JP4971738B2 - Switch operating circuit and power switch using the same - Google Patents

Description

  The present invention relates to an operation circuit for a switch such as a vacuum circuit breaker and a power switch using the same.

The operation circuit of the conventional switch is designed to attract the mover in a predetermined direction by passing a current through the opening coil of the operation mechanism controlled by the operation circuit and cancel the magnetic flux formed by the permanent magnet. However, the opening operation is performed without controlling the exciting current of the opening coil (see, for example, Patent Document 1 and Patent Document 2).
JP 2000-268683 A (paragraph number 0050, FIG. 1 and FIG. 3) Japanese Patent Laying-Open No. 2004-288502 (paragraph numbers 0008 and 0010 and FIG. 1)

Since the operation circuit of the conventional switch is configured as described above and does not control the excitation current of the opening coil of the operation mechanism, the operation mechanism and the switch driven by the operation mechanism are In operation, a large impact is generated when the movable part stops and the opening is completed.
The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a switch operating circuit capable of reducing an impact at the time of opening and a power switch using the switch operating circuit.

The switch operating circuit according to the present invention comprises a current supply source, an excitation control means, and a current attenuation means, wherein the current supply source is a DC power source having a constant voltage, and the excitation control The means supplies the opening coil of the operating mechanism having a movable element connected to the movable electrode of the switch, a yoke for supporting the movable element to be movable in a predetermined direction, and an opening coil from the power supply source. An exciting current is supplied to attract the movable element to a predetermined part of the yoke to open the switch, and the movable element is moving and a predetermined time has elapsed since the supply of the exciting current was started. The current attenuating means is a series circuit of an attenuating resistor, a diode and an inductive cut-off switch, and is connected to the opening coil and the excitation current is cut off. The circulating current flows through the opening coil as a circulating current and adjusts the resistance value of the damping resistor so that a predetermined circulating current flows when the opening of the switch is completed. The speed of attenuation is adjusted.

The switch operating circuit according to the present invention includes a current supply source, excitation control means, and current attenuation means, wherein the current supply source is a DC power source having a constant voltage, and the excitation control means. Is excited from the power supply source to the opening coil of the operating mechanism having a mover connected to the movable electrode of the switch, a yoke that supports the mover so as to be movable in a predetermined direction, and an opening coil. A current is supplied to attract the movable element to a predetermined portion of the yoke to open the switch, and the movable element is moving and a predetermined time has passed since the supply of the excitation current was started. The current attenuating means is a series circuit of an attenuating resistor, a diode and an inductive cutoff switch, and is connected to the opening coil and the excitation current is interrupted. the above The current flowing through the pole coil flows as a circulating current, and the resistance value of the damping resistor is adjusted to reduce the circulating current so that a predetermined circulating current flows when the opening of the switch is completed. Since the speed is adjusted, the excitation of the opening coil can be controlled to reduce the impact at the time of opening.

Embodiment 1 FIG.
1 to 6 show Embodiment 1 for carrying out the present invention. FIG. 1 is a circuit diagram of an operation circuit of a vacuum circuit breaker, and FIG. 2 is a diagram of a vacuum circuit breaker controlled by the operation circuit. FIG. 3 is a perspective view of the operation mechanism, FIG. 4 is a configuration diagram of a vacuum circuit breaker, FIG. 5 is a characteristic diagram showing the current of the operation mechanism and displacement of the mover, and FIG. 6 is a mover. It is a characteristic view which shows the spring force of the open spring which acts on, and the electromagnetic force of an operation mechanism.

  First, the configuration of the operation mechanism 20 will be described with reference to FIGS. Note that FIG. 2A shows a cross section taken along the cutting line DD in FIG. 2B as seen from the AA direction. In these drawings, an opening coil 22 and a closing coil 23, each having a winding wound in a rectangular ring shape, are mounted inside a yoke 21 formed by laminating electromagnetic steel sheets. In addition, two rectangular plate-like permanent magnets 24 are fixed to the inner central portion of the yoke 21 and a movable element 27 described later is fixedly sandwiched from the left and right directions in FIG. The connecting rod 26 penetrates the central portion of the yoke 21 in the vertical direction of FIG. 2B and is supported by the yoke 21 so as to be movable. A mover 27 having a rectangular cross section made of iron (see FIG. 2A) is fitted into the connecting rod 26 by an interference fit, and the connecting rod 26 and the connecting rod 26 are placed in the opening coil 22 and the closing coil 23. Move in the axial direction. The mover 27 is opposed to the permanent magnet 24 with a predetermined gap in the left-right direction in FIG.

