EP1416503A2

EP1416503A2 - Solenoid-operated switching device and control device for electromagnet

Info

Publication number: EP1416503A2
Application number: EP03024535A
Authority: EP
Inventors: Masato Hitachi Ltd. Int. Prop. Gp Yabu; Tomoyuki Hitachi Ltd. Int. Prop. Gp Kii; Ayuma Hitachi Ltd. Int. Prop. Gp Morita; Akio Hitachi Ltd. Int. Prop. Gp Nakazawa; Hisao Hitachi Ltd. Int. Prop. Gp Kawakami; Takumi Hitachi Ltd. Int. Prop. Gp Shinagawa; Tomohiro Hitachi Ltd. Int. Prop. Gp Sugino; Yasunobu Hitachi Ltd. Int. Prop. Gp Fujita; Matsuru Hitachi Ltd. Int. Prop. Gp Nakamura; Takashi Hitachi Ltd. Int. Prop. Gp Shiina; Sadao Hitachi Ltd. Int. Prop. Gp Satou; Kenichi Hitachi Ltd. Int. Prop. Gp Ogasawara; Satoshi Hitachi Ltd. Int. Prop. Gp Isono; Kenji Hitachi Ltd. Int. Prop. Gp Tsuchiya; Toshio Hitachi Ltd. Int. Prop. Gp Hashimoto; Keisuke Hitachi Ltd. Int. Prop. Gp Abe; Kenji Hitachi Ltd. Int. Prop. Gp Koyama; Masahiro Hitachi Ltd. Int. Prop. Gp Fukuchi
Original assignee: Hitachi Ltd
Current assignee: Hitachi Ltd
Priority date: 2002-10-30
Filing date: 2003-10-27
Publication date: 2004-05-06
Anticipated expiration: 2023-10-27
Also published as: EP1416503B1; EP1416503A3

Abstract

The present invention permits a configuration for workability enhancement by mounting an electromagnet 14 under the center of a casing 10, mounting a capacitor 16 and a control circuit board 18 on either side of the electromagnet 14, mounting an auxiliary contact 34, an indicator plate 36 , and a counter 38 over the electromagnet 14, attaching the auxiliary contact 34, indicator plate 36, and counter 38 to a plate 56 to make them integral with the electromagnet 14, and rendering the capacitor 16 and control circuit board 18 removable from the front. <IMAGE>

Description

FIELD OF THE INVENTION

The present invention relates to a solenoid operation device, a solenoid-operated switching device, and an electromagnet control device, and more particularly to a solenoid operation device that uses electromagnetic force to operate a circuit breaker or other switching device, a solenoid-operated switching device, and an electromagnet control device that provides drive control over an electromagnet, which serves as a driving source for driving a switching device.

BACKGROUND OF THE INVENTION

Electromagnetic force generated from an electromagnet is used for operating a circuit breaker or other switching device (refer to JP-A No. 2002-217026 (pages 2 to 4, Figs. 1 to 3)).

Meanwhile, an attempt is made to drive an electromagnet for stable operation by furnishing a capacitor for storing electrical power for electromagnetic coil excitation and a control circuit board for controlling the conduction direction of an electrical current supply from the capacitor to an electromagnetic coil in compliance with a "close contact" command or an "open contact" command for a switching device. In this instance, a solenoid-operated switching device may be composed by combining a solenoid operation device with a switching device.

If, for instance, a solenoid-operated switching device is composed by combining a solenoid operation device with a magnetic latch type, solenoid-operable switching device, the control circuit board to be used may comprise a microcomputer, a logic IC (CPLD/FPGA), a mechanical relay, or the like. The electrical current required for the "close contact" command and "open contact" command is approximately several tens of milliamperes. Therefore, a low-energy switching device may be configured.

SUMMARY OF THE INVENTION

When a solenoid operation device is to be installed adjacent to a circuit breaker or the like, an electromagnet, a capacitor, a control circuit board, and other components are housed in a casing in such a manner that the electromagnet and switching device are interconnected with a link mechanism. However, the steps for housing the electromagnet, capacitor, and control circuit board in a casing have to be performed in a narrow space within the casing. It is therefore necessary to lay out the components while considering the ease of installation, inspection, and servicing.

For cost reduction purposes, an attempt is made to employ standard-size steel pipes, which are defined, for instance, by the JIS, as lateral legs. When a circuit breaker or other switching device and an electromagnet are to be both housed in a casing, the electromagnet is generally positioned forward. However, the casing is wider than deep. To decrease the installation space, therefore, the employed electromagnet should have a rectangular cross section. Consequently, thin steel plates are stacked to form lateral legs, and the employed structure comprises a movable magnet core, stationary magnet core, and coil that have a square cross section. However, standard-size, circular steel pipes need to be shaped like a square if the employed movable magnet core and other components have a square cross section. The use of such square steel pipes increases the number of machining and assembling steps. Further, if the lateral legs are made by stacking thin steel plates, the number of parts and the cost both increase.

When the control circuit board is used to control the electromagnet, it is necessary to control the conduction direction for the electromagnetic coil in compliance with the "close contact" command and "open contact" command. To mount the control circuit board in the solenoid operation device, it is necessary to downsize the electronic, mechanical, and other parts to be mounted on the control circuit board.

Further, when the above solenoid-operated switching device is configured, the electrical current required for the "close contact" command and "open contact" command is approximately several tens of milliamperes. Therefore, a digital relay, which has been a mainstream relay in recent years, can be used as a relay for outputting the "close contact" command and "open contact" command to a circuit breaker.

However, a large number of conventional analog relays still exist as relays for issuing the "open contact" command to a circuit breaker. If a solenoid-operated switching device is applied to a distribution switchboard on which an analog relay is mounted, it is impossible to form an "open contact" command path, which requires several amperes of current.

A first object of the present invention is to provide a solenoid operation device that is configured so as to offer increased ease of operation.

A second object of the present invention is to provide an electromagnet operation device that can be configured to include an electromagnet that is wider than deep no matter whether the manpower required for manufacture is reduced.

A third object of the present invention is to provide an electromagnet control device that makes it possible to downsize the means for controlling the conduction direction for an electromagnetic coil in compliance with the "close contact" command and "open contact" command.

A fourth object of the present invention is to provide a solenoid-operated switching device that is capable of responding to a digital relay and analog relay.

To achieve the above first object, the present invention provides a solenoid operation device for connecting a shaft, which is coupled to an electromagnet's movable magnet core, to a switching device via a link mechanism and transmitting driving force, which is derived from electromagnetic force generated by an electromagnet, to the switching device via the link mechanism. The solenoid operation device is configured so as to independently position a capacitor for storing electrical power for electromagnetic coil excitation and a control circuit board for controlling the conduction direction of an electrical current supply from the capacitor to the electromagnetic coil in compliance with the "close contact" command and "open contact" command for the switching device.

To achieve the above second object, the present invention provides a solenoid operation device for connecting to the switching device via the link mechanism, which is coupled to the electromagnet's movable magnet core, and transmitting driving force, which is derived from electromagnetic force generated by the electromagnet, to the switching device via the link mechanism. The solenoid operation device is configured so as to furnish a movable magnet core, stationary magnet core, coil, and iron cover, which compose the electromagnet. The external shape of the iron cover is an oblong cylinder. The short diameter end of the cylinder is oriented in the direction of the depth of the switching device.

To achieve the above third object, the present invention provides an electromagnet control device, which comprises a contact opening means and a contact closing means. The contact opening means, which is provided as a conduction circuit for supplying power of a capacitor, which stores power supplied from a power supply, to the electromagnetic coil, forms a conduction circuit for separating the movable magnet core from the stationary magnet core at the time of "open contact" command generation. The contact closing means, which is provided as a conduction circuit whose conduction direction for the electromagnetic coil is opposite to that of the conduction circuit provided by the contact opening means, forms a conduction circuit for bringing the movable magnet core into contact with the stationary magnet core at the time of "close contact" command generation. The contact opening means includes a selector relay that is inserted into the conduction circuit for separating the movable magnet core from the stationary magnet core in compliance with the "open contact" command. The contact closing means includes a selector relay that is inserted into the conduction circuit for bringing the movable magnet core into contact with the stationary magnet core in compliance with the "close contact" command.

To achieve the above fourth object, the present invention provides a solenoid-operated switching device, which comprises a solenoid operation device and a switching device (circuit breaker). The solenoid operation device includes an electromagnet, a capacitor, and a control circuit board. The switching device is connected to the solenoid operation device via a link mechanism. The solenoid-operated switching device also comprises a bypass circuit, which forms a bypass between a part of the "open contact" command and the power supply via a resistor.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a front view of a solenoid operation device.

