JP2003031103A - Circuit breaker - Google Patents

Abstract

PROBLEM TO BE SOLVED: To automatically close the circuit breaker without employing separately an outside drive device or a power supply. SOLUTION: In the circuit breaker, when the shape memory alloy spring 5 is heated, the drive spring 7 is reversed by its shrinking shrinkage force and the energy of the compression spring 6 is accumulated and the moving contact 1 is cut off from the fixed contact 2, and when the shape memory alloy spring 5 is cooled, its shrinkage force becomes weak and releases the accumulated energy of the compression spring 6 and, thereby, the moving contact 1 is automatically contacted to the fixed contact 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a circuit breaker, and more particularly to a circuit breaker having a function of automatically turning on or off the circuit when it is cut off due to overcurrent.

[0002]

2. Description of the Related Art Conventionally, circuit breakers that have been interrupted by induced lightning or overcurrent are mainly manually re-closed. Although there are circuit breakers that have the function of automatically resetting, in these models, the circuit breaker uses an external drive device that is provided separately to reclose the circuit.

FIG. 7 shows a circuit breaker with an automatic closing function which uses a motor 502 as an external drive device as a conventional example. In this case, the power source 501 is connected to the motor 502 and the microcomputer 510. A current detector 509 is attached to the circuit breaker. The current detector 509
It is connected to the microcomputer 510, and the state of the load current is measured by the microcomputer 510.

When the circuit breaker is cut off due to overcurrent,
The microcomputer 510 compares the information on the current at the time of interruption and the preset condition to determine whether or not it is in a state in which it can be turned on again. When reclosing is possible, a control signal for driving the motor 502 is sent from the microcomputer 510.

Upon receiving the signal, the motor 502 rotates so as to drive the operating lever 9 of the circuit breaker in the OFF direction. The rotational movement of the motor shaft 503 is converted into a linear movement by the ball screw 504, and acts on the operation lever 9 via the lever 511. After the operation lever 9 is once set to the OFF position and the trip state is reset, the motor 502 is rotated in the opposite direction to move the operation lever 9 to the ON position, and the automatic re-closing is performed. As a technique of this kind, Japanese Patent Laid-Open No. 63-5
No. 1022 and Japanese Patent Laid-Open No. 2001-37067 can be cited.

[0006]

In the conventional circuit breaker with the automatic reclosing function, the motor 502 is provided separately from the circuit breaker.
It was necessary to provide an external drive device such as, and a large installation space was required. In addition, external drive device and microcomputer 5
It was necessary to separately prepare a power supply 501 for driving the device 10 and wire it.

SUMMARY OF THE INVENTION An object of the present invention is to provide a circuit breaker with an automatic re-closing function, which does not require an external drive unit or a power source to be separately prepared in view of the above problems.

[0008]

In order to achieve the above object, in the present invention, the movable contact is disconnected from the fixed contact by the contracting force that contracts when the breaking means is heated, and the energy of the charging means is accumulated. Then, as the breaking means cools and the contracting force becomes weaker, the accumulated energy of the making means is released and the movable contact is automatically made to the fixed contact.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION That is, according to the present invention, a fixed contact base provided with a fixed contact and a movable contact base provided with a movable contact, and the movable contact base is set to a closed position side so that the movable contact contacts the fixed contact. Detects the load current flowing through the movable contact and the fixed contact, the opening and closing mechanism that urges the movable contact block to the open position side where the movable contact does not contact the fixed contact, and the drive spring provided in the movable contact block. A current transformer, a resistance element for converting an output current value of the current transformer into a voltage value, a microcomputer for calculating the voltage value, and an external device for operating the opening / closing mechanism section by a control signal transmitted from the microcomputer. In a circuit breaker equipped with a power supply circuit for driving a microcomputer, the movable contact base is provided with a drive spring and a memory alloy spring which is a thermal expansion / contraction spring, and the thermal expansion / contraction spring is self-heated or by a separately provided heating element. Heated and stretchable Alternatively the heating element is connected to the power supply circuit, is heated by energizing the electric current, the energization of the thermal expansion and contraction spring or the heating element, the switching element is performed after disconnecting resistive element from the power supply circuit.

