Patent Description:
Some switch including a stationary electrode and a movable electrode is provided with a contact pressure spring that applies contact pressure to the stationary electrode and the movable electrode. When the switch is in a closed state, having the stationary electrode and the movable electrode closed, the contact pressure spring in a contracted state presses the movable electrode against the stationary electrode, thus applying the contact pressure to the stationary electrode and the movable electrode. When the switch performs opening of the stationary electrode and the movable electrode, the contact pressure spring is restored from the contracted state, so that the contact pressure becomes zero. After the contact pressure becomes zero, the movable electrode starts to separate from the stationary electrode.

<CIT>discloses a switch that includes a contact pressure spring between two movable shafts. One of the two movable shafts is a first movable shaft connected to a movable core of a handler. Another of the two movable shafts is a second movable shaft connected to a movable electrode. The first movable shaft is provided with, at an end opposite from an end connected to the movable core, a housing that houses the contact pressure spring. The second movable shaft is provided with a flange at an end opposite from an end connected to the movable electrode. The flange is connected to one end of the contact pressure spring inside the housing. The contact pressure spring is connected to an internal wall face of the housing at another end.

Document <CIT> shows a switch including a second conductor; a second movable electrode provided in a second hermetic space so as to be movable in a first direction in which it parts from the fixed electrode and in a second direction opposite the first direction; an opposed electrode slidably provided in the fixed electrode to face the second movable electrode so as to separate from and be in contact with the second movable electrode in an open state and a closed state respectively; a second driver which generates a driving force and moves the second movable electrode in the first direction when performing an opening operation; and a driving force transmitting mechanism which converts a direction of the driving force to the second direction opposite the moving direction of the second movable electrode to move the opposed electrode when the second driver moves the second movable electrode in the first direction.

Since the contact pressure spring according to the above conventional technique described in <CIT> is connected between the two movable shafts, the contact pressure spring could cause a moving speed differential between the first movable shaft and the second movable shaft. When the handler starts decelerating the movable core, with the movable electrode at a certain distance from the stationary electrode during withdrawal of the movable electrode, the first movable shaft is decelerated along with the movable core. The contact pressure spring contracts under inertial force from the second movable shaft, so that the second movable shaft, on the other hand, does not decelerate but continues moving at the same speed as before the movable core starts decelerating. Even when the handler makes the adjustment to decelerate the movable core, the moving speed differential is thus caused between the first movable shaft and the second movable shaft. Therefore, the speed adjustment that is made by the handler is not reflected in the speed of the movable electrode. Thus, the above conventional technique is problematic in that the speed of the movable electrode is uncontrollable even after the handler makes the speed adjustment.

The present invention has been made in view of the above, and an object of the present invention is to obtain a switch that enables speed of a movable electrode to be controlled in accordance with a speed adjustment that is made by a handler.

To solve the above-stated problem and achieve the object, a switch according to the present invention includes: a pair of electrodes that serve as a stationary electrode and a movable electrode; a handler including a first mover that operates in withdrawing the movable electrode from the stationary electrode and closing the movable electrode toward the stationary electrode; a second mover connected to the movable electrode; an elastic that is connected between the first mover and the second mover to press the movable electrode against the stationary electrode; and an attenuator that attenuates contraction of the elastic when the movable electrode is withdrawn from the stationary electrode. The switch further includes a permanent magnet at one of the first mover and the second mover; and a magnetic substance at another of the first mover and the second mover, and wherein the attenuator attenuates contraction of the elastic by attracting the magnetic substance to the permanent magnet.

The switch according to the present invention enables speed of the movable electrode to be controlled in accordance with a speed adjustment that is made by the handler.

With reference to the drawings, a detailed description is hereinafter provided with switches according to embodiments of the present invention. It is to be noted that these embodiments are not restrictive of the present invention.

<FIG> illustrates a switch, namely, a vacuum circuit breaker. In the vacuum circuit breaker <NUM>, which is the switch according to the first embodiment, opening and closing of a pair of electrodes serving as a stationary electrode <NUM> and a movable electrode <NUM> are performed inside a vacuum valve <NUM> having a higher vacuum. The vacuum valve <NUM> is a hollow body that is cylindrical. The stationary electrode <NUM> is fixed inside the vacuum valve <NUM>. The movable electrode <NUM> is movable with respect to the stationary electrode <NUM>. In a description below, the vacuum circuit breaker <NUM> may be said to be in a closed state when the stationary electrode <NUM> and the movable electrode <NUM> are electrically connected, and the vacuum circuit breaker <NUM> may be said to be in an open state when the conduction between the stationary electrode <NUM> and the movable electrode <NUM> is interrupted.