Fig. 2 is a side view of a solenoid-operated switching device;

Fig. 3 illustrates an operation that is performed when a status detection mechanism is turned on;

Fig. 4 illustrates an operation that is performed when the status detection mechanism is turned off;

Fig. 5A is a side view illustrating a status that is prevalent before an interlock rod is lifted;

Fig. 5B is a front view of an essential part;

Fig. 6A is a side view illustrating a status that is prevalent after the interlock rod is lifted;

Fig. 6B is a front view of an essential part;

Fig. 7A is a side view illustrating a status that is prevalent when the interlock rod cannot be lifted;

Fig. 7B is a front view of an essential part;

Fig. 8A is a side view illustrating a manual changeover operation that is performed when a front cover is installed;

Fig. 8B is a front view of an essential part;

Fig. 9A is a side view illustrating a manual power-on operation that is performed when the front cover is removed;

Fig. 9B is a front view of an essential part;

Fig. 9C is a top view of a handle that is used for a manual power-on operation;

Fig. 10 is a block diagram that illustrates the circuit configuration of an electromagnet control device;

Fig. 11 is a circuit diagram of a charger circuit;

Fig. 12 is a diagram illustrating the hysteresis characteristic of a recharging completion detection circuit;

Fig. 13 is a diagram illustrating the CO operation of a circuit breaker;

Fig. 14 is a diagram illustrating the O and CO operations of a circuit breaker;

Fig. 15 is a characteristic diagram illustrating the relationship between a capacitor charge voltage and capacitor charge energy;

Fig. 16 is a block diagram illustrating the circuit configuration of a control logic section;

Fig. 17 is a timing diagram illustrating the operation that is performed by the control logic section at the time of power on;

Fig. 18 is a timing diagram illustrating the operation that is performed by the control logic section at the time of power off;

Fig. 19 is a block diagram illustrating another embodiment of an electromagnet control device;

Fig. 20A is a circuit diagram illustrating the operating principle of an overcurrent relay;

Fig. 20B is a circuit diagram illustrating the operating principle of the overcurrent relay;

Fig. 21 is a block diagram illustrating an embodiment of a solenoid-operated switching device in which a bypass resistor is provided;

Fig. 22 is a perspective view of a solenoid-operated switching device in which a relay box is provided;

Fig. 23 is a circuit diagram of a solenoid-operated switching device to which a relay box is connected;

Fig. 24 is a vertical cross-sectional view of an electromagnet;

Fig. 25 is a horizontal cross-sectional view along section A-A of Fig. 24;

Fig. 26 is a horizontal cross-sectional view along section B-B of Fig. 24;

Fig. 27 is a horizontal cross-sectional view along section C-C of Fig. 24;

Fig. 28A illustrates a press forming method for an iron cover;

Fig. 28B illustrates a press forming method for the iron cover; and

Fig. 29 is an exploded perspective view of an electromagnet.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

One embodiment of the present invention will now be described with reference to the accompanying drawings. Fig. 1 is a front view of a solenoid operation device according to the present invention. Fig. 2 is a side view of a solenoid-operated switching device that includes a solenoid operation device and a circuit breaker. In Figs. 1 and 2, the solenoid operation device comprises a casing 10. The casing 10 has an opening 12 at the front. A detachable front cover (not shown) is fastened to the front of the casing 10. Within the casing 10, a capacitor 16 and a control circuit board 18 are positioned separately and independently around an electromagnet 14. The electromagnet 14 is fastened to the center of the bottom of the casing with bolts and nuts. The capacitor 16 and control circuit board 18 are separately fastened to the opposing lateral surfaces of the casing. More specifically, the capacitor 16 is fastened to the left-hand side of the casing 10 with bolts and nuts. The control circuit board 18 is fastened with bolts and nuts to the right-hand side of the casing 10 via spacers 20.

Further, the casing 10 houses not only a secondary plug 22 and

cables

24, 26, 28 and 30, but also an auxiliary contact 34, an indicator plate 36, a counter 38, which serve as a status detection mechanism for detecting the status of a vacuum circuit breaker (vacuum valve), which functions as a switching device. The secondary plug 22 is fastened to the top of the casing 10 with bolts and nuts. The secondary plug 22 is connected, for instance, to a power supply cable and a signal cable routed to a digital or analog relay. Cable 24 is connected to a plus terminal and a minus terminal of the capacitor 16. Cable 26 is connected to the auxiliary contact 34. Cable 28 is connected to the control circuit board 18 via connector 40. Cable 28 is connected to a limit switch 42. Cable 30 is connected to a coil 48 of the electromagnet 14.

Cables

28 and 30 are crimped to terminal 43 when they are connected. The limit switch 42 is fastened to the bottom of the casing 10 via a metal fitting 44. The limit switch 42 opens and closes its contact in accordance with the position of an interlock rod 46, which freely elevates perpendicularly along the casing 10. A signal indicating whether the contact is open or closed is supplied to the control circuit board 18.

The control circuit board 18 not only receives power from the secondary plug 22, but also receives a signal, which carries a "close contact" or "open contact" (power shutoff) command, from a digital or analog relay. Mounted on the control circuit board 18 are a control logic section, which performs logical operations to control the drive for the electromagnet 14, a recharger/discharger circuit for recharging/discharging the capacitor 16, and a relay and relay contact for controlling the conduction direction of the coil (electromagnetic coil) 48 (not shown). The control circuit board 18 also carries a light-emitting diode 50 for indicating that the capacitor 16 is completely recharged, an "ON" pushbutton (pushbutton switch) 52 for manually issuing a "close contact" command to a vacuum circuit breaker 32, and an "OFF" pushbutton (pushbutton switch) 54 for manually issuing an "open contact" (power shutoff) command to the vacuum circuit breaker 32.

The auxiliary contact 34, indicator plate 36, and counter 38 are positioned over the electromagnet 14 as a status detection mechanism for the vacuum circuit breaker 32 and connected to a plate 56. These components are integral with the electromagnet 14. The electromagnet 14 includes a movable magnet core 58, a stationary magnet core 60, a coil 48, a shaft 62, two movable

flat plates

64 and 66, a permanent magnet 68, cylindrical iron covers 70 and 72, mounting plates made of

iron

74 and 76, and a stationary rod 78. The coil (electromagnetic coil) 48 is housed in a coil bobbin 48a, which is positioned between mounting

plates

74 and 76. The stationary rod 78 is fastened not only to the bottom of the casing 10 with bolts and nuts but also to a base 80.

Shaft 62 is positioned at the center of the electromagnet 14 and oriented in the perpendicular direction. Further, the top of shaft 62 is inserted into a through hole 82 in plate 66, and the bottom of shaft 62 is inserted into a through hole 84 in mounting plate 76. Shaft 62 is free to move up and down and slide. The movable magnet core 58 and

movable plate plates

64 and 66 are fastened with nuts to the outer circumferential surface of the shaft 62. Shaft 88 is connected to the underside of shaft 62 via pin 86. Two movable flat plates (steel plates) 64 and 66, one large and one small, are installed over shaft 62. These two movable flat plates are used to increase the face-to-face distance between the upper movable flat plate 64 and iron cover 70 for the purpose of reducing the magnetic flux leakage to iron cover 70. Mounting plate 90 is connected to the bottom of shaft 62. A ring-shaped contact-opening spring 92 is mounted between mounting plate 90 and base 80 and centered with respect to the axial center of shaft 62. The contact opening spring 92 gives elastic force for separating the movable magnet core 58 from the stationary magnet core 60 to shaft 62 via mounting plate 90. The permanent magnet 68 is placed around the movable magnet core 58 and fastened to mounting plate 74. The stationary magnet core 80 is bolted down to mounting plate 76.

The bottom of shaft 88 is connected to a pair of levers 96 via pin 94. The lever 96 is a part of a link mechanism that changes the transmission direction of driving force derived from electromagnetic force generated by the electromagnet 14, and connected to lever 100 via shaft 98. Lever 100 is connected to a link plate 104 via pin 102. A stopper pin 106 is fastened to an end of the lever 96. When the vacuum circuit breaker 32 is tripped, the stopper pin 106 comes into contact with a stopper bolt 108, which is fastened to the base 80, thereby inhibiting the lever 96 from moving toward the base 80.

The link plate 104 is inserted into an insulation rack 110, which is fastened to the base 80, and free to move up and down (reciprocating motion). A contact pressure spring pusher 112 is formed over the link plate 104. A through hole is made in the contact pressure spring pusher 112. An axial end of an insulation rod 114 is inserted into the through hole. A bolt 118 is fastened to the axial end via a washer 116. Further, a contact pressure spring 120 is mounted between the contact pressure spring pusher 112 and the bottom of the insulation rod 114. The top of the insulation rod 114 is connected not only to a movable feeder 122 via a flexible conductor 121 but also to a movable conductor 124 for the vacuum circuit breaker 32. The movable conductor 124 is connected to a movable contact (not shown). A stationary contact (not shown) is positioned opposite the movable contact. The stationary contact is connected to a stationary conductor 126 and housed in an insulation sleeve 128 together with the movable contact. The insulation sleeve 128 is kept in a vacuum. The stationary conductor 126 is connected to a stationary feeder 129. The stationary feeder 129 is fastened to the insulation rack 110. An upper contactor 130 is connected to the stationary feeder 129. A lower contactor 132 is connected to the movable feeder 122. Distribution line or other power cables are connected to these

contactors

130 and 132.

