JPH08331748A - Circuit breaker - Google Patents

Abstract

PURPOSE: To simplify the circuit construction of a circuit breaker utilizing part of a detected current as an operating power source of a control circuit and to lessen power consumption. CONSTITUTION: An output of a rectifying circuit 30 converting secondary currents of transformers 21 and 22 detecting currents of AC circuits 11 and 12 into unilateral currents is divided into ones on the smoothing capacitor 50 side and the current detecting resistor 40 side and an instantaneous trip circuit 77 is operated with a voltage of the current detecting resistor 40 monitored, while an output voltage of the smoothing capacitor 50 is utilized as an operating power source of a control circuit 70.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a circuit breaker equipped with an electronic current detection device and a trip device, and more particularly to an electronic circuit breaker having a circuit configuration in which a part of the detected current is used as an operating power source for an electronic circuit. It relates to a circuit breaker.

[0002]

2. Description of the Related Art FIG. 9 shows, for example, JP-A-63-27432.
It is a circuit block diagram of the conventional circuit breaker shown by the 1st publication. In the figure, 10 is a load switching contact, 11 and 12 are AC electric circuits, 13 is an electromagnetic coil for driving the load switching contact 10, and 14 is a switching circuit. 21 and 22 are AC lines 1
A current transformer for detecting the currents 1 and 12, 30 is a current transformer 21,
A rectifying circuit for full-wave rectifying the secondary output of 22 and includes diodes 31 to 36. The rectifier circuit 30 is configured to obtain the respective phase currents of the AC electric circuits 11 and 12 and the combined current. A power supply circuit 37 supplies a reference voltage and a positive input voltage of a differential amplifier, which will be described later, and an operating power of the time limit circuit 90, respectively. Reference numeral 40 is a current detection resistor, which detects a combined current of the AC electric paths 11 and 12 as a voltage output across the resistors. Reference numerals 41 and 42 denote phase current detection resistors, which detect the current of each phase as a voltage output across the resistors.
Reference numerals 60, 62 and 64 denote differential amplifier circuits that convert the detection voltage of the current detection resistor 40 and the phase current detection resistors 41 and 42 into a signal with the intermediate potential of the power supply circuit 37 as a reference. The amplifier 61 is composed of four resistors, the differential amplifier circuit 62 is composed of an operational amplifier 63 and four resistors, and the differential amplifier circuit 64 is composed of an operational amplifier 65 and four resistors.

Numeral 90 is a time circuit, which discriminates the inverted output from the differential amplifier circuit 60 and sends an operation signal to the opening / closing circuit 14 to close the opening / closing circuit 14 when the level exceeds a predetermined level and time limit. A current is passed through 13 to open / close the load switching contact 10 by its electromagnetic force, and the current in the AC electric paths 11, 12 is cut off. The time limit circuit 90 is composed of an instantaneous trip circuit 71, a peak value conversion circuit 72, a short time limit trip circuit 73, a maximum phase selection circuit 74, an effective value conversion circuit 75, and a long time limit trip circuit 76. Corresponding to, a predetermined level and time limit are determined.

In the conventional circuit breaker configured as described above, the current of the rectifier circuit 30 that exactly corresponds to the current of the AC electric lines 11, 12 is detected by the current detection resistor 40 and the phase current detection resistors 41, 42. Therefore, it is necessary to connect these resistors 40, 41 and 42 downstream from the ground point G where the currents branched to the power supply circuit 37 and the time limit circuit 90 are collected.
Therefore, the current detection resistor 40 and the phase current detection resistor 41,
The output voltage of 42 has a negative polarity with respect to the ground point G.
This is inverted and amplified by the operation amplifier circuits 60, 62, and 64 so that the time limit circuit 90 performs positive polarity processing.

[0005]

As described above, the conventional circuit breaker has the current detecting resistor 40 and the phase current detecting resistor 4 as described above.
Since the output voltages of 1 and 42 have a negative polarity with respect to the ground point G, an operational amplifier and a resistor for inverting this to a positive polarity are required, and the circuit configuration is complicated. In addition, this increases the power consumption of the entire circuit and puts a heavy load on the power supply circuit. Furthermore, the input potential of the operational amplifier is the output voltage (+ V) and the output voltage (-V) of the power supply circuit. There is a restriction that the input side resistance Rin and the output side resistance Rout of each differential amplifier circuit must be set to satisfy this condition.

