JPH1014086A - Circuit breaker - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a circuit breaker which does not malfunction owing to overflow current to rush current and which operates instantly when discharging short-circuit current flows by detecting the differentiated value of short-circuit current and opening a contact of a contact switch when the differentiated value of the opposite polarity to that of the short-circuit current is at least a properly determined threshold value. SOLUTION: A threshold circuit 3 outputs an H-level signal when an absolute value of a signal output from a differentiating circuit 2 is a properly determined threshold value or above. A polarity judging circuit 4 outputs an H-level signal when the polarity of short circuit current and that of the differentiated value of the short circuit current are different. And, an AND circuit 5 outputs an H-level signal when the outputs of circuits 3, 4 are both H-level. By this, a thyristor 6 is turned on and a trip coil 7 is excited and then a contact device 10 is opened. Therefore, this circuit breaker does not malfunction owing to overflow current or rush current and it instantly opens the contact device when discharging short circuit current flows owing to a short circuit of a cord and thereby a fire can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a circuit breaker for wiring, and more particularly to a circuit breaker for wiring that breaks a circuit with a discharge short-circuit current generated by insulation breakdown of an insulator that cannot be detected by a conventional circuit breaker. You.

[0002]

Conventionally, such a circuit breaker for wiring uses a bimetal or an electromagnetic coil for detecting an overcurrent or a short-circuit current.

However, in this method, in order to avoid a malfunction due to an overflow and an inrush current as shown in FIG. 14, the detection current of the instantaneous interruption (detection interruption operation current in half to several cycles) is changed to the overflow and the inrush current. I couldn't make it smaller. Therefore, generally, the operating current of the instantaneous interruption was selected to be about 1000% of the rated current of the circuit breaker for wiring. For example,
The rated current of a circuit breaker used for general houses is 2
It is 0 A, and the operating current of the instantaneous interruption is about 200 A effective value. However, in the case of insulation deterioration of the coating of the cord used by connecting to the outlet or short-circuiting of the core due to melting of the coating due to overheating, the short-circuit current is from several tens to about 200 A, and the short-circuit current is not a continuous sine wave. As shown in FIG. 15, since the current becomes a discontinuous intermittent discharge-like current, the above-described conventional circuit breaker does not perform an instantaneous shut-off operation, it takes a long time to shut off, and in the worst case, a short-circuit may cause a fire or fire. There was something.

Accordingly, the object of the present invention is to prevent malfunction due to overflow or inrush current, and in the case of a core short circuit caused by melting of a cord film, the short-circuit current is equal to or less than the peak value of overflow or inrush current. However, the object of the present invention is to provide a circuit breaker for wiring that operates instantaneously by determining the waveform.

[0004]

In order to achieve the above object, according to the present invention, first, a differential value of a short-circuit current is detected, and a differential value of the short-circuit current on the opposite side to the polarity direction is detected. The contact of the contact switch is opened when the polarity differential value becomes equal to or larger than a suitably determined threshold value.

According to a second aspect of the present invention, a current transformer for converting a short-circuit current into a voltage and outputting the voltage, a first half of the waveform of a half-wave of the short-circuit current starting from zero and reaching a peak, and a zero from the peak. When the output voltage of the current transformer during the period from the peak to the return to zero becomes higher than the threshold when divided into the latter half before returning to the detector, the detector that drives the trip coil and the suction drive of the trip coil And an opening / closing mechanism for opening the contact.

Third, in the present invention, a current-voltage conversion means for converting a short-circuit current into a voltage, a differentiation circuit for obtaining a differential value of an output signal, and an absolute value of an output voltage of the differentiation circuit are appropriately determined. If the output voltage is equal to or higher than the threshold value, the polarity of the voltage output by the current-voltage conversion means is compared with the polarity of the voltage output by the differentiating circuit. If the outputs from the differentiating circuit and the polarity determining circuit are both at the H level, an AND circuit for operating the thyristor, and a gate connected to the output of the AND circuit A thyristor having an anode connected to a trip coil and a cathode connected to one pole; a trip coil having one end connected to the anode of the thyristor; And a contact opening / closing mechanism that opens.