When the "open contact" command enters the control circuit board 18, the signal generated from the control circuit board 18 energizes the coil (electromagnetic coil) 48 of the electromagnet 14. A magnetic field is then formed around the coil 48 using a path connecting the movable magnet core 58, stationary magnet core 60, mounting plate 76, cover 72, and mounting plate 74 in order named. A downward attraction force is then applied to the bottom end face of the movable magnet core 58 so that the movable magnet core 58 moves toward the stationary magnet core 60 and is attracted to the stationary magnet core 60. In this instance, the magnetic field formed by the permanent magnet 68 is oriented in the same direction as the magnetic field generated when the coil 48 is excited. Therefore, the movable magnet core 58 moves toward the stationary magnet core 60 while attraction force is great.

When the electromagnet 14 performs a contact closing operation (attraction), shaft 62 moves downward without regard to the elastic force of the contact opening spring 92 so that driving force derived from electromagnetic force generated by the electromagnet 14 is transmitted to the lever 96. The driving force is transmitted to the link plate 104 via shaft 98 and lever 100. The movable conductor 124 then moves upward to bring the movable contact into contact with the stationary contact, thereby initiating the contact closing operation of the vacuum circuit breaker 32. When the vacuum circuit breaker 32 performs a contact closing operation, the contact pressure spring 120 does not become compressed until the movable contact comes into contact with the stationary contact. However, when the movable contact comes into contact with the stationary contact, the contact pressure spring 120 is compressed. The contact pressure spring 120 remains compressed until the contact closing operation is completed. Meanwhile, the contact opening spring 92 is constantly compressed while the vacuum circuit breaker 32 performs a contact closing operation.

When the "open contact" (power shutoff) command enters the control circuit board 18 and the control circuit board 18 outputs a signal to the coil 48 in response to the "open contact" command, an electrical current flows to the coil 48 in a direction opposite to that for contact closing. As a result, a magnetic field, which is oriented in a direction opposite to that for contact closing, is formed around the coil 48. In this instance, the magnetic flux generated by the coil 48 counteracts the magnetic flux generated by the permanent magnet 68. Since the attraction force applied to the axial end face (lower surface) of the movable magnet core 58 is now weaker than the elastic force generated by the contact opening spring 92 and contact pressure spring 120, the movable magnet core 58 leaves the stationary magnet core 60 and moves upward. When shaft 62 moves upward in accordance with the ascent of the movable magnet core 58, the lever 96 moves upward, causing the link plate 104 to move downward. The movable contact of the vacuum circuit breaker 32 then leaves the stationary contact. Since the stationary contact is no longer in contact with the movable contact, the vacuum circuit breaker 32 performs a contact opening operation (power shutoff operation). In this instance, when the electromagnet 14 turns off, the contact pressure spring 120, which is compressed, first extends. When the contact pressure spring pusher 112 comes into contact with the washer 116, the movable contact of the vacuum circuit breaker 32 leaves the stationary contact so that the power shutoff operation of the vacuum circuit breaker 32 and the power shutoff (contact opening) operation of the electromagnet 14 are simultaneously performed.

In a process during which a contact closing operation or a contact opening operation (power shutoff operation) is being performed by the vacuum circuit breaker 32, the contact closing or contact opening state of the vacuum circuit breaker 32 is detected by the auxiliary contact 34, indicator plate 36, and counter 38.

More specifically, rod 134 is connected to the top of shaft 62, which is coupled to the movable magnet core 58, as shown in Fig. 2. A through hole is (not shown) is made in the top of rod 134. Pin 136 is inserted into the through hole. Pin 136 is inserted into elongated holes in

levers

138 and 140. Rod 134 is connected to

levers

138 and 140 via pin 136. Lever 138 is connected to the auxiliary contact 34 via axis 142. The auxiliary contact 34 has a normally open contact and normally closed contact. These contacts open/close in accordance with the up-down motion of shaft 62. More specifically, the normally open contact of the auxiliary contact 34 closes when axis 142 rotates in a certain direction, and the normally closed contact opens when axis 142 rotates in the opposite direction. In this instance, axis 142 can be rotated in accordance with the up-down motion of shaft 62 because an elongated hole is made in lever 138 with pin 136 inserted into the elongated hole. As a result, the normally open contact and normally closed contact can be closed/opened in accordance with the rotation of axis 142.

Lever 140 is connected to a stationary plate 146 via pin 144. The bottom of the stationary plate 146 is fastened to plate 56. Lever 140 can rotate around pin 144 in accordance with the up-down motion of shaft 62. The indicator plate 36 is integral with the leading end of lever 140. The upper front of the indicator plate 36 is marked "OFF", whereas the lower front is marked "ON". The "OFF" mark is visible from the front of the casing 10 while the indicator plate 36 is positioned as shown in Fig. 2. The "ON" mark is visible from the front of the casing 10 when the indicator plate 36 moves upward from the position indicated in Fig. 2. Concisely, either the "OFF" mark or "ON" mark is visible from the front of the casing 10 in accordance with the up-down motion of shaft 62.

Further, the indicator plate 36 is provided with spring 148. One end of spring 148 is connected to the axial end of lever 140 and the remaining end is connected to a counter lever 150 for the counter 38. Spring 148 expands and contracts in accordance with the rotation of lever 140. The counter lever 150 rotates around pin 152 (over an angular range of up to approximately 45 degrees). Each time the counter lever 150 rotates, the number of open/close operations of the vacuum circuit breaker 32 is mechanically counted.

The operation of the status detection mechanism will now be described in detail. First of all, when the vacuum circuit breaker 32 is turned on, shaft 62 moves downward as shown in Fig. 3, and lever 138 rotates clockwise around axis 142 in accordance with the motion of shaft 62. This rotation of lever 138 turns off the normally closed contact of the auxiliary contact 34, and then turns on the normally open contact. In this instance, the indicator plate 36 moves until the "ON" mark is visible from the front as shown in Fig. 4 because lever 140 rotates counterclockwise around pin 144. Further, spring 148 contracts, and the counter lever 150 rotates approximately 45 degrees around pin 152. This increments the counter 38 by one because it recognizes that the vacuum circuit breaker 32 is turned on once.

When the vacuum circuit breaker 32 starts its power shutoff operation, shaft 62 moves upward from the position shown in Fig. 4. Lever 138 then rotates counterclockwise around axis 142 in accordance with the ascent of shaft 62. Axis 142 for the auxiliary contact 34 rotates, causing the normally open contact of the auxiliary contact 34 to turn off and then the normally closed contact to turn on. Further, lever 140 rotates clockwise around pin 144 in accordance with the ascent of shaft 62 so that the indicator plate 36 moves so as to render the "OFF" mark visible from the front. In this instance, spring 148 expands in accordance with the rotation of lever 140, and the counter lever 150 rotates approximately 45 degrees around pin 152. It is preferable that spring 148 be slightly bent so as to make the "ON" mark of the indicator plate 36 visible from the front.

As described above, the auxiliary contact 34, indicator plate 36, and counter 38 detect the "on" or "off" state of the vacuum circuit breaker 32 each time the vacuum circuit breaker 32 performs a contact closing operation or contact opening operation (power shutoff operation).

Four wheels 154 are attached to both sides of the base 80 in such a manner that the base 80 can travel over a mount 156. More specifically, the solenoid-operated switching device, which includes the casing 10 in which the electromagnet 14 is housed and the insulation rack 110 in which the vacuum circuit breaker 32 is housed, can be transported toward the front of the casing 10 as it moves on the wheels 150.

In the present embodiment, however, power supply is shut off while the vacuum circuit breaker 32 is the OFF position. To permit the vacuum circuit breaker 32 to be transported (pulled out) when the interlock rod 46 is lifted, a bracket 162 is fastened, as shown in Fig. 5, to the mount 156 to specify the run position 158 and open-circuit position 160. In addition, an interlock lever 164 is fastened to the top of the interlock rod 46 and inserted into an operation hole 168 in a mounting member 165, which is attached to the bottom of the casing 10. A lock pin 170 is fastened to the bottom of the interlock rod 46. While the interlock lever 164 is lowered, the interlock rod 46 is inserted into a concave, which defines the run position 158 and open-circuit position 160, and brought into contact with the bracket 162 so as to inhibit the vacuum circuit breaker 32 from being pulled out.

Concisely, if the interlock rod 46 cannot be lifted while the vacuum circuit breaker 32 is in the OFF position for power shutoff, the vacuum circuit breaker 32 cannot be transported (pulled out).

