JP2010257658A - Electronic circuit breaker - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electronic circuit breaker which can make a circuit-breaking control circuit suitably continue its control after its circuit-breaking operation without taking any countermeasure such as enlargement of capacity of a power source capacitor and can stop the supply of a power source to the circuit-breaking control circuit after a lapse of a fixed period with cooling-off time of an electric circuit taken into account. <P>SOLUTION: A power source circuit 6 is arranged at a first side of a primary contact 4, a microswitch 11 and a relay contact 12 are arranged in parallel between electric circuits 3, the microswitch 11 performs opening and closing operations together with opening and closing operations of the primary contact 4, and the relay contact 12 performs an opening operation by controlling the circuit-breaking control circuit 5. The circuit-breaking control circuit 5 waits for a lapse of a fixed period for cooling the electric circuit 3 when a circuit-breaking operation is carried out in response to overcurrent of the electric circuit 3, and stops the supply of a power source to the circuit-breaking control circuit 5 by opening the relay contact 12. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a circuit breaker that protects an electric circuit, and more particularly to an electronic circuit breaker that measures an electric circuit current and interrupts the electric circuit when the current value satisfies a predetermined condition.

Circuit breakers include electronically controlled circuit breakers that do not use an overcurrent detection element such as a bimetal, but detect an overcurrent by electronic circuit control by reading the circuit current and perform a break operation. This electronic circuit breaker includes a main contact for breaking / connecting an electric circuit, a breaker mechanism for opening the contact, and a breaker control circuit for operating the breaker mechanism when a current that satisfies a predetermined condition flows in the circuit A power supply circuit for supplying power to the shutoff control circuit is incorporated.
Such an electronic circuit breaker is configured to stop the power supply to the break control circuit when the break mechanism is activated and the main contact is opened. For this reason, measures such as increasing the capacity of a capacitor for storing electric power have been taken, and the shut-off control circuit operates for a while after the shut-off operation, and has been devised so that necessary information is retained (for example, patent documents) 1).

JP 2008-29106 A

  However, measures for increasing the capacity of the capacitor are limited in a limited space of the circuit breaker, and it is difficult to use a capacitor having a sufficient capacity. In particular, when the circuit is interrupted by an overcurrent such as an overload, the electric circuit is in a heated state, so at least several tens of minutes are required until the electric circuit is cooled. For this reason, it is desirable to keep the shutoff control circuit in an active state during that time and to perform control taking temperature into account, but the control operation of the shutoff control circuit cannot be continued for such a long time.

In addition, since such an electronic circuit breaker has such a problem because the power circuit is connected to the secondary side of the main contact, the main contact that is not affected by the power-off operation as a countermeasure. The structure taken from the primary side can be considered. However, when the power is taken from the primary side of the main contact, the power supply circuit and the cutoff control circuit are always energized even if the electric circuit is cut off or the operation handle is turned off.
When this happens, when operating the circuit breaker for maintenance, testing, etc., it must be stopped until the primary side is energized. This is cumbersome and not desirable. Moreover, it goes backward from the viewpoint of energy saving, and the primary and secondary responsible disassembly points of the electric circuit during the interruption operation are unclear, which is not preferable.

  Therefore, in view of such problems, the present invention allows the interruption control circuit to continue to control well after the interruption operation without taking measures such as increasing the capacity of the power supply capacitor, and to take into consideration the cooling period of the electric circuit. An object of the present invention is to provide an electronic circuit breaker that stops the power supply to the shut-off control circuit after a certain time has elapsed.

In order to solve the above problems, the invention of claim 1 is directed to a main contact for opening and closing an electric circuit, a shut-off mechanism for opening the main contact, and an overcurrent that satisfies a predetermined condition flows in the electric circuit. An electronic circuit breaker having a shutoff control circuit for shutting down the shutoff mechanism, a power supply circuit for supplying power to the shutoff control circuit, and an operation handle for opening and closing the main contact, The power supply circuit includes first and second switch means connected in parallel, and is connected to the primary side of the main contact via a disconnectable power supply line, and the first switch means opens and closes the main contact. While the opening and closing operation is interlocked with the operation, the second switch means is opened by the control of the cutoff control circuit, and when the cutoff control circuit performs a cutoff operation due to the overcurrent, the cutoff operation is performed and then the electric circuit is opened. For cooling Characterized by opening operation of the second switch means after waiting for the constant time.
According to this configuration, since power is supplied to the cutoff control circuit from the primary side of the electric circuit, it is possible to continue the function of the cutoff control circuit even after the cutoff operation. Therefore, control by the shutoff control circuit can be continued even after shutting down without taking measures such as increasing the capacitor capacity of the power supply circuit, and the temperature of the electric circuit can be adjusted based on current information at shutoff and the elapsed time of shutoff. By analogy, appropriate shut-off control is possible.
In addition, the supply of power is stopped after a certain period of time has elapsed since the main contact was opened, so that even if the shut-off operation is performed, the shut-off control circuit does not continue to be charged forever, and wasteful power is consumed. Nor.