A concrete embodiment of the present invention will be described below with reference to FIGS. 1 to 5. 1 and 2 to 3 are cross-sectional views of one pole of a circuit breaker 1Z according to an embodiment of the present invention. FIG. 1 is a closed state, FIG. 2 is an open state when automatic reclosing is performed, FIG. 3 is a diagram showing an open circuit state due to the operation of the outer rod when automatic re-closing is not performed. FIG. 4 is a block circuit diagram of an electronic circuit. FIG. 5 shows a circuit breaker 1.
7 is an operation flowchart of Z.

In FIGS. 1, 2 and 3, the following components are arranged in the housing 14. Reference numeral 11 is a fixed contact base on the power source side, 2 is a fixed contact formed on the fixed contact base 11, 10 is a movable contact base, and 1 is a movable contact formed on the movable contact base 10. Reference numeral 7 is a drive spring, and one end 7B of the drive spring 7 is connected to and supported by the shape memory alloy spring 5. The other end 7A
Is attached between the insulating heat insulating plate 30 of the movable contact base 10 and the support base 14A provided on the housing 14.

The drive spring 7 is a snap spring, and when the drive spring 7 is curved and inverted so as to be convex toward the movable contact base 10, the movable contact 1 contacts the fixed contact 2 as shown in FIG. The torque is applied to apply pressure. On the contrary to the above, when the movable contact 1 is turned to the convex side toward the fixed contact 2 side while being curved toward the movable contact stand 10, the movable contact 1 is separated from the fixed contact 2 and cuts off as shown in FIG.

The compression spring 6 is attached to the central portion of the drive spring 7 in the vicinity of the apex of the convex shape, and applies a force that pushes up the drive spring 7 toward the movable contact base 10 so as to maintain the convex shape of the drive spring 7. There is. As for the compression spring 6, the drive spring 7 is the movable contact 1.
It acts as a closing means, that is, a closing spring, which is pressed during the reversal in the direction to accumulate energy, releases the accumulated energy, and makes the movable contact 1 into the fixed contact 2.

The shape memory alloy spring 5 is attached to the operating portion 7B of the drive spring 7. When the shape memory alloy spring 5 is heated, it contracts toward the fixed contact 2 with a stronger force than before heating. The contraction force reverses the drive spring 7 in the blocking direction, so that it functions as a blocking means, that is, a blocking spring. When it is cooled and the contracting force is weakened, it returns to the direction of the movable contact 1 and releases the accumulated energy of the compression spring 6.

Reference numeral 31 denotes an insulating heat insulating plate which prevents heat generated in the movable contact base 10, the conductor 13 and the fixed contact base 12 due to the load current from being directly transmitted to the shape memory alloy spring 5. Reference numeral 18 denotes a support portion of the movable contact base 10, which serves as a fulcrum when the movable contact base 10 is opened and closed.

A flexible conductor 13 connected to a part of the movable contact base 10 is connected to the load side fixed contact base 12, that is, a conductor. The current transformer 3 is installed on the load-side fixed contact stand 12. The secondary side of the current transformer 3 is connected to the electronic circuit 300 and detects the load current. When the shape memory alloy spring 5 is a self-heating element, the current from the electronic circuit 300 is
The shape memory alloy spring 5 is heated by flowing the wire 15 and the shape memory alloy spring 5.

The trip device 8 is attached to the electronic circuit 300. When the trip device 8 excites the electromagnet, the operation rod 8A is driven to push the trip rod 400B. 400A is a main mechanism portion, and 400C is a transmission rod that transmits an operating force.
By operating the operation lever 9, the circuit breaker 1Z can be opened and closed. Each of the above-described components is the housing 14
It is housed inside.

Next, the automatic re-closing (automatic closing) operation of the circuit breaker 1Z will be described with reference to FIGS.

When the circuit breaker 1Z is in the closed position shown in FIG. 1, the drive spring 7 is curved so as to be convex toward the movable contact base 10 side, and the torque for pressing the movable contact 1 against the fixed contact 2 is provided. And the movable contact 1 is turned on to the fixed contact 2. At this time, the shape memory alloy spring 5 attached to the operation portion 7B of the drive spring 7 exerts almost no force on the drive spring 7 as compared with the force of the compression spring 6.

