JP5066465B2 - Installation structure of oil level sensor for existing cable oil tank - Google Patents

Description

The present invention relates to a mounting structure of the existing cable oil tank for oil quantity sensor, in particular, data for remote monitoring is obtained by the simple structure, the oil amount for the existing cable oil vessel which can be provided easily in existing OF cable oil vessel the present invention relates to a mounting structure of the sensor.

  The OF cable (Oil Filled Cable) has a constant hydraulic pressure from the oil tank to prevent the insulation of the insulation paper impregnated with the sheath and oil from expanding and contracting due to changes in the current flowing through the conductor, and breaking the cable. The oil is supplied to the inside of the cable.

  As such an oil tank, for example, a pipe-type oil level gauge for checking the amount of oil in the oil tank is provided, and in order to prevent cable insulation breakdown accidents due to oil leakage etc., the upper and lower limits of the oil amount are set. Some have provided an alarm transmitter for issuing an alarm.

  Since oil leakage not only causes insulation breakdown accidents in OF cables, but also leads to environmental destruction, early detection of oil leakage and its repair are social responsibilities. In addition, many OF cables have passed over 30 years since installation, and there is an increasing need for monitoring the oil amount and hydraulic pressure in order to extend the life.

  Such a request can be dealt with by remodeling an existing oil tank and attaching a sensor (ultrasonic type, capacitance type, etc.) for monitoring the oil amount. However, since it is necessary to temporarily stop fueling and a large-scale remodeling of the oil tank is required, there are few examples of adoption.

  When a metal tube level meter (mag gauge) is used as the oil level gauge, the resolution as an oil level sensor is about 10 mm, but this performance is insufficient for monitoring the oil amount. Further, when a sensor having a high resolution such as a Hall element or an optical sensor is used, an increase in cost is inevitable.

In order to solve such problems, for example, an oil level gauge that can visually check the amount of oil in the oil tank is provided from the outside, and a capacitance level meter is installed on the oil level gauge and output from this level meter. There is an oil level gauge for cable lubrication that is remotely monitored by an electrical signal (for example, see Patent Document 1).
Japanese Utility Model Publication No. 4-79226

  However, according to the conventional oil level gauge, the structure is complicated, and fine adjustment is required to operate the oil level gauge normally and accurately, so that there are problems that the work of installation and adjustment becomes complicated.

Accordingly, an object of the present invention, data for remote monitoring is obtained by a simple structure, is to provide an existing cable oil bath oil amount sensor mounting structure that can be provided easily in existing OF cable oil vessel .

In order to achieve the above object, the present invention provides a cylindrical storage case for introducing oil to be supplied to an OF cable and a magnetic force source that is stored in the storage case and moves up and down according to the oil level of the oil. propagation and float with the permanent magnet, the ultrasonic waves generated on the basis of the float in the magnetic field produced by the magnetic field and current from the permanent magnet that changes according to the movement of the float while supporting vertically movably within said housing case An oil amount sensor for an existing cable oil tank provided with a probe to be provided, and a detection unit that is provided at one end of the probe and detects the ultrasonic wave generated in the probe;
And visible existing oil level gauge the amount of the oil stored in the existing oil tank for storing the oil from the outside, a first existing piping connecting the existing oil level gauge on the outside of the existing oil tank, the existing A second pipe branched from the first existing pipe outside the oil tank and connected to the storage case of the oil amount sensor for the existing cable oil tank;
Oil and the existing cable the storage case of the oil tank oil level sensor and the existing oil level gauge is to adjust the position of the second piping so that is disposed vertically and in parallel, is introduced into the storage case The height of the surface is configured such that the position can be adjusted to be the same as the height of the oil level of the existing oil level gauge, and based on the ultrasonic waves detected by the detection unit of the oil amount sensor for the existing cable oil tank The oil for the existing cable oil tank is characterized in that the distance from the detection unit to the permanent magnet of the float or the oil amount in the existing oil tank based on the distance or the oil level height of the existing oil level gauge is obtained. A mounting structure for a quantity sensor is provided.

  According to the present invention, data for remote monitoring can be obtained with a simple structure, and a sensor can be easily provided in an existing OF cable oil tank.

  FIG. 1 is a diagram illustrating an example of an oil amount measurement system according to an embodiment of the present invention.