In the above instance, a limit switch 42, which serves as an interlock switch, is ON so that a signal entered into the control circuit board 18 as a "close contact" command is not blocked by the limit switch 42.

If the interlock lever 164 is moved up while the vacuum circuit breaker 32 is in the OFF (power shutoff) position, the interlock rod 46 moves upward in accordance with the ascent of the interlock lever 164, as shown in Fig. 6, thereby allowing the vacuum circuit breaker 32 to be pulled out.

In other words, the solenoid-operated switching device can be pulled out forward and moved to the open-circuit position 160. In this instance, however, the limit switch 42 turns off in accordance with the ascent of the interlock rod 46, thereby forcibly inhibiting the "close contact" command from being input into the control circuit board 18. Thus, the vacuum circuit breaker 32 cannot be turned on.

If, on the other hand, the vacuum circuit breaker 32 is in the ON position for contact closing, the stopper pin 106 is in contact with the lock pin 170 as shown in Fig. 7, thereby inhibiting the interlock rod 46 from moving upward. In other words, even if the interlock lever 164 is operated, the interlock rod 46 cannot move upward because the stopper pin 106 is in contact with the lock pin 170. As a result, the vacuum circuit breaker 32 cannot be pulled out.

To permit the vacuum circuit breaker 32 to be manually turned off while a front cover 166 is installed over the casing 10, the present embodiment provides a hole 174 in the base 80 and at a position away from the front cover 166, into which a contact opening handle 172 is to be inserted, as shown in Fig. 8. Since the use of handle 172 for power shutoff provides an increase in the operating speed, it is applicable to all situations where a power shutoff operation needs to be performed. More specifically, handle 172 can be inserted into hole 174 no matter whether the front cover 166 is installed. When the leading end of handle 172 is inserted into hole 174 while the vacuum circuit breaker 32 is in the ON position to press the leading end of handle 172 against the underside of the stopper pin 106 and then handle 172 is pushed downward using the bottom of hole 174 as a fulcrum, the lever 96 rotates counterclockwise around shaft 98 to turn off the vacuum circuit breaker 32. If handle 172 is operated in this instance so as to apply a force greater than the attraction force of the permanent magnet 68 only at the beginning, the vacuum circuit breaker 32 can be turned off subsequently by the elastic force of the contact opening spring 92 and contact pressure spring 120.

To permit the vacuum circuit breaker 32 to be manually turned on only when the front cover 166 is removed, the present embodiment provides hole 178 in the base 80, subsequently to hole 174, as shown in Fig. 9. The leading end of a contact closing handle 176 can be inserted into hole 178.

The contact closing operation performed by the contact closing handle 176 does not provide an increase in the operating speed. To permit such a contact closing operation to be performed only when the vacuum circuit breaker 32 is removed from the distribution switchboard for in-house assembly, disassembly, servicing, or inspection (periodic inspection), therefore, the employed structure is such that hole 178 is exposed to view only when the front cover 166 is removed. When the vacuum circuit breaker 32 is to be turned on manually with the contact closing handle 176, the front cover 166 is removed and then the leading end of the contact closing handle 176 is inserted into hole 178 in the base 80. In this instance, the contact closing handle 176 is inserted into hole 178 in such a manner that the leading end of the contact closing handle 176 comes into contact with the top of the stopper pin 106. When the leading end of the contact closing handle 176 is later inserted outside the lever 96 and brought into contact with the top of the stopper pin 106, and then the contact closing handle 176 is moved upward using the top of hole 178 as a fulcrum, the lever 96 rotates clockwise around shaft 98, thereby turning on the vacuum circuit breaker 32.

In the present embodiment, the contact closing operation cannot be manually performed until the front cover 166 is removed. To permit the manual contact opening operation to be performed without removing the front cover 166, the present embodiment also provides hole 174 for accepting the contact opening handle 172 in the base 80, away from the front cover 166, and at a location facing the stopper pin 106, and provides hole 178 for accepting the contact closing handle 176 in the base 80, within the area for installing the front cover 166, and at a location facing the stopper pin 106.

The solenoid operation device is assembled by moving the electromagnet 14, capacitor 16, control circuit board 18, secondary plug 22, cables 24 to 28, and other components into the casing 10 from the front of the casing 10 on the base 80, fastening the electromagnet 14 to roughly at the center of the casing 10, and securing the capacitor 16 and control circuit board 18 to the lateral surfaces of the casing 10. Since the auxiliary contact 34, indicator plate 36, and counter 38 are integral with the electromagnet 14 via plate 56 in this instance, they are positioned over the electromagnet 14 when the electromagnet 14 is secured. Further, the cables 24 to 28 are integral with the secondary plug 22, connector 40, and limit switch 42. Therefore, the secondary plug 22 is secured to the top of the casing 10 while it is connected to cable 28 or and the like. When various sections of cable 28 are properly positioned relative to the casing 10, the leading end of cable 24 is connected to the capacitor 16, and connector 40, which is attached to the leading end of cable 28, is connected to the control circuit board 18. Then, the leader line 30 for the coil 48 and cable 28 are partly crimped. When shaft 88 is subsequently connected to lever 96 via pin 94, the electromagnet 14 is connected to the vacuum circuit breaker 32 via a link mechanism. The solenoid operation device is now completely assembled.

When the solenoid operation device is configured as an element of the solenoid-operated switching device, the electromagnet 14 is positioned roughly at the center of the casing 10, and the capacitor 16 and control circuit board 18 are positioned on either side of the electromagnet 14 and separately fastened to the lateral surfaces of the casing 10 as described above. This results in an increase not only in the ease of installation, servicing, and inspection but also in the workability. Further, it is possible to inhibit the shock and vibration generated by the electromagnet 14 from being transmitted to the capacitor 16 and control circuit board 18.

Further, the auxiliary contact 34, indicator plate 36, and counter 38 are joined to plate 56 to be integral with the electromagnet 14. This results in a simple configuration.

In the present embodiment, the electromagnet 14 is entirely covered with a member made of iron. Therefore, the magnetic field does not leak out of the electromagnet. As a result, erratic operations of a control circuit can be avoided. This also fixes a problem in which the characteristics of the electromagnet 14 vary depending on the position of a magnetic material such as the casing 10.

In the present embodiment, a solid lubricant is applied to sliding sections where one component member slides along another and to shaft support or rotary sections where one component member supports another that freely rotates.

More specifically, a dry bearing is used as a solid lubricant for sliding sections such as through hole 82 in plate 56 and through hole 84 in mounting plate 76 and for rotary or shaft support sections such as

pins

86, 94, 102, and 144 and shaft 98. For example, the sliding operation (up-down motion) of shaft 62, the rotation of

levers

96, 100, and 140, and the support of various other members can be performed smoothly. In addition, the electromagnet 14 can be hermetically sealed.

For pin 94, a C-ring is used as a retainer. Therefore, higher workability results than the use of a split pin.

The configuration of the electromagnet control device in which the control circuit board 18 is a main component will now be described in detail with reference to Fig. 10. The electromagnet control device comprises an AC/DC converter 200, a recharger circuit 202, a control logic section 204, and a discharger circuit 206. The discharger circuit 206 is connected to the capacitor 16 and electromagnetic coil 48.

The AC/DC converter 200 receives DC or AC control power P, N from the secondary plug 22. If DC power is received, the AC/DC converter 200 outputs it directly to the recharger circuit 202 and control logic section 204. If AC power is received, on the other hand, the AC/DC converter 200 converts it to DC power and then delivers it to the recharger circuit 202 and control logic section 204. The recharger circuit 202 rapidly recharges the capacitor 16 and then gradually performs a recharging operation until the maximum voltage is attained. Electrical power stored in the capacitor 16 is used to exercise drive control over the electromagnetic coil 48.

The discharger circuit 206 is provided with an FET (field-effect transistor) 208, which serves as a main control means, a pair of

relay contacts

210 and 212, a diode D1, and a resistor RL. FET 208 is inserted into a conduction circuit that receives power (electrical current) from the capacitor 16 and supplies it to the electromagnetic coil 48, and subjected to on/off control in accordance with a control signal from the control logic section 204.

Relay contacts

210 and 212, which constitute a pair of mechanical selector relays, are inserted into a conduction circuit that receives power from the capacitor 16 and supplies it to the electromagnetic coil 48.

Relay contacts

210 and 212 have the same changeover contacts and both comprise a normally open contact and normally closed contact. Relay contact 210 is connected so as to connect the normally open contact to one end of the electromagnetic coil 48, connect the normally closed contact to the other end of the electromagnetic coil 48, and connect the changeover contact to the plus side of the capacitor 16.

