EP3506330B1

EP3506330B1 - Electromagnetic operation mechanism drive circuit

Info

Publication number: EP3506330B1
Application number: EP16914221.3A
Authority: EP
Inventors: Yuto Kikuchi
Original assignee: Mitsubishi Electric Corp
Current assignee: Mitsubishi Electric Corp
Priority date: 2016-08-26
Filing date: 2016-08-26
Publication date: 2020-09-23
Anticipated expiration: 2036-08-26
Also published as: EP3506330A1; WO2018037547A1; CN109690718B; CN109690718A; EP3506330A4

Description

TECHNICAL FIELD

The present invention relates to an electromagnetic operation mechanism drive circuit having a protection circuit in, for example, electromagnetic operation mechanism drive circuits that perform opening/closing operation of electric power apparatuses.

BACKGROUND ART

In a known electromagnetic operation mechanism drive circuit that performs opening/closing operation of an electric power apparatus, for example, a vacuum valve of a vacuum circuit breaker, in the case of having two driving coils for contact closing and contact opening with respect to one movable core, when current is made to flow to one driving coil, voltage is generated by induced electromotive force at both ends of other driving coil to which current is not made to flow. The generated voltage is proportional to the ratio of winding turns of both driving coils; and thus, for example, when the number of winding turns of the driving coil for contact opening is 100 turns and the number of winding turns of the driving coil for contact closing is 500 turns, if a voltage of 100 v is applied to the driving coil for contact opening, a voltage of 500 v proportional to the ratio of winding turns is generated at both ends of the driving coil for contact closing. Accordingly, when the ratio of winding turns of both driving coils is large, there is some possibility that the voltage generated in the driving coil to which the current is not made to flow exceeds a breakdown voltage of a switch element for drive control and protective measures of the switch element for drive control are needed.
As the protective measures when a high voltage generated by the induced electromotive force at both ends of the driving coil for contact closing exceeds the breakdown voltage of the switch element for drive control in the electromagnetic operation mechanism drive circuit, for example, an electromagnetic operation mechanism drive circuit of Patent Document 1 includes: a drive circuit for contact closing in which a driving coil for contact closing is connected to a capacitor for contact closing, which serves as a direct current (DC) power source, via a driving switch element for contact closing, an overvoltage suppression unit on the contact closing side, in which a resistor and a switch element are connected in series, is connected in parallel to the driving coil for contact closing, and a protection switch element is provided between the driving coil for contact closing and the driving switch element for contact closing; a drive circuit for contact opening in which a driving coil for contact opening is connected to a capacitor for contact opening, which serves as a DC power source, via a driving switch element for contact opening and an overvoltage suppression unit on the contact opening side, in which a resistor and a switch element are connected in series, is connected in parallel to the driving coil for contact opening; and a voltage detection circuit which is provided in parallel to the driving switch element for contact closing and in series to the driving coil for contact closing. Then, the electromagnetic operation mechanism drive circuit is configured such that when the driving coil for contact opening is excited to generate induced electromotive force on the driving coil for contact closing side, the protection switch element is opened.
In contact closing operation, first, the protection switch element is closed. Next, the driving switch element for contact closing is closed and thus current flows from the capacitor for contact closing to the driving coil for contact closing. Just after the driving switch element for contact closing is closed, the switch element of the overvoltage suppression unit on the contact closing side is closed. After completion of the contact closing operation, the driving switch element for contact closing is opened. Voltage of the voltage detection circuit becomes a value near voltage of the capacitor for contact closing at the timing when the driving switch element for contact closing is opened. However, when the driving switch element for contact closing cannot be opened and is kept in a closed state, the voltage of the voltage detection circuit becomes a value near zero. When the voltage of the voltage detection circuit is near zero at the timing when the driving switch element for contact closing should be opened, a determination is made that the driving switch element for contact closing has a short circuit fault and the protection switch element is kept closed. Therefore, energy stored in the capacitor for contact closing is consumed until it becomes zero. The energy stored in the capacitor for contact closing becomes a value near zero; and thus, the current that flows through the driving coil for contact closing also becomes near zero and the protection switch element that does not have a capacity for interrupting current during driving can also interrupt.

