JPH03114116A - Vacuum circuit breaker - Google Patents

Abstract

PURPOSE:To prevent heat generation on an electrode part at a closing time by providing a flexible coil electrode having a spring action in the axial direction between a conduction axis and a main electrode. CONSTITUTION:A flexible coil electrode 38 composed of a multilayer thin plate or the like and having a spring action in the axial line direction of a movable conduction axis 18 is provided between the tip peripheral part 18a of the movable conduction axis 18 and the under surface peripheral part 35a of a main electrode 35. At a closing time of a vacuum circuit breaker 30, a movable electrode 32 is brought in contact with a fixed electrode 31, then the movable electrode 32 is pushed opposing to the spring action of the coil electrode 38 for making the tip part of the movable conduction axis 18 in contact with the rear of the main electrode 35. Then, a current of a feeding wire flows from the end of the movable condition axis 18 directly to the main electrode 35 while coming to flow through the arm part 38a and the circular are part 38b of the coil electrode 38 to the main electrode 35 thus to enlarge a passing sectional area of the current. The resistance of this electrode part, therefore, becomes smaller thus to reduce an amount of heat generation.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to a vacuum circuit breaker and a vacuum circuit breaker, and particularly to a flexible vacuum circuit breaker and a vacuum circuit breaker which generate a magnetic field parallel to an arc generated between electrodes. The present invention relates to a vacuum circuit breaker having a magnetic coil electrode.

(Prior art) Vacuum circuit breakers used for power transmission lines, distribution lines, etc. generate a magnetic field parallel to the arc generated between the electrodes when disconnecting.
A method is adopted in which the arc is cut using this magnetic field.

This typical vacuum circuit breaker is constructed as shown in FIG. That is, in FIG. 7, the vacuum circuit breaker, which is generally designated by the reference numeral 10, has an insulating container, such as an insulating cylindrical body 11, whose openings at both ends are closed with end plates 12 and 1B to make it airtight, and the inside is kept under vacuum. A pair of electrodes 15 and 16 facing each other are provided inside the vacuum container 14. The upper electrode 15 is attached to the tip of a fixed energizing shaft 17 that passes through the upper end plate 12, and the lower electrode 16 is attached to the tip of a movable energizing shaft 18 that passes through the lower end plate 13. There is.

The fixed current-carrying shaft 17 is connected to a power transmission line and a power distribution line (not shown), and the movable current-carrying shaft 18 is also connected to a power transmission line, a power distribution line, etc., and an external operation mechanism is attached to the base end thereof. 16, it can be moved up and down in the direction of the arrow.

Inside the vacuum vessel 14 through which the movable current-carrying shaft 18 passes, a bellows 19 and a protective bellows cover 20 for the bellows 19 are provided to surround the movable current-carrying shaft 18, and the movable current-carrying shaft 18 is maintained airtight. movement of the bellows 19, and prevents metal vapor caused by arcs from adhering to the bellows 19.

Note that 21 is a metal shield provided in the center of the vacuum container 14 so as to surround the pair of electrodes 15 and 16.

As shown in FIGS. 8 and 9, the electrodes 15, 16 are composed of a main electrode 22, 23 and a coil electrode 24, 25, and since they have the same structure, the lower electrode 16 will be explained below. I will explain about it.

A coil electrode 25 as shown in FIG. 9 is attached to the tip of the movable current-carrying shaft 18. This coil electrode 25 is
A central disk 26 made of a highly conductive metal plate and fixed to the tip of the current-carrying shaft 18 is provided with four horizontal arms 26a of equal length extending in the radial direction at approximately 90° intervals. There is.

Each of the four horizontal arms 26a is provided with, for example, a circular arc portion 26b extending counterclockwise, and the circular arc portion 26b generates a magnetic field parallel to the arc, the operation of which will be described later. A protrusion 26c extending upward in the axial direction is provided at the tip of the arcuate portion 26b.
c is fixed to the back surface of the disk-shaped main electrode 23 so as to be in electrical contact therewith.