Relay contact 212, on the other hand, is connected so as to connect the normally closed contact to one end of the electromagnetic coil 48, connect the normally open contact to the other end of the electromagnetic coil 48, and connect the changeover contact to FET 208. The changeover contact is also connected to the changeover contact of relay contact 210 via resistor RL and diode D1.

Relay contacts

210 and 212 constitute a pair of selector relays. When the "open contact" command (power shutoff command) is issued, the changeover contacts and normally closed contacts are mutually interconnected so that

relay contacts

210 and 212 function as a contact opening means for forming a conduction circuit that separates the movable magnet core 58 from the stationary magnet core 60 as a conduction circuit for receiving power from the capacitor 16 and supplying it to the electromagnetic coil 48. When the "close contact" command is issued,

relay contacts

210 and 212 change their contact connections. More specifically, the changeover contacts are connected to the normally open contacts so as to form a conduction circuit for bringing the movable magnet core 58 into contact with the stationary magnet core 60 as a conduction circuit for supplying power from the capacitor 16 to the electromagnetic coil 16 and as a conduction circuit that supplies power to the electromagnetic coil 48 in the direction opposite to that of a conduction circuit provided by the contact opening means. This conduction circuit is configured as a contact closing means for turning off the conduction circuit that is formed upon "open contact" command issuance. After a contact closing conduction circuit or contact opening (power shutoff) conduction circuit is formed by

relay contacts

210 and 212, FET 208 turns on and off to turn on and off the coil current of the electromagnetic coil 48.

In other words,

relay contacts

210 and 212, which serve as selector relays, are required to deliver their conduction performance only. Further, FET 208, which serves as a main switch, is provided with a large opening/closing capacity in order to reduce the cost and size.

In addition, the normally closed contacts of

relay contacts

210 and 212 are used as a contact opening means. Therefore, even if

relay contacts

210 and 212 malfunction, at least a contact opening operation will be properly carried out.

If FET 208 shuts off the coil current of the electromagnetic coil 48, an overvoltage proportional to the current conversion rate may be generated to damage the electromagnetic coil 48.

In the present embodiment, however, resistor RL and diode D1 are connected as energy consumption devices. Therefore, even if an overvoltage is generated by the electromagnetic coil 48 at the time of contact closing or opening, resistor RL can consume the energy arising out of the overvoltage.

As shown in Fig. 11, the recharger circuit 202 comprises a relay coil 214, a relay contact 216, an FET 218, a recharging completion detection circuit 220, a plurality of recharging resistors Rb and Rs, a diode D2, and a plurality of zener diodes ZD1 to ZDn. The zener diodes ZD1 to ZDn are series-connected to each other and connected across the capacitor 16. These zener diodes maintain the charge voltage of the capacitor 16 at a specified level.

Recharging resistors Rb and Rs have different resistance values. Their relationship is such that Rb > Rs. These recharging resistors Rb, Rs are series-connected together with diode D2 within a circuit that interconnects the AC/DC converter 200 and capacitor 16. At the beginning of recharging, the recharging completion detection circuit 220 outputs a High-level signal, thereby turning on FET 218 and relay 214 and causing relay contact 216 to switch from the normally closed contact to the normally open contact. Recharging resistor Rs, which has a small resistance value, is then inserted into a circuit for recharging the capacitor 16 to rapidly recharge the capacitor 16.

When the charge voltage of the capacitor 16 reaches voltage value Vt1, which is adequate for driving the electromagnet 14, the recharging completion detection circuit 220 outputs a Low-level recharging completion signal, thereby turning off FET 218 and relay 214 and causing relay contact 216 to revert from the normally open contact to the normally closed contact. Recharging resistor Rb, which has a great resistance value, is then inserted into a recharger circuit to gradually recharge the capacitor 16 until the maximum charge voltage Vmax is reached.

After the charge voltage of the capacitor 16 reaches Vt1, the recharging resistance switches to a high resistance side as described above. To avoid the thermal breakdown of the zener diodes ZD1 to ZDn, the current flow to the zener diodes ZD1 to ZDn can therefore be reduced after the charge voltage of the capacitor 16 reaches the Vmax level. FET 218, relay coil 214, and relay contact 216 constitute a recharging resistor selection means.

For the recharging completion detection circuit 220, a hysteresis upper limit value Vt1 and a hysteresis lower limit value Vt2 are set to define the range of recharging completion signal output voltage, as shown in Fig. 12. After the charge voltage of the capacitor 16 reaches the hysteresis upper limit value Vt1, the recharging completion detection circuit 220 outputs a Low-level signal as a recharging completion signal until the charge voltage of the capacitor 16 decreases to the hysteresis lower limit value Vt2 or smaller value. The hysteresis lower limit value Vt2 is set so that the residual voltage of the capacitor 16 does not decrease below the lower-limit voltage value, which defines a condition under which the recharging completion signal is output, even if a contact opening operation is performed immediately after the charge voltage of the capacitor 16 rises above the hysteresis upper limit value Vt1. Further, the setting selected as the charge voltage maximum value Vmax of the capacitor 16 is at least 90% of the minimum voltage within the control voltage variation range that is prescribed by the requirements for the vacuum circuit breaker 32, which is to be operated by the electromagnetic coil 48.

In other words, the vacuum circuit breaker must execute the following three types of duties. The hysteresis characteristics of recharging resistor Rs and recharging completion detection circuit 220 need to be set to fulfill the following duties:

Type A: "O" - 1 min - "CO" - 3 min - "CO"

Type B: "CO" - 15 s - "CO"

Type R: "O" - 0.35 s - "CO" - 3 min - "CO"

The symbol "O" represents a contact opening operation, whereas the symbol "C" represents a contact closing operation.

The above duties are defined by JEC-2300-1998. In reality, setup is performed with reference to Type B or R, which provide relatively short operating time intervals.

As shown in Fig. 13, the Type B duty is fulfilled, for instance, by determining the resistance value of recharging resistor Rs so that the time interval between the instant at which a "CO" operation is performed and the instant at which the capacitor residual voltage reaches Vt1 is 15 seconds or shorter. Further, the Type R duty is fulfilled by determining the hysteresis lower limit value Vt2 so that the output of the recharging completion detection circuit 220 remains at a Low level even if an "O" operation is performed once as shown in Fig. 14.

Further, the maximum charge voltage value Vmax of the capacitor 16, which is determined by the zener diodes ZD1 to ZDn, must be not greater than the minimum value (minimum voltage) within the control voltage variation range that is prescribed by the requirements for the vacuum circuit breaker. In addition, since the charge energy of the capacitor 16 is proportional to the square of the charge voltage as shown in Fig. 15, it should be set for a voltage that is at least 90% of the minimum value.

A 75% to 125% variation from the rated control voltage is defined by JEC-2300-1998. If, for instance, the rated control voltage is 100 VDC, the Vmax setting should be at least 75 V x 0.9 = 67.5 V.

Meanwhile, the "close contact" command is entered into the control logic section 204 via the limit switch 42, which serves as an interlock, and relay contact 222, which coordinates with relay 214, as shown in Fig. 16. In addition, the "open contact" command is also entered into the control logic section 204. The control logic section 204 is connected to

auxiliary contacts

48a and 48b, which open/close in accordance with the status of the vacuum circuit breaker 32. The control logic section 204 also performs logical operations in accordance with the "close contact" command, the "open contact" command, and the status of the vacuum circuit breaker 32, and generates control signals for controlling, for instance, FET 208, relay 214, and

relay contacts

210 and 212, which serve as selector relays. Relay contact 222 is configured as a contact closing command control means for inhibiting the input of the "close contact" command before the recharging completion detection circuit 220 generates a recharging completion signal.

The operation of the control logic section 204 will now be described with reference to Fig. 17. When a contact closing operation is to be performed in accordance with a control signal generated by the control logic section 204, the present embodiment accepts the "close contact" command to generate the control signal only when the interlock is on with the capacitor completely recharged.

More specifically, if the interlock turns on with relay contact 222 turned off when the "close contact" command is generated,

relay contacts

210 and 212, which serve as selector relays, switch to the normally open contact side. A circuit for a contact closing operation is then formed as a conduction circuit for the electromagnetic coil 48. Subsequently, FET 208 turns on to excite the electromagnetic coil 48. This brings the movable magnet core 58 into contact with the stationary magnet core 60, causing the vacuum circuit breaker 32 to perform a contact closing operation. In this process, auxiliary contact 48b, which indicates an "open" state of the vacuum circuit breaker 32, changes its status from ON,to OFF. Subsequently, the movable contact of the vacuum circuit breaker 32 comes into contact with the stationary contact. This turns on auxiliary contact 48a, which indicates a "closed" state of the vacuum circuit breaker 32.

After the vacuum circuit breaker 32 completes its contact closing operation, FET 208 turns off at an appropriate time. After FET 208 turns off, resistor RL consumes the energy stored in the electromagnetic coil 48. However,

relay contacts

210 and 212, which serve as selector relays, turn off to complete the contact closing operation after the coil current adequately attenuates.