When an overcurrent flows through the circuit breaker 1Z and a current is applied to the shape memory alloy spring 5 through the wiring 15 from the electronic circuit 300 measuring the load current, the shape heated by the self-heating action is generated. The memory alloy spring 5 contracts. By this contracting force, the drive spring 7 is reversed in the direction opposite to the fixed contact 2 side as shown in FIG.

Since the drive spring 7 is formed of a snap spring, when the operating portion 7B is pulled to the side opposite to the movable contact base 10 side with a sufficiently strong force, it becomes convex toward the movable contact base 10 side at the closed position. The drive spring 7 which has been curved so as to have a convex shape is inverted to a concave shape, and becomes a concave shape on the movable contact base 10 side. When the drive spring 7 has a concave shape toward the movable contact base 10, the movable contact 1 is separated from the fixed contact 2 and cut off, and the movable contact base 10 is biased toward the open position. That is, the shape memory alloy spring 5 functions as a blocking spring. The compression spring 6 is pressed by the drive spring 7 while the drive spring 7 is being reversed, and stores energy.

The torque applied to the movable contact base 10 by the drive spring 7 is the reversal of the bending direction.
The movable contact 1 to the fixed contact 2 from the torque in the direction of pressing
Reverse the torque in the direction of pulling away from. Due to the reversed torque of the drive spring 7 and the link mechanism (not shown) of the main mechanism portion 400a, the position of the operation lever 9 is changed from the ON position to the T position.
Move to the rip position. At this time, the trip device 8 is not driven and the transmission rod 400c does not move.

FIG. 2 is a diagram showing an open circuit state when automatic re-closing is performed. As shown in the figure, in the open position, the drive spring 7 has a concave shape on the movable contact base 10 side, and torque is applied to the movable contact 1 from the fixed contact 2 in the outward direction. Therefore, the latch mechanism, which is required in the conventional operation mechanism, for holding the movable contact base 10 at the open position is not required, and thus the configuration of the main operating device can be simplified. At this time, the compression spring 6 is compressed by the drive spring 7 and stores energy.

When the load current is cut off, the electronic circuit 300
From the current to the shape memory alloy spring 5,
The shape memory alloy spring 5 is no longer heated, and the temperature gradually decreases. When the temperature of the shape memory alloy spring 5 decreases, the force with which the shape memory alloy spring 5 pulls the drive spring 7 in the direction opposite to the movable contact base 10 side decreases.

The tensile force of the drive spring 7 is reduced, and the compression spring 6
When the compression spring force stored in is stronger, the compression spring 6
The stored energy is released, and the drive spring 7 presses the movable contact 1 toward the fixed contact 2.

When a force is applied to the drive spring 7 by the compression spring 6 in the direction of the movable contact table 10, the drive spring 7, which is concave toward the movable contact table 10 at the open position, protrudes in the direction of the movable contact table 10. Invert in the direction of the curve so that it becomes a shape. When the drive spring 7 has a convex shape toward the movable contact stand 10, the torque acts again in the direction in which the movable contact 1 is pressed by the fixed contact 2.

At this time, the supporting portion 18 is connected to the movable contact base 10 by
Works so as to smoothly move in a convex shape toward the movable contact base 10. In this way, by cooling the shape memory alloy spring 5, the movable contact 1 is closed to the fixed contact 2 again, and the closed position is automatically restored.

As described above, according to the circuit breaker 1Z of the present invention, since the circuit breaker 1Z is automatically reclosed (automatically closed) by the reversing action of the drive spring 7, an external drive device is not required and the installation area is reduced. It is possible to save space and improve workability by omitting wiring work between the power supply and the driving device.

Further, in addition to heating the shape memory alloy spring 5 by directly supplying an electric current thereto, as shown in FIG. 6, a heating element 50 may be installed near the shape memory alloy spring 5 to indirectly heat the shape memory alloy spring 5. Good. In this case, the heating element 50 is connected to the electronic circuit 300 via the wiring 15, and the electric current to flow is controlled by the electronic circuit 300.

