor temperature calculating means includes
The amount of heat generated by the conductor is calculated based on the current value measured by the conductor current measuring means, and the product of the calculated amount of heat generated by the conductor and the thermal resistance of the non-conductor portion is obtained. Calculate the loss temperature
The conductor temperature measuring device according to claim 2, wherein the temperature of the conductor is calculated by adding a loss temperature lost in the non-conductor portion to the surface temperature of the cable measured by the cable temperature measuring means. The conductor current measuring means has a current measurement contact portion for obtaining a current value of a current flowing through the conductor in contact with the cable surface,
The conductor temperature measuring device according to claim 2, wherein the cable temperature measuring unit includes a temperature measuring contact portion that acquires a surface temperature of the cable by contacting the cable surface.   The conductor temperature measuring device according to any one of claims 1 to 4, wherein the cable temperature measuring means is a thermocouple.   The conductor temperature measuring device according to claim 5, wherein the temperature measuring contact portion of the cable temperature measuring means made of a thermocouple includes a thermal resistance reducing portion that reduces the thermal resistance of the temperature measuring contact portion. The non-conductor portion has an insulator formed around the conductor, and a sheath formed around the insulator,
The conductor temperature measuring device according to any one of claims 1 to 6, wherein the conductor temperature calculation means calculates the temperature of the conductor further considering a current value of a sheath current flowing through the sheath. Allowable temperature determining means for determining whether or not the conductor temperature calculated by the conductor temperature calculating means exceeds a predetermined allowable temperature;
A cumulative time calculating means for calculating a cumulative time when it is determined by the allowable temperature determining means that the temperature of the conductor exceeds a predetermined allowable temperature;
Cumulative time determination means for determining whether or not the cumulative time calculated by the cumulative time calculation means exceeds a predetermined time;
Notification means for notifying the determination when the accumulated time is determined by the accumulated time determining means to exceed a predetermined time;
The conductor temperature measuring device according to any one of claims 1 to 7, further comprising: The non-conductor portion has an insulator formed around the conductor, a sheath formed around the insulator, and an exterior provided around the sheath,
The conductor temperature calculating means includes
Wc = (n · Rac) · (I1 / ηo) ² Calculates the heat generation amount Wc of the conductor according to the formula 1 represented by ² ;
The total thermal resistance RTh of the non-conductor portion is calculated by Equation 2 represented by RTh = R1 + (1 + P) · R2,
According to Equation 3 represented by Td = Wd (R1 / 2 + R2), a loss temperature Td due to dielectric loss in the nonconductor is calculated.
The temperature T1 of the conductor is calculated by Equation 4 represented by T1 = Wc · RTh + Td + T0,
In Equations 1 to 4, n is the number of core wires of the cable, Rac is an AC conductor effective thermal resistance at a constantly allowable temperature of the conductor, I1 is a current value measured by the conductor current measuring means, and ηo is a multi-constant value. Reduction ratio, R1 is the thermal resistance of the insulator constituting the non-conductor portion, P is the ratio of the loss generated in the sheath to the loss generated in the conductor, R2 is the thermal resistance of the exterior, and Wc is the formula 1 The amount of heat generated by the conductor calculated from the equation (2), RTh is the total thermal resistance of the non-conductor portion calculated from Equation 2, Td is the loss temperature due to dielectric loss in the non-conductor portion calculated from Equation 3, and T0 is the temperature The surface temperature of the cable measured by the cable temperature measuring means,
The conductor temperature measuring device according to claim 1.

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