JPH088457Y2 - Cable water resistance tester - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a cable water resistance test device that accommodates a cable in a water tank, heats water in the water tank, and tests the water resistance characteristics of the cable at a predetermined temperature. .

(Prior Art) For example, in a crosslinked polyethylene insulator of a CV cable, when a very small amount of water is present inside, a so-called water tree is generated when a high voltage is applied, which causes a decrease in insulation resistance.

Therefore, for this type of cable, the Karl Fischer method or the like is used to measure the moisture content in the insulator and to perform a predetermined water resistance test.

FIG. 3 shows a block diagram of a conventional general cable water resistance test apparatus.

The device shown in the figure has a water tank 3 on the floor 1 via an insulator 2.
Is placed.

The water tank 3 is filled with water 4, and a heater 5 is arranged to heat the water 4. A temperature measuring sensor 6 is provided to measure the heated water temperature. The heater 5 is a so-called throw-in heater using nichrome wire. The temperature measurement sensor 6 is
It consists of thermocouples and thermistors.

The insulator 2 is provided to electrically isolate the water tank 3 from the ground. The cable 10 is housed in the water tank 3 and heated in the range of 90 ° C. ± 2 ° C., for example. The cable 10 is, for example, a CV cable in which an inner semiconductive layer, an insulator, and an outer semiconductive layer are coextruded on a conductor 11 in three layers. A predetermined test voltage is applied to the cable 10 by a test transformer 12 from a terminal (not shown).

A control unit 20 is provided to heat the water 4 in the water tank 3 to the constant temperature described above.

The control unit 20 includes a heater power supply unit 21, a temperature control unit 22, and a temperature recording unit 23.

The temperature control unit 22 is a circuit that is connected to the heater power supply unit 21 and supplies constant power to the heater 5. The temperature recording unit 23 is a circuit that receives the output of the temperature measurement sensor 6, records the temperature on a chart or the like, and outputs the temperature to the temperature control unit 22. Temperature recorder 23
Is composed of a pen recorder or the like. The temperature control unit 22 is composed of a circuit that compares the set temperature with the measured temperature output from the temperature recording unit 23 by on / off control or phase control and controls the electric power supplied to the heater 5 and the like.

When a predetermined test voltage is applied to the cable 10 by the device as described above, the tan δ and the insulation resistance of the cable are measured by a measuring device (not shown).

(Problems to be Solved by the Invention) By the way, in the above-mentioned device, the outer semiconductive layer of the cable 10 accommodated in the water tank 3 is the water 4 in the water tank 3.
Is in electrical contact with. Therefore, for example, in the case of tan δ measurement, it is necessary to electrically isolate the cable shield and the ground circuit.

Therefore, not only is the water tank 3 insulated from the floor surface 1 by the insulator 2, but the heater 5 and the temperature measurement sensor 6 are pulled up from the water tank 3 from the start to the end of the tan δ measurement.

However, in this case, when the tan δ measurement time becomes long, the water temperature becomes lower than the reference value, and it becomes impossible to keep the temperature at a continuous constant temperature. This may result in the inability to continuously measure and record characteristics. Further, once raising the heater 5 and the temperature measuring sensor 6 from the water tank 3 is not desirable in terms of measurement workability.

The present invention has been made in view of the above points, and does not require a heater or a temperature measurement sensor to be pulled up, and various cable tests can be performed while maintaining a constant water temperature. The purpose is to provide a test device.

(Means for Solving the Problems) A cable water resistance test apparatus of the present invention is a water heater that heats water in a water tank containing a cable, and a temperature measurement that measures the heated water temperature. In the arrangement of the sensors, both the heater and the temperature measuring sensor are electrically isolated from the water in the water tank by a container made of an electric insulator submerged in the water tank. It is characterized by that.

(Operation) In the above-mentioned device, since the heater and the temperature measuring sensor are both housed in a container made of an electric insulator submerged in the water tank, a shield for a cable housed in the water tank is also provided. And electrically isolated. On the other hand, thermally, it is possible to indirectly heat the water in the water tank through the water in the container and to measure the temperature of the water in the water tank.

(Embodiment) The present invention will be described in detail below with reference to an embodiment shown in the drawings.

FIG. 1 is a block diagram showing an embodiment of a cable water resistance test apparatus of the present invention.

In the device shown in the figure, a water tank 3 is placed on a floor surface 1 via an insulator 2, and water 4 is contained in the water tank 3. The cable 10 to be subjected to the water resistance test is immersed in the water 4.