The present invention has been made in order to solve such a problem, and provides a circuit breaker which can perform positive polarity processing with a simple circuit configuration, consumes less power, and has high operating accuracy. is there.

[0007]

SUMMARY OF THE INVENTION A circuit breaker according to the present invention is a load switching contact which is inserted into an AC electric path and is opened and closed by an electromagnetic coil, a current transformer which detects a current in the AC electric path, and a current transformer. A rectifier circuit that converts the secondary current of the current transformer into a unidirectional current, a switching element connected between the output terminals of this rectifier circuit, a current detection resistor connected in series with this switching element, A phase current detection resistor for detecting a current, a smoothing capacitor connected in parallel to the series circuit of the switching element and the current detection resistor, and a control circuit to which an operating power is supplied from the output end of the smoothing capacitor, the control circuit Switching element control means for turning on / off the switching element,
The instantaneous maximum value of the voltage generated by the current flowing to the current detection resistor is monitored, and when this is a predetermined value or more, the instantaneous trip circuit that opens and closes the load switching contact via the electromagnetic coil, and the phase current detection resistor And a timed trip circuit that monitors the voltage generated by the flowing current and, after the timed processing, opens the load switching contact via the electromagnetic coil.

In the above structure, a Zener diode is connected in parallel with the smoothing capacitor.

Further, in the above-mentioned structure, the switching element control means monitors the voltage of the voltage dividing resistor connected in parallel with the smoothing capacitor within a predetermined range, conducts the switching element at the upper limit of the voltage range, and switches the voltage range. It has a switching signal generation circuit for generating a signal to make it non-conductive at the lower limit of the above.

Further, in the above structure, the switching element control means has a switching signal generating circuit for generating a pulse train signal of a predetermined cycle for making the switching element conductive / non-conductive.

Further, a load opening / closing contact which is inserted into an AC electric line and is opened / closed by an electromagnetic coil, a current transformer for detecting a current in the AC electric line, and a secondary current of the current transformer is converted into a unidirectional current. Rectifier circuit, first switching element connected between output terminals of the rectifier circuit, current detection resistor connected in series with the first switching element, phase current detection for detecting current of each phase of the AC circuit Resistance, first above
Of the smoothing capacitor connected in parallel to the series circuit of the switching element and the current detection resistor, the second switching element provided between the first switching element and the smoothing capacitor, and the output terminal of the smoothing capacitor. A control circuit to which power is supplied is provided, and this control circuit monitors the instantaneous maximum value of the voltage generated by the current flowing to the current detection resistor, and when this is a predetermined value or more, the load switching contact is connected via the electromagnetic coil. An instantaneous trip circuit for opening and disconnecting, a voltage generated by a current flowing to the phase current detection resistor is monitored, and a timed trip circuit for opening and closing the load opening / closing contact via the electromagnetic coil after timed processing of the voltage, And a switching element control means for connecting / disconnecting the first switching element and the second switching element in opposite phases.

Further, in the above structure, the switching element control means monitors the voltage of the smoothing capacitor within a predetermined range, and rises (falls) at the upper limit of the voltage range and falls (rises) at the lower limit of the voltage range. And a switching signal generation circuit for making the first switching element and the second switching element conductive / non-conductive in opposite phases by this pulse signal.

Further, in the above structure, the switching element control means includes a switching signal generating circuit for generating a pulse signal of a predetermined cycle for conducting / non-conducting the first switching element and the second switching element in opposite phases. I have.

Further, in the above configuration, the control circuit monitors the voltage of the smoothing capacitor within a predetermined range and generates a pulse signal that rises (falls) at the upper limit of the voltage range and falls (rises) at the lower limit of the voltage range. Then, the voltage of the switching signal generation circuit that makes the first switching element conductive / non-conductive by this pulse signal and the voltage of the current detection resistor are detected, and the second switching element is reversed from the first switching element by this voltage value. And an instantaneous current detection circuit that makes conduction / non-conduction in phase.

Further, in the above structure, the phase current detecting resistor is a return path of the current flowing through the current detecting resistor and the operating power supply current of the switching element control means, the instantaneous trip circuit and the timed trip circuit.