FIG. 3 is a diagram showing an open circuit state by the operation of the pulling rod 400B when the automatic reclosing is not performed. When the automatic reclosing is not performed, the trip rod 400B is driven by the operation rod 8A of the trip device 8 of the electronic circuit 300, and the transmission rod 400C of the main mechanism portion 400A is connected to the movable contact base 1.
By moving in the opposite direction to the 0 side, a force in the opposite direction to the movable contact base 10 side is applied to the convex apex portion of the drive spring 7.

By the force from the transmission rod 400C, the drive spring 7 is reversed from the convex curve toward the movable contact base 10 side to the concave curve by the snap spring action, and the movable contact base 10 is opened. It becomes a state. At this time, the operation lever 9 is moved to the Trip position by the main mechanism section 400A.

When a short-circuit current flows, an instantaneous operating mechanism (not shown) operates to directly drive the transmission rod 400C,
The main mechanism portion 400A moves the transmission rod 400C in the direction opposite to the movable contact 1 side, and reverses the curvature of the drive spring 7 from the convex shape toward the movable contact 1 side to the concave shape, and moves the movable contact 1 to the open position. To do.

The operation of the aforementioned electronic circuit 300 will be described with reference to FIG. FIG. 4 is a block circuit diagram of the electronic circuit 300.

As shown in FIG. 4, the power supply side terminal 16 and the load side terminal 17 are connected to the power supply side conductor 16 and the load side conductor 17 which are composed of three phases. Power supply side terminals 16a, 16b,
16c and the load side terminals 17a, 17b, 17c between the fixed contact 2 (2a, 2b, 2c) and the movable contact 1 (1a, 1
b, 1c) are respectively connected, and when the movable contact 1 contacts the fixed contact 2, a load current flows. Current transformer 3 (3
a, 3b, 3c) converts the load current into a few thousandths and sends it to the electronic circuit 300. In the initial state, the switching element 206 is ON and the switching element 207 is OFF.
It has become.

The load current converted by the secondary side of the current transformer 3 is a full-wave rectifier 4a composed of a rectifying diode,
The resistor element 202 (202a, 202a, 4b, 4c)
b, 202c). In order to obtain the magnitude of the load current, the voltage across the resistance element 202, which is set to a predetermined level by the power supply circuit 200 including transistors, Zener diodes, etc., is measured.

The voltage across the resistor element 202 passes through the signal amplification section 203 (203a, 203b, 203c), the noise absorption section 204 (204a, 204b, 204c), the over-input protection section 205 (205a, 205b, 205c).
It is input to the A / D converter 100D in the microcomputer 100. The signal input to the A / D converter 100D is converted into a digital signal, and a central processing unit (hereinafter referred to as CP
The effective value is calculated at 100 A (denoted by U).

The result of the calculation is compared with the set current value of the characteristic setting section 302 input through the I / O port 100C3 in the CPU 100A. In the CPU 100A, when the calculated value is an overcurrent that is equal to or greater than the set current value, the preset maximum automatic reloading number is compared with the automatic reloading number stored in the memory 100B to perform automatic reloading. Determine whether to do.

The power supply circuit 200 serves as a power supply for the operational amplifier and the microcomputer 100 which constitute the signal amplification section 203 and the like. As the memory 100B, a memory such as a flash memory in which data is not lost even if power is not supplied is used.

When the CPU 100A determines that automatic reclosing is possible, the switching element 206 is turned off and the switching element 207 is turned on via the I / O port 100C2. Switching element 20
When 6 is turned off, all the current flowing through the resistance element 202 can be commutated to the shape memory alloy spring 5 (5a, 5b, 5c).

Shape memory alloy springs 5a, 5b, 5 for three phases
c is connected in series, and the shape memory alloy springs 5a, 5 of each phase are connected.
b and 5c are heated at the same time. By simultaneously heating the shape memory alloy springs 5 of the respective phases, the movable contacts 1a, 1b, 1c can be simultaneously opened.

