JPH0511621Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to a narrow commutation type current limiting device that limits and interrupts short-circuit current in the event of a short-circuit accident in a power system.

[Conventional technology]

As a conventional circuit breaker, as shown in FIG.
There is a rotating arc type gas circuit breaker in which an annular arc induction board 5 (integrated or separate) is installed inside the circuit breaker, and opening/closing electrodes, that is, a fixed electrode 1 and a movable electrode 2, are arranged between the arc induction board (for example, Japanese Patent Publication No. 59 −47413).

In this type of rotating arc type gas circuit breaker, an arc is generated between the contact finger 7, which is pressed by a pressing spring 6, in conjunction with an operating mechanism (not shown) in response to an operating command for interrupting.

When the breaking current is small, the arc driving force by the arc drive coil 3 is small, so the arc rises while looping, and the legs of the arc first move to the arc induction board 5 and then run on the top surface of the arc induction board 5. The arc moves to the conductive cylindrical body 4 and extinguishes while rotating in the arc rotation state shown as the small current arc rotation mode _A1 .

However, when the interrupting current is large, the electromagnetic force caused by the arc drive coil 3 is large, so that part of the arc current flows from the movable electrode 2 through the arc induction board 5, from the drive coil 3 to the fixed electrode 1, and the other part flows through the cover. The arc flows through the plate 8 to the fixed electrode 1, and the arc column as shown in the large current arc rotation mode _A2 rotates as if licking the inner edge of the arc induction plate 6, extinguishing the arc.

At this time, if the breaking current waveform is the waveform shown in Figure 4a, the coil current waveform (or primary drive magnetic field waveform) will be as shown in Figure b, and the shunt arc current waveform will be as shown in Figure c. There is.

[Problem that the invention attempts to solve]

With conventional rotating arc type gas circuit breakers, when a short circuit large current occurs, for example 7.2KV, 40KA or more,
The high current arc rotation mode _A2 occurred, making it impossible to extinguish the arc and limiting the breaking performance. Moreover, there was a problem that the life of the electrode material with which the rotating arc came into contact was short.

This problem can be solved by quickly extinguishing the branched arc flowing between the arc induction panel 5 and the cover plate 8, but this type of circuit breaker is placed in a sealed container to fill with arc extinguishing gas. The conventional arc extinguishing method by spraying was not suitable, and a new method was desired.

[Means for solving problems]

In order to achieve this purpose, this invention has the following structure. That is, a pair of separable electrodes is arranged, an arc runner electrode is provided in parallel on each electrode, an intermediate electrode is provided between the pair of arc runner electrodes, and either one of the electrodes is connected to the intermediate electrode. A narrow arc extinguishing method is adopted in which a pair of arc extinguishing plates are used to sandwich these electrodes between the arc runner electrodes, forming a narrow space that becomes gradually narrower at the tip of the arc runner electrode than at the electrode part, and The electrode and the other arc runner electrode are of a magnetically driven rotating arc extinguishing type with an arc driving coil, and one end of the arc driving coil is connected to the intermediate electrode, and the other end is connected to the thin arc extinguishing type. Connected to the arc runner electrode at.

[Effect]

With this structure, the arc drive coil is short-circuited during the conventional large current, and the generated shunt arc is extinguished in the narrow space formed by the arc-extinguishing plate.
All the current was made to flow through the arc drive coil.

In addition, although copper-based materials were conventionally used for the arc drive coil, iron-based and carbon-based materials can now be used, eliminating the shunt arc and allowing the entire current to flow through the arc drive coil. So,
By inserting a resistor into the circuit, the short-circuit electrode limits the current flow, making it possible to extend the life of the circuit.

The extinction of the shunt arc is based on the following principle.

A cover plate 8 electrically connected to a fixed electrode and an arc induction board 5 electrically connected to a conductive cylindrical body 4 so as to short-circuit a drive coil 3 in a conventional magnetic drive circuit arc circuit breaker.
During this time, a shunt arc appears and disappears during a half cycle of the breaking current, as shown in the waveform of FIG. 4c. After examining the conditions for the generation and extinction of this shunt arc, it was found that the following conditions are satisfied.

r _p ≧Z ₀ where r _p is the shunt arc resistance Z ₀ is the impedance of the drive coil (Z ₀ =√ ² + ² , R is the coil resistance, and ωL is the reactance of the coil).