According to a fourth aspect of the present invention, a current-voltage converter for converting a short-circuit current into a voltage, a differentiating circuit for obtaining a differential value of an output signal, and an output voltage of the differentiating circuit being higher than a predetermined threshold value If so, a threshold circuit for setting the output to H level;
The polarity of the voltage output by the current-to-voltage converter is compared with the polarity of the voltage output by the differentiating circuit. A voltage detection circuit for detecting the voltage, a voltage threshold circuit for setting the output to the H level if the signal output from the voltage detection circuit is equal to or more than a predetermined value, and
When the outputs from the differentiating circuit, the polarity determining circuit, and the voltage threshold circuit are all at the H level, an AND circuit for operating the thyristor, a gate is connected to the output of the AND circuit, and the anode side is connected to the trip coil. The thyristor includes a thyristor having a cathode connected to one pole, a trip coil having one end connected to an anode of the thyristor, and a contact opening / closing mechanism for opening a contact device by energizing the trip coil.

A fifth aspect of the present invention provides a current transformer for converting a short-circuit current into a voltage and outputting the voltage, a thyristor receiving the output of the current transformer at a gate, and a trip coil for supplying a current by turning on the thyristor. The current transformer and the thyristor are connected by a switching mechanism that opens and closes the contacts when the trip coil is energized. When the signal is divided into the latter half before returning to the above, the output voltage of the latter half that returns from the peak to zero is connected to the polarity that triggers the thyristor.

In a sixth aspect of the present invention, a current transformer A for converting a short-circuit current into a voltage and outputting the voltage, and an output of the current transformer A connected to a gate and a cathode via a voltage dividing resistor, A thyristor A having a cathode connected to one pole, an anode connected to the cathode of thyristor A, and a cathode connected to thyristor A
A diode B connected to the anode of the current transformer, a current transformer B for converting a short-circuit current into a voltage and outputting the voltage, and an output of the current transformer B connected to the gate and the cathode via a voltage dividing resistor, and the other of the circuit breaker A thyristor B having a cathode connected to the pole of the thyristor B, a diode A having an anode connected to the cathode of the thyristor B and a cathode connected to the anode of the thyristor B, and a coil winding connected between the anode of the thyristor A and the anode of the thyristor B The current transformer A is connected to the thyristor A, and the connection between the current transformer B and the thyristor B is half of the short-circuit current. When the waveform of the wave segment is divided into the first half of the waveform starting from zero and reaching the peak, and the second half of returning from the peak to zero, each change in the latter half returning from the peak to zero. Output voltage of the vessel is one in which formed by connecting a polarity to trigger each thyristor.

According to a seventh aspect of the present invention, the current transformer A and the current transformer B of the sixth aspect are such that two secondary windings are wound on the same core and one of the windings is connected to the current transformer. As A, the remaining winding is a current transformer B.

Thus, the contact can be opened by detecting whether the differential value of the falling portion of the short-circuit current from the peak of the half cycle to zero has exceeded an appropriately determined threshold value. Therefore, as shown in FIG. 15, in the case of a core short-circuit due to melting of the coating such that the ground fault current waveform width of each half cycle becomes narrower than that of a normal sine wave, the maximum value of the current differential value is the half cycle current. Appears just before returning to zero, and the differential value at that time is different between the sine wave having the same peak value and the short-circuit current of the waveform of the code fault described above. With the short-circuit discharge current caused by an accident, a circuit breaker that performs an instantaneous interruption operation can be configured.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings.

FIG. 14 shows an example of the waveform of the overflow current when the incandescent lamp is turned on. In the case of an incandescent lamp having a rating of 20 A, the peak value of the current at the beginning of lighting reaches about 300 A.

FIG. 15 shows a short-circuit current waveform in the case of insulation deterioration of the film of the cord connected to the outlet, short-circuiting of the core wire due to melting of the film due to overheating, and short-circuiting due to tracking. At several hundred amperes, the fundamental frequency is the same as the commercial frequency, but the conduction time width of the current for each half-wave is narrower than the conduction time width of the current for each half-wave of the sine wave AC of the commercial frequency. It has the characteristic that there is.

FIG. 1 is a diagram showing a first embodiment of the present invention.

In FIG. 1, reference numeral 1 denotes a current-to-voltage converter which outputs a voltage proportional to the current flowing in the main circuit of the circuit breaker.