(Configuration of oil quantity measurement system)
This oil amount measurement system 100 stores oil supplied to an underground cable for transmission (not shown) and is connected in parallel to an oil tank 1 having a tubular oil level gauge 2 on a side wall and the oil level gauge 2. Magnetostrictive oil amount sensor 3 provided in the state, terminal box 6 connected to magnetostrictive oil amount sensor 3 via signal line 8A, and alarm receiver panel connected to terminal box 6 via signal line 8B 7 and a measuring device 10 installed in the apparatus. The terminal box 6 is not necessarily required, and may be installed as necessary.

  Here, the oil tank 1 is an existing oil tank, and the oil level gauge 2 is attached at the time of shipment from the factory, but there is no equivalent to the magnetostrictive oil amount sensor 3 of the present embodiment, and a magnetostrictive type. The oil amount sensor 3 is attached at a later date.

  The alarm receiving board 7 is installed in a management office or the like away from the oil tank 1 and is a facility having a function of monitoring the state of the OF cable and the oil tank 1.

  FIG. 2 is a diagram illustrating an example of the configuration of the oil level gauge and the magnetostrictive oil amount sensor. FIG. 3 is a diagram showing an example of the configuration of the main part of the magnetostrictive oil amount sensor.

(Configuration of oil level gauge 2)
The oil level gauge 2 is a level gauge already provided on the side wall of the oil tank 1 shown in FIG. 1, and the oil 20 in the oil tank 1 is introduced into a metal pipe (chamber) 21. In front of the oil level gauge 2, there is a window 22 formed of a transparent material such as glass so that the oil level 1 a in the oil tank 1 can be identified. The window 22 is provided with a scale (for example, 1 cm unit) (not shown) indicating the level of the oil level 1a.

  The oil level gauge 2 has holders 23A and 23B attached to both ends, and the holders 23A and 23B are fixed to the side wall surface of an oil tank (not shown) with screws. The holders 23 </ b> A and 23 </ b> B have a cavity as a first pipe (not shown) communicating with the metal pipe 21 at the center, and the oil 20 is introduced from the oil tank 1 through the cavity.

  Connectors 24A and 24B having hollow portions communicating with the cavities of the holders 23A and 23B are coupled to the holders 23A and 23B, and the connectors 24A and 24B are connected pipes made of 3 / 8A SUS pipes. One end of 25A, 25B is connected. The other ends of the connection pipes 25A and 25B are connected to the magnetostrictive oil amount sensor 3. Valves 26A and 26B for introducing / blocking the oil 20 with respect to the magnetostrictive oil amount sensor 3 are provided in the middle of the connection pipes 25A and 25B.

(Configuration of magnetostrictive oil amount sensor 3)
The magnetostrictive oil amount sensor 3 includes a cylindrical storage case 31 formed of a SUS pipe connected to the other ends of the connection pipes 25A and 25B, and an oil level 1a in the storage case 31 attached to the upper end of the storage case 31. , A probe 33 to which a current pulse P is applied from a current pulse generator (not shown) provided inside the detection unit 32, and a probe having a permanent magnet built in and supported by the probe 33. 33 includes a float 34 movably provided in the vertical direction, and a terminal portion 35 provided at an end of the detection unit 32, and is provided side by side with the existing oil level gauge 2 described above. Further, the magnetostrictive oil amount sensor 3 is connected in parallel to the oil level gauge 2 via connection pipes 25A and 25B as second pipes branched from the connectors 24A and 24B which are part of the pipe of the oil level gauge 2. The oil level 1a of the oil 20 that is connected and introduced into the storage case 31 is adjusted in position and configured to be the same height as the oil level 1a in the metal pipe 21 of the oil level gauge 2.

  The magnetostrictive oil amount sensor 3 is based on a magnetic field generated by a permanent magnet as a magnetic source built in the float 34 and a current pulse P applied from a current pulse generator provided inside the detection unit 32. By measuring the propagation speed of the ultrasonic wave accompanying the torsional strain generated in the storage case 31, the oil level of the oil 20 introduced into the storage case 31 can be measured. The operating temperature range of the magnetostrictive oil amount sensor 3 of the present embodiment is -20 to 80 ° C., the pressure resistance property is 35 MPa, the nonlinearity is ± 0.025 FS, and the resolution is 0.01% FS or less.

  The detection unit 32 includes, for example, a coil wound around the probe 33, a current pulse generator, and a signal processor. The detection unit 32 generates ultrasonic waves generated when the current pulse P is applied to the probe 33 from the current pulse generator. It is detected electrically with a signal processor.

  The probe 33 is formed by processing a material having conductivity, corrosion resistance and magnetic sensitivity, for example, stainless steel (SUS304, SUS316, etc.) into a rod shape.