When, on the other hand, a contact opening operation is to be performed, no particular limitations are imposed. When FET 208 turns on upon issuance of the "open contact" command as shown in Fig. 18, the electromagnetic coil 48 is excited by a current that flows in a direction opposite to that for contact closing because

relay contacts

210 and 212 are on the normally closed contact side. The movable magnet core 58 then leaves the stationary magnet core 60, causing the vacuum circuit breaker 32 to perform a contact opening operation. In the process in which the contact opening operation is performed, auxiliary contact 48a, which indicates a "closed" state of the vacuum circuit breaker 32, changes its status from ON to OFF. Subsequently, auxiliary contact 48b, which indicates an "open" state of the vacuum circuit breaker 32, changes its status from OFF to ON.

In the present embodiment,

relay contacts

210 and 212 make a conduction circuit changeover and FET 208 provides conduction circuit on/off. It is therefore possible to use small-capacity relay contacts as

relay contacts

210 and 212 and a large-capacity FET as FET 208. As a result, the cost and size can be both reduced.

Further, a sequence operation defined for the control logic section 204 can be executed to implement an open circuit priority function and pumping inhibition function.

Another embodiment of the present invention will now be described with reference to Fig. 19. The present embodiment is similar to that is shown in Fig. 10 except that relay contacts 224 to 230, which serve as selector relays operating according to a control signal from the control logic section 204, are employed in replacement of

relay contacts

210 and 212, which serve as selector relays.

Relay contact 224 is configured so that it is connected to the plus side of the capacitor 16 under normal conditions (in the OFF state) with its contact open. Further, relay contact 224 responds to the "close contact" command only, turns on to close the contact, and becomes connected to one end of the electromagnetic coil 48 via relay contact 228. Relay contact 226 is configured so that it is connected to the plus side of the capacitor 16 in the OFF state with its contact closed. Further, relay contact 226 responds to the "close contact" command only and turns on to close the contact.

Relay contacts

228 and 230 is configured so as to respond to the "open contact" command only and turn on. Relay contact 228 is connected to one end of the electromagnetic coil 48 in the OFF state, and connected to one end of the electromagnetic coil 48 and FET 208 in the ON state to form a conduction circuit for conducting a contact opening operation. Relay contact 230 is connected to the other end of the electromagnetic coil 48 and resistor RL in the OFF state, and connected to the other end of the electromagnetic coil 48 and the plus side of the capacitor 16 in the ON state to form a conduction circuit for conducting a contact opening operation.

More specifically, when the "close contact" command is generated,

relay contacts

224 and 226 turn on with

relay contacts

228 and 230 turned off so that

relay contacts

224, 228, and 230 constitute a contact closing means for forming a contact closing conduction circuit for the electromagnetic coil 48. When, on the other hand, the "open contact" command is generated,

relay contacts

224 and 226 turn off with

relay contacts

228 and 230 turning on so that

relay contacts

226, 228, and 230 are inserted into a conduction circuit for contact opening to form a contact opening means for opening the vacuum circuit breaker 32.

In the present embodiment, relay contacts 224 to 230 make a conduction circuit changeover and FET 208 provides conduction circuit on/off. It is therefore possible to use small-capacity relay contacts as relay contacts 224 to 230 and a large-capacity FET as FET 208. As a result, the cost and size can be both reduced.

When the "close contact" command is generated and

relay contacts

224 and 226 then turn on, the present embodiment turns on FET 208 to excite the electromagnetic coil 48, causing the vacuum circuit breaker 32 to perform a contact closing operation. When the "open contact" command is generated and then relay contacts 228 to 230 turn on, the present embodiment turns on FET 208 to excite the electromagnetic coil 48, causing the vacuum circuit breaker 32 to perform a contact opening operation. Therefore, it is possible to prevent the vacuum circuit breaker 32 from malfunctioning even when voltage-driven FET 208 malfunctions due, for instance, to surge noise with relay contacts 224 to 230 turned off.

When the above embodiment of the solenoid operation device is combined with the magnetic latch type solenoid-operated vacuum circuit breaker 32 to form a solenoid-operated switching device, the control logic section 204 may, for instance, comprise a microcomputer, a logic IC (CPLD/FPGA), or mechanical relay. The electrical current required for the "close contact" command and "open contact" command is approximately several tens of milliamperes. Therefore, a low-energy switching device may be configured.

In recent years, a digital relay has been a mainstream relay for giving the "open contact" command to a circuit breaker. The use of such a digital relay is convenient when the circuit breaker to be controlled operates from a small current. However, a large number of conventional analog relays exist as relays that give the "open contact" command to a circuit breaker. Therefore, if the solenoid-operated switching device according to the present invention is applied to a distribution switchboard on which an analog relay is mounted, a mismatch occurs in terms of the electrical current value of the "open contact" command.

If, for instance, a current greater than specified flows to a current transformer 302, which detects a current flow to a circuit breaker 300 (a circuit breaker equivalent to the vacuum circuit breaker 32), as shown in Figs. 20A and 20B, a main contact 306, which is connected to a disc 304, closes to operate an auxiliary contactor 308. In this instance, the auxiliary contactor 308 outputs the "open contact" command (trip command) to the circuit breaker 300 and, at the same time, an indicator 310 operates. In other words, the "open contact" command is required to provide a current for operating not only the circuit breaker 300 but also the indicator 310. The current adequate for such a purpose is 2 to 5 A. Therefore, when the solenoid-operated switching device is to be configured, it is necessary to ensure that the analog relay and circuit breaker 300 both operate normally.

When the solenoid-operated switching device is to be configured in accordance with the present embodiment, a bypass circuit is formed as shown in Fig. 21 so as to form a bypass, via resistor 312, between a part of the "open contact" command and the minus (ground) side (control power supply N) of the AC/DC converter 200, which serves as a power supply. Further, an auxiliary contact 314 for disconnecting the bypass circuit in response to an opening operation of the vacuum circuit breaker 32 and a jumper switch 313 for opening/closing the contact in response to the operation are inserted into the bypass circuit. Furthermore, resistor 312 is mounted on the control circuit board 18.

If the above configuration is adopted and an analog relay is used in a configuration in which the input impedance of the control logic section 204 is high and a current of several tens of milliamperes flows to the control logic section 204, the jumper switch 313 may be turned on to close the bypass circuit so as to bypass the "open contact" command, which is output from the analog relay and several amperes, via resistor 312 and auxiliary contact 314.

Resistor 312 can be set in accordance with the rated control voltage. If, for instance, a 100 VDC input is used, resistor 312 may be set to approximately 30 ohms. In this instance, the "open contact" command current transmitted from the analog relay is approximately 3 A. This current is adequate not only for operating the indicator 310 and circuit breaker 300 but also for opening auxiliary contact 314 in synchronism with the circuit breaker 300. Therefore, compatibility can be maintained even when a conventional relay is used.

No matter whether a digital relay or analog relay is used, the present embodiment can steadily operate both the relay and circuit breaker.

In the embodiment described above, resistor 312 is mounted on the control circuit board 18. However, resistor 312 does not always have to be mounted on the control circuit 18. Alternatively, resistor 312 may be housed in a relay box 316 only when an analog relay is used. The relay box 316 may be mounted on the front cover (front panel) 166, as shown in Figs. 22 and 23, for relaying a signal from the secondary plug 22 to the control circuit board 18 and other components.

When the above configuration is adopted, the solenoid-operated switching device can use a digital relay as is if it is employed. If an analog relay is employed, on the other hand, the purpose can be achieved by furnishing the relay box 316. Therefore, the above configuration permits the use of either a digital relay or analog relay.

The relay box 316 does not have to be mounted directly in the switching device. It may be positioned anywhere between the analog relay and switching device.

In the embodiment described above, one phase is provided for the vacuum circuit breaker 32. However, three phases can be alternatively provided for the vacuum circuit breaker 32. Individual phases of the vacuum circuit breaker may be joined via shaft 98 so as to perform an opening/closing operation for each phase of the vacuum circuit breaker with a single electromagnet 14.

Another alternative is to interconnect a plurality of electromagnets 14 via shaft 98 and series-connect the coils 48 of individual electromagnets 14 to operate the vacuum circuit breaker 32.

The structure of the electromagnet 14 will now be described in detail with reference to Figs. 24 to 29. Fig. 24 is a vertical cross-sectional view of the electromagnet 14. Fig. 25 is a horizontal cross-sectional view along section A-A of Fig. 24. Fig. 26 is a horizontal cross-sectional view along section B-B of Fig. 24. Fig. 27 is a horizontal cross-sectional view along section C-C of Fig. 24.