Further, in the above structure, a bypass line is provided which is directly connected from the rectifier circuit to one end of the electromagnetic coil.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1. First Embodiment FIG. 1 is a circuit configuration diagram showing a first embodiment of the present invention, in which 10 to 14, 21, 22, 30 to 3 are shown.
Reference numerals 6 and 40 to 42 are the same as those of the conventional device shown in FIG. A smoothing capacitor 50 smoothes the output voltage from the rectifier circuit 30. A first switching element 51 is connected in parallel with the rectifier circuit 30 and the smoothing capacitor 50, and switches the current to the smoothing capacitor 50 and the current detection resistor 40 by switching. A Zener diode 55 prevents the charging voltage of the smoothing capacitor 50 from rising above a predetermined voltage. A second switching element 52 disconnects the rectifying circuit 30 and the smoothing capacitor 50 via the transistors 53 and 54. 56 is a diode which prevents the charge of the smoothing capacitor 50 from flowing back through the second switching element 52 when the second switching element 52 becomes non-conductive. Reference numeral 57 is a bypass wire that bypasses the second switching element 52 and directly connects the rectifier circuit 30 and the electromagnetic coil 13. Reference numeral 58 is a second Zener diode, which protects the first switching element 51 from overvoltage.

Reference numeral 70 is a control circuit including an instantaneous trip circuit 77, a timed trip circuit 78, and a switching signal generation circuit 79. The instantaneous trip circuit 77 includes an AC electric circuit 11,
The voltage of the current detection resistor 40 proportional to the combined current of 12 is monitored, and when this voltage exceeds a predetermined value, the switching circuit 14
Send an actuation signal to. The timed trip circuit 78 includes a phase current detection resistor 4 that is proportional to the current of each phase of the AC electric circuits 11 and 12.
The maximum phase selection circuit, the peak value conversion circuit for each phase, the short time period trip circuit, the maximum phase selection circuit, the effective value conversion circuit, and the long time period trip circuit described in the above conventional example are monitored by monitoring the voltages of 1 and 42. A predetermined level and a time limit are determined in accordance with the respective cutoff time characteristics of the switching circuit, and when these exceed a predetermined value, the switching circuit 1
4 sends an actuation signal. Switching signal generation circuit 7
Reference numeral 9 is for outputting a pulsed voltage having a constant cycle shorter than a half cycle of the AC circuit current. The multi-vibrator is used to generate a pulse, or the clock pulse for the arithmetic processing of the timed trip circuit 78 is divided. Then, a pulse signal having a predetermined cycle is obtained.

The operation of the above circuit configuration will be described with reference to FIG. The output current of the rectifier circuit 30 is the smoothing capacitor 50.
Is smoothed by the zener diode 55 to be a constant voltage, and serves as an operating power source for the control circuit 70 (instantaneous trip circuit 77, timed trip circuit 78, switching signal generation circuit 79). Here, while the pulsed voltage output from the switching signal generating circuit 79 shown in FIG. 2B is applied to the base of the first switching element 51 by conduction, the output of the rectifying circuit 30 is the first switching element. In the period in which the pulsed voltage output is applied to the base of the first switching element 51 in a non-conducting manner while being supplied to the current detecting resistor 40 through 51, the first switching element 51 is in a non-conducting state and the rectifying circuit 30 The output is sent to the Zener diode 55 side. The current that has flowed to the Zener diode 55 side is smoothed by the smoothing capacitor 50 and serves as the operating power supply for the control circuit 70. The voltage waveform at the point B of the current detection resistor 40 is shown in FIG. 2 (where the non-conduction period of the output of the switching signal generation circuit 79 is cut out from the current waveform at the point F of the output of the rectifier circuit 30 shown in FIG. The waveform is as shown in (c). Figure 2
The instantaneous maximum values of the currents flowing in (a) and (c) are equal, and this instantaneous maximum value is monitored by the instantaneous trip circuit 77. When this exceeds a predetermined value, an actuation signal is sent to the switching circuit 14. The load switching contact 10 is opened via the electromagnetic coil 13.

The current flowing through the phase current detecting resistors 41 and 42 has a continuous waveform similar to that before switching division because the return current C from the zener diode 55 and the control circuit 70 is added to the current of the current detecting resistor 40. The voltage appearing at the phase current detecting resistors 41 and 42 has the waveform shown in FIG. This voltage output is processed by the timed trip circuit 78. In this process, the peak level conversion, short time period trip, maximum phase selection, effective value conversion, and long time period trip corresponding to each phase are determined and the predetermined level and time period are determined, When the predetermined value is exceeded, an operation signal is sent to the switching circuit 14 to open / close the load switching contact 10 via the electromagnetic coil 13.

