JP2807409B2 - Check device for complete bridge type oil leak point measuring device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a check device of a complete bridge type oil leak point measuring device for measuring an oil leak position of an OF cable.

[0002]

2. Description of the Related Art Various devices have been proposed for measuring the oil leak position of an OF cable. Among them, there is a complete bridge type oil leak point measuring device which can easily correct a measurement error due to a temperature change (see Japanese Patent Application No. 55-51643). This complete bridge type oil leak point measuring device 10 is shown in FIG.
The configuration is as shown in FIG. That is, the measuring device 10
Is a first resistance oil passage 16 connected between the pressure oil tank 12 and the first sound cable 14.
A second resistance oil passage 20 connected between the pressure oil tank 12 and the cable 18 to be measured;
And a differential pressure gauge 24 connected between a connection point 22a between the first resistance oil passage 16 and the connection point 22a between the cable under test 18 and the second resistance oil passage 20. The first and second resistance oil passages 16 and 20 are composed of oil flow pipes having a sufficiently small oil flow resistance as compared with the cables 14 and 18, and the second resistance oil passage 20 is of a variable oil flow resistance type. . The cables 14 and 18 communicate with each other through a communication pipe 25.

Next, the operation of the measuring instrument 10 will be described. The resistance values of the first and second resistance oil passages 16 and 20 are represented by r ₁ and r ₂ , the length of each cable 14 and 18 is represented by L, and from the connection point 22a of the cable 18 to be measured to the leak position 18a. Is the distance x. Then, in an equilibrium state of the bridge constituted by the first and second resistance oil passages 16 and 20 and the cables 14 and 18 (a state where the indication of the differential pressure gauge 24 is zero), x = r ₂ / (r ₁ + r) ₂ ) × 2L (1) This equation holds when there is no temperature change during cable measurement.

By the way, the hydraulic pressure of a cable changes according to the temperature of the cable, and the change occurs when the amount of compensation for the expansion and contraction of the insulating oil in the cable accompanying the rise and fall of the temperature flows through a passage in the cable. It is proportional to the product of the flow rate and the oil flow resistance of the oil passage. Assuming that the temperature change causes a change g in the amount of oil per unit time in the cables 14 and 18, as described above, r ₁ and r ₂ are sufficiently smaller than the oil flow resistance of the cable. It is known that approximately includes a differential pressure of g (r ₁ -r ₂ ) (2). Therefore, the third resistance oil passage 28 is inserted in series with the remaining one-phase cable 26 of the three phases, and the third resistance oil passage 28 is changed according to the change of the resistance value r ₂ of the second resistance oil passage 20. The resistance value of 28 is r ₁ -r ₂
, The differential pressure gauge 30 shown in the equation (2) is displayed on the correction differential pressure gauge 30. Thus, the differential pressure gauge 2
4 and the difference in readings between the correction differential pressure gauge 30 can be obtained leakage oil position 18a of the temperature-corrected from the value of the resistance value r ₂ when the zero. When using this complete bridge type oil leak point measuring device on site, it is necessary to check the operating function of the measuring device itself in advance. Conventionally, 3
This check was performed by connecting the synthetic resin pipe to the resistance oil passage of the measuring instrument in a simulated manner.

[0005]

However, when a pipe made of synthetic resin is connected and an oil leak point measuring device is checked, since the pipe made of synthetic resin is generally electrically insulative, power is supplied to the pipe. Can't change the oil temperature. In this case, the oil temperature can be changed by putting a pipe in the water tank and heating it, or by putting warm water in the water tank, but this will cause unevenness in the oil temperature distribution and will work satisfactorily as a check device. There was a problem not to do.

[0006]

SUMMARY OF THE INVENTION The present invention provides a check device for a complete bridge type oil leak point measuring device which solves the above-mentioned problems. A check device, comprising a predetermined number of metal pipes including a single metal pipe provided with a simulation oil leak point, said metal pipe having an oily point at one end through an insulating joint. A measuring instrument is attached, and the metal pipe is connected to a power supply for electric heating.