In FIG. 1, reference numeral 2 denotes a differentiating circuit, which outputs a differential value of the output waveform of the current / voltage converting means 1.

In FIG. 1, reference numeral 3 denotes a threshold value circuit, which determines whether or not the absolute value of the signal output from the differentiating circuit 2 is equal to or more than an appropriately determined threshold value. An H-level output is generated only when it is determined that it is equal to or greater than the threshold value.

In FIG. 1, reference numeral 4 denotes a polarity determination circuit which compares the polarity of the voltage output by the current-to-voltage converter 1 with the polarity of the voltage output by the differentiating circuit 2 to determine the polarity of the short-circuit current and the short-circuit current. It is determined whether or not the polarity of the differential value is different polarity, and when it is determined that the polarity is different, an H-level output is generated.

In FIG. 1, reference numeral 5 denotes an AND circuit, which sets the output to the H level when the two outputs of the threshold circuit 3 and the polarity determination circuit 4 are both at the H level.

In FIG. 1, reference numeral 6 denotes a thyristor which, when the output voltage of the AND circuit 5 is at the H level, short-circuits between the anode and the cathode to perform an ON operation.

In FIG. 1, reference numeral 7 denotes a trip coil. When the thyristor 6 is turned on, the trip coil is excited and acts on a contact opening / closing mechanism (not shown) to open the contact device 8.

The operation of the above embodiment will be described in detail below with reference to a waveform time chart.

FIG. 2 is an operation time chart of each part of the first embodiment when the current flowing through the circuit breaker is a sine wave overflow having a peak value of 280 A. In the figure, the waveform (a) is the current waveform of the first half wave of the overflow flowing through the circuit breaker, and at the same time, the output voltage of the current / voltage detecting means 1 in FIG. 1 is similar to the waveform (a). It becomes a waveform.

(B) is an output waveform of the differentiating circuit 2;
When the waveform in (a) is a sine wave, the waveform in (b) is s
In the first half before the waveform of (a) reaches the peak value from zero, it becomes the same polarity as the waveform of (a), and the second half of the waveform of (a) returns from the peak value to zero in the first half until the waveform of (a) reaches the peak value. Then, the polarity is opposite to that of the waveform (a).

The waveform (d) is the output of the polarity judging circuit 4, and the first half in which the waveform (a) has the positive polarity and the waveform (b) has the positive polarity has the same polarity as each other. The output is at the L level, and the waveform of (a) has a positive polarity and the waveform of (b) has a negative polarity.
Level.

(E) is an output waveform of the threshold circuit 3,
Inside the threshold circuit, the output waveform of the differentiating circuit 2 (b)
Is used to detect whether the waveform reaches an appropriately determined threshold level a. In this example, by setting the threshold level a to a level slightly higher than the peak of the absolute value of (c) in the latter half of (c) (the range where the waveform of (d) is at the H level), The output of the threshold circuit 3 remains at the L level as shown in (e).

(F) is the output of the AND circuit 5 at this time. The output of (d) goes to the H level in the latter half of the waveform.
Since the output of threshold circuit 3 remains at L level, A
The output of the ND circuit also remains at the L level, and the thyristor 6
The contact 7 is not opened because the trip coil is not driven and the trip coil is not driven.

FIG. 3 is an operation time chart of each part of the first embodiment in the case where the current flowing through the circuit breaker is a discharge short circuit due to a code accident having a peak value of 280 A. The waveform in this case is characterized in that the conduction time width of each half-wave current is shorter than that of the sine wave as shown in FIG.

In the figure, the waveform (a) is the current waveform of the short-circuit current flowing through the circuit breaker, and at the same time, the output voltage of the current / voltage detecting means 1 in FIG. 3 is similar to the waveform (a). (The dotted line shows the case of the sine wave overflow of FIG. 2 for comparison.)

(B) is an output waveform of the differentiating circuit 2;
The magnitude of the gradient with respect to time of the waveform (a) at that time is output. In the first half of the waveform (a) from zero to the peak value, it has the same polarity as the waveform (a),
In the second half, where the peak value of the waveform (a) returns to zero,
The polarity is opposite to that of the waveform (a).