Instantaneous trip circuit 77 and timed trip circuit 7
8 outputs an operation signal output to the switching circuit 14, and at the same time,
The voltage output is also given to the base of the transistor 54, and the second switching element 52 is made non-conductive via the transistor 53. Further, at this time, the switching signal generating circuit 79 stops its output, so that the first switching element 51 becomes non-conductive, and all the current from the rectifying circuit 30 can be supplied to the coil 13 through the bypass line 57. , The tripping electromagnetic force of the coil 13 is strengthened. A voltage supply path is provided to the base of the transistor 53 through the resistor 47 when the device starts up.
This is to bring the switching element 52 of 1 to the conductive state.

As described above, in the circuit configuration described above, the current of the rectifier circuit 30 depends on the switching interval of the first switching element 51 and the current detection resistor 40 and the control circuit 70.
Since the voltage is switched over to and supplied to the current detection resistor 40, a voltage that faithfully reproduces the current of the rectifier circuit 30 that corresponds to the currents of the AC electric paths 11 and 12 can be obtained in the current detection resistor 40. The circuit breaking operation can be performed without requiring such positive polarity processing. On the other hand, the voltage shown in FIG. 2D is applied to the control circuit 70, and the rectifying circuit 30 supplies the operating power.

Embodiment 2. In the first embodiment, the power supply voltage setting of the control circuit 70 is set by the Zener diode 55, and the current detection resistor 40 and the current detection resistor 40 are smoothed by the ratio of the conduction period and the non-conduction period of the transistor 51 controlled by the switching signal generation circuit 79. The current division ratio to the capacitor 50 is determined. Therefore, if the setting of the conduction / non-conduction ratio is inadequate, the Zener diode 55 overheats, or the supply voltage to the control circuit 70 decreases, which hinders the operation of the control circuit 70.

The second embodiment is intended to improve this point. FIG. 3 shows a circuit configuration diagram thereof, and FIG. 4 shows signal waveforms of respective portions of FIG. In the figure, 10
14, 21, 22, 30-36, 40-42, 47, 4
8, 50 to 54, 56, 57, 70, 77 and 78 are the same as those described in the first embodiment shown in FIG.
45 and 46 are voltage dividing resistors, which divide the output side voltage of the smoothing capacitor 50 at the connection point E to its resistance ratio. A switching signal generation circuit 80 generates a pulse signal that makes the first switching element 51 conductive / non-conductive according to the voltage of the smoothing capacitor 50.

Next, the operation will be described. The switching signal generation circuit 80 outputs an output when the voltage at the point E becomes equal to or higher than the upper limit of the predetermined voltage range, and causes a current to flow through the base of the first switching element 51 to make it conductive. For this reason,
The current from the rectifier circuit 30 is the first switching element 51.
Then, the voltage of the smoothing capacitor 50 is discharged through the drive of the control circuit 70 and the voltage dividing resistors 45 and 46, and gradually decreases. Then, when the voltage at the point E becomes equal to or lower than the lower limit of the predetermined voltage range, the switching signal generation circuit 80 stops the output, so that the first switching element 51 becomes non-conductive, and the current from the rectifier circuit 30 is the first switching. The smoothing capacitor 50 is charged through the second switching element 52 without flowing into the circuit of the element 51.

The voltage of the predetermined range set in the switching signal generation circuit 80 has a certain width, and the output of the switching signal generation circuit 80 has the waveform of FIG. Therefore, the voltage waveform generated in the current detection resistor 40 becomes the waveform shown in FIG. 4D, in which the first switching element 51 is lacking in the non-conduction state from the current at the point F shown in FIG. 4A. . The instantaneous trip circuit 77 monitors this instantaneous waveform value, and when it exceeds a predetermined value, the switching circuit 14
An operation signal is transmitted to the load opening / closing contact 10 via the electromagnetic coil 13. The current flowing through the phase current detection resistors 41 and 42 has a continuous waveform equivalent to that before switching division because the return current C from the voltage dividing resistors 45 and 46 and the control circuit 70 is added to the current of the current detection resistor 40. It becomes an electric current. Since the following operation is the same as that of the first embodiment, its explanation is omitted.