  The structure of the vacuum circuit breaker as a switch and a power switch will be described with reference to FIG. The vacuum valve 32 is configured by accommodating a fixed contact 32a and a movable contact 32b disposed with a predetermined gap from the fixed contact 32a in a vacuum container. The movable contact 32 b is connected to the connecting rod 26 of the operation mechanism 20 through an insulating member 34 and a contact pressure spring 35. The connected vacuum valve 32 and the operation mechanism 20 are arranged in parallel at predetermined intervals for three phases and are accommodated in the accommodation box 31. A spring receiver 37 is fixed to the lower end portion of the connecting rod 26, and a coiled open spring 36 as a spring member is inserted between the yoke 21 of the operation mechanism 20 and the spring receiver 37 in a compressed state. In the opening operation, a spring force in the downward opening direction is applied to the connecting rod 26 via the spring receiver 37 to assist the driving force during the opening.

  Next, the operation circuit will be described. In FIG. 1, there are three operation mechanisms 20 controlled by the operation circuit 1 for three phases (see FIG. 4), and as shown in FIG. 1, three opening coils 22 are connected in parallel, Three closing coils 23 are connected in series. An opening capacitor 8 which is a current supply source for exciting the opening coil 22, a closing capacitor 9 which is a current supply source for exciting the closing coil 23, an opening capacitor and a closing capacitor A charging DC power supply 10 is charged to charge 8 and 9 to a constant voltage via converters 11 and 12. The converters 11 and 12 always maintain the charging voltages of the opening and closing capacitors 8 and 9 at a predetermined constant value even when the voltage of the charging DC power supply 10 fluctuates, so that stable opening and closing operations are possible. Secure.

  The opening capacitor 8 is connected to three opening coils 22 connected in parallel via a discharge switch 6 as excitation control means. A series circuit of the attenuation resistor 13, the diode 14, and the inductive cutoff switch 15 is connected in parallel to the opening opening coil 22 connected in parallel. This series circuit is the current attenuating means in the present invention. The closing capacitor 9 is connected to three closing coils 23 connected in series via the discharge switch 7. Further, a series circuit of the attenuation resistor 16, the diode 17, and the inductive cutoff switch 18 is connected in parallel to the closing coil 23 connected in series. For example, thyristor switches that can be controlled from the outside are used as the induction cutoff switches 15 and 18. The operation circuit 1 is configured as described above.

  Next, the operation will be described. In FIG. 1, the vacuum circuit breaker is in an open state, the discharge switches 6 and 7 and the inductive cut-off switches 15 and 18 are open, and the closing capacitors 8 and 9 are each charged to a predetermined voltage. To do. Further, as shown in FIGS. 2 and 4, the movable element 27 of the operation mechanism 20 has a lower end in contact with a predetermined portion on the lower inner side of the yoke 21, and the vacuum circuit breaker is in an open state. When the discharge switch 7 is closed in order to close the vacuum bulb 32, the voltage of the closing capacitor 9 is applied to the three closing coils 23 connected in series, and the exciting current is applied to each closing coil 23. The electric energy charged in the closing capacitor 9 is consumed by the closing coil 23.

  When an exciting current flows through the closing coil 23, the magnetic force of the permanent magnet 24 is canceled by the induced magnetic flux, and an electromagnetic force that attracts the movable element 27 upward in FIGS. 2 and 4 works. The movable element 27 is an open spring. It is driven upward by overcoming the spring force of 36. As a result, the movable electrode 32b of the vacuum valve 32 connected to the movable element 27 is driven. In addition, as a main movable part at the time of opening and closing operation of the vacuum circuit breaker, there are a movable contact 32b, an insulating member 34, a contact pressure spring 35, a connecting rod 26, a movable element 27, and a spring receiver 37. In the following explanation, The names of the movable contact 32b and the movable element 27 will be described as representatives of the movable part.