RELATED ART DOCUMENT

PATENT DOCUMENT

Patent Document 1: JP-A-2013-109997
Another electromagnetic operation mechanism is disclosed in US 2012/292998 A1 .

SUMMARY OF THE INVENTION

PROBLEMS TO BE SOLVED BY THE INVENTION

In the known electromagnetic operation mechanism drive circuit, the voltage detection circuit determines a short circuit fault state of the driving switch element for contact closing and thus the protection switch element can control so as not to interrupt the current during driving. However, in the contact closing operation, there generates no difference in voltage detected by the voltage detection circuit between when the switch element of an overvoltage suppression circuit on the contact closing side has an open circuit fault and when it does not have the open circuit fault; and accordingly, the fault of the switch element of the overvoltage suppression circuit on the contact closing side cannot be detected. Thus, when the switch element of the overvoltage suppression circuit on the contact closing side has the open circuit fault, the protection switch element interrupts current in a state where an excessive voltage is applied and accordingly there is some possibility that a failure that damages the protection switch element or the like is generated. Accordingly, a problem exists in that it is necessary to detect in advance that the switch element of the overvoltage suppression circuit on the contact closing side has a fault and to protect by stopping interrupting operation of the protection switch element.
The present invention has been made to solve the above described problem, and an object of the present invention is to provide an electromagnetic operation mechanism drive circuit in which interrupting operation of a protection switch element is made to stop and contact closing operation can be safely terminated even when a switch element of an overvoltage suppression circuit on the contact closing side of the electromagnetic operation mechanism drive circuit that performs opening/closing operation of an electric power apparatus has an open circuit fault.

MEANS FOR SOLVING THE PROBLEMS

In order to solve the aforementioned problem, according to the present invention, there is provided an electromagnetic operation mechanism drive circuit that performs opening/closing operation of an electric power apparatus, the electromagnetic operation mechanism drive circuit including: a movable core coupled to the electric power apparatus that is made to perform opening/closing operation; a driving coil for contact closing and a driving coil for contact opening, which drive the movable core; a capacitor for contact closing which is connected to the driving coil for contact closing, and supplies electric power; a driving switch element for contact closing which controls the supply of electric power from the capacitor for contact closing to the driving coil for contact closing; a protection switch element which is provided between the driving switch element for contact closing and the driving coil for contact closing, and is opened when the driving coil for contact opening is excited to generate induced electromotive force in the driving coil for contact closing; an overvoltage suppression circuit on the contact closing side in which a loop circuit on the contact closing side, in which a current attenuation capacitor and a current attenuation resistor are connected in series and a discharge resistor is connected in parallel to these, is connected in series to a loop circuit switch element on the contact closing side; and a voltage detection circuit on the contact closing side in which the overvoltage suppression circuit on the contact closing side is connected in parallel to the driving switch element for contact closing, and which detects voltage of the loop circuit switch element on the contact closing side, wherein opening/closing states of the loop circuit switch element on the contact closing side and the driving switch element for contact closing are determined by the voltage detected by the voltage detection circuit on the contact closing side; and the protection switch element is not made to open when the loop circuit switch element on the contact closing side and the driving switch element for contact closing cannot be closed.

ADVANTAGEOUS EFFECT OF THE INVENTION

According to the electromagnetic operation mechanism drive circuit of the present invention, a configuration is made such that voltage applied to the switch element of the overvoltage suppression circuit on the contact closing side is detected; and therefore, an effect exists in that an open circuit fault of the switch element of the overvoltage suppression circuit on the contact closing side can be detected and interrupting operation of the protection switch element can be stopped even if the open circuit fault occurs in the switch element of the overvoltage suppression circuit on the contact closing side when the driving coil for contact opening is excited to generate induced electromotive force on the driving coil for contact closing side.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a circuit diagram showing the configuration of an electromagnetic operation mechanism drive circuit according to Embodiment 1;
FIG. 2 is a time chart for explaining contact closing operation in Embodiment 1;
FIG. 3 is a time chart for explaining contact opening operation in Embodiment 1;
FIG. 4 is a circuit diagram showing the configuration of an electromagnetic operation mechanism drive circuit according to Embodiment 2; and
FIG. 5 is a circuit diagram showing the configuration of an electromagnetic operation mechanism drive circuit according to Embodiment 3.

