JPH0540857U - Leakage detector - Google Patents

Abstract

(57) [Summary] [Structure] In this device, a hygroscopic member 11 is wound around the conductor 5 of the cable 3 in which water leakage should be detected. And conductor 5
And a pair of electrodes 13A, 13 connected to the hygroscopic member 11
The electrical resistance between B is measured. The hygroscopic member 11 has a low electric resistance even with a small amount of water leakage, and can detect water leakage with high sensitivity. [Effect] This shortens the test time of the leak test,
Enables safe and efficient automated testing.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a water leak detection device used when performing a water leak inspection of a watertight cable.

[0002]

[Prior Art]

 Watertight cables such as CV cables installed outdoors are filled with watertight compounds between conductor gaps and between conductors and insulators to prevent running water. In such cable manufacturing, one end of the cable is cut out and used as a sample for a water leak test. FIG. 2 shows a schematic diagram of a conventional device for a water leakage test. In the figure, a water tank 1 is filled with water 2, and a cable 3 is fixed to the bottom of the water tank 1 so as to penetrate through a seal 4. The conductor 3 of the cable 3 has a stranded wire structure. A watertight compound (not shown) is filled between the insulator of the cable 3 and the conductor 5 and in the gap between the conductors 5. Therefore, when water pressure is applied to one end of the cable 3 by the water tank 1, if the water pressure is within a certain range, it should have a watertight property that prevents the water 2 from leaking to the outside.

Therefore, for the test of the cable 3, the setting as shown in the figure is performed, the receiving tray 6 is arranged below the conductor 5 exposed on the outside of the cable 3, and the sulfuric acid 7 is accommodated therein. A thermocouple 8 is attached to the bottom of the tray 6, and the thermocouple 8 is connected to the temperature recorder 9. When the temperature recorder 9 is operated in the above-mentioned state, should water leak from the cable 3, the water 2 will flow into the tray 6 and the sulfuric acid 7 will generate heat. As a result, the output of the thermocouple 8 changes, and the change is recorded by the temperature recorder 9. A large number of thermocouples are connected to the temperature recorder 9 from the same device, and these temperature changes are recorded on the recording paper 10. This makes it possible to conduct a water leak test on many cable terminals at once.

[0004]

[Problems to be solved by the device]

 By the way, the conventional leak detection device as described above requires caution in handling because it uses a chemical such as sulfuric acid that generates heat. Another problem is that if the amount of water leakage is extremely small, it will take time to generate heat, and the detection of water leakage will be delayed and the test time will increase. Further, there is a problem that it is easily affected by atmospheric temperature and humidity. The present invention has been made in view of the above points, and provides a water leak detection device that is simple and can use a large number of water leak tests at the same time as before, and further shortens the time for water leak detection and enhances sensitivity. The purpose is to do.

[0005]

[Means for Solving the Problems]

 The water leakage detection device of the present invention detects the water leaking from the other end of the cable by applying water pressure to one end of the cable and covering the conductor exposed at the other end of the cable. It is characterized by comprising a hygroscopic member, a pair of electrodes connected to the exposed conductor and the hygroscopic member, and a monitoring unit for measuring an electric resistance between the pair of electrodes.

[0006]

[Action]

 In this device, a hygroscopic member 11 is wound around the conductor 5 of the cable 3 whose water leakage should be detected. Then, the electric resistance between the pair of electrodes 13A and 13B connected to the conductor 5 and the hygroscopic member 11 is measured. The hygroscopic member 11 can detect the water leakage with high sensitivity because the electric resistance is lowered even if the water leakage is slight. This will shorten the test time of the leak test and enable safe and efficient automatic test.

[0007]

【Example】

 Hereinafter, the present invention will be described in detail with reference to the embodiments shown in the drawings. FIG. 1 is a schematic view showing an embodiment of a water leakage detection device of the present invention. In the figure, it is assumed that the cable 3 to be subjected to the water leakage test has one end exposed from the tank 1 as described above with reference to FIG. A hygroscopic member 11 made of gauze or the like is wound around the conductor 5 exposed at the end of the cable 3. Further, an electrode plate 12 made of lead or the like is wound around the outer periphery of the hygroscopic member 11. Then, one end of an electrode 13A made of a bare copper wire is bound to the electrode plate 12, and the other end is connected to the terminal 10A of the monitoring unit 10. Further, one end of the other electrode 13B is bound to the conductor 5, and the other end thereof is connected to the terminal 10B of the monitoring unit 10.

