JPS60160527A - Vacuum switch - 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 [Technical Field of the Invention] The present invention relates to a vacuum switch, and particularly relates to an electrode opening/closing operation thereof.

[Prior art]

Figure 1 is a schematic diagram showing the cross-sectional configuration of a conventional vacuum switch, in which (1) is an insulating cylinder made of ceramic or the like that constitutes the vacuum vessel, and (2a) and (2b) are the insulating cylinders that constitute the vacuum vessel. End plate, (3) is a bellows, (4a) and (4b) are each an electrode, (5m) - (5b) are each an electrode (
4m).

(4b) is the connected electrode rod, (6) is the fixed part, (
7) A movable operating rod, (8) a link mechanism, (9) a driving source, and αO a fixed part. In addition, the electrode (4a), (
The space 1jx between 4b) is temporarily called a stroke, and x=0
is the closed pole point and x = d is the fully open pole point.

Figure 2 is a diagram showing the desired opening/closing operation of a vacuum switch.
The vertical axis represents stroke 1, and the horizontal axis represents time t. Therefore, the electrode velocity is dx/dt, and the electrode acceleration is d2x/'dt2
The force applied to the electrode is the electrode acceleration d2x/d
(Proportional to 2.

In other words, the ideal drive characteristics are (11) In the opening operation, the speed near the opening point, that is, the initial opening speed, is high, the final speed, that is, the speed near x = d, is small, and the fully opening point In other words, at point x = d, the change in velocity (i.e. acceleration) is zero and the object comes to rest without any shocking collision.

(2) In the closing operation, the speed at which x=OK approaches, that is, the final speed, is high, but it is desirable that the speed be close to 0 just before x = 0.

In addition, the desired characteristics other than those shown in Figure 2 are as follows: (3) In the event of an accident, when short-circuit current is applied, large electrodes should be used to prevent electrode break-off arcs due to electromagnetic force. There is a demand for an operating mechanism that generates a pressure force and generates a very small electrode pressure force when turning on or energizing the rated current range during normal operation.

(4) There is a demand for a drive mechanism that has as few mechanical retaining parts as possible, has less mechanical wear, and is lightweight.

By the way, in the conventional structure shown in FIG.
The force transmitted from the electrode rod (5b) to the movable operating rod (7)
It has not only a component force in the axial direction, but also components in other directions, and the drive source (9) and link mechanism (8)
, the electrode rod (5b) is arranged in a straight line defined by the axis of the electrode rod (5a) due to friction, wear and deformation, play, time responsiveness, etc. in power transmission of each part roughly classified as the movable operating rod (7). It was difficult to drive accurately in the direction. 8 again
In contrast to the desired characteristics explained in relation to Fig. 2, in the structure shown in Fig. 1, the initial opening velocity is small and the final velocity is large, and this large final velocity suddenly increases due to the impactful collision near x = d. It is a win if the operating characteristics become zero,
This has caused problems such as a prolonged arc time when the current is cut off,9 and re-ignition.

In addition, in the structure shown in FIG. 1 during the closing operation, the larger the final velocity, the more the terminal velocity collides with the electrode (4a) and becomes zero, so the electrode (4a)
The impact force against the electrodes became excessive, causing so-called chattering to become severe, and the chattering arc caused significant wear and tear on the electrodes, causing electrode welding. In addition, there was a drawback that the voltage resistance of the vacuum switch was reduced due to electrode surface roughness due to electrode wear and welding.

On the other hand, if the final velocity at closing is too small, the pre-arc phenomenon will cause electrode wear, so the characteristic (2) above is desired, but the structure shown in Figure 1 does not It was not possible to realize the characteristics.

Furthermore, the structure shown in FIG. 1 has the disadvantage that the characteristics of (31 and (41) described above cannot be realized.

[Summary of the invention]

This invention was made in order to eliminate the drawbacks of the conventional ones as described above.
Applying the principle of LIM motor (hereinafter abbreviated as LIM), the axis of the movable electrode rod constitutes the secondary conductor of LIM, and the magnetic field running in the axial direction of the electrode rod is applied to the secondary conductor. It is generated by a primary side multiphase induction coil installed in a fixed iron core disposed with a gap g between the rod and the current flowing through the electrode rod due to the voltage generated by the traveling magnetic field and this magnetic field. The applied force gives the electrode rod a thrust in its axial direction. Indakshi,
The desired characteristic shown in FIG. 2 and explained as fil, (2) above can be obtained from the relationship between the torque of the motor and its speed.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 3 is a schematic diagram showing the cross-sectional structure of an embodiment of the present invention. In the figure, the same reference numerals as in FIG. Number of magnetic poles p
1 pitch τ, and a multiphase current of frequency f is passed through it.