MODE FOR CARRYING OUT THE INVENTION

Details of an electromagnetic operation mechanism drive circuit according to embodiments of the present invention will be described with reference to FIG. 1 to FIG. 5. Here, the electromagnetic operation mechanism drive circuit performs opening/closing operation of, for example, a vacuum valve of a vacuum circuit breaker serving as an electric power apparatus; and a movable core is made to reciprocate and to perform opening/closing operation of opening/closing contacts of the vacuum valve coupled to the movable core by energizing driving coils for contact closing and contact opening, which are arranged on both sides of the movable core.

Embodiment 1.

FIG. 1 is a circuit diagram showing the configuration of an electromagnetic operation mechanism drive circuit according to Embodiment 1; FIG. 2 is a time chart for explaining contact closing operation; and FIG. 3 is a time chart for explaining contact opening operation.
First, by using FIG. 1, description will be made on the configuration of the electromagnetic operation mechanism drive circuit according to Embodiment 1, for example, the configuration of opening/closing a vacuum valve of a vacuum circuit breaker. The electromagnetic operation mechanism drive circuit includes: a movable core 1 that opens/closes opening/closing contacts of the vacuum valve; a driving coil for contact closing 2 which excites and drives (moves) the movable core 1; a capacitor for contact closing 4 which supplies electric power to the driving coil for contact closing 2; a driving switch element for contact closing 5 which controls the supply of electric power from the capacitor for contact closing 4 to the driving coil for contact closing 2; a protection relay 7 serving as a protection switch element which is provided between the driving switch element for contact closing 5 and the driving coil for contact closing 2; an overvoltage suppression circuit on the contact closing side in which a loop circuit on the contact closing side 10, in which a current attenuation capacitor 10a and a current attenuation resistor 10b are connected in series and a discharge resistor 10c is connected in parallel to these, is connected in series to a loop circuit switch element on the contact closing side 6; and a voltage detection circuit on the contact closing side 13 which detects voltage of the loop circuit switch element on the contact closing side 6. Then, the overvoltage suppression circuit on the contact closing side is connected in parallel to the driving switch element for contact closing 5. Furthermore, in order to protect current from flowing back, a diode 8 is provided between the driving coil for contact closing 2 and the protection relay 7 and a diode 9 is provided between the protection relay 7 and the loop circuit on the contact closing side 10.
Similarly, the electromagnetic operation mechanism drive circuit includes: a driving coil for contact opening 3 which excites and drives the movable core 1; a capacitor for contact opening 14 which supplies electric power to the driving coil for contact opening 3; a driving switch element for contact opening 15 which controls the supply of electric power from the capacitor for contact opening 14 to electric power to the driving coil for contact opening 3; and an overvoltage suppression circuit on the contact opening side in which a loop circuit on the contact opening side 20, in which a current attenuation capacitor 20a and a current attenuation resistor 20b are connected in series and a discharge resistor 20c is connected in parallel to these, is connected in series to a loop circuit switch element on the contact opening side 16. Then, the overvoltage suppression circuit on the contact opening side is connected in parallel to the driving switch element for contact opening 15. Furthermore, in order to protect current from flowing back, a diode 18 is provided between the driving coil for contact opening 3 and the driving switch element for contact opening 15 and a diode 19 is provided between the driving switch element for contact opening 15 and the loop circuit on the contact opening side 20.
Next, the operation of the electromagnetic operation mechanism drive circuit according to Embodiment 1 will be described.
First, operation in the case of closing operation will be described with reference to the electromagnetic operation mechanism drive circuit shown in FIG. 1 and the time chart of contact closing operation shown in FIG. 2. In the contact closing operation, first, the protection relay 7 is closed at Time t1. Next, the loop circuit switch element on the contact closing side 6 of the loop circuit on the contact closing side 10 is closed at Time t2 and the driving switch element for contact closing 5 which drives and controls the driving coil for contact closing 2 is further closed at Time t3; and thus, current flows through a path from the capacitor for contact closing 4 to the driving coil for contact closing 2, the diode 8, the protection relay 7, and the driving switch element for contact closing 5. The contact closing operation is executed by this series of operation. After the contact closing operation is completed, the driving switch element for contact closing 5 is opened at Time t4; and thus, energy stored in the driving coil for contact closing 2 passes through the diode 8, the diode 9, and the current attenuation resistor 10b and the energy is stored in the current attenuation capacitor 10a. Then, after the energy stored in the driving coil for contact closing 2 moves to the current attenuation capacitor 10a, the loop circuit switch element on the contact closing side 6 is opened at Time t5. With this operation, the energy stored in the current attenuation capacitor 10a is discharged by the loop circuit on the contact closing side 10 which is composed of the discharge resistor 10c and the current attenuation resistor 10b and the energy is gradually attenuated. The protection relay 7 is opened at Time t6 after completion of the discharge and thus the contact closing operation is completed.