When the CPU 100A determines that the automatic reclosing is not performed, the trigger signal is generated in the trigger unit 201 through the I / O port 100C1 and the trip device 8 is operated.
To drive the transmission rod 400c to move the movable contact 1 (1
a, 1b, 1c) to the open position.

Next, the operation of the circuit breaker 1Z will be described with reference to FIG. FIG. 5 is an operation flowchart of the circuit breaker 1Z.

In step S1, the circuit breaker is manually turned on. In step S2, the load current is applied to the current transformer 3, and in step S3, the power supply circuit 200 turns off.
N In step S4, the number of automatic reloading is set to n = 0.
In step S5, the CPU 10 in the microcomputer 100
The rated current Ir, the operating time ts, and the maximum number of times of automatic re-entry nm are set to 0A. If the maximum number of automatic re-entry times nm is set to zero, it is possible to do without re-entry.

In step S6, a current flows through the power supply circuit 200, the rectifying circuit 4, and the resistance element 202. Step S7
At, the conduction current I of the resistance element 202 is converted into a voltage value. In step S8, the voltage value is A / D converted by the A / D converter 100D. In step S9, the CPU 10
At 0 A, the energizing current I and the rated current Ir are compared. If the energizing current I> the rated current Ir, the process proceeds to step S10.

In step S10, the overcurrent conduction time t
Is compared with the operation time ts, and if the overcurrent energization time t ≧ the operation time ts, the process proceeds to step S11. Step S
In 11, the automatic re-feeding number n is compared with the maximum automatic re-feeding number nm. If the automatic re-feeding number n ≦ the maximum automatic re-feeding number nm, the process proceeds to step S12.

In step S12, the number n of automatic re-inputs is incremented by 1. In step S13, the switching element 20
6 is turned off, and the switching element 20 is turned on in step S14.
Turn on 7. In step S15, a current is applied to the shape memory alloy spring 5 to heat it.

In step S16, the shape memory alloy spring 5 contracts, and in step S17, the movable contact 1 becomes the open position. When the shape memory alloy spring 5 is cooled in step S18, the movable contact 1 is reclosed in step S19 to reach the closed position, and the energization starts again, and the process returns to step S6.

At step S11, the number of automatic re-inputs n>
If the maximum number of times of automatic re-entry is nm, step S
Go to 20. In step S20, the CPU 100A outputs a signal to the trigger unit 201 and causes the trigger unit 201 to transmit a trigger signal.

In step S21, the trip device 8 is operated by the trigger signal. When the drive rod 400C is driven in step S22, the movable contact 1 is in the open position in step S23. After that, the movable contact 1 is not reclosed.

In step S9, energizing current I ≦ rated current Ir
In the case of and in step S10, if the overcurrent energization time t <the operation time ts, the process returns to step S6 to continue detecting the load current.

As described above, according to the embodiment of the present invention, the shape memory alloy spring, which is a thermal expansion / contraction spring, is arranged in the drive spring, and the shape memory alloy spring is connected to the power supply circuit of the electronic circuit. The circuit breaker can be automatically re-closed by using, and a separate power supply is not required for the automatic re-closing. Further, since the contraction of the shape memory alloy spring due to cooling is utilized, the safety is enhanced because the shape memory alloy spring is re-closed after the ambient temperature of the housing or the like is sufficiently lowered.

[0052]

As explained above, according to the circuit breaker of the present invention, an external drive device is not required for automatic reclosing or automatic closing of the circuit breaker, and the installation area can be saved. Workability can be improved by omitting wiring work between the power supply and the drive device.

By holding the movable contact at the open position by the drive spring, the structure of the main operating device can be simplified.

[Brief description of drawings]

FIG. 1 is a diagram showing a closed position of a circuit breaker according to an embodiment of the present invention.

FIG. 2 is a diagram of an open state when automatic reclosing of the circuit breaker according to the embodiment of the present invention is performed.

FIG. 3 is a diagram of an open circuit state when automatic reclosing of the circuit breaker according to the embodiment of the present invention is not performed.

FIG. 4 is a block circuit diagram of an electronic circuit in the circuit breaker of FIG.

5 is an operation flowchart of the circuit breaker of FIG.