A top part of <FIG> illustrates the vacuum circuit breaker <NUM> in the closed state. A bottom part of <FIG> illustrates the vacuum circuit breaker <NUM> in the open state. In <FIG>, constituent elements of the vacuum circuit breaker <NUM> include constituent elements shown in section and constituent elements shown in plan view. Some sections have no hatching.

The vacuum circuit breaker <NUM> includes a handler <NUM> that operates to withdraw the movable electrode <NUM> from the stationary electrode <NUM> and close the movable electrode <NUM> toward the stationary electrode <NUM>. The term "withdraw" refers to separating the movable electrode <NUM>, in contact with the stationary electrode <NUM>, from the stationary electrode <NUM>. The term "close" refers to drawing the movable electrode <NUM> that is away from the stationary electrode <NUM> to the stationary electrode <NUM> and establishing contact between the movable electrode <NUM> and the stationary electrode <NUM>. The handler <NUM> includes a cylindrical case <NUM>. A columnar stationary core <NUM> and a cylindrical movable core <NUM> are housed in the case <NUM>. The stationary core <NUM> and the movable core <NUM> are arranged coaxially with each other. The stationary core <NUM> is fixed inside the case <NUM>. The movable core <NUM> is movable inside the case <NUM> with respect to the stationary core <NUM>. The movable core <NUM> is capable of axial reciprocation. A permanent magnet <NUM> is provided at a portion of the stationary core <NUM> to make contact with the movable core <NUM> in the closed state.

The handler <NUM> includes a plurality of drive coils <NUM> for driving the movable core <NUM>. The plurality of drive coils <NUM> include a withdrawal drive coil <NUM> and a closing drive coil <NUM>. Each of the drive coils <NUM> is surrounded by the stationary core <NUM> and is wound about the axis of the stationary core <NUM>. Each drive coil <NUM> generates magnetic flux that passes through the stationary core <NUM> and the movable core <NUM>. The handler <NUM> is provided with a drive circuit that causes electric current pass through each of the plurality of drive coils <NUM>. The drive circuit is not illustrated in <FIG>.

A movable shaft <NUM> is provided at one of axial ends of the movable core <NUM> that is opposite from another axial end facing the stationary core <NUM>. The movable shaft <NUM> passes through a hole formed in the case <NUM>, extending out of the case <NUM>. A spring bearing <NUM> is provided at a portion outside the case <NUM> of the movable shaft <NUM>. A coil spring <NUM> is provided as an elastic between the case <NUM> and the spring bearing <NUM>. The coil spring <NUM> is connected at one end to an external wall face of the case <NUM>. The coil spring bearing <NUM> is connected at another end to the spring bearing <NUM>. The movable shaft <NUM> passes through an interior of the coil spring <NUM>.

The movable shaft <NUM> is connected to a decelerator <NUM> at an end opposite from the movable core <NUM>. The decelerator <NUM> decelerates the movable core <NUM> during the withdrawal of the movable electrode <NUM>. A dashpot is usable as the decelerator <NUM>.

A movable shaft <NUM> is provided at the axial end of the movable core <NUM> that faces the stationary core <NUM>. The movable shaft <NUM> passes through the stationary core <NUM>, extending out of the case <NUM>. The movable shaft <NUM> is connected at one end to the movable core <NUM>. A hollow housing <NUM> is provided at another end of the movable shaft <NUM>. A coil spring <NUM> is housed as an elastic in the housing <NUM>. The coil spring <NUM> is a contact pressure spring that presses the movable electrode <NUM> against the stationary electrode <NUM>. The movable shaft <NUM> and the housing <NUM> are constituent elements that move integrally with the movable core <NUM> and are regarded as a part of the handler <NUM>. The movable shaft <NUM> and the housing <NUM> function as a first mover that operates in withdrawing and closing the movable electrode <NUM>. The configuration of the handler <NUM> in the first embodiment is an example. The configuration of the handler <NUM> may be appropriately altered.