  If the current continues to flow through the closing coil 23, the movable element 27 is accelerated too much and the impact force when the movable element 27 collides with the upper inner side of the yoke 21 becomes excessive. In order to prevent this, when the movable element 27 and the movable contact 32b are accelerated to a predetermined speed during driving, the discharge switch 7 is opened to interrupt the current flowing from the closing capacitor 9 to the closing coil 23. To do. Further, the induction cutoff switch 18 is closed in synchronization with the opening of the discharge switch 7. If the inductive cut-off switch 18 is closed, the current that has been flowing through the discharge switch 7 so far is transferred to the series circuit of the damping resistor 16 and the diode 17 and is circulated through the circuit formed by the closing coil 23 and the series circuit. Circulates. The circulating current flowing through the closing coil 23 is gradually attenuated. In addition, since the current flowing through the closing coil 23 is not interrupted, a sudden change in the current flowing through the closing coil 23 due to the opening of the discharge switch 7 can be suppressed, and the occurrence of a surge can be prevented. The movable element 27 continues to move upward even after the current flowing from the closing capacitor 9 to the closing coil 23 is interrupted.

  When the mover 27 moves to a predetermined position and the discharge switch 7 is closed again and the mover 27 is driven, the movable contact 32b connected to the mover 27 contacts the fixed contact 32a. Even after the movable contact 32 b comes into contact with the fixed contact 32 a, the movable element 27 continues to move upward while compressing the contact pressure spring 35, and the upper end of the movable element 27 collides with the upper inner side of the yoke 21. Stop in contact. After stopping, even if the current flowing through the closing coil 23 becomes zero, the magnetic flux generated by the permanent magnet 24 flows from the yoke 21 to the movable element 27 through the contact portion with the movable element 27, and the movable element 27 enters the yoke 21. The sucked state is continued and the vacuum valve 32 maintains a closed state. The contact pressure spring 35 is further compressed after the movable contact 32b comes into contact with the fixed contact 32a, so that the contact pressure between the fixed contact 32a and the movable contact 32b is secured. The induction cutoff switch 18 is opened after a predetermined time from the completion of the opening. By opening the inductive cutoff switch 18, when the opening coil 22 is excited, an induction current flows in the closing coil 23 in a direction that cancels the magnetic flux of the opening coil 22, and the opening coil 22. It is possible to prevent the driving force of the movable element 27 from being reduced.

  Next, when the discharge switch 6 is closed in order to open the closed vacuum bulb 32, the voltage of the opening capacitor 8 is applied to the three opening coils 22 connected in parallel. Electric current flows and the electric energy charged in the opening capacitor 8 is consumed by the opening coil 22. When a current flows through the opening coil 22, the magnetic force of the permanent magnet 24 is canceled by the induced magnetic flux, and the electromagnetic force that attracts the movable element 27 downward between the yoke 21 and the movable element 27 in FIGS. 2 and 4. The mover 27 is driven downward. At this time, a spring force of an open spring 36 is applied to the mover 27 in addition to the electromagnetic force, and the mover 27 and the movable electrode 32b connected thereto are accelerated by both.

  If the current continues to flow through the opening coil 22, the mover 27 and the movable contact 32 b are excessively accelerated, and the impact force when the mover 27 collides with the lower inner side of the yoke 21 becomes excessive. In order to prevent this, the discharge switch 6 is opened during driving to interrupt the exciting current flowing from the opening capacitor 8 to the opening coil 22. The induction cutoff switch 15 is closed in accordance with the opening of the discharge switch 6. If the inductive cutoff switch 15 is closed, the current that has been flowing through the discharge switch 6 so far circulates in a circulation circuit constituted by the series circuit of the attenuation resistor 13 and the diode 14 and the opening coil 22. The circulating current flowing through the opening coil 22 is gradually attenuated. Since the current flowing through the discharge switch 6 moves toward the attenuation resistor 13, a sudden change in the current flowing through the opening coil 22 is suppressed, and the occurrence of a surge due to the opening of the discharge switch 6 can be prevented.

  Here, the change in current from the closing of the discharge switch 6 to the opening of the discharge switch 6 during the movement of the movable element 27 will be described with reference to FIG. When the discharge switch 6 is closed at time tn, the current flows as shown by the curve J1, the movable element 27 starts moving and the contact pressure spring 35 gradually expands at time ts, and the vacuum valve 32 starts opening at time tp. To do. An inflection point P of the current appears at the opening time tp.