[0007]

By using the above-described check device of the oil leak point measuring device, the current flowing through the metal pipe connected to the oil leak point measuring device is changed, so that the metal pipe is filled by resistance heating of the metal pipe. Since the temperature of the insulating oil can be changed, even if the change in oil pressure due to leakage and the change in oil pressure due to temperature coexist, the oil pressure change due to temperature change is corrected and the oil leak point is determined. The check of the leak point measuring device can be performed.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on embodiments shown in the drawings. FIG. 1 is an explanatory view of a check device of a complete bridge type oil leak point measuring device according to the present invention. In the figure, the same reference numerals are used for the same portions as those in FIG.
In the figure, 1 is a check device, 2a, 2b, 2c are copper tubes, 3
Is an insulating joint, and 4 is a lead wire for electrically connecting the copper tube. As shown in FIG. 1, in this embodiment, three copper pipes 2a, 2b, and 2c are connected to an oil leak point measuring device 10 via an insulating joint 3 and a copper pipe 2d. Three copper tubes 2a, 2b,
One of the copper pipes 2c is provided with a simulation valve 5 which becomes an oil leak point. These three copper tubes 2a, 2b, 2
“c” is electrically connected in series with a lead wire 4, and further connected to a sliding voltage regulator 7 serving as a power supply for energization and heating with an energization lead wire 6. The electrical connection between the copper tubes 2b and 2c may be shared by the metal communication tube 25 in FIG. 2 used in the description of the related art.

The check of the oil leak point measuring device is performed in the following procedure. 1) Fill the three copper tubes 2a, 2b, 2c with insulating oil. 2) Next, the valve 5 is adjusted to cause oil leakage, the resistance value r ₂ of the second resistance oil passage 20 is changed, and the bridge is balanced (the indication of the differential pressure gauge 24 is set to zero). The position of the oil leak point (valve 5) when there is no temperature change is checked according to the above-mentioned equation (1). 3) Then, current is applied to the three copper tubes 2a, 2b, 2c through the lead wires 4, 6 while adjusting the voltage with the sliding type voltage regulator 7, and the temperatures of the copper tubes 2a, 2b, 2c are reduced. When the temperature is increased by resistance heating, the temperature of the filled insulating oil also increases. Then, an oil flow is generated, but the resistance value of the third resistance oil passage 28 is changed to be r ₁ -r ₂ , and the difference between the values indicated by the differential pressure gauge 24 and the correction differential pressure gauge 30 becomes zero. to check the position of the leakage oil point (valve 5) from the resistance value r ₂ of the time. In the present invention, the metal pipe is not limited to a copper pipe, but may be aluminum. Further, the number of metal pipes is not limited to three.

[0010]

As described above, according to the present invention, there is provided a check device for a complete bridge type oil leak point measuring device for a single-core three-phase cable, comprising a single metal member provided with a simulation oil leak point. It consists of a predetermined number of metal pipes including a pipe, and the metal pipe has the oil leak point measuring device attached to one end thereof through an insulating joint, and the metal pipe is connected to a power supply for energization and heating. Therefore, by energizing the metal pipe, the temperature of the insulating oil filled in the metal pipe can be changed, and an oil flow can be generated according to the temperature change. There is an excellent effect that the influence of a change in the oil flow inside can be checked.

[Brief description of the drawings]

FIG. 1 is an explanatory view of one embodiment of a check device of a complete bridge type oil leak point measuring instrument according to the present invention.

FIG. 2 is an explanatory diagram of a complete bridge type oil leak point measuring device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Check device 2a, 2b, 2c, 2d Copper tube 3 Insulation joint 4, 6 Lead wire 5 Valve 7 Sliding voltage regulator 10 Measuring device 12 Pressure oil tank 14, 18, 26 Cable 16, 20, 28 Resistance oil passage 18a Oil leak position 22, 22a Connection point 24, 30 Differential pressure gauge 25 Communication pipe

Claims (1)

(57) [Claims] 1. A check device for a single-core three-phase cable full-bridge type oil leak point measuring device, comprising a predetermined number of metal pipes including one metal pipe provided with a simulation oil leak point. A complete bridge type oil leak point measuring instrument, wherein the metal pipe is connected to the oil leak point measuring instrument at one end via an insulating joint, and the metal pipe is connected to a power supply for energizing and heating. Checking device.