The monitoring unit 10 is a device for measuring the electrical resistance between the electrodes 13A and 13B. The monitoring unit 10 is provided with a power supply 14, a resistor 15, a variable resistor 16 and a recorder 17. The power supply 14 and the resistor 15 are connected in series to the terminal 10A, and the variable resistor 16 is inserted between the resistor 15 and the terminal 10B. The voltage across the variable resistor 16 is measured by the recorder 17, and the result is recorded on the recording paper 18. As described above, in the device of the present invention, the water that has leaked into the gap between the conductors 5 is absorbed by the hygroscopic member 11 to reduce the electric resistance between the electrodes 13A and 13B. Therefore, by comparing the electrical resistance between the electrodes 13A and 13B in the dry state with the subsequent change in electrical resistance, it is possible to determine whether or not water has leaked to the conductor 5. The operating principle of the monitoring unit 10 will be described with reference to FIG.

FIG. 3 shows an equivalent circuit of the monitoring unit 10. In the figure, assuming that the voltage of the power source 14 is E1, the resistance of the resistor 15 is R1, the resistance of the variable resistor 16 is R2, and the resistance between the terminals 10A and 10B is R3, the voltage E0 input to the recorder 17 is as shown in the figure. It can be obtained by a simple expression. That is, the voltage E0 is obtained by the product of E1 and the value obtained by dividing R2 by the sum of the resistances R1, R2 and R3. Therefore, if the electric resistance R3 of the material changes, the input voltage E0 of the recorder 17 also changes and can be detected. Further, according to the connection of this embodiment of the present invention, even if the temperature recorder as used in FIG. 2 is used as the recorder 17, the output of many samples can be monitored and recorded as it is. You can

FIG. 4 shows an embodiment in which, for example, four monitoring units are connected to the recorder 17. In this case, the variable resistors VR1, VR2, VR3, VR4 of the respective monitoring units are selected so as to have successively larger values. As a result, if the recorder 17 is used as a temperature recorder, four types of input signals can be used to set the temperature within a range of plus or minus several degrees around 40 ° C, 50 ° C, 60 ° C, and 70 ° C, respectively. The output can be recorded on the recording paper 18. As a result, the lines recorded on the recording paper 18 do not overlap each other, and it is possible to clearly monitor a large number of samples at the same time. The present invention is not limited to the above embodiments. In the above embodiment, the hygroscopic member is gauze and the electrode is constituted by binding a bare copper wire, for example, but a special clip or the like is used as the electrode or various other materials that easily absorb water are used. The configuration may be changed.

[0011]

[Effect of the device]

 In the water leakage detection device of the present invention described above, since the hygroscopic member is arranged so as to cover the conductor of the cable and the electric resistance between the conductor and the hygroscopic member is measured, the water leakage is monitored. It does not require special chemicals, is not easily affected by the temperature of the atmosphere, and can automatically and efficiently detect water leaks in a short time. In addition, since this type of test also requires measurement of the ambient temperature, it can be used as an actual temperature recorder with the configuration of the above-mentioned embodiment, and thus a more efficient test is performed. .. Also, since it can be almost completely automated, it can be used for maintenance and inspection of various production equipment and test equipment that are sensitive to water leakage.

[Brief description of drawings]

FIG. 1 is a schematic view showing an embodiment of a water leakage detection device of the present invention.

FIG. 2 is a schematic diagram showing the overall configuration of a conventional test apparatus for detecting water leakage.

FIG. 3 is a connection diagram showing an equivalent circuit of a monitoring unit of the present invention.

FIG. 4 is a connection diagram showing an application example of the present invention.

[Explanation of symbols]

 3 cable 5 conductor 10 monitoring part 11 hygroscopic member 12 electrode plate 13A, 13B electrode 17 recorder

Front page continuation (72) Hidemitsu Abe 2-1-1, Oda Sakae, Kawasaki-ku, Kawasaki-shi, Kanagawa Prefecture Showa Electric Wire & Cable Co., Ltd. (72) Kenji Kato 2-1-1, Oda Sakae, Kawasaki-ku, Kawasaki-shi, Kanagawa Prefecture No. 1 Showa Electric Wire & Cable Co., Ltd.

Claims (1)

[Scope of utility model registration request] 1. A hygroscopic member for covering water, which is exposed at the other end of the cable, by applying water pressure to one end of the cable to detect water leaking from the other end through the conductors of the cable. A water leakage detection device comprising: a pair of electrodes connected to the exposed conductor and the hygroscopic member; and a monitoring unit that measures an electrical resistance between the pair of electrodes.