(2) is a fixed iron core fixed to a fixed part αO, and in the example shown in the figure, it is formed into a concentric cylindrical shape with a gap g interposed between the electrode rod (5b) K, and a multiphase coil Q■ is provided in it. ing. Ruts are liquid dampers. Further, the electrode rod (5b) forms a short-circuited secondary conductor, an, (2), (5
b) Configure LIM by: An axial thrust acts on the movable rod (5b) by such a LIM, and the direction of this thrust can be reversed by reversing the phase rotation direction of the multiphase current flowing through the multiphase coil @■. In addition, the linear traveling distance d of the electrode rod (5b) is the distance between the electrodes (4a) and (4b) in Fig. 3.
is equal to d, which is expressed as the fully open distance. In the embodiment shown in FIG. 3, g(d≦τ). Similar to the case shown in FIG. 1, the bellows (3) has a self-closing force F due to atmospheric pressure. (d=
0) and has a bellows holding force Fd at stroke x = d.

FIG. 4 is a characteristic diagram showing the speed and thrust characteristics of the LIM having the configuration shown in FIG. 3, where the vertical axis shows the thrust and the horizontal axis shows the speed. However, the thrust F is expressed as a value F/ normalized with respect to K, the ratio v/v8 is a constant of the speed v and the synchronous speed v8, and I is the current of the LIM. Curves A1B and C in FIG. 5 show the characteristics of LIMs with different structures, but since these are well known from the characteristics of general induction motors, a general explanation thereof will be omitted. The slippage of LIM is 5 = (v - v)/v, but v/v,
If we express the characteristics in Figure 4 using S instead, F/K ==
f(v/v,) = aG (1+ (sG)2)
It is expressed as =-(2). However, G = k2τ2/
g·ρ (3), where k2 is a constant. v −
0, that is, the value of F at tr = 1 is the starting thrust F,
Then, F: KG(14G2)...(4), and in the device shown in Fig. 3, it is desirable that the value of F8 is large, and as shown in Fig. 4, F, /≧0.8. Design the LIM as follows. It is desirable that the value of G is 0.5 to 2. Furthermore, in order to increase F,
Experiments were conducted using examples of the surface material of the electrode rod (5b) such as copper, copper alloy, aluminum, aluminum alloy, etc., and it was found that the optimum magnetic pole pitch τ was in the range of 20-5Q mm. From the examples of each Miyabi, it was found that it is necessary to satisfy T≧d. Also, from the viewpoint of electrical characteristics, it is desirable to make g as small as possible, but if g is less than Q, 1 mm, contact friction between the electrode rod (5b) and the fixed iron core (22) will occur, which must be avoided. No.

FIG. 5 is a characteristic diagram showing the operating characteristics of the opening force and closing force of the vacuum switch in one embodiment of the present invention. The horizontal axis shows time t, and the vertical axis shows force, and the opening start point and the closing start point are shown corresponding to FIG. 2.

F shown in the figure. , Fd are the bellows self-closing force and bellows opening holding force, respectively, as explained earlier, F□, F
2. F3. F41F5. F6. F7 is the thrust force that each LIM acts on the electrode rod (5b). As explained earlier, the direction of thrust can be reversed by reversing the phase rotation direction of the multiphase alternating current flowing through the induction coil, and as is clear from equations (4) and (1), F Since F increases or decreases in proportion to X2, F can be changed by changing I.

The operation of the apparatus shown in FIG. 3 will be explained below with reference to FIGS. 2 and 5. At the opening point, a current of
Fi money which is F8 corresponding to is generated. Electrode rod (5b)
starts opening the electrode and obtains the speed dx/dt shown in Fig. 2. Then, when the phase rotation is reversed and the current is changed to 2, a thrust force F2 is generated and the electrode rod (5b) is opened in the opening direction. The motion of is braked and the speed dx/dt decreases. Then, near the fully open position, the phase rotation is reversed again and the current is changed to
If we subtract F3, which is F corresponding to 3, we get Fa +F
d=0, and the electrode rod (5b) comes to rest in equilibrium in the state of x=d.