Here, when the loop circuit switch element on the contact closing side 6 has an open circuit fault after the protection relay 7 is closed and before the loop circuit switch element on the contact closing side 6 is closed (before Time t2), voltage V detected by the voltage detection circuit on the contact closing side 13 becomes the same as voltage Vc of the capacitor for contact closing 4 and a change is not generated during a period of time after the loop circuit switch element on the contact closing side 6 is closed and until the driving switch element for contact closing 5 is closed (from Time t2 to t3), for the loop circuit switch element on the contact closing side 6 has the open circuit fault. However, when the loop circuit switch element on the contact closing side 6 does not have the open circuit fault, the loop circuit switch element on the contact closing side 6 is closed and thus the voltage V detected by the voltage detection circuit on the contact closing side 13 becomes nearly zero. More specifically, when the loop circuit switch element on the contact closing side 6 has the open circuit fault at the time of Time t3, the voltage V of the voltage detection circuit on the contact closing side 13 does not become zero, but it becomes the same as the voltage Vc of the capacitor for contact closing 4. This generates a difference in detected voltage V between the open circuit fault and normal operation of the loop circuit switch element on the contact closing side 6; and therefore, the presence or absence of the open circuit fault of the loop circuit switch element on the contact closing side 6 can be determined and the open circuit fault of the loop circuit switch element on the contact closing side 6 can be detected until the driving switch element for contact closing 5 is closed (until Time t4) .
Furthermore, when the driving switch element for contact closing 5 has a short circuit fault while the driving switch element for contact closing 5 is closed (a period of time from Time t3 to t4), the voltage V of the voltage detection circuit on the contact closing side 13 becomes nearly zero for a period of time after the loop circuit switch element on the contact closing side 6 is opened and until the protection relay 7 is opened (a period of time from Time t5 to t6). When the driving switch element for contact closing 5 does not have the short circuit fault, the voltage V of the voltage detection circuit on the contact closing side 13 becomes a value near the voltage Vc of the capacitor for contact closing 4. More specifically, when the driving switch element for contact closing 5 has the short circuit fault at the time of Time t5, the voltage V of the voltage detection circuit on the contact closing side 13 becomes nearly zero. This generates a difference in detected voltage V between the short circuit fault and normal time of the driving switch element for contact closing 5 and therefore a determination can be made that the driving switch element for contact closing 5 has the short circuit fault. Further, when the driving switch element for contact closing 5 has the short circuit fault, the protection relay 7 is kept in a closed state, whereby current that flows through the driving coil for contact closing 2 also becomes near zero and interruption can be performed can be performed by even the protection relay 7 that does not have a capacity for interrupting the current when the driving coil for contact closing 2 is driven.
Subsequently, operation in the case of contact opening operation will be described with reference to the drive circuit shown in FIG. 1 and the time chart of contact opening operation shown in FIG. 3. In the contact opening operation, first, the loop circuit switch element on the contact opening side 16 is closed at Time t7 and the driving switch element for contact opening 15 which drives and controls the driving coil for contact opening 3 is further closed at Time t8; and thus, current flows through a path from the capacitor for contact opening 14 to the driving coil for contact opening 3, the diode 18, and the driving switch element for contact opening 15. The contact opening operation is executed by this series of operation. After the contact opening operation is completed, the driving switch element for contact opening 15 is opened at Time t9; and thus, energy stored in the driving coil for contact opening 3 passes through the diode 18, the diode 19, and the current attenuation resistor 20b and the energy is stored in the current attenuation capacitor 20a. Then, after the energy stored in the driving coil for contact opening 3 moves to the current attenuation capacitor 20a, the loop circuit switch element on the contact opening side 16 is opened at Time t10. With this operation, the energy stored in the current attenuation capacitor 20a is discharged by the loop circuit on the contact opening side 20 which is composed of the discharge resistor 20c and the current attenuation resistor 20b and the energy is gradually attenuated. This completes the contact closing operation.
As described above, according to the electromagnetic operation mechanism drive circuit according to Embodiment 1, the voltage of the loop circuit switch element on the contact closing side of the overvoltage suppression circuit on the contact closing side is detected, whereby opening/closing states of the loop circuit switch element on the contact closing side and the driving switch element for contact closing are determined; and when the loop circuit switch element on the contact closing side has the open circuit fault or when the driving switch element for contact closing has the short circuit fault, the protection relay is kept in the closed state during the contact closing operation and a control is made so as not to interrupt the current. Therefore, an effect exists in that the protection relay is protected from a large current and the contact closing operation can be safely completed.