  The float 34 has, for example, a case portion 34B formed by bending a SUS material, and is formed so as to have a through-hole through which the probe 33 can be inserted in the center of the case portion 34B. The base material 34 </ b> A and the permanent magnet 341 are fixed to each other so as to float on the oil level in the storage case 31. The float 34 shown in FIG. 3 is provided with two symmetrical permanent magnets 341 that are symmetrical about the probe 33. The float 34 may be a permanent magnet 341 incorporated in an oil-resistant engineering plastic such as polyacetal. In the present embodiment, the float 34 is formed with a specific gravity of 0.53 and a diameter of 28 mm, and the storage case 31 is formed with a diameter of 32 mm.

  The terminal part 35 is connected to a signal line 8A connected to the measuring apparatus 10.

(Configuration of measuring apparatus 10)
FIG. 4 is a block diagram showing the configuration of the measuring apparatus.

  The measuring apparatus 10 includes a calculation unit 11 that performs calculation processing on a detection signal output from the detection unit 32 of the magnetostrictive oil amount sensor 3, and a storage unit that stores a program for causing the calculation unit 11 to perform calculation processing and a table 12a. 12 and a display unit 13 for displaying the calculation result of the calculation unit 11 on a display panel such as a liquid crystal display (LCD) as the oil level height. The calculation unit 11 includes a control unit that executes calculation processing according to a preset program.

  The detection unit 32 includes a current pulse generator 4A that generates a current pulse P, and a signal processor 4B that detects ultrasonic waves generated in the probe 33 based on application of the current pulse P. The detection unit 32 is configured to automatically generate a current pulse P with a constant period from the current pulse generator 4A when a voltage is supplied from a power source (not shown). The position information of the float 34 generated at 33 is continuously output as an analog signal.

  The storage unit 12 is configured by, for example, a non-volatile semiconductor memory, and has a data logger that records the calculation results and temperature data such as the outside air temperature and the oil temperature in addition to the data of the table 12a. The table 12 a has the oil amount per unit length of the existing oil level gauge 2 and the characteristic values (measurement length and output value) of the magnetostrictive oil amount sensor 3.

(Mounting method of magnetostrictive oil quantity sensor 3)
For example, when the magnetostrictive oil amount sensor 3 of the present embodiment is attached to an existing oil tank 1 in a substation or the like, first, as shown in FIG. One end of the connection pipes 25A and 25B, to which the valves 26A and 26B are already attached, is connected to the connectors 24A and 24B, and the storage case 31 of the magnetostrictive oil amount sensor 3 is connected to the other end of the connection pipes 25A and 25B. When the magnetostrictive oil amount sensor 3 is attached to the oil level gauge 2, the state may be a state where the magnetostrictive oil amount sensor 3 is completed, or in a state where the storage case 31 and other members are divided. There may be. In the divided state, after attaching the storage case 31, the detector 32, the probe 33, and the float 34 are sequentially attached to the storage case 31.

(Operation of oil quantity measurement system)
FIG. 5 is a diagram illustrating the operating principle of the magnetostrictive oil amount sensor. 5 will be described based on the probe 33 and one permanent magnet 341 in order to simplify the description. Hereinafter, the operation of the oil amount measurement system of the present embodiment will be described with reference to FIGS. 1 to 5.

  The current pulse generator 4 provided in the detection unit 32 generates a current pulse P by a rectangular wave based on the application of the voltage, and applies the current pulse P to the probe 33. Thereby, the current generated by the current pulse P causes the probe 33 to generate a circumferential magnetic field C.

  As shown in FIG. 5, an axial magnetic field D is applied to the probe 33 from a permanent magnet 341 provided inside the float 34. In contrast to this axial magnetic field D, the circumferential magnetic field C generated in the probe 33 by the current pulse P generates an oblique synthetic magnetic field E.

  The synthetic magnetic field E causes the probe 33 to generate local torsional distortion called the Wiedemann effect. This torsional distortion becomes an ultrasonic wave Sb and propagates on the probe 33 toward the both ends of the probe 33 at the speed of sound.