Note that 27 is a reinforcing plate for the main electrode 23 attached to the center of the back surface of the main electrode 23.

(Problem to be Solved by the Invention) By the way, in a vacuum circuit breaker having such a configuration, when the electrode is turned on, the current flowing through the vacuum circuit breaker passes through the movable energizing shaft, the disc, the arm, the arc, and the protrusion. Then, the main electrode of the fixed electrode, the protruding part, the circular arc part,
It is designed to reach a fixed current-carrying shaft via the arm portion and the disc.

In this type of current flow, the cross-sectional area of the current path in the arms, arcs, or protrusions of the coil electrode is smaller than that of the current-carrying shaft or main electrode, so the electrical resistance increases and the amount of heat generated at the extracted part increases. There is a problem that the capacity of the vacuum circuit breaker cannot be increased.

In order to reduce this resistance, the cross-sectional area of the arm, arc, or protrusion of the coil electrode can be increased, but if this cross-sectional area is increased, the arc becomes shorter and the magnetic field parallel to the arc is reduced. It becomes weaker and it becomes difficult to interrupt the arc.

Therefore, in order to strengthen the magnetic field and reduce the electrical resistance, the coil electrode may be made larger and its cross-sectional area may be increased, but doing so would increase the size of the vacuum circuit breaker.

In addition, when such a vacuum circuit breaker is used on power transmission lines, etc., each power transmission line is shut off at the same time, causing a large switching surge voltage to occur on the power transmission line, causing problems such as failure of equipment connected to it. There is.

In order to solve these problems, it is possible to install surge protection devices such as CR surge suppressors and lightning arresters that protect against switching surges, but installing such surge protection devices only increases the size of the vacuum circuit breaker. However, there is a problem in that installing the surge protection device requires additional work.

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a vacuum circuit breaker that does not increase electrical resistance when electrodes are inserted.

[Structure of the invention]

(Means for Solving the Invention) The present invention provides a vacuum circuit breaker in which an electrode consisting of a main electrode and a coil electrode is arranged so as to be able to be freely connected and separated in an insulating vacuum container whose openings at both ends are closed with end plates. The coil electrode is made of a flexible material having a spring action in the direction of movement of the electrode, one end of the coil electrode is connected to the current-carrying shaft, the other end of the coil electrode is connected to the main electrode, and the electrode is turned on. When the main electrode is disconnected, the tip of the current-carrying shaft is electrically contacted with the back surface of the main electrode, and when the main electrode is cut off, the back surface of the main electrode is electrically separated from the top of the current-carrying shaft.

Further, a stopper is provided between the tip of the current-carrying shaft and the back surface of the electrode to prevent the coil electrode from moving excessively in the axial direction.

(Operation) When the movable energizing shaft of the vacuum circuit breaker is moved in the axial direction and the movable electrode is inserted into the fixed electrode, the power supply line is closed, and 1
Power is supplied from one transmission line to other transmission lines. Furthermore, when the movable current-carrying shaft is moved in the axial direction and the movable electrode is separated from the fixed electrode, the power supply line is cut off, and the supply of power from one power transmission line to the other power transmission lines is cut off. .

In a vacuum circuit breaker that operates in this way, when the movable electrode is connected to the fixed electrode, the current flows from the current-carrying shaft directly to the fixed electrode via the movable electrode, and from the current-carrying shaft directly to the fixed electrode. Some flow through the flexible coil electrode to the movable electrode, and some flow to the fixed electrode. These two current paths increase the cross-sectional area of the electrode portion, reduce electrical resistance, and reduce heat generation.

Also, when the movable electrode is separated from the fixed electrode,
The current flowing from the movable electrode to the fixed electrode is immediately interrupted, and the current flows from the flexible coil electrode to the fixed electrode via the movable electrode. The current flowing through this flexible coil electrode does not weaken the magnetic field parallel to the arc.

Further, the flexible coil electrode is limited in its axial movement to prevent excessive pressure or repulsion between the current-carrying shaft and the electrode.

