JPH033203A - Arc drive type variable resistor - Google Patents

Abstract

PURPOSE:To obtain an arc drive type variable resistor which can increase resistance at high speed by forming an environment of a space where the arc moves by a mixed gas of sulfur hexafluoride and other insulating gas. CONSTITUTION:The title item consists of two column-shaped resistors 1 and 1', main terminals 2 and 2', variable contacts 3 and 3' which are provided at both of them so that they can rotate and are in contact state normally, and a case 4 which stores them. In an arc drive type variable resistor, a mixed gas obtained by mixing sulfur hexafluoride, nitrogen, air, helium, hydrogen, etc., is used as an insulating gas. For example, by mixing the sulfur hexafluoride gas with volume ratio of 10% to the nitrogen, insulating resistance is enhanced by two times or more as compared with the nitrogen. However, arc running time becomes larger by approximately 20%. Thus, as compared with gas containing only sulfur hexafluoride gas, atmosphere with less reduction in insulating resistance can be formed without delaying the running time of arc, thus increasing the resistance rapidly.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an arc-driven variable resistor suitable for current limiting of power lines.

(Prior art and its problems to be solved) A variable resistor is connected in series to a power line, for example a distribution line,
A so-called current-limiting method has been proposed that attempts to protect the line and power equipment connected to it from large currents by rapidly increasing its resistance value from zero when an accident such as a short circuit occurs. There is an arc-driven variable resistor in which an arc replaces the sliding contact of a conventional variable resistor.

As shown in Figure 1, this variable resistor consists of two parallel, insulated columnar resistors (1) (1°) (one of which may be an ordinary conductor), and a main terminal (2). (2'), movable contacts (3) (3') which are rotatably provided on each of them and are always in contact with each other, and a case (4) that accommodates these.

For example, connect the main terminals (2) (2') to the distribution lines (5) (5).
') are connected in series between the movable contacts (3) and (3') due to an overcurrent detected at the time of an accident in the distribution line (5'). (1) (1'
), the movable contactor (3) (3')
The arc (6) generated between the columnar resistors (1) (1')
Transfer it between one end and thereby [line (5) → main terminal (2)]
) → Resistor (1) → Arc (6) → Resistor (lo) → Line (5”)] to form a circuit of resistor (1) (1°)
are inserted in series into the distribution line. Then, due to the electromagnetic force (7) generated by the current flowing in the arc (6),
The arc (6) is connected to the resistor (1) as shown by the dotted line inside.
) (1"), the main terminal (
2) It functions to rapidly increase the resistance value seen from between (2' and 2) and limit the current flowing through the line to a predetermined value.

Unlike conventional variable resistors, this arc-driven variable resistor does not have mechanical moving parts such as sliding contacts, so it has advantages such as no problems such as poor contact and easy maintenance. There is.

However, on the other hand, since the dielectric strength of the space after the arc has moved has decreased, the voltage generated by the product of the current and the resistance value may cause damage between the movable contacts (3) (3') or between the columnar resistor (1). In some cases, dielectric breakdown occurs in the space between (1'), making it impossible to increase the resistance value, and the current limiting effect may become unsatisfactory.

Therefore, in the case (4) in Figure 1 that houses the resistors (1) (1'), etc., sulfur hexafluoride gas (8), which is well known as an insulating material with high dielectric strength (high arc-extinguishing performance), is used. Attempts have been made to seal the atmosphere in the space in which the arc moves to one with high dielectric strength.

According to this method, the dielectric strength of the space after the arc moves as described above can be quickly recovered, but on the other hand, the moving speed of the arc becomes slow, making it impossible to rapidly increase the resistance value which is essential for current limiting. It was revealed that this would lead to difficulties.

(Objective of the Invention) The present invention aims to improve the dielectric strength of the arc moving space. The present invention provides an arc-driven variable resistor that can improve the moving speed of the arc while achieving quick recovery, and ensures line protection through current limiting.

(Means of the present invention for solving the problem) The present inventor has discovered that the cause of slowing down the moving speed of the arc is the density of sulfur hexafluoride gas, and that because this density is large, the drag force that impedes the movement of the arc becomes large. As a means to solve this problem, we propose mixing sulfur hexafluoride gas with nitrogen, air, helium, hydrogen, or other gases.

Figure 3 shows sulfur hexafluoride gas (SF4) and nitrogen gas (N2)
It is clear from this figure that the increase in dielectric strength exceeds the increase in arc travel time, and furthermore, it is This is noticeable in a small range of sulfur fluoride gas mixing ratio.

This tendency is also obtained when sulfur hexafluoride gas is mixed with gases other than nitrogen, so the type of gas that should be mixed with sulfur hexafluoride gas should be determined according to the required density and dielectric strength. The moving speed of the arc can be made high by selecting the mixing ratio and using it as the arc moving space atmosphere. For example, 10% by volume of nitrogen gas
By mixing sulfur hexafluoride gas, the dielectric strength is improved to more than twice that of nitrogen gas (approximately 70% of sulfur hexafluoride gas alone), but the arc travel time is only about 20%. It is. Therefore, compared to the case of using sulfur hexafluoride gas alone, it is possible to form an atmosphere in which the dielectric strength is less reduced without slowing down the arc travel time so much, and the resistance value can be rapidly increased.

Experiments have shown that by using this as an atmosphere for the space in which the arc moves, the purpose of current limiting of a distribution line with a line voltage of 6600 V can be achieved.

It has also been revealed that depending on the purpose, it is possible to use a mixed gas with a volumetric mixing ratio of 1 to 60% sulfur hexafluoride gas and 99 to 40% nitrogen gas. It has been revealed that by mixing in, it is possible to create products that meet even more demands.

(Effects of the Invention) According to the present invention, it is possible to obtain an arc-driven variable resistor that can increase the resistance at a high speed, so when used as a current limiter for protecting distribution lines, a large current limiting effect can be obtained. .

[Brief explanation of drawings]

FIGS. 1 and 2 are explanatory diagrams of an arc-driven variable resistor, and FIG. 3 is a side view of the relationship between gas density, dielectric strength, and mixed gas ratio. (1) (1')...Column resistor, (2) (2°)
...Main terminal, (3) (3')...Movable contact, (4)
... Case, (5) (5') ... Distribution line, (6)
...Arc, (7)...Electromagnetic force, (8)...Insulating gas. agent

Claims (1)

[Claims] (1) An arc-driven variable resistor that generates an arc between one ends of resistors arranged in parallel and moves this arc in one direction between the resistors using electromagnetic force to vary the electrical resistance. An arc-driven variable resistor characterized in that the atmosphere in the space in which the arc moves is a mixed gas atmosphere of sulfur hexafluoride gas and another insulating gas.