Embodiment 2.

FIG. 4 is a circuit diagram showing the configuration of an electromagnetic operation mechanism drive circuit according to Embodiment 2. A difference from the circuit diagram showing the configuration of the electromagnetic operation mechanism drive circuit according to Embodiment 1 shown in FIG. 1 is that a resistor 11 is provided in parallel to a series circuit of a protection relay 7 and a diode 8. Other configuration is the same as that of Embodiment 1 and therefore a description thereof will be omitted.
Next, the operation of the electromagnetic operation mechanism drive circuit according to Embodiment 2 will be described with reference to the drive circuit shown in FIG. 4.
Before contact closing operation is started, a connection is made through a path from a capacitor for contact closing 4 to a driving coil for contact closing 2, a resistor 11, a diode 9, a discharge resistor 10c, and a voltage detection circuit on the contact closing side 13; and voltage detected by the voltage detection circuit on the contact closing side 13 is determined by the driving coil for contact closing 2, the resistor 11, the diode 9, and the discharge resistor 10c. Here, when a driving switch element for contact closing 5 has a short circuit fault or a loop circuit switch element on the contact closing side 6 has a short circuit fault, the voltage detected by the voltage detection circuit on the contact closing side 13 becomes zero; and therefore the presence or absence of the short circuit fault of the driving switch element for contact closing 5 or the loop circuit switch element on the contact closing side 6 can be determined and the protection relay 7 can be protected before the start of the contact closing operation. Furthermore, when the driving switch element for contact closing 5 has an open circuit fault or the loop circuit switch element on the contact closing side 6 has an open circuit fault, the driving switch element for contact closing 5 and the loop circuit switch element on the contact closing side 6 are each made to close for a constant time before the start of the contact closing operation, whereby the voltage of the voltage detection circuit on the contact closing side 13 does not become zero, the presence or absence of the open circuit fault of the driving switch element for contact closing 5 or the loop circuit switch element on the contact closing side 6 can be determined, and the protection relay 7 can be protected before the start of the contact closing operation.
As described above, according to the electromagnetic operation mechanism drive circuit according to Embodiment 2, the resistor is provided in parallel to the protection relay, whereby the presence or absence of a fault of the driving switch element for contact closing or the loop circuit switch element on the contact closing side is determined before the start of the contact closing operation and thus an effect exists in that the protection relay can be protected.

Embodiment 3.