(Embodiment) An embodiment of the vacuum circuit breaker of the present invention will be described below with reference to FIGS. 1 to 6. In the above drawings, the same parts as in FIGS. 7, 8, and 9 will be explained using the same reference numerals, and detailed explanation thereof will be omitted.

The vacuum circuit breaker designated by the reference numeral 3o in FIG. 1 has fixed electrodes 31. The structure is similar to the conventional vacuum circuit breaker 1o shown in FIG. 7 except for the movable electrode 32.

This fixed electrode 31 is attached to the fixed energizing shaft 17, and the movable electrode 32 is attached to the movable energizing shaft 18, but both the fixed electrode 31 and the movable electrode 32 have the same structure except that the energizing shaft is fixed and movable. Therefore, the movable electrode 32 will be explained below. That is, as shown in FIG. 2, a vertical hole 33 with a length to extending in the axial direction is bored at the tip of the movable current-carrying shaft 18 to which the movable electrode 32 is attached, and a plurality of holes extending in the radial direction are formed in the opening of the vertical hole 33. The protrusions 34 are provided at appropriate intervals in the circumferential direction. The inner diameter of the vertical hole 33 is set to do, and the inner diameter of the projection 34 is set to dl. A stopper 36 having a length tl is inserted into the vertical hole 33 and is attached to extend downward from the center of the lower surface of the main electrode 35 . The tip of this stopper 36 has a maximum diameter of d.
Two protrusions 37 are provided so that when the stopper 36 is inserted into the vertical hole 33, the protrusion 37 can be inserted between the plurality of protrusions 34. This main electrode 35 is connected to the vertical hole 33
The protrusion 37 of the stopper 36 is rotated by a certain angle after being inserted into the movable current-carrying shaft 18, and the axial movement of the protrusion 37 of the stopper 36 is limited within a certain range by the protrusion 34 of the movable current-carrying shaft 18.

Furthermore, a flexible coil electrode 38 is provided on the tip outer circumferential portion 18a of the movable current-carrying shaft 18 and the lower surface outer circumferential portion 35a of the main electrode 35, which is made of a multilayer thin plate or the like and has a spring action in the axial direction of the movable current-carrying shaft 18. (See Figure 3). This coil electrode 38 has a tip outer peripheral portion 1 of the movable current-carrying shaft 18.
Four arm portions 38a are provided to be attached to 8a. The respective arm portions 38a have the same length and are configured to slope upward as they extend in the radial direction. An arcuate portion 38b is provided at the tip of the arm portion 38a and is configured to incline upward and extend on the circumference in a counterclockwise direction. installed on. Each of these arcuate parts 3
8b forms a coil.

In the vacuum circuit breaker 30 configured as described above, when the movable electrode 32 is separated from the fixed electrode 31, that is, in the cutoff state, it is in the relative position as shown in FIG. In this case, the movable current-carrying shaft 18 and the end face of the main electrode 35 are connected to the coil electrode 3
8, and the main electrode 35 and the movable current-carrying shaft 18 are connected via the coil electrode 38 (the second
(see figure).

Next, when the movable electrode 32 is inserted into the fixed electrode 31,
The movable energizing shaft 18 is moved in the axial direction of the solid arrow by the operating force of the operating device, and the movable electrode 32 is brought into contact with the fixed electrode 31. When the movable energizing shaft 18 is further pushed in this state, the movable electrode 32 is pushed against the spring action of the coil electrode 38, and the tip of the movable energizing shaft 18 is brought into contact with the back surface of the main electrode 35. Such an action is also performed on the fixed electrode 31. Therefore, in the closed state of this vacuum circuit breaker 30,
The current of the power supply line flows directly from the end face of the movable current-carrying shaft 18 to the main electrode 35 and also flows to the main electrode 35 via the arm portion 38a2 of the coil electrode 38 and the arc portion 38b, so that the current passage cross-sectional area is increased. Ru. Therefore, the resistance of this electrode portion becomes smaller and less heat is generated.