In the second embodiment, the switching signal generation circuit 80 monitors the voltage at the point E and the first switching element 51 is controlled so that the point E becomes a voltage within a predetermined range.
Since the switching of the control circuit 70 is controlled, the power supply voltage of the control circuit 70 is kept constant in a normal state without using a Zener diode, and the voltage at point D shown in FIG. Is supplied to. The current to the voltage dividing resistors 45 and 46 is 0.1, which enables the voltage at the point B to be monitored.
By using a relatively high resistance value of about mA, it is possible to suppress current consumption and heat generation in this portion.

Embodiment 3. The second embodiment described above operates without problems in a normal state. However, the instantaneous trip circuit 7
If the output voltage from the current transformers 21 and 22 suddenly increases for some reason when the operating voltage of 7 is set relatively high, the voltage at point D rises before the instantaneous trip circuit 77 operates. However, even if the first switching element 51 is in the conductive state, the voltage drop of the current detection resistor 40 and the protection resistor 43 causes F
A state in which the voltage at the point becomes higher than the point D occurs, a part of the current that should originally flow in the first switching element 51 leaks to the smoothing capacitor 50, the voltage at the point D rises, and the control circuit 70.
Operation of the switching signal generation circuit 80
The switching control by becomes impossible. Further, due to the current leaking to the smoothing capacitor 50 side, an error corresponding to the leak current occurs in the detection voltage of the detection resistor 40. In order to prevent this phenomenon, it is conceivable to reduce the protective resistance 43,
In this case, the first switching element 51 needs to have a high withstand current, which causes a problem that the circuit becomes large.
The third embodiment is intended to solve such a problem.

FIG. 5 is a circuit configuration diagram showing a third embodiment of the present invention, which is 10 to 14, 21, 22, 30 to 36,
40-43, 45-48, 50-54, 56-58, 7
0, 77, 78, 80 are the same as those shown in FIG. Reference numerals 60 and 61 denote transistors connected in parallel to the output of the switching signal generation circuit 80.
The second switching element 5 via the transistor 53
2 and the transistor 61 controls the first switching element 51.

The operation of the above circuit configuration will be described with reference to FIG. When the voltage at the point E becomes equal to or higher than the upper limit of the predetermined voltage range, the switching signal generation circuit 80 causes a current to flow through the base of the transistor 61 to make it conductive as shown in FIG. The switching element 51 is made conductive. At this time, at the same time, an output is given to the transistor 60 to make it conductive, and the second switching element 52 is made non-conductive via the transistor 53. That is,
The first switching element 51 and the second switching element 52 are opened and closed in opposite phases by the output of the switching signal generation circuit 80. When the second switching element 52 is non-conducting, all the current from the rectifier circuit 30 flows to the first switching element 51, the voltage of the smoothing capacitor 50 drives the control circuit 70, and the voltage dividing resistors 45 and 46. It gradually decreases due to discharge.

In this state, the outputs from the current transformers 21 and 22 suddenly increase, and the voltage at the point F becomes D as shown in FIG. 6 (g) due to the voltage drop of the current detection resistor 40 and the protection resistor 43.
Even if the voltage rises above the point, the second switching element 52
Is non-conductive, no current leaks to the smoothing capacitor 50. Therefore, the voltage at the point D does not rise, the switching control of the switching signal generation circuit 80 which is supplied with power from the point D is normally performed, and when the voltage at the point B becomes equal to or higher than a predetermined value, the instantaneous trip circuit. 77 works. Therefore, not only does the detection voltage of the current detection resistor 40 have no error,
It is also possible to increase the resistance value of the protection resistor 43,
As the first switching element 51, a small element having a small withstand current can be used.

When the voltage at the point E becomes lower than the lower limit of the predetermined voltage range, the switching signal generating circuit 80 stops the output, so that the first switching element 51 becomes non-conductive and the second switching element 52 becomes conductive. To do. Therefore, the current from the rectifier circuit 30 does not flow to the resistors 43 and 40, and the smoothing capacitor 50 is charged. There is a certain width between the upper limit value and the lower limit value of the predetermined voltage range, and the conduction / non-conduction of the first switching element 51 is the state of FIG. 6D, and the conduction / non-conduction of the second switching element 52. Figure 6 (e)
In this state, the voltage waveform generated in the current detection resistor 40 becomes a waveform lacking during the non-conduction of the first switching element 51 as shown in FIG. The instantaneous trip circuit 77 monitors the instantaneous maximum value of the waveform. When the maximum value exceeds a predetermined value, the instantaneous trip circuit 77 sends an operation signal to the switching circuit 14 as shown in FIG. It is sent out and the opening / closing contact 10 is opened via the electromagnetic coil 13.