The housing <NUM> includes an opening <NUM> in an end closer to the vacuum valve <NUM>, and a movable shaft <NUM> passes through the opening <NUM>. The movable shaft <NUM> is a second mover connected to the movable electrode <NUM>. The movable shaft <NUM> extends out of the housing <NUM> through the opening <NUM>. Inside the vacuum valve <NUM>, the movable shaft <NUM> is connected to the movable electrode <NUM> and extends out of the vacuum valve <NUM>. The movable shaft <NUM> is axially movable while maintaining the vacuum in the vacuum valve <NUM>. The movable electrode <NUM> is connected to one end of the movable shaft <NUM>. An insulating rod that insulates the movable shaft <NUM> and the movable electrode <NUM> from each other is provided between the movable shaft <NUM> and the movable electrode <NUM>. Illustration of the insulating rod is omitted in <FIG>.

A flange <NUM> is provided at another end of the movable shaft <NUM>. The flange <NUM> is arranged inside the housing <NUM>. An outside diameter of the flange <NUM> is greater than an inside diameter of the opening <NUM>. In the closed state of the vacuum circuit breaker <NUM>, the flange <NUM> is positioned away from an internal wall face <NUM> of the end of the housing <NUM> that is closer to the vacuum valve <NUM>. In the open state of the vacuum circuit breaker <NUM>, the flange <NUM> is in contact with the internal wall face <NUM>.

The coil spring <NUM> is connected at one end to the flange <NUM>. The coil spring <NUM> is connected at another end to an internal wall face of the housing <NUM> that is closer to the handler <NUM>. In other words, the coil spring <NUM> is connected between the first mover and the second mover. An elastic other than the coil spring <NUM> may be connected between the first mover and the second mover. Such an elastic may be a spring other than the coil spring <NUM>, such as a disk spring or a flat spring. The elastic in the vacuum circuit breaker <NUM> may be an elastic other than the spring.

The handler <NUM> is provided with a shock absorber <NUM>. The shock absorber <NUM> is an attenuator that attenuates contraction of the coil spring <NUM> when the movable electrode <NUM> is withdrawn from the stationary electrode <NUM>. When force is applied in the direction of the handler <NUM> to an end <NUM> of the shock absorber <NUM> that is closer to the vacuum valve <NUM>, the shock absorber <NUM> displaces the end <NUM> toward the handler <NUM>. The shock absorber <NUM> generates resisting force against the force applied to the end <NUM>, thus decelerating moving speed of the moving end <NUM>.

The movable shaft <NUM> is provided with a flat plate <NUM> at a portion between the vacuum valve <NUM> and the housing <NUM>. The movable shaft <NUM> passes through the flat plate <NUM>. The flat plate <NUM> is fixed to the movable shaft <NUM>. The flat plate <NUM> moves integrally with the movable shaft <NUM>. In the closed state of the vacuum circuit breaker <NUM>, the end <NUM> and the flat plate <NUM> face each other. In the open state of the vacuum circuit breaker <NUM>, the end <NUM> is in contact with the flat plate <NUM>.

A description is provided next of operation of the vacuum circuit breaker <NUM>. Position P1 denotes a position of the movable core <NUM> in the closed state. Position P2 denotes a position of the movable electrode <NUM> in the closed state. Position P3 denotes a position of the movable core <NUM> in the open state. Position P4 denotes a position of the movable electrode <NUM> in the open state.

In a process the movable electrode <NUM> is being withdrawn from the stationary electrode <NUM>: the movable core <NUM> shifts from position P1 to position P3; and the movable electrode <NUM> shifts from position P2 to position P4. In a process the movable electrode <NUM> is being closed toward the stationary electrode <NUM>: the movable core <NUM> shifts from position P3 to position P1; and the movable electrode <NUM> shifts from position P4 to position P2. In a description below, the movable core <NUM> may be said to be shifting in an opening direction when the movable electrode <NUM> is being withdrawn, and the movable core <NUM> may be said to be shifting in a closing direction when the movable electrode <NUM> is being closed. The closing direction is opposite to the opening direction.