  Thereafter, when the discharge switch 6 is opened and the inductive cutoff switch 15 is closed at time tf, the current flowing through the discharge switch 6 is circulated by the series circuit of the damping resistor 13 and the diode 14 and the opening coil 22. Start circulating in the circuit. This circulating current starts to decrease from the current decrease start point R and attenuates as shown by the curve J2. Although the circulating current continues to attenuate, the mover 27 continues to move downward, and at time tq, the lower end of the mover 27 collides with the lower inner side of the yoke 21 and stops, thereby completing the opening of the vacuum valve 32. To do. If the speed of attenuation is determined by adjusting the resistance value of the attenuation resistor 13 so that a circulating current of a predetermined value or more remains at the time tq at this time, the inflection point appearing at the time tq when the opening is completed. Q can be easily grasped. By grasping the elapsed time from the time tn when the discharge switch 6 is closed or the time ts when the diode 17 starts moving to the time tq when the opening is completed and the inflection point Q appears, the opening time and opening It is possible to know if there is an abnormality in polar operation.

  In addition, when the mover 27 repels after colliding with the yoke 21 and is once separated, it temporarily increases as shown by a curved line J3 indicated by a dotted line. Therefore, by monitoring the current flowing through the opening coil 22, it is possible to know whether or not rebounce has occurred in the mover 27 during opening. After the mover 27 comes into contact with the yoke 21, the magnetic flux generated by the permanent magnet 24 passes from the yoke 21 to the mover 27 through the contact portion with the mover 27 even when the current flowing through the opening coil 22 becomes zero. The state in which the mover 27 is in contact with the lower inner portion of the yoke 21 is continued by the electromagnetic attraction force due to the flow and the spring force of the release spring 36, and the vacuum valve 32 is maintained in the open state. After a predetermined time from the completion of the opening, the induction cutoff switch 15 is opened. By opening the inductive cutoff switch 15, when the closing coil 23 is excited, an inductive current flows in the direction of canceling the magnetic flux of the closing coil 23 to the open circuit opening coil 22, thereby closing the coil. Accordingly, it is possible to prevent the driving force of the movable element 27 from being reduced by the force 23. Further, since the opening capacitor 8 is provided separately from the closing capacitor 9, the opening operation is highly independent. Of course, since the opening capacitor 8 is charged so that the voltage of the DC power supply 10 for charging or the voltage of the AC power supply that is the source of the DC power supply fluctuates constantly, the movable element 27 is stabilized. Can be driven.

Here, when the discharge switch 6 is opened and the inductive cut-off switch 15 is closed, the circulating current j flowing through the opening coil 22 has an inductance L of the opening coil 22, a resistance R 1, and a resistance of the attenuation resistor 13. When the value is R2, it is expressed by the following formula.
j = A · exp (−R · t / L)
Where A: amplitude, t: time, R = R1 + R2
Note that the inductance L changes with the movement of the mover 27 and is not strictly a constant value.
The rate of current attenuation can be adjusted by adjusting the resistance value R2 of the attenuation resistor 13. Therefore, the resistance value R2 of the attenuation resistor 13 can be adjusted to set the speed of current attenuation to an appropriate value so that the opening operation can be performed reliably and the impact during the opening operation can be reduced.

  When the discharge switch 6 is not opened in the middle of the opening as in the prior art, the current decay rate is slow as shown by a curve J4 indicated by a one-dot chain line in FIG. For this reason, since the mover 27 is excessively accelerated at the time of opening and the impact when the mover 27 collides with the yoke 21 becomes excessive, it is necessary to make the operation mechanism 20 a strong structure that can withstand this. It becomes. On the other hand, in this embodiment, after the mover 27 and the movable contact 32b are accelerated to a sufficient speed in the middle of opening, the movable coil 8 is moved by cutting off the excitation of the opening coil 22 by the opening capacitor 8. The driving force acting on the child 27 is limited to prevent the mover 27 from being accelerated too much, the impact when the mover 27 collides with the yoke 21 is reduced, and the operation mechanism 20 and the vacuum circuit breaker 30 are reduced in size and weight. The price can be reduced.