Therefore, the electrode rod (5b) stops moving near the fully open position without receiving any collision force.

In addition, at the starting point of pole closing, a current is passed through the induction coil (c) with a phase rotation that generates a thrust in the direction of pole closing.

It generates a thrust force F corresponding to the current I5, gradually accelerates as shown in Fig. 2, reverses the phase rotation just before the closed pole point x = 00, applies a braking force F5 corresponding to the current I5, and suddenly decelerates. Speed dx/dt 'e #1 is set to zero and the electrode (4b
) is brought into contact with the electrode (4a) to achieve complete closure, and then a strong closing pressure F6 that sufficiently overcomes the electromagnetic separation force due to the application of the short circuit current is applied to suppress chattering arcs. , and when the vacuum switch returns from the short-circuit current state to the steady current region, the electrode pressing force can be reduced from F to F7.

Of course, if the vacuum switch is not under short-circuit current conditions from the beginning, Fl and F6 shown in Figure 5 can be set to a smaller thrust than the magnitude shown in Figure 5, and when switching at a steady current, the impact force Fewer operations are possible, contributing to stable operation and longer life of the vacuum switch. In the embodiment shown in FIG. 5, Fl, F5. The size of F is generally designed to be sufficiently larger than the size of Fd.

To summarize the above, according to the present invention, immediately after the opening start point and the closing start point of the vacuum switch, a large starting thrust is applied to quickly move the movable side electrode (4b) to the desired speed for the vacuum switch. Then, at the end of the opening and closing operations, an electrical braking force is applied to bring the speed dx/dt to almost zero, and then the opening and closing operations are completed, and the state is set at the moment the operation is completed. Shock can be removed. After the opening operation is completed, the thrust of the LIM is kept in equilibrium with the bellows opening holding force, and after the closing operation is completed, a thrust can be applied that completely suppresses the electromagnetic opening force due to chattering and short-circuit current. .

In addition, as is clear from the structure shown in Figure 3, there is no mechanical retaining part on the movable side, so the weight of the movable part of the vacuum switch is reduced, and the movable side has a non-contact structure with the fixed side. It requires little operating energy and has almost no friction or wear parts, so it is highly reliable and has a long life.

In addition, in the embodiment shown in FIG. 3, the induction coil is firmly fixed to the fixed iron core (a), but
The present invention is not limited to such a structure.

FIG. 6 is a schematic diagram showing the cross-sectional structure of another embodiment of the present invention. In the figure, the same reference numerals as in FIG. The coil @υ and the fixed core ■ are connected to the insulating tube (11, end plate (2a), (2b
), it is installed in a vacuum container composed of a bellows (3), and part of the induction coil Q1) and fixed core (2) are housed on the inner diameter side of the bellows (3). The structure shown in FIG. 6 can also achieve the same effect as the structure shown in FIG. 3, and in the structure shown in FIG. A larger thrust can be obtained by increasing the magnetic pole pitch τ of the LIM (see equation (3)).

Furthermore, in the embodiment shown in FIG. 3, the cross section of the electrode rod (5b) is assumed to be circular;
Any structure is sufficient as long as it can serve as a short-circuited secondary conductor of M, so it can have a polygonal cross section, a cruciform cross section, or a Y-shaped cross section, and the cross section of the fixed core can be determined accordingly. Furthermore, it is clear that what forms the secondary side short-circuit conductor of the LIM does not need to be the electrode rod (5b) itself, but may be any conductor connected thereto. In this 8A specification, the term "electrode rod" includes the conductor connected to the electrode rod (5b).

〔Effect of the invention〕

As described above, according to the present invention, since the movable electrode rod is driven by the LIM principle, (11) the movable electrode moves in a straight line on its central axis, improving the current interrupting ability of the switch.

(2) Since the fixed iron core constituting the stator side of the LIM serves as a guide for the movable electrode rod, movement becomes smooth and deformation of the movable electrode rod due to electromagnetic force caused by short-circuit current can be prevented.