In the closed state of the vacuum circuit breaker <NUM>: the movable core <NUM> is attracted to the permanent magnet <NUM> by magnetic force of the permanent magnet <NUM>; with the movable core <NUM> being attracted to the permanent magnet <NUM>, the end of the movable core <NUM> that is closer to the stationary core <NUM> is in contact with the stationary core <NUM>; the movable shaft <NUM> is at a position that is closest to the vacuum valve <NUM> in an axial moving range of the movable shaft <NUM>; the flat plate <NUM> is sandwiched between the housing <NUM> and an external wall face of the vacuum valve <NUM>; the coil spring <NUM> is contracted between the internal wall face of the housing <NUM> and the flange <NUM>; and the movable shaft <NUM> presses the movable electrode <NUM> against the stationary electrode <NUM> due to reaction force of the coil spring <NUM>.

In the closed state of the vacuum circuit breaker <NUM>: coil spring <NUM> is contracted between the external wall face of the case <NUM> and the spring bearing <NUM>; the coil spring <NUM> applies reaction force to the spring bearing <NUM>; and the vacuum circuit breaker <NUM> maintains the closed state because the force the movable core <NUM> is attracted to the permanent magnet <NUM> is greater than the reaction force of the coil spring <NUM>.

When the vacuum circuit breaker <NUM> is in the closed state, the handler <NUM> causes electric current to flow through the withdrawal drive coil <NUM> in response to a withdrawal operation command input to the handler <NUM>. The operation command is input to the handler <NUM> from a control panel that controls the vacuum circuit breaker <NUM>. The control panel is not illustrated in <FIG>.

With the current flowing through the withdrawal drive coil <NUM>, the withdrawal drive coil <NUM> generates electromagnetic force that can counteract the magnetic force of the permanent magnet <NUM>. The magnetic force of the permanent magnet <NUM> weakens by being counteracted by the generated electromagnetic force of the withdrawal drive coil <NUM>. When the reaction force of the coil spring <NUM> becomes greater than the force that causes the movable core <NUM> to be attracted to the permanent magnet <NUM> due to the weakened magnetic force of the permanent magnet <NUM>, the coil spring <NUM> is restored from the contracted state to a state of its equilibrium length, shifting the spring bearing <NUM> in the opening direction. The movable shaft <NUM> and the movable core <NUM> move in the opening direction along with the spring bearing <NUM>. This is how the movable core <NUM> of the vacuum circuit breaker <NUM> is moved in the opening direction.

The movable shaft <NUM> and the housing <NUM> move in the opening direction along with the movable core <NUM>. The movement of the housing <NUM> in the opening direction gradually decreases a distance between the flange <NUM> and the internal wall face <NUM> and causes the coil spring <NUM> to stretch. The stretching of coil spring <NUM> lessens contact pressure between the stationary electrode <NUM> and the movable electrode <NUM>. The movable shaft <NUM> and the housing <NUM> move further in the opening direction after the flange <NUM> contacts the internal wall face <NUM>; accordingly, the movable shaft <NUM> moves in the opening direction along with the movable shaft <NUM> and the housing <NUM>. As the movable shaft <NUM> moves in the opening direction, the movable electrode <NUM> is withdrawn from the stationary electrode <NUM>. This is how the vacuum circuit breaker <NUM> transitions from the closed state to the open state.

The flat plate <NUM> moves in the opening direction along with the movable shaft <NUM> and reaches the end <NUM>. The flat plate <NUM> applies the force to the end <NUM> in the opening direction. The shock absorber <NUM> generates the resisting force against the force applied to the end <NUM>. The shock absorber <NUM> absorbs kinetic energy of the movable shaft <NUM> by generating the resisting force, thus easing the movable shaft <NUM>. A detailed description of the function of the shock absorber <NUM> will be provided later.

When the vacuum circuit breaker <NUM> is in the open state: the handler <NUM> causes the electric to flow through the closing drive coil <NUM> in response to a closing operation command input to the handler <NUM>; with the electric current flowing through the closing drive coil <NUM>, the closing drive coil <NUM> generates electromagnetic force that attracts the movable core <NUM>; and due to the generated electromagnetic force of the closing drive coil <NUM> and the magnetic force of the permanent magnet <NUM>, the movable core <NUM> moves in the closing direction while causing the coil spring <NUM> to contract. As the movable core <NUM> moves in the closing direction, the movable shaft <NUM> and the housing <NUM> move in the closing direction along with the movable core <NUM>. The movable shaft <NUM> moves in the closing direction along with the housing <NUM>, thus causing the movable electrode <NUM> to reach the stationary electrode <NUM>. Moreover, the coil spring <NUM> in the housing <NUM> is contracted and thus applies the contact pressure to the stationary electrode <NUM> and the movable electrode <NUM>. This is how the vacuum circuit breaker <NUM> transitions from the open state to the closed state.