FIG. 5 is a circuit diagram showing the configuration of an electromagnetic operation mechanism drive circuit according to Embodiment 3. A difference from the circuit diagram showing the configuration of the electromagnetic operation mechanism drive circuit according to Embodiment 1 shown in FIG. 1 is that a voltage detection circuit on the contact opening side 23 is provided in parallel to a loop circuit switch element on the contact opening side 16 and a driving switch element voltage detection circuit for contact opening 24 is provided in parallel to a driving switch element for contact opening 15. Other configuration is the same as that of Embodiment 1 and therefore a description thereof will be omitted.
Next, the operation of the electromagnetic operation mechanism drive circuit according to Embodiment 3 will be described with reference to the drive circuit shown in FIG. 5 and the time chart of contact opening operation shown in FIG. 3.
Incidentally, normal operation in contact opening operation is described in Embodiment 1 and therefore a description thereof will be omitted.
Here, when the loop circuit switch element on the contact opening side 16 has an open circuit fault before the loop circuit switch element on the contact opening side 16 is closed (before Time t7), voltage V detected by the voltage detection circuit on the contact opening side 23 becomes the same as voltage Vo of the capacitor for contact opening 14 and a change is not generated during a period of time after the loop circuit switch element on the contact opening side 16 is closed and until the driving switch element for contact opening 15 is closed (from Time t7 to t8), for the loop circuit switch element on the contact opening side 16 has the open circuit fault. However, when the loop circuit switch element on the contact opening side 16 does not have the open circuit fault, the loop circuit switch element on the contact opening side 16 is closed and thus the voltage V detected by the voltage detection circuit on the contact opening side 23 becomes nearly zero. More specifically, when the loop circuit switch element on the contact opening side 16 has the open circuit fault at the time of Time t8, the voltage V of the voltage detection circuit on the contact opening side 23 does not become zero, but it becomes the same as the voltage Vo of the capacitor for contact opening 14. This generates a difference in detected voltage V between the open circuit fault and normal operation of the loop circuit switch element on the contact opening side 16; and therefore, the presence or absence of the open circuit fault of the loop circuit switch element on the contact opening side 16 can be determined and the open circuit fault of the loop circuit switch element on the contact opening side 16 can be detected until the driving switch element for contact opening 15 is closed (until Time t9) .
Furthermore, when the loop circuit switch element on the contact opening side 16 has a short circuit fault while the loop circuit switch element on the contact opening side 16 is closed (a period of time from Time t7 to t10), the voltage V of the voltage detection circuit on the contact opening side 23 becomes nearly zero even if the loop circuit switch element on the contact opening side 16 is opened (after Time t10); and therefore, a determination can be made that the loop circuit switch element on the contact opening side 16 has the short circuit fault.
Moreover, when the driving switch element for contact opening 15 has an open circuit fault before the driving switch element for contact opening 15 is closed (before Time t8), voltage V of the driving switch element voltage detection circuit for contact opening 24 does not become zero while the driving switch element for contact opening 15 is closed (a period of time from Time t8 to t9); and therefore, a determination can be made that the driving switch element for contact opening 15 has the open circuit fault.
Additionally, when the driving switch element for contact opening 15 has a short circuit fault while the driving switch element for contact opening 15 is closed (a period of time from Time t8 to t9), the voltage V of the driving switch element voltage detection circuit for contact opening 24 becomes nearly zero even if the driving switch element for contact opening 15 is opened (after Time t9) . This can determine that the driving switch element for contact opening 15 has the short circuit fault.
As described above, according to the electromagnetic operation mechanism drive circuit according to Embodiment 3, the voltage detection circuit on the contact opening side is provided in parallel to the loop circuit switch element on the contact opening side to detect voltage and the driving switch element voltage detection circuit for contact opening is provided in parallel to the driving switch element for contact opening to detect voltage, whereby an effect exists in that a fault of the driving switch element for contact opening or the loop circuit switch element on the contact opening side can be determined in the contact opening operation. Furthermore, in contact closing operation, an effect exists in that the same effect as that of Embodiment 1 can be obtained.
In addition, the present invention can freely combine the respective embodiments and appropriately modify and/or omit the respective embodiments, within the scope of the present invention.
Furthermore, the same reference numerals as those shown in the drawings represent identical or corresponding elements.