(3) Since the movable electrode rod can be driven almost without contact, there is no wear and tear on the operation mechanism, and a stable and long-life vacuum switch can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing the cross-sectional configuration of a conventional vacuum switch, and FIG. 2 is an operation diagram showing the desired opening/closing operation of the vacuum switch.
FIG. 3 is a schematic diagram showing a cross-sectional configuration of an embodiment of the present invention;
FIG. 4 is a characteristic diagram showing the speed and thrust characteristics of the LIM configured as shown in FIG. 3, and FIG. 5 is a characteristic diagram showing the operating characteristics of the opening force and closing force of the vacuum switch in one embodiment of the present invention. be. 11... Insulating cylinder, (za), (zb)... End plate, (
3)...Bellows, (4a)...Fixed side electrode, (4
b)...Movable side electrode, (5a)...Fixed 1ll11
Electrode rod, (5b)...Movable side electrode rod, Qno...-Next side polyphase induction coil, (A)...Fixed iron core. Note that the same reference numerals in each figure indicate the same or corresponding parts. Attorney Masuo Oiwa Figure 6 Procedural Amendment (Voluntary) Commissioner of the Japan Patent Office 1. Indication of the case Japanese Patent Application No. 58-192726 2. Title of the invention Vacuum switch 3. Person making the amendment Relationship to the case Patent applicant Address: 2-2-3 Marunouchi, Chiyoda-ku, Tokyo Name:
(601,) Mitsubishi Electric Corporation Representative Hitoshi Katayama 4, Agent Address 2-2-3 Marunouchi, Chiyoda-ku, Tokyo Procedural Amendment (Method) % Formula % 1, Indication of Case Patent Application No. 58- 192726 No. 3,
Relationship with the case of the person making the amendment Patent applicant address 2-2-3 Marunouchi, Chiyoda-ku, Tokyo Name (ω
l) Mitsubishi Electric Corporation Representative Hitoshi Katayama Section 4 is a characteristic diagram showing agent work characteristics. '' should be corrected to read, ``and a characteristic diagram showing the operating characteristics of the closing force, and Fig. 6 is a schematic diagram showing the cross-sectional configuration of another embodiment of the present invention.''(that's all)

Claims (5)

[Claims] (1) A fixed electrode connected to the end of a fixed electrode rod fixed to a fixed part in a vacuum container consisting of an insulating tube, an end plate, and a bellows; A movable electrode is provided, and a movable electrode rod to which the movable electrode is connected is fixed to the bellows, and the movable electrode is brought into contact with the fixed electrode according to elastic expansion and contraction in the axial direction of the bellows. A movable electrode rod that moves over a movable distance d from a closed position where the two electrodes are in contact to an open position where a predetermined distance is maintained between the two electrodes, and a secondary conductor to which this movable electrode rod is short-circuited. As,
A cylindrical fixed core that surrounds this secondary conductor with a gap gf to form a linear induction motor, a primary multiphase induction coil provided within this fixed core, and this multiphase induction A vacuum switch equipped with means for controlling the phase rotation direction and amplitude of a multiphase alternating current flowing through a coil. (2) The surface material of the movable electrode rod is copper, copper alloy, aluminum, or aluminum alloy, and the cross-sectional shape taken on a plane perpendicular to the axial direction is circular, annular,
The vacuum switch according to claim 1, wherein the vacuum switch has a polygonal shape, a Y-shape, or a cross shape. (3) The primary side multiphase induction coil forming the linear induction coil has a magnetic pole pitch of 2Qmm to 5Q*na, and this magnetic pole pitch °C is greater than the movable distance of the movable side electrode by 6 or more. 2. The vacuum switch according to claim 1, wherein the vacuum switch is set to a value of . (4) The means for controlling the phase rotation direction and amplitude of the multiphase alternating current is to adjust the magnitude of the thrust force F transmitted to the movable electrode rod by the linear induction motor to the bellows opening holding force Fd.
2. The vacuum switch according to claim 1, further comprising means for controlling the amplitude of said multiphase alternating current to be equal to or greater than . (5) The means for controlling the phase rotation direction and amplitude of the multiphase alternating current generates a thrust in a direction opposite to the speed of the movable electrode rod at the end of the opening operation or the closing operation to move the movable electrode rod. 2. The vacuum switch according to claim 1, further comprising means for controlling the brake.