The waveform (d) is the output of the polarity judging circuit 4, and the first half in which the waveform (a) has the positive polarity and the waveform (b) has the positive polarity has the same polarity as each other. The output is at the L level, and the waveform of (a) has a positive polarity and the waveform of (b) has a negative polarity.
Level.

(E) is an output waveform of the threshold circuit 3,
Inside the threshold circuit, the output waveform of the differentiating circuit 2 (b)
Is determined as shown in (c), and it is detected whether or not the waveform reaches the threshold level a defined in FIG. In this example, the width of the current is narrower than in the previous example of FIG. 2, so if the peak value of the short-circuit current is the same as in the example of FIG. 2 and can exceed the level of the threshold value a determined in FIG. 2, so that the output of the threshold circuit 3 has an absolute value of (c) as shown in (e). H is detected at two points, rising and falling, of the short-circuit current (a) exceeding the threshold value a.
Level.

(F) is the output of the AND circuit 5 at this time. In the output of (e), the output of the threshold circuit becomes H level in the first half of the waveform, but the output of the polarity discriminating circuit 4 is Since the output is low, the output of the AND circuit 5 is also low, but in the second half of the waveform, the output of the polarity determination circuit 4 changes to the high level. When the waveform becomes H level, the output waveform of the AND circuit 5 becomes H level, the thyristor 6 is turned on, the trip coil 7 is attracted, and the contact 8 is opened.

As described above, in FIG.
If the magnitude of the current flowing through the circuit breaker is set to a constant value by setting (c) to a level slightly higher than the peak value of the waveform, it will not operate with a sine wave, but the discharge due to a code fault as shown in FIG. A circuit breaker that operates with a short-circuit current can be configured.

FIG. 4 is a time chart when the current flowing through the circuit breaker overflows with a peak value of 280 A, and the phase at which the current starts to flow is slightly delayed as compared with FIG. In the figure, the waveform (a) is a current waveform of the overflow flowing through the circuit breaker, and at the same time, the output voltage of the current / voltage detecting means 1 in FIG. 1 is similar to the waveform (a).

(B) is an output waveform of the differentiating circuit 2;
When the waveform in (a) is a sine wave, the waveform in (b) is s
At the same time as the cosine wave obtained by differentiating the in-wave, the current rises abruptly at the moment of application, so that the output of the differentiation circuit generates a very large voltage at the time of application. Also,
In the first half of the waveform (a) from the zero to the peak value, the polarity is the same as that of the waveform (a), and in the second half where the peak value of the waveform (a) returns to zero, the waveform of the (a) It has the opposite polarity.

The waveform (d) is the output of the polarity judging circuit 4, and the first half in which the waveform (a) has a positive polarity and the waveform (b) has a positive polarity has the same polarity as each other. The output is at the L level, and the waveform of (a) has a positive polarity and the waveform of (b) has a negative polarity.
Level.

(E) is an output waveform of the threshold circuit 3,
Inside the threshold circuit, the output waveform of the differentiating circuit 2 (b)
Is determined as shown in (c), and it is detected whether or not the waveform reaches the threshold level a determined in FIG. In this example, since the differential value exceeds the threshold value at the beginning of the injection, the H level is output only at that time.

(F) is the output of the AND circuit 5 at this time. The output of (d) is at the H level in the latter half of the waveform.
Since the output of the second half of the threshold circuit 3 remains at L level, the output of the AND circuit also remains at L level. In the first half, the waveform of (e) becomes H level,
Since the waveform of (d) is at the L level, it remains at the L level throughout, the thyristor 6 is not tripped, and the contact 8 does not open.

That is, the absolute value of the differential value of the short-circuit current waveform is
The trip coil is attracted when the two conditions, that is, whether the polarity of the short-circuit current waveform and the polarity of the differential value thereof are different from each other, are determined whether or not the threshold value exceeds an appropriate threshold value. In other words, in the latter half (falling part) of the current where the short-circuit current returns from the peak value to zero, it is determined whether or not the differential value of the short-circuit current exceeds an appropriately determined threshold value. Does not malfunction irrespective of the closing phase in the overflow where becomes a sine wave current. In the code fault current as shown in FIG. 4, even a short-circuit current smaller than the overflow is detected.
An operable circuit breaker can be provided.