The function of the shock absorber <NUM> is described here. Suppose that the decelerator <NUM> starts to decelerate the movable core <NUM> after the movable electrode <NUM> is separated from the stationary electrode <NUM> in the withdrawal of the movable electrode <NUM>. The movable shaft <NUM> and the housing <NUM> start to decelerate along with the movable core <NUM>, because the movable shaft <NUM> and the housing <NUM> are integral with the movable core <NUM>. When the housing <NUM> starts decelerating, inertial force caused by the movement of the movable shaft <NUM> in the opening direction is applied on the coil spring <NUM>. While the housing <NUM> decelerates, if the coil spring <NUM> contracts due to the inertial force, the movable shaft <NUM> does not decelerate but keeps moving at the same speed as before the movable core <NUM> starts decelerating. Accordingly, the shock absorber <NUM> attenuates the contraction of the coil spring <NUM> in the first embodiment, thus decelerating the movable shaft <NUM>.

<FIG> is used for explaining the function of the shock absorber, which serves as the attenuator of the vacuum circuit breaker illustrated in <FIG>. <FIG> illustrates a waveform representing a relationship between position of the movable shaft <NUM> and time, and a waveform representing a relationship between position of the movable shaft <NUM> and the time. The waveform representing the relationship between the position of each of the movable shafts <NUM> and <NUM> and the time may hereinafter be referred to as "travel waveform" in a description below.

A broken line graph in <FIG> exemplifies the travel waveform of the movable shaft <NUM> in the withdrawal of the movable electrode <NUM>. A solid line graph exemplifies the travel waveform of the movable shaft <NUM> in the withdrawal of the movable electrode <NUM>. The travel waveforms illustrated in <FIG> indicate a case when the decelerator <NUM> decelerates the movable core <NUM> after the separation of the movable electrode <NUM> from the stationary electrode <NUM>, and no deceleration of the movable shaft <NUM> is performed by the shock absorber <NUM>.

A vertical axis of the graphs illustrated in <FIG> represents the position, and a horizontal axis represents the time. In order to have the travel waveforms of the movable shaft <NUM> and the movable shaft <NUM> superimposed for illustration, <FIG> has a position on the vertical axis that denotes a position of the movable shaft <NUM> in the open state aligned with a position on the vertical axis that denotes a position of the movable shaft <NUM> in the open state.

At time t0, the vacuum circuit breaker <NUM> is in the closed state. In the closed state of the vacuum circuit breaker <NUM>, the movable shaft <NUM> and the movable shaft <NUM> remain in constant positions, respectively. In <FIG>, a distance between the graph for the movable shaft <NUM> and the graph for the movable shaft <NUM> along the vertical axis represents a length of the coil spring <NUM> contracted from the equilibrium length. At time t0, the movable core <NUM> is at position P1. At time t0, the movable electrode <NUM> is at position P2.

The vacuum circuit breaker <NUM> starts the withdrawal in accordance with the operation command. At time t1, the movable electrode <NUM> starts to shift in the opening direction from position P2. The movable electrode <NUM> separates from the stationary electrode <NUM>. As the decelerator <NUM> starts to decelerate the movable core <NUM> after time t1, the movable shaft <NUM> is decelerated along with the movable core <NUM>. On the other hand, the movable shaft <NUM> lags behind the movable shaft <NUM> in starting the deceleration because the coil spring <NUM> contracts. At following time t2, the vacuum circuit breaker <NUM> is in the open state. At time t2, the movable core <NUM> is at position P3. At time t2, the movable electrode <NUM> is at position P4.

In the first embodiment, when the flat plate <NUM> reaches the end <NUM> during the movement of the movable shaft <NUM> in the opening direction, the shock absorber <NUM> generates the resisting force against the force that is applied in the opening direction by the flat plate <NUM>, thus easing the movement of the flat plate <NUM> in the opening direction. By easing the movement of the flat plate <NUM> in the opening direction, the shock absorber <NUM> suppresses the contraction of the coil spring <NUM> during the deceleration of the movable shaft <NUM>. This is how the shock absorber <NUM> attenuates the contraction of the coil spring <NUM> after the decelerator <NUM> has started decelerating the movable core <NUM>.