When the movable electrode 32 is separated from the fixed electrode 31, that is, when it is cut off, the movable energizing shaft 18 is moved in the direction of the dotted arrow by the operating force of the operating device, and the movable electrode 32 is separated from the fixed electrode 31. In this cutoff operation, the end face of the movable energizing shaft 18 is separated from the main electrode 35 of the movable electrode 32, and only the current is allowed to flow from the movable energizing shaft 18 to the main electrode 35 via the coil electrode 38.

When the movable energizing shaft 18 is further moved in the direction of the dotted arrow, the movable electrode 32 is separated from the fixed electrode 31, and a gap is generated between the movable electrode 32 and the fixed electrode 31. This arc current flows to the main electrode 35 via the movable current-carrying shaft 18, the arm portion 38a2 of the coil electrode 38, and the arc portion 38b. This arc current also flows to the fixed electrode, and the current flowing through the circular arc portion 38b of the movable electrode 32 and the current flowing through the circular arc portion of the fixed electrode 31 generates a strong magnetic field parallel to the arc, and a lateral electric force is applied to the arc. is given and the arc is interrupted.

Therefore, due to the movable electrode 32 having the flexible coil electrode 38 and the fixed electrode 31, the electrode portion generates less heat when power is supplied, making it suitable for long-term use. In addition, when breaking, a strong magnetic field parallel to the arc is generated, similar to a normal vacuum circuit breaker, and the arc is properly interrupted.

In a vacuum circuit breaker that performs such an action, a stopper 36 is provided between the movable energizing shaft 18 and the main electrode 35, so even if there is a spring action on the coil electrode 38, the main electrode 35 is not connected to the fixed electrode. It is neither excessively protruded in the direction nor pushed in the direction of the movable current-carrying shaft 18.

FIGS. 4 and 5 show an improved version of the movable energizing shaft 18 and coil electrode 38 in FIGS. 2 and 3 to increase the current capacity during energization and to make it easier to attach the stopper of the main electrode 35. It is.

In FIG. 4, the movable current-carrying shaft 40 has a diameter of dm, and its tip has a small diameter of dn. Further, a diameter d larger than the diameter dm of the movable current-carrying shaft 40 is provided at the center of the coil electrode 41.
z disk 42 is provided, and four arm portions 42a extending radially from this disk 42 are provided. This arm 4
The lengths of the coils 2a are the same, and each of the coils 2a is provided with an arcuate portion 42b extending counterclockwise from the tip thereof to form a flexible coil. The disc 42 is fixed to the upper end 40a of the small diameter dn of the movable current-carrying shaft 40, and the tip 42c of the arc portion 42b is fixed to the lower outer circumference of the main electrode 43.

The lower side of the main electrode 35 has an arm portion 42a of the coil electrode 41.
A stopper 43 is provided that extends downwardly through the space and engages the lower portion of the disc 42.

With the electrode configured in this way, the tip of the movable current-carrying shaft 40 can be brought into direct contact with the main electrode 35 via the large disc 42, similar to the electrode 32, so that the electrical resistance at the time of injection is reduced. be able to. Further, since the stopper 43 is attached to the lower part of the main electrode 35 and engaged with the lower side of the disk 42, the attachment can be easily performed.

A vacuum circuit breaker having a flexible coil electrode as shown in FIGS. 2 and 3 or 4 and 5, and a commonly used vacuum circuit breaker as shown in FIGS. 7, 8, and 9. When used in combination with a vacuum circuit breaker having a fixed coil electrode, it is possible to prevent switching surges that occur when three phases are simultaneously cut off, which is the largest among switching surges.

