JPS636699Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a device for discharging accumulated charges after a DC withstand voltage test of a power cable or the like is completed.

If this discharge occurs rapidly, there is a risk that an oscillating surge voltage will occur and damage cables and the like. Conventionally, therefore, the power supply was disconnected and the battery was allowed to discharge naturally, and after a while, the battery was discharged through a high resistance. However, when it came to 275KV class cables, it took more than two hours for the natural discharge to occur.

This idea makes it possible to use water resistance to shorten the discharge time, and especially when making the internal water conductive to lower the resistance value, a conductive liquid with a uniform concentration can be used to reduce the water resistance. It is designed so that it can be easily filled.

Example (Figure 1) 10 indicates the total water resistance.

12 is a ground electrode, and 14 is a high voltage electrode, which are made of metal discs.

16 is an insulated pipe made of FRP, for example;
It maintains the distance between the ground electrode 12 and the high voltage electrode 14, and also serves as a winding frame for an insulating tube 20, which will be described next. Also, fill the inside with insulating oil 18,
To prevent flashover due to high DC voltage.

20 is an insulating tube made of, for example, polyethylene. This is elongated and wrapped onto the insulating pipe 16 as described above. When winding, for example, do the following. That is, the inlet 1 whose lower end 200 is provided on the ground electrode 12
Connect to 21, then 201, 202, 203
...and so on, revealing only the outer diameter and rolling it. Then, at the point 20 in contact with the high voltage electrode 14
9 is connected to the hole 141 provided in the electrode 14. The hole 141 and another hole 14 provided in the electrode 14
3 is connected with a pipe 22. In hole 143,
Connect the upper end 210 of another insulating tube 20, wrap it between the previously rolled insulating tubes 20, and lower it. And...217,218,2
19, and when it touches the ground electrode 12, connect it to the outlet 123 provided on the same electrode 12.

In the above manner, it starts from the ground electrode 12, goes back and forth between the high voltage electrode 14, and then returns to the ground electrode 12.
A passage for the liquid returning to No. 2 is formed, and the liquid can be safely sent even when a voltage is applied.

Note that the method of wrapping the insulating tube 20 is not limited to the above case. For example, it may be wound without leaving any gaps, then wound in the same way on the outside, and then returned to make a reciprocating motion.

Note that the insulating tube 20 wound as described above
It is better not to put a cover on the outside of the This is because if the cover is covered, there is a risk of condensation forming on the inner surface and causing a flashover.

26 is a tank, which is provided separately from the water resistance 10. This is to fill the insulating tube 20 with a conductive liquid of a certain concentration, and is one of the important elements of this invention. Also, its capacity is large,
For example, approximately twice the amount of liquid in the insulating tube 20 is appropriate.

The bottom of the tank 26 is connected by a pipe 28 to the inlet 121 of the water resistor 10 and its outlet 123
is connected to the upper part of the tank 26 by a pipe 30 to form a liquid circulation circuit 24 including the insulating tube 20 and the tank 26.

32 is a pump, 34 is a flow meter, 36 is a thermometer,
38 is an ammeter, and 40 is a pure water device.

When the insulating tube 20 is filled with water by the pump 32, the water flows through the inlet 121 and the outlet 12.
3. Ground electrode 1 on the inner surface of holes 141 and 143
2 and the high-voltage electrode 14 and are electrically connected to each other by directly contacting them. Therefore, the ground electrode 12 and the high voltage electrode 1
Two water resistance circuits are formed in parallel between the four.

Further, 42 indicates a cable, and 44 indicates a charging portion thereof.

In the case of a 275 KV class power cable, if the resistance value of the water resistor 10 is about 1000 MΩ, even if the cable is connected directly to the charging section 44 from the beginning of discharge, the discharge will be minute.

As shown above, the length of each insulating tube 20 forming two water resistance circuits is 50 m, and the inner diameter is 15 mm.
When the inside is filled with pure water, the combined resistance value becomes
It becomes more than 1000MΩ.

To lower the resistance value of water resistance 10, do the following.

First, salt or the like is dissolved in pure water in the tank 26 to make the whole a conductive liquid with a uniform concentration.