Since the shock absorber <NUM> attenuates the contraction of the coil spring <NUM>, the vacuum circuit breaker <NUM> enables the deceleration of the movable shaft <NUM> to concur with the deceleration of the movable shaft <NUM>. Since the deceleration of the movable shaft <NUM> is caused to concur with the deceleration of the movable shaft <NUM>, the vacuum circuit breaker <NUM> enables the speed adjustment that is made by the handler <NUM> to be accurately reflected in speed of the movable electrode <NUM>. The travel waveform of the movable shaft <NUM> approximates the travel waveform of the movable shaft <NUM>.

In the vacuum circuit breaker <NUM>, a longitudinal magnetic field may be generated between the stationary electrode <NUM> and the movable electrode <NUM>. The longitudinal magnetic field generated causes an arc that occurs between the stationary electrode <NUM> and the movable electrode <NUM> during interruption to extend over entire electrode faces, so that electric current density by the arc discharge lowers. With the lower electric current density, melting of the stationary electrode <NUM> and the movable electrode <NUM> is suppressed. Since vapor that results from the melting is suppressed, easy current interruption is possible in the vacuum circuit breaker <NUM>. The vacuum circuit breaker <NUM> may be provided with electrodes that generate the longitudinal magnetic field. The electrodes that generate the longitudinal magnetic field are not illustrated in <FIG>.

Decelerating the movable electrode <NUM> during the withdrawal of the movable electrode <NUM> from the stationary electrode <NUM> enables improved interruption performance of the longitudinal magnetic field in the vacuum circuit breaker <NUM>. Where the deceleration of the movable electrode <NUM> is required thus, the vacuum circuit breaker <NUM> enables the movable electrode <NUM> to decelerate in accordance with the speed adjustment that is made by the handler <NUM>. Since the movable electrode <NUM> is decelerated in accordance with the speed adjustment that is made by the handler <NUM>, the vacuum circuit breaker <NUM> is capable of achieving a higher interruption performance.

The attenuator of the vacuum circuit breaker <NUM> may be a mechanism other than the shock absorber <NUM> as far as the mechanism: generates resisting force against the force applied on the elastic in conjunction with the movement of the movable shaft <NUM>; and attenuates the contraction of the elastic. The attenuator may be a mechanism such as a dashpot or a mechanical linkage. The switch according to the first embodiment may be a circuit breaker other than the vacuum circuit breaker <NUM> or a disconnector.

The switch according to the first embodiment includes the attenuator that attenuates the contraction of the elastic when the movable electrode <NUM> is withdrawn from the stationary electrode <NUM> and thus enables the movable electrode <NUM> to decelerate in accordance with the speed adjustment that is made by the handler <NUM>. Therefore, the switch enables the speed of the movable electrode <NUM> to be controlled in accordance with the speed adjustment that is made by the handler <NUM>.

<FIG> illustrates a switch according to an embodiment of the present invention, namely, a vacuum circuit breaker. The vacuum circuit breaker <NUM> includes a permanent magnet and a magnetic substance constituting the decelerator. In the embodiment, constituent elements identical with those in the above-described switch have the same reference characters, and a description is provided mainly of difference from the switch.

A top part of <FIG> illustrates the vacuum circuit breaker <NUM> in a closed state. A bottom part of <FIG> illustrates the vacuum circuit breaker <NUM> in an open state. In <FIG>, constituent elements of the vacuum circuit breaker <NUM> include constituent elements shown in section and constituent elements shown in plan view. Some sections have no hatching.

The movable shaft <NUM> is provided with, at the end in an opening direction, a flange <NUM> that serves as the permanent magnet. The flange <NUM> corresponds to the permanent magnet. The housing <NUM> has, in a closing direction, an end <NUM> that is a magnetic substance. The end <NUM> has the opening <NUM> through which the movable shaft <NUM> is passed. In the vacuum circuit breaker <NUM>, the housing <NUM> as the first mover is provided with the magnetic substance; and the movable shaft <NUM> as the second mover is provided with the permanent magnet. In the closed state of the vacuum circuit breaker <NUM>, the flange <NUM> is positioned away from the end <NUM> of the housing <NUM>. In the open state of the vacuum circuit breaker <NUM>, the flange <NUM> is in contact with the end <NUM>.