According to a second aspect of the present invention, in the configuration according to the first aspect, the second switch means performs a closing operation in response to a setup completion signal output when the shut-off control circuit is activated.
According to this configuration, even if the second switch means is in the open state, the closing operation is performed by turning on the operation handle. Control can continue.

According to a third aspect of the present invention, in the configuration according to the first or second aspect of the present invention, the apparatus has a display unit that displays a case where the blocking mechanism section performs a blocking operation and the second switch means is in a closed state. And
According to this configuration, since the control operation state of the circuit breaker that has performed the breaking operation can be recognized at a glance, it is easy to grasp the state of the circuit breaker.

According to the present invention, since the power is supplied to the cutoff control circuit from the primary side of the electric circuit, the function of the cutoff control circuit can be continued even after the cutoff operation. Therefore, control by the shutoff control circuit can be continued even after shutting down without taking measures such as increasing the capacitor capacity of the power supply circuit, and the temperature of the electric circuit can be adjusted based on current information at shutoff and the elapsed time of shutoff. By analogy, appropriate shut-off control is possible.
In addition, the supply of power is stopped after a certain period of time has elapsed since the main contact was opened, so that even if the shut-off operation is performed, the shut-off control circuit does not continue to be charged forever, and wasteful power is consumed. Nor.

It is a circuit block diagram showing an example of an electronic circuit breaker according to the present invention.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, embodiments of the invention will be described in detail with reference to the drawings. FIG. 1 is a circuit block diagram showing an example of an electronic circuit breaker according to the present invention, wherein 1 is a primary side terminal which is a power source side, 2 is a secondary side terminal which is a load side, 3 is an electric circuit, and 4 is an electric circuit Main contact 5 for opening and closing 3, 5 is a cut-off control circuit for outputting a cut-off signal in accordance with the state of the electric circuit current, 6 is a power supply circuit for supplying power to the cut-off control circuit 5, and 7 is an electric circuit for opening the main contact 4. A trip coil for carrying out the breaking operation 3, and a display unit 8 comprising LEDs for displaying the state of the breaker after the breaking operation. The trip coil 7 operates a shut-off mechanism (not shown) by the trip operation to open the main contact 4.
The main contact 4 is opened and closed by opening and closing an operation handle (not shown). In addition, the electric circuit 3 is an electric circuit composed of three wires, for example, a single-phase three-wire type or a three-phase electric circuit, but may be a two-wire type electric circuit.

The power supply circuit 6 is connected to the primary circuit 3 of the main contact 4 via a power supply line 10. A microswitch 11 serving as a first switch means and a second switch means are provided in the middle of the power supply line 10. A relay contact 12 is provided in parallel.
The microswitch 11 is configured to open and close in conjunction with the opening and closing operation of the main contact 4, and opens and closes by operating the operating handle. On the other hand, the relay provided with the relay contact 12 has the relay coil 13 connected to the cutoff control circuit 5 via the relay drive circuit 14 and is opened and closed under the control of the cutoff control circuit 5.

  The interruption control circuit 5 includes a port 20 for outputting various control signals, a timer 21 for counting a predetermined time, an A / D conversion unit 22 for A / D converting current information of the electric circuit 3 detected by the current transformer 16, and various information. Are stored in the storage unit 23, an arithmetic control unit 24 including a CPU, and the like.

  A trip coil drive circuit 17 for driving the trip coil 7, a relay drive circuit 18 for opening / closing the relay contact 12, and a display unit drive circuit 19 for causing the display unit 8 to blink are connected to the port 20. Control signals are individually output from 24. The storage unit 23 stores current map information that associates a current value and time for determining the interruption in addition to the interruption information including the control program, current information at the time of interruption, time information, and the like.

  The electronic circuit breaker configured as described above operates as follows. In a steady state where the main contact 4 is in a closed state and power is supplied to a load (not shown) connected to the secondary terminal 2, the circuit current detected by the current transformer 16 is A / D conversion unit 22. And A / D converted and sent to the arithmetic control unit 24. The arithmetic control unit 24 constantly monitors the circuit current, and outputs a cut-off signal when the relationship between the current and time satisfies the condition based on the current map information stored in the storage unit 23. For example, a shut-off condition that shuts off when a current of 125% of the rated current flows for 60 minutes is stored, and if such a condition is satisfied, it is determined that an overcurrent has occurred and a shut-off signal is output.