  As described above, if a circulating current of a predetermined value or more flows at the time tq (see FIG. 5) when the opening is completed, the inflection point Q can be easily grasped and the completion of the opening can be known. For this reason, the value of the attenuation resistor 13 is adjusted to set the speed of decrease of the circulating current to a predetermined value, and the circulating current exceeding the predetermined value is flowing at the time tq when the opening is completed. Alternatively, the timing (time) for opening the discharge switch 6 may be determined such that a circulating current of a predetermined value or more is flowing at the time tq when the opening is completed.

  On the other hand, the displacement of the movable contact 32b changes as shown by a solid curve ds1 in FIG. That is, a short time after the discharge switch 6 is closed, the mover 27 starts moving at a time ts at the mover movement start point Act1. Furthermore, since the contact pressure spring 35 is extended, the movable contact 32b starts to open at a slightly delayed time tp and the opening start point Act2. At this time, an inflection point P appears in the current J1 flowing through the opening coil 22. After the opening of the discharge switch 6 at time tf, the movable element 27 continues to move downward, and at time tq, at the opening completion point Act31, the movable element 27 comes into contact with the yoke 21 and stops. When the excitation control of the opening coil 22 as described above is not performed, the displacement of the mover 27 becomes the opening completion point Act32 as shown by the dashed-dotted curve ds2 in FIG. The time is shortened.

  At the time of closing, in order to keep the closing speed below a certain level as described above, after the energizing element 23 is sufficiently accelerated by energizing the closing coil 23, the discharge switch 7 is once opened and the closing capacitor 9 is opened. The acceleration current of the mover 27 due to electromagnetic force is suppressed by interrupting the excitation current from the power source, and the discharge switch 7 is closed again shortly before the closing is completed to supply the exciting current from the closing capacitor 9. By restarting, the closing speed is suppressed to a certain level or less, and the impact force generated in the operation mechanism 20 and the vacuum valve 32 is minimized. On the other hand, at the time of opening, after the opening coil 22 is energized and the mover 27 is sufficiently accelerated, the discharge switch 6 is opened to cut off the exciting current from the opening capacitor 8, and then re-excitation is performed. Do not do. The reason is as follows.

1. In response to variations in the completion time of the opening, it is necessary to adjust the timing of the reclosing in order to close the discharge switch 6 again to enable the holding of the opening. In particular, it is necessary to adjust the timing for reclosing the discharge switch 6 in response to a change in the opening time due to contact wear or the like, but the adjustment is complicated.
2. Since the closing time is longer than the opening time, the effect of reducing acceleration by blocking the exciting current to the opening coil 22 by opening the discharge switch 6 is great. Further, since the spring force of the opening spring 36 is applied at the time of opening, the electromagnetic force for holding the movable contact 32b at the opening position when the opening is completed may be small. Therefore, it is not necessary to supply current to the opening coil 22 again in the vicinity of the opening completion point. In consideration of changes in the opening time due to contact wear or the like, the decay rate of the current flowing through the opening coil 22 after the opening of the discharge switch 6 is set to an appropriate value by adjusting the resistance value of the attenuation resistor 13, for example. Even if the contacts are consumed, the acceleration can be reliably reduced over the entire period of use. For this reason, even if it does not re-energize for maintaining an open state at the time of opening operation, opening can be performed reliably and the impact at the time of completion of opening can be reduced effectively.

  3. After completion of the opening, the open state is maintained by the magnetic flux of the permanent magnet 24 mounted on the yoke 21 so as to face the mover 27, but the distance by which the mover 27 can be attracted to the open position by the permanent magnet 24. Is limited. For this reason, the entire movable part including the movable element 27 and the movable contact 32b is repelled by the impact when the opening is completed, and depending on the repelled distance, the repelled movable 27 is opened in the state where the current of the opening coil 22 is attenuated. Although there is a risk that the force of pulling back to the pole position is insufficient and it is not possible to hold the fully opened position, but the open spring 36 is arranged in a compressed state between the spring receiver 37 and the yoke 21 and is connected via the spring receiver 37. Since the force acting in the opening direction with respect to the rod 21 is generated, the repelling movable element 27 can be pushed back, and the movable element 27 and the movable contact 32b can be held in the open position.

