JPS60208013A - Method of producing strand insulated conductor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a method for manufacturing a wire insulated conductor that reduces alternating current resistance due to the skin effect.

BACKGROUND OF THE INVENTION In recent years, with the increase in power consumption and the increase in the capacity of power plants, the capacity of power transmission lines is also increasing significantly. With this increase in capacity, there is a strong demand for performance improvements in the permissive cables that transmit power to increase the capacity.

Without improving the performance of electric power cables, it would be foolish to increase the cost of line construction, so attempts are being made to solve this problem by laying nine major cables on the existing lines. To achieve this, it is necessary to increase the current density of the power cable, but simply increasing the conductor cross-sectional area will suddenly increase loss due to the so-called skin effect of alternating current. In order to solve this problem, it is necessary to use a ground wire insulated conductor in which all the wires are insulated.

Conventionally, various methods have been proposed for obtaining such a wire insulated conductor, but the most economical method is a method of forming a copper oxide (CuO) film on the surface of a copper wire.

The method for forming a copper oxide film is to store a conductor made of twisted copper wires in an airtight container, inject ammonia water or ammonia gas and oxygen, and heat it in a humid atmosphere at a constant temperature within the temperature range of 40 to 100 degrees Celsius. A method of forming a copper oxide film on the surface of each strand by holding it for a certain period of time (Japanese Patent Laid-Open No. 57-21-
No. 0517) has been proposed and proposed.

However, with this method, when the conductor size is relatively small, that is, when the number of strands constituting the conductor is small,
A copper oxide film is uniformly formed on all the wires in the inner and outer layers of the conductor, but as the conductor size increases, the thickness of the copper oxide film formed on the copper wires in the inner and outer layers of the conductor becomes less uniform. The drawback was that it was difficult.

In other words, the formation mechanism of a copper oxide film in a humid atmosphere containing ammonia water or ammonia gas and oxygen is due to water vapor containing ammonia contacting and condensing on the copper surface, resulting in a rapid oxidation reaction of copper by oxygen. However, in the case of large-sized conductors that are made by twisting an extremely large number of copper wires, and which are compression-molded to increase the space factor to 85-95%, these reactive gases are An oxide film is formed from the outermost wire of the conductor, which has a high chance of coming into contact with the conductor, and progresses to the inside of the conductor. The drawback was that it was time consuming.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for forming a copper oxide film of uniform thickness on all the wires in the inner and outer layers of a conductor in a relatively short period of time even in the case of a large-sized conductor.

That is, in the present invention, a conductor made of twisted copper wires is placed in an airtight container with ammonia gas 0.5 container 1% JL and oxygen 10
In an atmosphere with a relative humidity of 80% or more, and at a pressure lower than atmospheric pressure by 0 to 50 μHg, the capacity is 40 to 10
This is a method for producing an insulated wire conductor characterized by forming a copper oxide film on the surface of the copper wire by holding the wire at a temperature of 0°C.

The inside of the airtight container must be maintained at a pressure 0 to 50 mHg lower than atmospheric pressure, that is, a negative pressure of 0 to -50 mHg. Copper oxide skin 81 is formed almost uniformly, but the reason is not clear.

The ammonia gas concentration in the container must be 0.5% or more, the oxygen concentration must be 10% by volume or more, and the relative humidity must be 80% or more. This is because if the amount is less than this, rapid formation of a copper oxide film, which is the object of the present invention, cannot be expected. The higher the ammonia gas concentration, oxygen concentration, and relative humidity, the faster the copper oxide film is formed.

1. As a method of maintaining the pressure inside the container at a negative pressure of O to -50 mg, the conductor may be housed in an airtight container, the container may be evacuated, and after the pressure is reduced, ammonia water or ammonia gas and oxygen may be added. Alternatively, the pressure may be reduced after adding ammonia water or ammonia gas and oxygen.

A good dense blackened film (CuO film) cannot be formed in an atmosphere in which the pressure inside the container is increased by 150 μm and further reduced. When the pressure inside the container is higher than atmospheric pressure and is positive, a copper oxide film with a uniform thickness can be obtained on the wire surface of the inner and outer layers of the conductor.
takes an extremely long time and is not practical.

Next, the present invention will be explained with examples.