For 275KV cable, for example tank 26
If the amount of pure water inside is 5, initially there will be
Add 0.5cc of 10% salt water to make a salt solution of about 0.0001%.

The pump 32 is operated to circulate the liquid in the circulation circuit 24. Then, the conductive liquid in the tank 26 is sent into the insulating tube 20, and the pure water inside is forced out by the conductive liquid and discharged.
As a result, the pure water in the insulating tube 20 is transferred to the tank 26.
is replaced by a conductive liquid inside.

Note that if the amount of water in the tank 26 is small, locally highly concentrated salt water will enter the insulating tube in order to obtain the target resistance value, causing resistance imbalance in the longitudinal direction and causing problems in terms of withstand voltage. arise. If the capacity of the tank 26 is set to be approximately twice that of the insulating tube 20 as described above, saline solution (conductive liquid) of substantially uniform concentration can be mixed throughout the insulating tube.

Note that in the claims, the statement that the capacity of the tank 26 is greater than the amount of liquid contained in the portion of the circulation circuit 24 excluding the tank 26 means that the conductive liquid in the tank 26 and the returning pure water are This means that if you take care to avoid mixing as much as possible, you can achieve your goal with at least that amount of volume.

Next, as the discharge progresses, the concentration of the conductive liquid in the tank 26 is increased a little more than the above, and the conductive liquid in the tube 20 is replaced in the same manner as above. By repeating this process, the resistance value of the water resistance 10 can be gradually lowered.

In the case of 275KV cable, as shown in "Figure 2",
If the resistance value of the water resistor 10 is set to about 1000 MΩ (pure water inside the tube 20) at the beginning of discharge, and then gradually lowered to about 50 MΩ after 30 minutes, discharge can be carried out without difficulty.

In addition, since the water temperature in the tube 20 rises with discharge, it is monitored by the thermometer 36 and the resistance value is controlled.

Effects of the invention Similar to this invention, a discharge device has already been proposed in which a water-filled insulating tube is spirally wound to create water resistance, and a conductive liquid is mixed inside to lower the resistance value. (Jitsugan No. 55-082306).

However, in that device, a highly concentrated conductive liquid is directly mixed into the water inside the insulating tube and is diffused throughout the tube so that the concentration inside is uniform. For this reason, 1. It is difficult to control the resistance value. 2. When a highly concentrated conductive liquid is pumped into the inside of the insulating tube, the resistance value changes suddenly only in that area, which causes an imbalance in the voltage in the longitudinal direction of the water resistance. There were problems in that there was a possibility that this would occur and cause a flashover.

However, in this invention, the insulating tube 2
0 and a tank 26 provided outside the liquid circulation circuit 24, and the capacity of the tank 26 is greater than the amount of liquid contained in the portion of the circulation circuit 24 excluding the tank 26. Therefore, as described above, by creating a conductive liquid at a certain concentration in the tank 26 and replacing it with the liquid in the insulating tube 20, the concentration of the conductive liquid in the insulating tube 20 (water resistance) is adjusted. (resistance value) can be changed.

Therefore, the above-mentioned problems are solved: 1. The concentration of the conductive liquid in the insulating tube 20 becomes uniform, and a sudden unbalance of voltage in the longitudinal direction does not occur.

2. Enables fine control of resistance value. This effect can be obtained.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of an embodiment of this invention, and FIG. 2 is a diagram showing changes in the resistance value of the water resistor 10 during discharge. 10: Water resistance, 12: Ground electrode, 14: High voltage electrode, 20: Insulating tube, 24: Circulation circuit, 2
6: Tank.

Claims (1)

[Claims for Utility Model Registration] An insulating tube 20 is provided between the ground electrode 12 and the high voltage electrode 14, and the insulating tube 20 is reciprocated between them, and the liquid filled in the insulating tube 20 connects the ground electrode 12 and the high voltage electrode 14 with electricity. A liquid circulation circuit 24 including an insulating tube 20 and a tank 26 provided outside the insulating tube 20 is formed, and the capacity of the tank 26 is determined by excluding the tank 26 from the circulation circuit 24. A discharge device for a DC withstand voltage test, characterized in that the amount of liquid contained in the part is exceeded.