  Therefore, it is not necessary to reclose the discharge switch 6 with respect to variations in the opening completion time, so that the excitation control of the opening coil 22 can be easily controlled and the configuration can be simplified. Further, since re-energization is unnecessary, the effect of reducing the acceleration of the mover 27 and the like is increased. On the other hand, at the time of closing, a large electromagnetic force is required since the closing is achieved by overcoming the repulsive force of the contact pressure spring when the closing is completed. For this reason, although control is complicated at the time of closing, it is effective to reclose the discharge switch 7 at an appropriate timing after the discharge switch 7 is once opened as described above.

  FIG. 6 is an explanatory diagram showing the force acting on the mover 27 depending on the position of the mover 27. In the case of a suction type that drives the mover 27 to cancel the magnetic flux of the permanent magnet 24 by the opening coil 22 and attract the mover 27 to a predetermined part of the yoke 21 as in the operation mechanism 20 at the time of opening. Since the mover 27 approaches the opening coil 22 as the opening progresses, when the current of the opening coil 22 is not controlled, the electromagnetic force increases as the mover 27 approaches the opening position as shown by the curve MF2. Become. On the other hand, the spring force SF of the open spring 36 decreases as it approaches the open position. By cutting off the supply current to the opening coil 22 in the middle of the opening operation, the electromagnetic force is reduced as shown by the curve MF1, and therefore, the movable element 27 obtained by adding the electromagnetic force MF1 and the spring force SF of the opening spring 36 is added. The working driving force changes as shown by the curve TF, and the acceleration amount of the mover 27 in the latter half of the opening operation can be appropriately reduced.

  In FIG. 1, the connection of the opening or closing coils 23, 23 is connected in parallel or in series as viewed from the opening capacitor 8 or the closing capacitor 9 that is a current source. Depending on the current source, a parallel connection or a serial connection may be used. In addition, for a three-phase switchgear, if there are multiple opening coils or closing coils in each phase, even if these multiple opening or closing coils are connected in series-parallel, Good. The switch is not limited to a vacuum circuit breaker, and may be a vacuum electromagnetic switch or other switches.

It is a circuit diagram of the operation circuit of the vacuum circuit breaker which is Embodiment 1 of this invention. It is a block diagram which shows the structure of the operation mechanism of a vacuum circuit breaker. It is a perspective view of an operation mechanism. It is a block diagram of a vacuum circuit breaker. It is a characteristic view which shows the electric current and the displacement of a needle | mover of an operation mechanism. It is a characteristic view which shows the spring force of the open spring which acts on a needle | mover, and the electromagnetic force of an operation mechanism.

Explanation of symbols

1 Operation circuit, 6, 7 Discharge switch, 8 Opening capacitor,
9 Capacitor for closing, 13 Attenuating resistor, 14 Diode, 15 Inductive cutoff switch,
16 damping resistor, 17 diode, 18 inductive cutoff switch, 20 operation mechanism,
21 yoke, 22 opening coil, 23 closing coil, 24 permanent magnet,
26 connecting rod, 27 mover, 30 vacuum circuit breaker, 31 storage box, 32 vacuum valve,
32a fixed contact, 32b movable contact, 36 open spring.

Claims (3)

A current supply source, excitation control means, and current attenuation means,
The current supply source is a DC power source having a constant voltage,
The excitation control means includes a movable element connected to a movable electrode of a switch, a yoke that supports the movable element so as to be movable in a predetermined direction, and an opening coil of an operating mechanism that has an opening coil. An excitation current is supplied from a supply source to attract the movable element to a predetermined portion of the yoke to open the switch, and the movable element is in the process of moving and starts supplying the excitation current. The exciting current is cut off when a predetermined time has passed.
The current attenuating means is a series circuit of an attenuating resistor, a diode, and an inductive cutoff switch, and is connected to the opening coil and the current flowing through the opening coil is circulated when the exciting current is interrupted. A switching circuit in which the circulating current decay speed is adjusted so that a predetermined circulating current flows when the opening of the switch is completed by adjusting the resistance value of the damping resistor while flowing as a current. Operation circuit. 2. The switch according to claim 1 , wherein the series circuit is configured such that the inductive cutoff switch is closed in synchronism with the cutoff of the excitation current and is opened after a predetermined time after the excitation current is cut off. Operation circuit. The said excitation control means determines the time which interrupts | blocks the said excitation current so that the circulating current which is flowing at the time of completion of opening of the said switch may become a predetermined value. Switch operating circuit.

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