A description is provided next of operation of the vacuum circuit breaker <NUM>. When the movable electrode <NUM> is withdrawn, the movable shaft <NUM> and the housing <NUM> move in the opening direction along with the movable core <NUM>. The movement of the housing <NUM> in the opening direction gradually decreases a distance between the flange <NUM> and the end <NUM> and causes the coil spring <NUM> to stretch. The movable shaft <NUM> and the housing <NUM> move further in the opening direction after the flange <NUM> contacts the end <NUM>; accordingly, the movable shaft <NUM> moves in the opening direction along with the movable shaft <NUM> and the housing <NUM>.

Suppose that the decelerator <NUM> starts to decelerate the movable core <NUM> after the movable electrode <NUM> is separated from the stationary electrode <NUM>. The movable shaft <NUM> and the housing <NUM> start decelerating along with the movable core <NUM>. In the second embodiment, the end <NUM> is attracted to the flange <NUM> by magnetic force of the flange <NUM> after the flange <NUM> contacts the ends <NUM>. Since the end <NUM> is attracted to the flange <NUM>, separation of the flange <NUM> from the end <NUM> is suppressed in a state the inertial force is applied to the movable shaft <NUM> in the opening direction. With the maintained contact between the flange <NUM> and the end <NUM>, contraction of the coil spring <NUM> is suppressed during the deceleration of the movable shaft <NUM>. This is how the flange <NUM> and the end <NUM> attenuate the contraction of the coil spring <NUM> after the decelerator <NUM> has started decelerating the movable core <NUM>. The attenuator attenuates the contraction of the elastic by having the magnetic substance attracted to the permanent magnet.

In the embodiment, the attenuator that includes the flange <NUM> as the permanent magnet and the end <NUM> as the magnetic substance is non-limiting. The entire flange <NUM> that serves as the permanent magnet is non-limiting. The attenuator may include a permanent magnet as a portion of the flange <NUM>. Not only the end <NUM> but also any other portion of the housing <NUM> may serve as the magnetic substance of the attenuator. The entire housing <NUM> may serve as the magnetic substance. In the second embodiment, the housing <NUM> of the first mover and the movable shaft <NUM>, which is the second mover, may be provided with the permanent magnet and the magnetic substance, respectively. The switch according to the second embodiment may be a circuit breaker other than the vacuum circuit breaker <NUM> or a disconnector.

The switch according to the embodiment: includes the attenuator that attenuates the contraction of the elastic when the movable electrode <NUM> is withdrawn from the stationary electrode <NUM>; and thus enables the movable electrode <NUM> to decelerate in accordance with the speed adjustment that is made by the handler <NUM>. Therefore, the switch enables the speed of the movable electrode <NUM> to be controlled in accordance with the speed adjustment that is made by the handler <NUM>.

The above configurations illustrated in the embodiments are illustrative of contents of the present invention, can be combined with other techniques that are publicly known, and can be partly omitted or changed. The scope is defined solely by the appended claims.

Claim 1:
A switch (<NUM>) comprising:
a pair of electrodes serving as a stationary electrode (<NUM>) and a movable electrode (<NUM>);
a handler (<NUM>) including a first mover (<NUM>, <NUM>) to operate in withdrawing the movable electrode (<NUM>) from the stationary electrode (<NUM>) and closing the movable electrode (<NUM>) toward the stationary electrode (<NUM>);
a second mover (<NUM>) connected to the movable electrode (<NUM>) ;
an elastic (<NUM>) connected between the first mover (<NUM>, <NUM>) and the second mover (<NUM>) to press the movable electrode (<NUM>) against the stationary electrode (<NUM>);
an attenuator (<NUM>) to attenuate contraction of the elastic (<NUM>) when the movable electrode (<NUM>) is withdrawn from the stationary electrode (<NUM>);
a permanent magnet (<NUM>) at one of the first mover (<NUM>, <NUM>) and the second mover (<NUM>); and
a magnetic substance (<NUM>) at another of the first mover (<NUM>, <NUM>) and the second mover (<NUM>), and wherein
the attenuator attenuates contraction of the elastic (<NUM>) by attracting the magnetic substance (<NUM>) to the permanent magnet (<NUM>).