Fourth Embodiment 7 is a circuit configuration diagram showing a fourth embodiment of the present invention.
2, 30-36, 40-43, 45-48, 50-5
4, 56 to 58, 70, 77, 78 and 80 are the same as those shown in FIG. Reference numeral 90 denotes an instantaneous current detection circuit forming a part of the control circuit 70. When the voltage detected by the current detection resistor 40 becomes a predetermined value or more, the transistor 62 is turned on, the transistor 53 is turned off, and the second switching element is turned on. 52 is made non-conductive.

The operation of the above circuit configuration will be described with reference to FIG. When the outputs from the current transformers 21 and 22 are normal, the detection voltage of the current detection resistor 40 is also normal, and the instantaneous current detection circuit 9
0 outputs no output, and other circuit interruption operations are the same as those of the conventional device. The output from the current transformers 21 and 22 suddenly rises,
When the instantaneous maximum voltage value of the current detection resistor 40 becomes equal to or higher than the set value, the instantaneous current detection circuit 90 outputs an output to make the transistor 62 conductive as shown in FIG. The element 52 is turned off (FIG. 8 (e)). Therefore, due to the voltage drop of the current detection resistor 40 and the protection resistor 43, even if the voltage at the point F rises above the voltage at the point D as shown in FIG. 8G, the second switching element 52 is non-conductive. No current leaks to the smoothing capacitor 50. Therefore, the voltage at the point D does not rise, the switching control of the switching signal generation circuit 80 is normally performed, and no error occurs in the detection voltage of the current detection resistor 40. Therefore, the resistance value of the protective resistor 43 can be increased, and the first switching element 51 can be a small element having a small withstand current.

The voltage waveform generated in the current detection resistor 40 is
By the output of the switching signal generation circuit 80, FIG.
As shown in (f), the waveform is missing during the non-conduction of the first switching element 51. The instantaneous trip circuit 77 monitors the instantaneous maximum value of this waveform, and when the maximum value exceeds a predetermined value, the instantaneous trip circuit 77 sends it to the switching circuit 14 as shown in FIG. An operation signal is sent to open and close the switching contact 10 via the electromagnetic coil 13. In the above embodiment, the current detection device for the circuit breaker for the single-phase two-wire AC circuit is described for the sake of simplicity, but the present invention is applied to the three-phase three-wire and three-phase four-wire AC circuit. Is easy to apply to.

[Brief description of drawings]

FIG. 1 is a circuit configuration diagram of a circuit breaker according to a first embodiment of the present invention.

FIG. 2 is a waveform diagram illustrating the operation of the circuit breaker according to the first embodiment of the present invention.

FIG. 3 is a circuit configuration diagram of a circuit breaker according to a second embodiment of the present invention.

FIG. 4 is a waveform diagram illustrating an operation of the circuit breaker according to the second embodiment of the present invention.

FIG. 5 is a circuit configuration diagram of a circuit breaker according to a third embodiment of the present invention.

FIG. 6 is a waveform diagram illustrating an operation of the circuit breaker according to the third embodiment of the present invention.

FIG. 7 is a circuit configuration diagram of a circuit breaker according to a fourth embodiment of the present invention.

FIG. 8 is a waveform diagram illustrating the operation of the circuit breaker according to the fourth embodiment of the present invention.

FIG. 9 is a circuit configuration diagram showing a conventional circuit breaker.

[Explanation of symbols]

10 load switching contacts, 11, 12 AC electric circuit, 13 electromagnetic coil, 14 switching circuit, 21, 22 current transformer, 30
Rectifier circuit, 40 current detection resistor, 41, 42 phase current detection resistor, 43 protection resistor, 45, 46 voltage dividing resistor, 5
0 smoothing capacitor, 51 first switching element,
52 second switching element, 53, 54 transistor, 55 zener diode, 57 bypass line,
58 Zener diode, 60, 61, 62 Transistor, 70 Control circuit, 77 Instantaneous trip circuit, 78
Timed trip circuit, 79 switching signal generation circuit,
80 switching signal generation circuit, 90 instantaneous current detection circuit.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shuko Kanedaka 2-3-3 Marunouchi, Chiyoda-ku, Tokyo Sanryo Electric Co., Ltd. (72) Yuji Tsuchimoto 2-3-2, Marunouchi, Chiyoda-ku, Tokyo Sanryo Electric Co., Ltd.