In other words, Figure 6 shows the sine waveform of a three-phase AC power supply,
A vacuum circuit breaker 10 having a generally used fixed coil electrode is used for the S phase, and a vacuum circuit breaker 30 having a flexible coil electrode of the present invention is used for the R and T phases. In a power supply circuit using such a vacuum circuit breaker, when power needs to be cut off, the electrodes of the vacuum circuit breakers of each phase are simultaneously tripped. In this case, the S-phase vacuum circuit breaker is opened at, for example, 10 points because there is no play between the electrodes, but the R-phase and T-phase vacuum circuit breakers are delayed by ΔT due to the spring action of the coil electrodes. Opened. Therefore, when the S phase is cut off at current zero point To, the T phase is cut off at point T1 with a delay of 1/3π, and the R phase is cut off at point 12 with a delay of 2/3π. Due to this delay, the high frequency current generated by restriking the S phase is superimposed on the R phase and T phase. At this time, the R phase and T phase are not yet opened, so there is no arc in the R phase and T phase, and the three phases are not cut off at the same time. Therefore, a severe surge is generated when power is cut off) Phase simultaneous cut-off is 2/3
This can be reliably prevented with a delay of π.

In the above case, if the breaking current is small, the arc will be extinguished at the current zero point, so a vacuum circuit breaker used in a small current area will reliably prevent three-phase simultaneous breaking.

〔Effect of the invention〕

In the vacuum circuit breaker of the present invention, a flexible coil electrode having a spring action in the axial direction is provided between the current-carrying shaft and the main electrode, so that when the electrode is in the closed state, the current-carrying shaft and the main electrode are in contact with each other.
When in the cutoff state, the current-carrying shaft is separated from the main electrode, allowing current to flow from the current-carrying shaft to the main electrode via the coil electrode. As a result, it is possible to prevent the electrode portion from generating heat when it is turned on, and to generate a strong parallel magnetic field in the arc when it is turned off.

Further, since the coil electrode is supported by a stopper attached to the current-carrying shaft and the main electrode, the coil electrode, that is, the main electrode, is not excessively protruded or pressed from the current-carrying shaft.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing the outline of the vacuum circuit breaker of the present invention, and FIG.
The figure is a cross-sectional view of the electrode used in the vacuum circuit breaker of Figure 1, Figure 3 is a plan view of the coil electrode used in the electrode shown in Figure 2, and Figures 4 and 5 are: Figures 2 and 3
6 is a characteristic diagram showing waveforms of a three-phase AC power supply, and FIG. 7 is a cross-sectional view showing an outline of a conventional vacuum circuit breaker. 8 is a sectional view of an electrode used in the vacuum circuit breaker of FIG. 7, and FIG. 9 is a plan view of a coil electrode used in the electrode shown in FIG. 10... Vacuum circuit breaker, 11... Cylindrical body, 12.13
... End plate, 14 ... Vacuum container, 15.16 ... Electrode, 17.18 ... Current-carrying shaft, 19 ... Bellows, 2
0... Bellows cover, 21... Shield, 22.
23... Main electrode, 24.25... Coil electrode, 26
...Disk, 26a...Arm part, 26b...Circular arc part,
27... Reinforcement plate, 30... Vacuum circuit breaker, 31.32
...electrode, 33...vertical hole, 34...protrusion, 35.
...Main electrode, 36...Stopper, 37...Protrusion, 3
8... Coil electrode, 40... Electrode, 41... Coil electrode, 42... Coil plate, 43... Main electrode, 44
···stopper

Claims (1)

[Scope of Claims] 1. A vacuum circuit breaker in which an electrode consisting of a main electrode and a coil electrode is disposed in a movable manner in an insulating vacuum container whose openings at both ends are closed with end plates, wherein the coil electrode is flexible and has a spring action in the moving direction of the electrode, and one end of the coil electrode is connected to the current-carrying shaft, and the other end of the coil electrode is connected to the main electrode, and when the electrode is inserted, the main electrode A vacuum circuit breaker characterized in that the back surface of the main electrode is electrically separated from the tip of the current-carrying shaft when the tip of the current-carrying shaft electrically contacts the back surface of the electrode and is interrupted. 2. The vacuum circuit breaker according to claim 1, wherein a stopper is provided between the tip of the current-carrying shaft and the back surface of the electrode to prevent the coil electrode from moving excessively in the axial direction. .