  FIG. 6 is a diagram schematically showing the operation of the magnetostrictive oil amount sensor. The ultrasonic wave Sb generated in the probe 33 and reaching the upper end of the probe 33 is detected as an analog detection signal by the signal processor 4 </ b> B inside the detection unit 32. The current pulse generator 4 generates a current pulse P. The time when the current pulse P reaches the permanent magnet 341 is t1, the speed is V1, and the probe 33 is detected by the magnetic field generated by the permanent magnet 341 and the magnetic field based on the current pulse P. When the time until the ultrasonic wave Sb is generated and reaches the signal processor 4B is t2, and the speed is V2, the distance L from the end face of the detection unit 32 to the permanent magnet 341 is L = V1 × t1 = V2. Xt2 (m).

  On the other hand, the time t from when the current pulse P generated by the current pulse generator 4 is applied to the probe 33 until the ultrasonic wave Sb is detected by the signal processor 4B is t = t1 + t2. Since t1 = L / V1 and t2 = L / V2, t = L / V1 + L / V2. Furthermore, since the speeds of the current pulse P and the ultrasonic wave Sb are V1 >> V2, t≈L / V2. Therefore, the distance L to the permanent magnet 341 can be obtained by L≈V2 × t.

  The detection unit 32 detects the value of the distance L as an analog signal corresponding to the type of the magnetostrictive sensor 3 by the signal processor 4B, and the signal of the measuring device 10 is detected via the signal line 8A, the terminal box 6, and the signal line 8B. Output to the calculation unit 11. This detection signal is, for example, a voltage value of 1 to 5 V and a current value of 4 to 20 mA.

  The calculation unit 11 refers to the conversion data in the table 12a, calculates the distance L to the permanent magnet 341, and converts it into an oil amount. This conversion can be performed by the oil amount display value of the existing oil level gauge 2, the oil amount per unit length, and the characteristic values (measurement length, output value) of the magnetostrictive oil amount sensor 3.

  FIG. 7 is a diagram showing output characteristics of the magnetostrictive oil quantity sensor with respect to the reading value of the oil level gauge. The output of the magnetostrictive oil amount sensor 3 is the oil level height obtained by the measuring device 10 based on the ultrasonic wave Sb generated in the probe 33. It can be seen that the magnetostrictive oil amount sensor 3 of the present embodiment can measure without error over the entire area with respect to the reading value of the oil level gauge 2 provided together.

  FIG. 8 is a diagram showing the followability of the magnetostrictive oil quantity sensor with respect to the oil quantity change in the oil tank. About the responsiveness with respect to an oil amount change, it measured about the oil amount change based on throwing in the oil 20 of 50 liters per minute. The magnetostrictive oil amount sensor 3 of the present embodiment has a time t1 from the start of oil 20 addition until the oil level becomes stable, which is about 1 minute 30 seconds, and it has been confirmed that the follow-up has no practical problem. It was.

  In addition, when the oil level height data recorded in the data logger of the recording unit 12 is compared with the reading value of the oil level gauge 2 every month, it is almost the same within an error range of ± 1 liter, There was no change in the oil amount detectability with respect to changes in the outside air temperature and the oil temperature. From this, it was confirmed that the long-term performance has stable detectability.

(Effect of embodiment)
According to the present embodiment, the following effects are obtained.
(1) A storage case 31 is provided via a connecting pipe branched from a pipe connected to the oil level gauge 2 by installing a magnetostrictive oil amount sensor 3 on the oil level gauge 2 provided outside the existing oil tank 1 by bolt-on. Since the oil 20 is introduced into the oil tank, the oil amount data can be transmitted to a remote place easily and at low cost without modifying the oil tank 1 itself.
(2) Since the oil amount data of the existing oil tank 1 can be easily obtained as an analog value at a location away from the oil tank 1, the OF cable can be monitored finely and maintenance efficiency can be improved.
(3) When the magnetostrictive oil amount sensor 3 is provided, it is only necessary to provide the oil surface 1a so that the height of the oil surface 1a is the same as that of the oil surface 1a of the oil level gauge 2, so that troublesome adjustment work is unnecessary. Oil leakage due to additional construction to the oil tank 1 is difficult to occur.

  In the above-described magnetostrictive oil amount sensor 3, the present inventors have confirmed that there is a difference in followability to changes in the oil amount depending on the volume of the storage case 31 and the oil flow resistance of the connecting pipes 25A and 25B. In this embodiment, when the storage case 31 is formed of a SUS pipe having a diameter of 32 mm and the connection pipes 25A and 25B are formed of SUS pipes of 3 / 8A based on this fact, good followability to changes in the oil amount can be obtained. It was.