DESCRIPTION OF REFERENCE NUMERALS

1 Movable core, 2 Driving coil for contact closing, 3 Driving coil for contact opening, 4 Capacitor for contact closing, 5 Driving switch element for contact closing, 6 Loop circuit switch element on the contact closing side, 7 Protection relay, 8,9,18,19 Diode, 10 Loop circuit on the contact closing side, 10a Current attenuation capacitor, 10b Current attenuation resistor, 10c Discharge resistor, 11 Resistor, 13 Voltage detection circuit on the contact closing side, 14 Capacitor for contact opening, 15 Driving switch element for contact opening, 16 Loop circuit switch element on the contact opening side, 20 Loop circuit on the contact opening side, 20a Current attenuation capacitor, 20b Current attenuation resistor, 20c Discharge resistor, 23 Voltage detection circuit on the contact opening side, 24 Driving switch element voltage detection circuit for contact opening

Claims

An electromagnetic operation mechanism drive circuit that performs opening/closing operation of an electric power apparatus, the electromagnetic operation mechanism drive circuit comprising:
a movable core (1) coupled to the electric power apparatus that is made to perform opening/closing operation;

a driving coil for contact closing (2) and a driving coil for contact opening (3), which drive the movable core (1) ;

a capacitor for contact closing (4) which is connected to the driving coil for contact closing (2), and supplies electric power;

a driving switch element for contact closing (5) which controls the supply of electric power from the capacitor for contact closing (4) to the driving coil for contact closing (2);

a protection switch element (7) which is provided between the driving switch element for contact closing (5) and the driving coil for contact closing (2), and is opened when the driving coil for contact opening (3) is excited to generate induced electromotive force in the driving coil for contact closing (2);

an overvoltage suppression circuit on the contact closing side in which a loop circuit on the contact closing side (10), in which a current attenuation capacitor (10a) and a current attenuation resistor (10b) are connected in series and a discharge resistor (10c) is connected in parallel to these, is connected in series to a loop circuit switch element on the contact closing side (6); and

a voltage detection circuit on the contact closing side (13) in which the overvoltage suppression circuit on the contact closing side is connected in parallel to the driving switch element for contact closing (5), and which detects voltage of the loop circuit switch element on the contact closing side (6),

wherein opening/closing states of the loop circuit switch element on the contact closing side (6) and the driving switch element for contact closing (5) are determined by the voltage detected by the voltage detection circuit on the contact closing side (13); and

the protection switch element (7) is not made to open when the loop circuit switch element on the contact closing side (6) and the driving switch element for contact closing (5) cannot be closed.
The electromagnetic operation mechanism drive circuit according to claim 1,
further comprising a resistor (11) that is connected in parallel to the protection switch element (7).
The electromagnetic operation mechanism drive circuit according to claim 1 or claim 2,
further comprising: a capacitor for contact opening (14) which is connected to the driving coil for contact opening (3), and supplies electric power;

a driving switch element for contact opening (15) which controls the supply of electric power from the capacitor for contact opening (14) to the driving coil for contact opening (3);

an overvoltage suppression circuit on the contact opening side in which a loop circuit on the contact opening side (20), in which a current attenuation capacitor (20a) and a current attenuation resistor (20b) are connected in series and a discharge resistor (20c) is connected in parallel to these, is connected in series to a loop circuit switch element on the contact opening side (16); and

a voltage detection circuit on the contact opening side (23) in which the overvoltage suppression circuit on the contact opening side is connected in parallel to the driving switch element for contact opening (15), and which detects voltage of the loop circuit switch element on the contact opening side (16),

wherein an opening/closing state of the loop circuit switch element on the contact opening side (16) is determined by the voltage detected by the voltage detection circuit on the contact opening side (23).
The electromagnetic operation mechanism drive circuit according to claim 3,
further comprising a driving switch element voltage detection circuit (24) for contact opening which detects voltage of the driving switch element for contact opening (15), and

wherein an opening/closing state of the driving switch element for contact opening (15) is determined by the voltage detected by the driving switch element voltage detection circuit for contact opening (24).