In the present invention, the shunt arc is inserted into a narrow space formed by an arc-extinguishing plate (for example, ceramics), and the narrow space is tapered so that it is wide near the electrode and narrows at the tip of the runner electrode. This is based on the principle that by inserting the arc into a narrower space, the shunt arc resistance increases, and when the above conditions are met, the arc is extinguished. The resistance r _p of the shunt arc in this thin line is an order of magnitude higher than that of conventional rotating arcs or spray arcs, so it is recommended to use not only copper-based coil materials but also iron-based and carbon-based materials. Now I can do it.

〔Example〕

An embodiment of the present invention will be described.

Figure 1 is its plan view, and Figure 2 is A-A in Figure 1.
FIG. 3 is a side sectional view taken along line A'.

Its structure is as follows.

An arc runner electrode (hereinafter referred to as runner electrode) 3 is provided above each of the fixed electrode 1 and the movable electrode 2.
and 4 are provided in parallel, and an intermediate electrode 10 is provided between these runner electrodes 3 and 4. Between this intermediate electrode 10 and one of the runner electrodes (3 in the figure), the thickness of the protruding parts 3' and 10' of these electrodes is wide in the vicinity of the electrode and narrow at the tip of the runner electrode or intermediate electrode. The protrusions 3' and 10' are mounted between a pair of arc-extinguishing plates 6 (for example, made of ceramics), and the narrow space formed thereby is a tapered narrow arc-extinguishing plate. As a method, an arc drive coil 7 and a conductive cylindrical body 7 are disposed between the intermediate electrode 10 and the other runner electrode (4 in the figure), and a magnetically driven rotating arc extinguishing method is adopted.

The intermediate electrode 10 and the conductive cylindrical body 8 are connected to an arching piece 8'
The runner electrode 4 is provided with a protrusion 4' near the electrode, and has a cylindrical shape at the tip. Further, one end of the arc drive coil 7 is connected to the conductive cylinder 8, and the other end is connected to a runner electrode (3 in the figure). This is just a connection in which the narrow space between the intermediate electrode 10 and the runner electrode 3 is short-circuited by the arc drive coil 7.

In the next energized state, the fixed electrode 1 and the movable electrode 2 are in contact (although FIG. 2 shows an open state).

When a short-circuit current occurs, the movable electrode 2 is opened by an external mechanism (not shown), and an arc is generated between the fixed electrode 1 and the movable electrode 2. This arc is elongated with the opening operation of the movable electrode 2, becomes arcuate, and finally moves to the protrusions 3' and 4' of the runner electrodes 3, 4, the intermediate electrode 10, and the arc guide ring 8' of the cylindrical electrode 8.

The arc that comes into contact with the intermediate electrode 10 or the arc guide ring 8' forms an electrode point and is separated. The current path at this time is fixed current 1 → fixed side runner electrode 3 →
Projection 3' → Arc a → Intermediate electrode projection 10' → Intermediate electrode 10 → Arc drive coil 7 → Conductive cylinder 8 → Arc b → Movable runner electrode 4 → Current collector →
The movable electrode 2 becomes the movable electrode 2, and the shape of its passage becomes a convex shape with respect to the fixed electrode 1 and the movable electrode 2, so that the arc a receives an electromagnetic force that moves upward in FIG. To explain this specifically,
In FIG. 2, the direction of the magnetic field created by the current flowing upward through the fixed runner electrode 3 is from the front of the paper to the opposite direction in the gap between the fixed runner electrode 3 and the intermediate electrode 10 (right-handed screw rule). ,
The direction of the magnetic field created by the current flowing downward through the intermediate electrode 10 is from the front of the page to the other side of the page in the gap, and the direction of the magnetic field created by the current flowing upward through the conductive cylinder 8 is from the front of the page in the gap. The direction of the magnetic field created by the current flowing downward through the movable runner electrode 4 is from the front of the page to the other side of the paper in the gap. The direction of the overall magnetic field due to the above four currents is from the front of the page to the other side, taking into consideration the distance of the currents. Therefore, according to Fleming's left-hand rule, the arc a in the gap is the second
In the figure, it is subjected to an electromagnetic force that moves upward.