  The present invention can be applied not only to an oil tank for power cables but also to a general tank or the like provided with an external oil level gauge such as a glass tube. If the oil level 1a of the magnetostrictive oil level sensor 3 and the oil level 1a of the oil level meter 2 are the same, the magnetostrictive oil level sensor 3 and the oil level meter 2 are not provided close to each other. Good.

FIG. 1 is a diagram illustrating an example of an oil amount measurement system according to an embodiment of the present invention. FIG. 2 is a diagram illustrating an example of the configuration of the oil level gauge and the magnetostrictive oil amount sensor. FIG. 3 is a diagram illustrating an example of a configuration of a main part in the magnetostrictive oil amount sensor. FIG. 4 is a block diagram showing the configuration of the measuring apparatus. FIG. 5 is a diagram illustrating the principle operation of the magnetostrictive oil amount sensor. FIG. 6 is a diagram schematically showing the operation of the magnetostrictive oil amount sensor. FIG. 7 is a diagram showing output characteristics of the magnetostrictive oil quantity sensor with respect to the reading value of the oil level gauge. FIG. 8 is a diagram showing the followability of the magnetostrictive oil quantity sensor with respect to the oil quantity change in the oil tank.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Oil tank, 1a ... Oil level, 2 ... Oil level meter, 3 ... Magnetostrictive oil quantity sensor, 4A ... Current pulse generator, 4B ... Signal processor, 6 ... Terminal box, 7 ... Alarm receiving board, 8A, 8B Signal line, 10 Measurement device, 11 Calculation unit, 12 Storage unit, 12a Table, 13 Display unit, 21 Metal tube, 22 Window, 23A, 23B Holder, 24A, 24B Connector, 25A, 25B ... Connection piping, 26A, 26B ... Valve, 30 ... After installation, 31 ... Storage case, 32 ... Detection part, 33 ... Probe, 34 ... Float, 35 ... Terminal part, 100 ... Oil quantity measurement system, 341 ... permanent magnet

Claims (4)

A cylindrical storage case that introduces oil to be supplied to the OF cable, a float that is accommodated in the storage case and moves up and down according to the oil level of the oil, and has a permanent magnet that serves as a magnetic source; and the float Provided at one end of the probe, and a probe for propagating ultrasonic waves generated based on a magnetic field from the permanent magnet that changes according to the movement of the float and a magnetic field generated by energization while supporting the storage case so as to be movable up and down. And an oil amount sensor for an existing cable oil tank provided with a detection unit for detecting the ultrasonic wave generated in the probe,
And visible existing oil level gauge the amount of the oil stored in the existing oil tank for storing the oil from the outside, a first existing piping connecting the existing oil level gauge on the outside of the existing oil tank, the existing A second pipe branched from the first existing pipe outside the oil tank and connected to the storage case of the oil amount sensor for the existing cable oil tank;
Oil and the existing cable the storage case of the oil tank oil level sensor and the existing oil level gauge is to adjust the position of the second piping so that is disposed vertically and in parallel, is introduced into the storage case The height of the surface is configured so that the position can be adjusted to be the same as the height of the oil level of the existing oil level gauge,
The distance from the detection unit to the permanent magnet of the float based on the ultrasonic wave detected by the detection unit of the oil amount sensor for the existing cable oil tank , or the oil amount in the existing oil tank based on the distance, or the existing oil mounting structure of the existing cable oil tank oil level sensor, characterized in Rukoto oil surface height of the surface meter is required. The distance L from the detection unit to the permanent magnet of the float is generated by the probe when the current pulse P generated from the current pulse generator reaches the permanent magnet at time t1, the velocity of the current pulse P is generated by V1, and the probe. When the time until the ultrasonic wave Sb reaches the signal processor is t2, and the velocity of the ultrasonic wave Sb is V2,
L = V1 × t1 = V2 × t2 (m)
And
The time t until the ultrasonic wave Sb generated by the probe is detected by the signal processor when the current pulse P generated by the current pulse generator is applied to the probe is t = t1 + t2, and the distance L is
  L ≒ V2 × t
The mounting structure of the oil amount sensor for an existing cable oil tank according to claim 1, wherein the structure is obtained by a calculation unit of a measuring device connected to the detection unit. 3. The existing cable according to claim 1, wherein the oil amount in the existing oil tank is obtained by converting the distance L into an oil amount by a calculation unit of a measuring device connected to the detection unit. Mounting structure of oil level sensor for oil tank. The oil level height of the existing oil level gauge is obtained by calculating the distance L by a calculation unit of a measuring device connected to the detection unit. Mounting structure for cable oil level sensor.

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