A test voltage is applied to the cable 10 from a test transformer 12 via a cable head (not shown). Further, a heater 5 for heating the water in the water tank 3 and a temperature measuring sensor 6 for measuring the temperature of the heated water are provided.
The water temperature is controlled by the control unit 20.

The above configuration is the same as that of the conventional device described above with reference to FIG. 3, and each component is the same as that of the conventional device.

Here, the apparatus of the present invention is provided with a container 31 for housing the heater 5 and a container 32 for housing the temperature measuring sensor 6. Each of these containers is made of an electric insulator such as heat-resistant glass. Each of the containers 31 and 32 is filled with an appropriate amount of water similar to the water 4 contained in the water tank 3. In addition, each container 31, 32 is a water tank 3
The height is selected such that the side wall of the inside water 4 projects above the water surface by a predetermined height. This height is equal to the water 4 in the aquarium 3.
The height should be high enough to ensure sufficient electrical insulation between the container and the water in the containers 31 and 32.

That is, in the above device, even if the semiconductive layer of the cable 10 is in contact with the water in the water tank 3, the heater 5 and the temperature measuring sensor 6 are both electrically isolated from the water 4 in the water tank 3. ing. Therefore, even if a high voltage is applied to the outer semiconductive layer of the cable 10, or if the cable 10 suffers a dielectric breakdown or the like, the voltage will not be applied to the heater 5 or the temperature measuring sensor 6. Of course, cable 10 tan
Also in the measurement of δ, the shielding layer and the heater 5 and the temperature measuring sensor 6 can be completely electrically isolated.

Further, when the temperature control unit 22 supplies a predetermined electric power to the heater 5 housed in the container 31, the water inside the container 31 is heated, and the heat causes the water 4 in the water tank 3 to pass through the container 31. To heat. Therefore, it is possible to indirectly heat the water 4 in the water tank 3 and control the temperature thereof.

On the other hand, the heat of the water 4 in the water tank 3 is transferred to the water contained therein via the container 32, and in equilibrium, the container 32 is
The water temperature inside and outside the same is the same. Therefore, it is possible to indirectly and accurately measure the water temperature of the water 4 in the water tank 3 by the temperature measuring sensor 6 including a thermocouple or the like.

From the above, it is preferable that each of the containers 31 and 32 is made of a material having excellent electrical insulation and good thermal conductivity.

Further, since the water temperature is measured by the temperature measuring sensor 6 and the water is heated by the heater 5 to control the temperature, the heater 5 and the temperature sensor 6 should be accommodated in separate containers. Moreover, as shown in the figure, it is preferable to arrange the both in positions as far apart as possible in the water tank 3.

FIG. 2 shows the measurement results of the water temperature in the device of the present invention. In the graph of the figure, the horizontal axis represents time and the vertical axis represents water temperature.

As shown in the figure, in the device of the present invention, the heater 5
In any test of the cable 10, the water temperature is stably controlled within the range of 90 ° C. ± 2 ° C. On the other hand, in the conventional apparatus, since the heater 5 is taken out during the tan δ test, the water temperature may drop by 5 ° C to 10 ° C depending on the test time.

Therefore, according to the device of the present invention, various tests can be performed by keeping the temperature constant.

(Effect of Device) The cable water resistance test device of the present invention described above is
Since the container made of an electric insulator is immersed in the water tank containing the cable and the heat sensitive heater and the temperature measuring sensor are housed therein, these are electrically isolated from the water in the water tank. As a result, various water resistance tests of the cable can be directly executed without interrupting the water temperature control in the water tank.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a cable water resistance test apparatus of the present invention, FIG. 2 is a graph showing changes in water temperature in the water tank, and FIG. 3 is an example of a conventional cable water resistance test apparatus. It is a block diagram showing. 1 ... Floor surface, 2 ... Insulator, 3 ... Water tank, 4 ... Water,
5 ... Heater, 6 ... Temperature measurement sensor, 10 ... Cable, 11 ... Conductor, 12 ... Test transformer, 20 ... Control section.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Creator Hisao Takeshima 2-1-1 Oda Sakae, Kawasaki-ku, Kawasaki-shi, Kanagawa Showa Electric Wire & Cable Co., Ltd.

Claims (1)

[Scope of utility model registration request] 1. A heating tank for heating water in the water tank and a temperature measuring sensor for measuring the heated water temperature are arranged in a water tank containing a cable. The sensor is electrically isolated from the water in the water tank by a container made of an electric insulator submerged in the water tank.