  This cutoff signal is output as a trip coil drive signal from the port 20, and the trip coil drive circuit 17 supplies a drive current to the trip coil 7. Thus, the trip coil 7 trips and the main contact 4 opens. That is, the circuit breaker performs a breaking operation. In response to the opening operation of the main contact 4, the microswitch 11 is also opened. However, the relay does not operate, and the relay contact 12 remains closed.

  The arithmetic control unit 24 that has output the shut-off signal also starts the timer 21 to start counting for a predetermined time, and activates the display unit driving circuit 19 to start blinking the display unit 8. The timer 21 counts a predetermined time, for example, 60 minutes until the load electric circuit connected to the secondary side terminal 2 is cooled by energization of the overcurrent.

When the timer 21 counts up after a predetermined time has elapsed, the arithmetic control unit 24 outputs a count up signal. This count-up signal is sent as an off signal from the port 20 to the relay drive circuit 14 and is output to the display unit drive circuit 19 as a stop signal.
As a result, the relay contact 12 is opened, the connection between the electric circuit 3 and the power supply circuit 6 is cut, and the supply of power to the interruption control circuit 5 is stopped. Further, the display unit 8 stops blinking.

  Thus, in the electronic circuit breaker in which the electric circuit 3 is interrupted and the interruption control circuit 5 is stopped, the main contact 4 is closed and the electric circuit 3 is reconnected if the operation handle is turned on (closing operation). . Further, the micro switch 11 is also closed, and the shutoff control circuit 5 starts a setup operation. The setup is completed by the closing operation of the microswitch 11, and the shut-off control circuit 5 that has started up outputs a closing signal to the relay driving circuit 14 via the port 20, and the relay contact 12 is also closed. That is, the relay contact 12 is also closed immediately after the operation handle is turned on, and the electronic circuit breaker returns to a steady state where the circuit current is monitored.

  If the operating handle is turned on before the timer 21 counts up, the main contact 4 is closed and the electric circuit is energized in this case as well. However, since the interruption control circuit 5 during the timer count continues the control operation, the arithmetic control unit 24 takes into consideration the electric current value at the time of interruption, the elapsed time of interruption, and the electric current value after turning on. , Outputs a cut-off signal.

Thus, since power is supplied to the cutoff control circuit from the primary side of the electric circuit, the function of the cutoff control circuit can be continued even after the cutoff operation. Therefore, control by the shutoff control circuit can be continued even after shutting down without taking measures such as increasing the capacitor capacity of the power supply circuit, and the temperature of the electric circuit can be adjusted based on current information at shutoff and the elapsed time of shutoff. By analogy, appropriate shut-off control is possible.
In addition, the supply of power is stopped after a certain period of time has elapsed since the main contact was opened, so that even if the shut-off operation is performed, the shut-off control circuit does not continue to be charged forever, and wasteful power is consumed. In addition, the primary and secondary responsibility resolution points will not be unclear.
Further, even when the relay contact 12 is in an open state, the circuit breaker is closed by turning on the power, so that even if a breaking operation due to an overcurrent or the like occurs immediately thereafter, the breaking control circuit 5 continues good control. In addition, since the display unit 8 can recognize at a glance the control operation state of the circuit breaker that has been interrupted, it is easy to grasp the state of the circuit breaker.

  In the above-described embodiment, the count-up time of the timer 21 is 60 minutes, but this time is arbitrary and can be changed depending on the characteristics of the electric wires reaching the load.

  3 .... Electric circuit, 4 .... Main contact, 5 .... Shut-off control circuit, 6 .... Power supply circuit, 8 .... Display section, 11 .... Micro switch (first switch means), 12 .... Relay contact (No. 1) 2 switch means), 21..Timer.

Claims (3)

A main contact for opening and closing an electric circuit; an interrupting mechanism for opening the main contact; an interrupt control circuit for operating the interrupting mechanism when an overcurrent that satisfies a predetermined condition flows in the electric circuit; and the interrupt An electronic circuit breaker having a power supply circuit for supplying power to the control circuit, and an operation handle for opening and closing the main contact,
The power supply circuit is connected to the primary side of the main contact through a power line that can be disconnected with first and second switch means connected in parallel,
The first switch means opens and closes in conjunction with the opening and closing operation of the main contact, while the second switch means opens by the control of the cutoff control circuit,
The shut-off control circuit is configured to open the second switch means after waiting for a predetermined time for cooling the electric circuit after the shut-off operation when the shut-off operation is performed due to the overcurrent. Circuit breaker. 2. The electronic circuit breaker according to claim 1, wherein the second switch means closes in response to a setup completion signal output when the shut-off control circuit is activated. 3. The electronic circuit breaker according to claim 1, further comprising a display unit configured to display a case where the blocking mechanism section performs a blocking operation and the second switch unit is in a closed state.

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