FIG. 6 is a diagram showing a mode of indirectly heating a heat expansion / contraction spring in the present invention.

FIG. 7 is a diagram showing a conventional circuit breaker with an automatic closing function using a motor.

[Explanation of Codes] 1 ... Movable contact, 2 ... Fixed contact, 3 ... Current transformer, 4 ... Rectifier, 5 ... Shape memory alloy spring, 6 ... Compression spring, 7 ... Drive spring, 8 ... Trigger device, 9 ... Operation lever, 10 ... Movable contact stand, 11 ... Power source side fixed contact stand, 12 ... Load side fixed contact stand, 13 ... Conductor, 14 ... Case, 15 ... Wiring, 16 ... Power source side terminal, 17 ... Load side Terminal, 18 ... Supporting part, 30, 3
1 ... Insulating plate, 50 ... Heating element, 400A ... Link part, 40
0B ... external rod, 400C ... transmission rod, 300 ... electronic circuit,
200 ... Power supply circuit, 201 ... Trigger part, 100 ... Microcomputer, 100C1, 100C2, 100C3, 100C4
... I / O port, 100A ... CPU, 100B ... Memory, 100D ... A / D conversion, 302 ... Characteristic setting section, 20
6, 207 ... Switching element, 202 ... Resistor element, 2
03 ... Signal amplifying section, 204 ... Noise absorbing section, 205 ... Over-input protection section, 502 ... Motor, 501 ... Power supply, 503 ...
Motor shaft, 504 ... Ball screw, 509 ... Current detector,
510 ... Microcomputer, 511 ... Lever.

Claims (8)

[Claims] 1. In a circuit breaker for making or breaking a movable contact with a fixed contact, a contracting force of a breaking means that contracts when heated causes a drive spring to be reversed to cut the movable contact from the fixed contact, and at the same time, a closing means. Accumulates the energy of
A circuit breaker characterized in that as the breaking means cools and the contracting force becomes weaker, the accumulated energy of the making means is released and the movable contact is automatically made to the fixed contact. 2. A current transformer for detecting a load current of the movable contact is connected to an electronic circuit, and a current from the electronic circuit is supplied to the breaking means to heat the breaking means. The circuit breaker according to 1. 3. A microcomputer for detecting a load current of the movable contact by a current transformer, and selecting the drive of the interrupting means or the transmission rod of the main operating portion by the detected current. The circuit breaker according to Item 1. 4. The circuit breaker according to claim 1, wherein a power supply circuit and the breaking means are connected to a secondary side of a current transformer that detects a load current of the movable contact. 5. A power supply circuit, the breaking means and a resistor are connected to a secondary side of a current transformer that detects a load current of the movable contact, and the breaking means is provided between the power supply circuit and the breaking means and the resistor. The circuit breaker according to claim 1, further comprising a switching element that switches to a resistor. 6. The circuit breaker according to claim 1, wherein a memory alloy spring is used as the breaking means, and the memory alloy spring is a self-heating element. 7. The memory alloy spring is used as the breaking means, and a heating element for heating the memory alloy spring is arranged in the vicinity of the memory alloy spring. The circuit breaker described in. 8. A fixed contact base having fixed contacts and a movable contact base having movable contacts, and urging the movable contact base toward the closed position so that the movable contacts come into contact with the fixed contacts. An opening / closing mechanism for urging the movable contact base toward the open position where the movable contact does not contact the fixed contact, a drive spring provided on the movable contact base, and a load current flowing through the movable contact and the fixed contact are detected. A current transformer, a resistance element for converting an output current value of the current transformer into a voltage value, a microcomputer for calculating a voltage value, and an external device for operating an opening / closing mechanism section by a control signal transmitted from the microcomputer. A device and a circuit breaker having a power supply circuit for driving the microcomputer, comprising a drive spring provided on a movable contact base and a memory alloy spring which is a heat expansion / contraction spring, and the heat expansion / contraction spring is self-heated or separately provided. Heating element The heat expansion / contraction spring or the heating element is connected to a power supply circuit, and is heated by supplying an electric current. A circuit breaker characterized in that it is carried out after disconnecting from.