Example 1 88 annealed copper wires with a diameter of 2.3 tm were twisted together, and a segment with a space factor of 93%, which was compression-molded into a fan-shaped cross section, was placed in an airtight steel container and the pressure inside the container was raised to -20 mHH using a vacuum pump.
After reducing the pressure to
After 10 hours, the segment was taken out while maintaining the volume at 0 and the relative humidity at 95 to 100 degrees, and keeping the pressure inside the container at a negative pressure of -20 mHg using a vacuum pump.

Example 2 The same untreated segment used in Example 1 was placed in a stainless steel air container, the inside of the container was evacuated to -10 mHg, and moist ammonia gas and oxygen gas were injected, and ammonia gas & [ヲ1゜～15capacity, oxygen concentration 20
After 10 hours, the segment was removed while keeping the relative humidity at 90 to 95 degrees, the temperature at about 65 DEG C., and the pressure inside the container at a negative pressure of 110 inches Hg.

Example 3 The same untreated segment used in Example 1 was placed in a stainless steel airtight container, and water was poured into the container. ~15
The capacity was set at 100 °C and the relative humidity was set at 80-90 °C, the inside of the container was constantly evacuated to -30 mHg to create a reduced pressure state, and the segment was taken out after 10 hours at a temperature inside the container of about 70°C.

Comparative Example 1 Is the container vacuumed in Example 1? hmm! The experiment was conducted under exactly the same conditions as in Example 1, except that the pressure was not reduced and the positive pressure was constantly maintained at a value p 0.2 kg/cm higher than atmospheric pressure.

Comparative Example 2 An experiment was conducted under exactly the same conditions as in Example 3, except that in Example 3, the container was not evacuated and the positive pressure was constantly maintained at 0.5 ky/cm2 higher than atmospheric pressure.

Comparative Example 3 In Example 2, the ammonia gas allO91 volume biased
The experiment was conducted under exactly the same conditions as in Example 2, except that the temperature was changed to 1.

Comparative Example 4 In Example 2, an experiment was conducted under exactly the same conditions as in Example 2, except that the oxygen concentration was changed to 5 volumes.

Comparative Example 5 In Example 2, an experiment was conducted under exactly the same conditions as in Example 2, except that the relative humidity was 60%.

Next, the copper oxide film thickness of the segments obtained in each of the above examples and comparative examples was measured by cathodic reduction method (electrolyte Q, lN-K
Ct was measured at a current density of 0.5 mA/an) Ic. Incidentally, the oxide film thickness measurement was performed on the strands of each layer constituting the segment. The central strand constituting the segment is the first layer, and the second and third layers are sequentially placed outward.
The fourth layer was the 51st layer (outermost layer). The results thus measured are shown in the table below.

As is clear from the examples above, according to the present invention, a substantially uniform copper oxide coating thickness can be obtained for the wires of each layer constituting the segment. On the other hand, in the comparative examples, although some copper oxide films were formed on the outermost layer wires, almost no copper oxide film was formed on the inner layer wires.

Next, for the segments obtained in each example and each comparative example, six divided conductors were obtained by twisting each segment, and the AC resistance (RAc) and DC resistance (RD, ) of these divided conductors were measured. The ratio of resistance (RAC/RDC) is 1.05 to 1.10 for the divided conductor of the above embodiment according to the present invention.
In contrast, the divided conductor of the above comparative example had 1.
2 to 14, and the variation in the ratio was extremely large.

Incidentally, in the case of a divided conductor made of copper gauze without a copper oxide film formed thereon, it was 1.3 to 1.4. Therefore, it is clear that the strand insulated conductor according to the present invention has significantly reduced AC loss due to the skin effect.

As described above, according to the present invention, it is possible to form a copper oxide film with a substantially uniform thickness on the surface of copper wire in any layer of the conductor. A seven-wire insulated conductor with significantly reduced AC loss can be obtained.

Claims (1)

[Claims] (1) A conductor made of stranded copper wires is heated in an airtight container in an atmosphere with a relative humidity of 80% or more and an atmosphere with a relative humidity of 80% or more and an atmosphere containing 0.5 or more volumes of ammonia gas and 100% or more oxygen.
~50+a+Hg A method for manufacturing a wire insulated conductor, characterized by forming a copper oxide film on the surface of a copper wire by maintaining the temperature at a temperature of 40 to 100° C. under a low pressure.