FIG. 5 shows a second embodiment of the present invention.
The first embodiment differs from FIG. 3 in that a voltage detecting circuit 8 between the poles of the circuit breaker and a voltage for setting the output to the H level when the voltage output from the circuit 8 is not less than a predetermined value appropriately determined. The threshold circuit 9 is provided, and the output is set to the H level only when all the outputs of the threshold circuit 3, the polarity determination circuit 4, and the voltage threshold circuit 9 are at the H level in the AND circuit. . Other configurations are the same.

Reference numeral 8 in FIG. 5 denotes a voltage detection circuit which detects a voltage between the poles of the circuit breaker.

The reference numeral 9 in FIG. 5 indicates that the output is H only when the voltage output from the voltage detection circuit 8 is equal to or higher than a predetermined fixed value.
Level.

Reference numeral 5 in FIG. 5 denotes an AND circuit, which sets the output to the H level only when all the outputs of the threshold circuit 3, the polarity determination circuit 4, and the voltage threshold circuit 9 are at the H level. .

The circuit operation after the AND circuit is the same as that of the first embodiment. When the output of the AND circuit becomes H level, the thyristor 6 is turned ON, the trip coil is excited, and acts on the contact switching mechanism (not shown). The contact device 8 is opened.

FIG. 6 is a time chart of the operation of the second embodiment shown in FIG. 5 when the current flowing through the circuit breaker overflows. In the figure, the waveform (a) is a current waveform of the overflow flowing through the circuit breaker, and at the same time, the output voltage of the current / voltage detecting means 1 in FIG. 3 is similar to the waveform (a).

(B) is an output waveform of the differentiating circuit 2;
When the waveform in (a) is a sine wave, the waveform in (b) is s
In the first half before the waveform of (a) reaches the peak value from zero, it becomes the same polarity as the waveform of (a), and the second half of the waveform of (a) returns from the peak value to zero in the first half until the waveform of (a) reaches the peak value. Then, the polarity is opposite to that of the waveform (a).

The waveform (d) is the output of the polarity judging circuit 4, and the first half in which the waveform (a) has the positive polarity and the waveform (b) has the positive polarity has the same polarity as each other. The output is at the L level, and the waveform of (a) has a positive polarity and the waveform of (b) has a negative polarity.
Level.

(E) is an output waveform of the threshold circuit 3,
Inside the threshold circuit, the output waveform of the differentiating circuit 2 (b)
Is used to detect whether the waveform reaches an appropriately determined threshold level a. In this example, by setting the threshold level a to a level slightly higher than the peak of the absolute value of (c) in the latter half of (c) (the range where the waveform of (d) is at the H level), The output of the threshold circuit 3 remains at the L level as shown in (e).

(F) is an output waveform of the voltage threshold circuit, and the voltage (h) between both electrodes of the circuit breaker detected by the voltage detection circuit 8 in FIG. It detects whether it reaches the above. When the voltage is equal to or higher than the threshold, the output is set to the H level.

(G) shows the output of the AND circuit 5 at this time. The output of (D) becomes H level in the latter half of the waveform, and the output (F) of the voltage threshold circuit becomes H level. Since the output (e) of the threshold circuit 3 remains at the L level, AND
The output of the circuit also remains at L level, the thyristor 6 is not tripped, and the trip coil is not driven.
0 does not open.

FIG. 7 is a time chart in the case where the current flowing through the circuit breaker is a short circuit due to a code fault with a peak value of 280A. The waveform in this case is characterized in that the conduction time width of each half-wave current is shorter than that of the sine wave as shown in FIG.

In the figure, the waveform (a) is the current waveform of the short-circuit current flowing through the circuit breaker, and at the same time, the output voltage of the current / voltage detecting means 1 in FIG. 5 is similar to the waveform (a).

(B) is an output waveform of the differentiating circuit 2;
The magnitude of the gradient with respect to time of the waveform (a) at that time is output. In the first half of the waveform (a) from zero to the peak value, it has the same polarity as the waveform (a),
In the second half, where the peak value of the waveform (a) returns to zero,
The polarity is opposite to that of the waveform (a).