As shown in Figs. 24 to 27, the electromagnet 14 comprises a coil 48, which is shaped like a cylinder; a movable magnet core 58, which is shaped like a column; a stationary magnet core 60, which is shaped like a column; a shaft 62, which is inserted into the axial center of the movable magnet core 58 and stationary magnet core 60; oval-shaped, movable

flat plates

64 and 66, which are fastened to shaft 62; an oval-shaped permanent magnet 68, which is fastened to mounting plate 74; oval-shaped iron covers 70 and 72, which are formed as lateral legs; and mounting plate 76, which is fastened to the stationary rod 78 to support iron cover 72.

As iron covers 70 and 72, which enclose shaft 62 and coil 48, standard-size steel pipes that conform to the JIS or other standard and have a circular cross section are used after being partly flattened by a pressing machine.

For example, the circular steel pipes should be partly flattened in the radial direction by a pressing machine as shown in Fig. 28A, and then pressed in the axial direction as shown in Fig. 28B to smooth out an end face of iron covers 70 and 72 through which a magnetic field passes.

The flattening test defined by JIS G 3454 or other similar standard stipulates that chips and cracks must be checked for when a steel pipe is flattened until its short diameter H is two-thirds the outside diameter D. It means that no performance problem arises even if the steel pipes are flattened to such a short diameter. It is therefore preferable that the short diameter of iron covers 70 and 72 of the present embodiment be not smaller than two-thirds the original steel pipe outside diameter.

The permanent magnet 68 and movable

flat plates

62 and 64 also have an oval external shape in accordance with iron covers 70 and 72. Therefore, the resulting opposing areas of the permanent magnet 68, the movable

flat plates

62 and 64 and the iron covers 70 are larger than when the permanent magnet 68 and the movable

flat plates

62 and 64 are circular but not oval. This results in an increase in the attraction force.

The movable

flat plates

62 and 64, which are thin steel plates, can be made with a pressing machine. The permanent magnet 68 can be sinter-molded. Therefore, the cost does not increase even when the movable

flat plates

62 and 64 and permanent magnet 68 are shaped like an oval.

Meanwhile, the movable magnet core 58 and stationary magnet core 60 can be made of a standard-size steel bar that is defined by JIS 7. Therefore, when the movable magnet core 58 and stationary magnet core 60 are shaped like a column, the resulting cost is lower than when they are shaped like a square or rectangle.

For assembling the electromagnet 14 for the above configuration, the stationary magnet core 60 is bolted down to mounting plate 76 in advance with the stationary rod 78 and shaft 62 passed through mounting plate 76 as shown in Fig. 29. With the resulting state maintained, iron cover 72 is first installed over mounting plate 76 from above, and then mounting plate 74 to which the coil 48 and permanent magnet 68 are glued or otherwise fastened beforehand, movable magnet core 58, movable flat plate 66, and movable flat plate 64 are sequentially mounted in order named. Next, shaft 62, movable magnet core 58, and movable

flat plates

64 and 66 are secure with nut 65. Subsequently, iron cover 70 and plate 56 are mounted on mounting plate 74, and then nut 55 is tightened on the stationary rod 78 to complete the assembly of the electromagnet 14.

For positioning the assembled electromagnet 14 in front of the vacuum circuit breaker 32, the short diameter side of iron covers 70 and 72, which are shaped like an oval, is positioned in the direction of the depth of the casing 10 and vacuum circuit breaker 32.

In the present embodiment, the electromagnet 14 is mounted while the short diameter side of iron covers 70 and 72, which are shaped like an oval, is positioned in the direction of the depth of the casing 10 and vacuum circuit breaker 32. Therefore, the installation space for the electromagnet 14, which is wider than deep, can be reduced. Further, it is also possible to decrease the installation space for the solenoid operation device and downsizes the switching device (vacuum circuit breaker 32) in which the solenoid operation device is mounted as well as the distribution switchboard on which the switching device is mounted.

Further, the present embodiment can reduce the size of the solenoid operation device without increasing the cost, because only the iron covers 70 and 72 which can be press-formed, the movable

flat plates

64 and 66 which can be made with a pressing machine, and the permanent magnet 68 which is molded are shaped like an oval. Further, as the iron covers 70 and 72 for the electromagnet 14 are shaped like an oval that look like a racetrack, the present embodiment reduces the dead space and enhances the efficiency of use of an occupied area.

As described above, the solenoid operation device of the present invention permits a configuration for workability enhancement. Even when the manpower for manufacture is reduced, the solenoid operation device can configure an electromagnet that is wider than deep and reduce the required installation space. The electromagnet control device of the present invention can downsize the control means for controlling the conduction direction for the electromagnetic coil in compliance with the "open contact" command and "close contact" command. The solenoid-operated switching device of the present invention permits the use of either a digital relay or analog relay.

Claims

A solenoid operation device, comprising:

an electromagnet having a movable magnet core and a stationary magnet core, which face each other, and a coil that, depending on electromagnetic force, separates said movable magnet core from said stationary magnet core or brings said movable magnet core into contact with said stationary magnet core;

a capacitor for storing the power for exciting said coil;

a control circuit board for controlling the conduction direction of a current supply from said capacitor to said coil in response to a "close contact" command or an "open contact" command for a switching device; and

a shaft that is connected to said movable magnet core to transmit driving force, which is derived from electromagnetic force generated by said electromagnet, to said switching device via a link mechanism;

wherein said capacitor and said control circuit board are independently positioned around said electromagnet.
A solenoid operation device, comprising:

an electromagnet having a movable magnet core and a stationary magnet core, which face each other, and a coil that, depending on electromagnetic force, separates said movable magnet core from said stationary magnet core or brings said movable magnet core into contact with said stationary magnet core;

a capacitor for storing the power for exciting said coil;

a control circuit board for controlling the conduction direction of a current supply from said capacitor to said coil in response to a "close contact" command or an "open contact" command for a switching device;

a shaft that is connected to said movable magnet core to transmit driving force, which is derived from electromagnetic force generated by said electromagnet, to said switching device via a link mechanism; and

a casing for housing said electromagnet, said capacitor, and said control circuit board;

wherein said electromagnet is fastened to the bottom center of said casing; and wherein said capacitor and said control circuit board are separately fastened to said casing.
The solenoid operation device according to claim 2, wherein said casing has a front opening, and wherein a front cover is fastened to the front of said casing but freely detachable.
The solenoid operation device according to claim 2, further comprising a status detection mechanism that is interlocked with a shaft connected to said movable magnet core to detect the status of said switching device, wherein said status detection mechanism is integral with said electromagnet.
The solenoid operation device according to claim 4, wherein said status detection mechanism comprises an auxiliary contact that is interlocked with a shaft connected to said movable magnet core to open and close; an indicator plate that is interlocked with a shaft connected to said movable magnet core to indicate whether said switching device is on or off; and a counter that is interlocked with a shaft connected to said movable magnet core to count the number of open/close operations performed by said switching device, wherein said auxiliary contact, said indicator plate, and said counter are integral with each other and positioned over said electromagnet.
The solenoid operation device according to claim 2, further comprising a contact opening spring that is positioned toward the bottom of said electromagnet to give elastic force for separating said movable magnet core from said stationary magnet core to a shaft connected to said movable magnet core.
The solenoid operation device according to claim 2, further comprising an interlock rod that is free to move up and down; and an interlock switch that opens/closes in response to the up-down motion of said interlock rod, wherein said interlock switch forcibly blocks a "close contact" command input to said control circuit when said interlock rod ascends.
The solenoid operation device according to claim 7, further comprising a lock pin that is fastened to said interlock rod to move up or down together with said interlock rod; and a stopper pin that is positioned within an ascent/descent region of said lock pin and fastened to said link mechanism, wherein said lock pin comes into contact with said stopper pin to block the ascent of said interlock rod when said switching device is on.
The solenoid operation device according to claim 8, further comprising a base that is positioned toward the bottom of said casing to enclose said stopper pin and connected to said casing, wherein a hole for accepting a contact opening handle is in said base, away from a front cover, and facing said stopper pin, and wherein a hole for accepting a contact closing handle is in said base, within a region of said front cover, and facing said stopper pin.
The solenoid operation device according to claim 2, wherein a solid lubricant is used for sliding sections where one component member slides along another and for shaft support or rotary sections where one component member supports another which freely rotates.
An electromagnet control device, comprising:

a contact opening means for forming a conduction circuit for separating a movable magnet core from a stationary magnet core upon "open contact" command issuance as a conduction circuit for receiving power from a capacitor, which stores power supplied from a power supply, and supplying it to an electromagnetic coil; and

a contact closing means for forming a conduction circuit for bringing said movable magnet core into contact with said stationary magnet core upon "close contact" command issuance as a conduction circuit for supplying power to said electromagnetic coil in the direction opposite to that of a conduction circuit provided by said contact opening means;