Claims (10)

[Claims] 1. A load switching contact that is inserted into an AC electric circuit and is opened and closed by an electromagnetic coil, a current transformer that detects a current in the AC electric circuit, and a secondary current of the current transformer is converted into a unidirectional current. Rectifier circuit, switching element connected between output terminals of this rectifier circuit, current detection resistor connected in series with this switching element, phase current detection resistor for detecting current of each phase of the alternating current circuit, switching element and A smoothing capacitor connected in parallel to a series circuit of current detection resistors, and a control circuit to which an operating power source is applied from the output end of the smoothing capacitor, the control circuit being a switching element for making the switching element conductive / non-conductive The instantaneous maximum value of the voltage generated by the current flowing through the control means and the current detection resistor is monitored, and when this is a predetermined value or more, it is passed through the electromagnetic coil. The instantaneous trip circuit that opens the load switching contact and the voltage generated by the current flowing in the phase current detection resistor are monitored, and after the time processing, the load switching contact is opened via the electromagnetic coil. A circuit breaker having a disconnection circuit. 2. The circuit breaker according to claim 1, wherein a zener diode is connected in parallel to the smoothing capacitor. 3. The switching element control means monitors the voltage of the voltage dividing resistor connected in parallel with the smoothing capacitor within a predetermined range, conducts the switching element at the upper limit of the voltage range, and turns off at the lower limit of the voltage range. 2. The circuit breaker according to claim 1, further comprising a switching signal generation circuit that generates a signal for making it conductive. 4. The switching element control means has a switching signal generating circuit for generating a pulse train signal of a predetermined cycle for making the switching element conductive / non-conductive, according to any one of claims 1 to 3. The circuit breaker according to the item. 5. A load switching contact that is inserted into an AC electric circuit and is opened and closed by an electromagnetic coil, a current transformer that detects a current in the AC electric circuit, and a secondary current of the current transformer is converted into a unidirectional current. Rectifier circuit, first switching element connected between output terminals of the rectifier circuit, current detection resistor connected in series with the first switching element, phase current detection for detecting current of each phase of the AC circuit A resistor, a smoothing capacitor connected in parallel to a series circuit of the first switching element and the current detection resistor, a second switching element provided between the first switching element and the smoothing capacitor, and the smoothing capacitor. The control circuit is supplied with operating power from the output end of the control circuit, and the control circuit monitors the instantaneous maximum value of the voltage generated by the current flowing to the current detection resistor, When the value is equal to or more than the value, the instantaneous trip circuit that opens and closes the load switching contact via the electromagnetic coil and the voltage generated by the current flowing to the phase current detection resistor are monitored, and after this is timed, the voltage is generated via the electromagnetic coil. A circuit comprising: a timed trip circuit for opening and closing the load switching contact; and a switching element control means for electrically connecting / disconnecting the first switching element and the second switching element in opposite phases. Circuit breaker. 6. The switching element control means monitors the voltage of the smoothing capacitor within a predetermined range and generates a pulse signal that rises (falls) at the upper limit of the voltage range and falls (rises) at the lower limit of the voltage range, 6. The circuit breaker according to claim 5, further comprising a switching signal generation circuit that connects / disconnects the first switching element and the second switching element in opposite phases by the pulse signal. 7. The switching element control means has a switching signal generation circuit for generating a pulse signal of a predetermined cycle for conducting / non-conducting the first switching element and the second switching element in opposite phases. The circuit breaker according to claim 5. 8. The control circuit monitors the voltage of the smoothing capacitor within a predetermined range and generates a pulse signal that rises (falls) at the upper limit of the voltage range and falls (rises) at the lower limit of the voltage range, and the pulse signal is generated. The voltage of the switching signal generation circuit that makes the first switching element conductive / non-conductive by the signal and the voltage of the current detection resistor is detected, and by this voltage value,
The circuit breaker according to claim 5, further comprising: an instantaneous current detection circuit that makes the second switching element conductive / non-conductive in a phase opposite to that of the first switching element. 9. The phase current detection resistor is a return path between the current flowing through the current detection resistor and the operating power supply current of the switching element control means, the instantaneous trip circuit and the timed trip circuit. The circuit breaker according to any one of claims 1 to 8. 10. The circuit breaker according to claim 1, further comprising a bypass wire connected directly from the rectifier circuit to one end of the electromagnetic coil.