The shunt arc a in the narrow space moves through the tapered narrow space toward a narrower narrow part due to the electromagnetic force, and the shunt arc resistance increases rapidly.
When the impedance Z ₀ of the arc drive coil is exceeded, the shunt arc a shown in FIG. 2 disappears, and the current begins to flow into the arc drive coil 7.

The current path at this time is fixed electrode → fixed runner electrode 3 → arc drive coil 7 → conductive cylinder 8
→ arc b → runner electrode 4 → current collector 5 → movable electrode 2. That is, the arc drive coil 7 is added to the circuit.
is inserted, and the circuit current is significantly limited.

Next, in the magnetically driven rotating arc extinguishing chamber, current flows into the arc drive coil 7, generating a magnetic field that acts perpendicularly to the arc b, causing the arc b to rotate at high speed in a direction that follows Fleming's left hand rule. conduct. This high-speed rotation of the arc cools the arc and extinguishes it with a short-circuit current of zero. Due to this arc-extinguishing action, arc b is extinguished, and the space in which arc b was rotating is filled with an arc-extinguishing medium (for example, SF ₆
Due to the electron adsorption effect in the gas), it becomes highly insulating and functions as a disconnector.

With the above operation, the increase in shunt arc resistance r _p is much larger than in other arc extinguishing methods. This comparison is
This is possible according to the potential gradient according to the following equation.

Arc resistance at unit arc length = potential gradient/arc current Potential gradient is the arc voltage at unit length, usually expressed in volts/cm. Generally, the potential gradient in SF ₆ gas is 14.1 (V/cm) at 1 atm and 100 A.
However, for a narrow arc, the equation is as follows: E=K/√ g: Fine gap length K: Arc-extinguishing plate material coefficient The smaller the fine gap length g, the greater the potential gradient. In the inventor's experiment, the voltage rose to about 200V/cm. In other words, compared to a conventional arc in SF ₆ gas, the resistance increase value of a narrow arc increases by more than an order of magnitude, so copper was conventionally used as the material for the arc drive coil, but iron-based or It was found from the above-mentioned branch arc extinguishing condition [r _p >Z ₀ ] that a carbon type was also applicable. As a result, when the shunt arc was extinguished and the arc drive coil was inserted into the circuit, an iron-based or carbon-based arc drive coil was inserted, making it possible to greatly limit the short-circuit current.

[Effect of idea]

According to the present invention, the shunt arc can be extinguished in the narrow arc extinguishing chamber, so the breaking performance has been dramatically improved. In addition, since it has become possible to use iron-based or carbon-based materials for the arc drive coil, the short-circuit current is limited to a small value, and the life of the electrode material is also improved.

[Brief explanation of the drawing]

FIG. 1 is a plan view of an embodiment of the present invention, FIG. 2 is a side sectional view taken along line A-A' in FIG. 1, FIG. 3 is a sectional view showing the structure of a conventional current limiting device, and FIG. The figure is a time chart showing a conventional breaking current waveform. 1... fixed electrode, 2... movable electrode, 3, 4...
Arc runner electrode, 5... Current collector, 6... Arc extinguishing plate, 7... Conductive cylindrical body.

Claims (1)

[Claims for Utility Model Registration] 1. A pair of separable electrodes is arranged, and an arc runner electrode is provided in parallel on each electrode,
An intermediate electrode is provided between the pair of arc runner electrodes, and a pair of arc extinguishing plates are inserted from the electrode section to the tip of the arc runner electrode so that these electrodes are sandwiched between the intermediate electrode and one of the arc runner electrodes. A narrow arc extinguishing method is used in which a narrow space is formed that gradually becomes narrower, and the intermediate electrode and the other arc runner electrode are provided with an arc drive coil, which is a magnetically driven rotating arc extinguishing method. A narrow commutation current limiting device, characterized in that one end of the arc drive coil is connected to an intermediate electrode, and the other end is connected to the arc runner electrode of the narrow arc extinguishing method. 2. The narrow commutation type current limiting device according to claim 1 of the registered utility model, characterized in that an iron-based or carbon-based material is used as the material of the arc drive coil.