wherein said contact opening means includes a selector relay that is inserted into a conduction circuit for separating said movable magnet core from said stationary magnet core in compliance with said "open contact" command; and
wherein said contact closing means includes a selector relay that is inserted into a conduction circuit for bringing said movable magnet core into contact with said stationary magnet core in compliance with said "close contact" command.
The electromagnet control device according to claim 11, wherein said selector relays have the same changeover contacts and both comprise a normally open contact and a normally closed contact, and wherein the normally closed contact of each of said selector relays is inserted into a conduction circuit for said contact opening means.
The electromagnet control device according to claim 11, further comprising a main control means, which is inserted into a conduction circuit provided by said contact closing means or a conduction circuit provided by said contact opening means to close the conduction circuit provided by said contact closing means if a conduction circuit is formed by said contact closing means upon "close contact" command issuance or otherwise open the conduction circuit provided by said contact closing means, and close the conduction circuit provided by said contact opening means upon "open contact" command issuance or otherwise open the conduction circuit provided by said contact opening means.
An electromagnet control device, comprising:

a contact opening means for forming a contact opening conduction circuit for separating a movable magnet core from a stationary magnet core upon "open contact" command issuance as a conduction circuit for receiving power from a capacitor, which stores power supplied from a power supply, and supplying it to an electromagnetic coil; and

a contact closing means for forming a contact closing conduction circuit for bringing said movable magnet core into contact with said stationary magnet core upon "close contact" command issuance as a conduction circuit for supplying power to said electromagnetic coil in the direction opposite to that of a conduction circuit provided by said contact opening means;

wherein said contact opening means includes a pair of contact opening selector relays that are inserted into said contact opening conduction circuit in compliance with said "open contact" command and a contact closing selector relay that is inserted into said contact opening conduction circuit until said "close contact" command is issued; and
wherein said contact closing means includes a contact closing selector relay that is inserted into a contact closing conduction circuit in compliance with said "close contact" command and a pair of contact opening selector relays that are inserted into said contact closing conduction circuit until said "open contact" command is issued.
The electromagnet control device according to claim 14, further comprising a main control means, which is inserted into a conduction circuit provided by said contact closing means or a conduction circuit provided by said contact opening means to close said contact closing conduction circuit if said contact closing conduction circuit is formed upon said "close contact" command issuance or otherwise open said contact closing conduction circuit, and close said contact opening conduction circuit if said contact opening conduction circuit is formed upon said "open contact" command issuance or otherwise open said contact opening conduction circuit.
The electromagnet control device according to claim 13 or 15, wherein an energy consumption device, which is connected across said electromagnetic coil via said selector relay to consume the energy of said electromagnetic coil, is inserted between said selector relay and said main control means.
The electromagnet control device according to claim 16, wherein said energy consumption device comprises a resistor and a diode, which are series-connected.
The electromagnet control device according to claim 11 or 14, further comprising:

a zener diode that is connected across said capacitor to maintain the charge voltage of said capacitor at a specified level;

a plurality of recharging resistors that have different resistance values and are series-connected between said power supply and said capacitor;

a recharging completion detection circuit for generating a recharging completion signal when the charge voltage of said capacitor is adequate for driving said electromagnet; and

a recharging resistor selection means for selecting, before said recharging completion signal is generated, a recharging resistor having a small resistance value from said plurality of recharging resistors and inserting the selected recharging resistor into a circuit joining said power supply and said capacitor, and selecting, when said recharging completion signal is generated, a recharging resistor having a great resistance value from said plurality of recharging resistors and inserting the selected recharging resistor into a circuit joining said power supply and said capacitor.
The electromagnet control device according to claim 18, further comprising a contact closing command control means for inhibiting a "close contact" command from being input into said contact closing means before said recharging completion signal is generated.
The electromagnet control device according to claim 18, wherein a hysteresis upper limit value and a hysteresis lower limit value are set for said recharging completion detection circuit to define a voltage range for generating said recharging completion signal, and wherein said recharging completion detection circuit generates said recharging completion signal during the time interval between the instant at which the charge voltage of said capacitor reaches said hysteresis upper limit value and the instant at which the charge voltage of said capacitor decreases to said hysteresis lower limit value or smaller.
The electromagnet control device according to claim 20, wherein the hysteresis lower limit value of said recharging completion detection circuit is set so that even if a contact opening operation is performed immediately after the charge voltage of said capacitor rises above said hysteresis upper limit value, the residual voltage of said capacitor does not decrease below the lower-limit voltage value at which said recharging completion signal is generated.
The electromagnet control device according to claim 11 or 14, wherein the charge voltage maximum value setting for said capacitor is at least 90% of the minimum voltage within a control voltage variation range that is prescribed by the requirements for the switching device to be operated by said electromagnetic coil.
A solenoid-operated switching device, comprising:

a switching device that, depending on driving force, separates a movable contact and a stationary contact, which face each other, or brings said movable contact into contact with said stationary contact;

an electromagnet that is connected to said switching device via a link mechanism;

a control circuit board for controlling the conduction direction of a current supply from a capacitor to a coil of said electromagnet in compliance with a "close contact" command or an "open contact" command for said switching device; and

a bypass circuit for forming a bypass between a part of said "open contact" command and a power supply for said control circuit board via a resistor.
A solenoid-operated switching device, comprising:

a switching device that, depending on driving force, separates a movable contact and a stationary contact, which face each other, or brings said movable contact into contact with said stationary contact;

an electromagnet including a coil that, depending on electromagnetic force, separates a movable magnet core and a stationary magnet core, which face each other, or brings said movable magnet core into contact with said stationary magnet core;

a capacitor for receiving power from a power supply and storing the received power;

a control circuit board for controlling the conduction direction of a current supply from said capacitor to said coil of said electromagnet in compliance with a "close contact" command or an "open contact" command for said switching device;

a shaft that is coupled to said movable magnet core to transmit driving force, which is derived from electromagnetic force generated by said electromagnet, to said switching device via a link mechanism; and

a bypass circuit for forming a bypass between a part of said "open contact" command and said power supply via a resistor.
The solenoid-operated switching device according to claim 23, wherein said bypass circuit includes an auxiliary contact for opening said bypass circuit in response to a contact opening operation of said switching device.
The solenoid-operated switching device according to claim 23, wherein an auxiliary contact for opening said bypass circuit in response to a contact opening operation of said switching device and a jumper switch for opening/closing a contact in response to an operation are series-connected within said bypass circuit.
The solenoid-operated switching device according to claim 23, wherein a resistor for said bypass circuit is mounted on said control circuit board.
The solenoid-operated switching device according to claim 23, further comprising a relay box for relaying said "open contact" command to said control circuit board, and wherein the resistor for said bypass circuit is mounted in said relay box.
The solenoid-operated switching device according to claim 23, further comprising a relay box for relaying said "open contact" command to said control circuit board, wherein said relay box is positioned between said control box and a relay for outputting said "open contact" command to said relay box, and wherein the resistor for said bypass circuit is mounted in said relay box.
A solenoid operation device, comprising:

an electromagnet having a movable magnet core and a stationary magnet core, which face each other; a coil that, depending on electromagnetic force, separates said movable magnet core from said stationary magnet core or brings said movable magnet core into contact with said stationary magnet core; and an iron cover that encloses said coil as a lateral leg and forms a path for the magnetic flux generated by said coil; and

a shaft that is connected to said movable magnet core to transmit driving force, which is derived from electromagnetic force generated by said electromagnet, to a switching device via a link mechanism;

wherein said iron cover is made of a cylinder having an oval external shape, and wherein the short diameter side of said cylinder is positioned in the direction of the depth of said switching device.
A solenoid operation device, comprising:

an electromagnet having a movable magnet core and a stationary magnet core, which face each other; a coil that, depending on electromagnetic force, separates said movable magnet core from said stationary magnet core or brings said movable magnet core into contact with said stationary magnet core; a permanent magnet that forms a path for a magnetic field generated by said coil and generates electromagnetic force for keeping said movable magnet core in contact with said stationary magnet core; a movable flat plate that is fastened to said movable magnet core and positioned to face said permanent magnet; and an iron cover that encloses said coil as a lateral leg and forms a path for the magnetic flux generated by said coil; and

a shaft that is connected to said movable magnet core to transmit driving force, which is derived from electromagnetic force generated by said electromagnet, to a switching device via a link mechanism;

wherein said permanent magnet and said movable flat plate have an oval external shape, wherein the short diameter sides of said permanent magnet and said movable flat plate are positioned in the direction of the depth of said switching device, wherein said iron cover is made of a cylinder having an oval external shape, and wherein the short diameter side of said cylinder is positioned in the direction of the depth of said switching device.
The solenoid operation device according to claim 30, wherein said iron cover is obtained by flattening part of a circular steel pipe until the steel pipe has an oval external shape.
The solenoid operation device according to claim 32, wherein the outside diameter in the direction of the short diameter of said iron cover is at least two-thirds the outside diameter of an original steel pipe.