The waveform (d) is the output of the polarity judging circuit 4, and the first half in which the waveform (a) has the positive polarity and the waveform (b) has the positive polarity has the same polarity as each other. The output is at the L level, and the waveform of (a) has a positive polarity and the waveform of (b) has a negative polarity.
Level.

(E) is an output waveform of the threshold circuit 3,
Inside the threshold circuit, the output waveform of the differentiating circuit 2 (b)
Is determined as shown in FIG. 6C to detect whether the waveform reaches the threshold level a determined in FIG. 6C. In this example, since the width of the current is narrower than that in the example of FIG. 6, if the peak value of the short-circuit current is the same as in the example of FIG. 6 and can exceed the level of the threshold value a determined in FIG. 6, so that the output of the threshold circuit 3 has an absolute value of (c) as shown in (e). The H level is set at two points, the rise and fall of the short-circuit current exceeding the threshold value a.

(F) is an output waveform of the voltage threshold circuit 9, and when a code fault occurs, the voltage (h) between both poles of the circuit breaker is set to an appropriate threshold value at which the trip coil can operate. When the voltage is equal to or higher than b, the output goes high.

(G) shows the output of the AND circuit 5 at this time. In the first half of the waveform, the output (e) of the threshold circuit becomes H level, but the output of the polarity discrimination circuit 4 (d) becomes L. Therefore, the output of the AND circuit 5 is also at the L level, but in the latter half of the waveform, the polarity determination circuit 4 (d)
Changes to the H level, and while the output (f) of the voltage threshold circuit 9 is at the H level, the waveform of (e) changes to H level.
When the level becomes the level, the output waveform of the AND circuit 5 becomes H level, the thyristor 6 is turned on, the trip coil 7 is attracted, and the contact 10 is opened.

As described above, in FIG.
(C) If the magnitude of the current flowing through the circuit breaker is set to a constant value by setting the level to a level slightly higher than the peak value of the waveform, the sine wave does not work, but the short-circuit current of the code fault as shown in FIG. Then, an operating circuit breaker can be configured.
In addition, by taking AND of the three conditions of the output of the voltage threshold circuit 9, the threshold circuit 3, and the polarity determination circuit 4,
Compared to the embodiment of FIG. 1, even when the short-circuit current has a sinusoidal waveform, the peak value becomes larger than the example shown in FIG. ,
The timing of the H level of the threshold (e) and the H level of the voltage threshold circuit (f) are shifted as shown in FIG. 8, so that the trip coil does not operate, and only at the time of discharge short-circuit current due to a code fault as shown in FIG. A circuit breaker that operates reliably can be configured.

The operation time chart of FIG. 8 will be described below.

FIG. 8A shows a sine-wave short-circuit current having a larger peak value than that shown in FIG. 6A. (C)
Is the absolute value of the output (b) of the differentiating circuit 2 corresponding to (c) in FIG. 6, and since the absolute value of the short-circuit current in (a) is larger than the current shown in FIG. At the beginning and the end of the waveform, the gate-cathode voltage exceeds the threshold value a as shown at (c), and the output (e) of the threshold circuit 3 becomes H level at the beginning and the end of the half wave. The voltage detection circuit 8 is (h)
The voltage between the two poles of the circuit breaker is detected as shown in the following. At the timing when the output (e) of the threshold circuit 3 becomes H level,
Since the voltage between both electrodes is lower than the threshold value b determined by the voltage threshold circuit 9 and the voltage threshold circuit 9 is at the L level, the output of the AND circuit remains at the L level, and the trip coil operates in the attracting operation. The contact device 10 does not perform the opening operation. That is, the short-circuit current is a sine wave as an operating condition, and if the peak value is near the above-mentioned peak current of the overflow, the malfunction does not occur reliably even if the peak value is slightly increased, and the current waveform of the discharge short-circuit current due to a code accident is generated. Then, an operating circuit breaker can be configured.

FIG. 9 is a view showing a third embodiment.
This is an embodiment of claim 5.

In FIG. 9, reference numeral 20 denotes a current transformer A, which is arranged at one pole of the circuit breaker and outputs a voltage proportional to the differential value of the short-circuit current waveform flowing in the main circuit of the circuit breaker. That is, FIG.
It corresponds to the function of the current-voltage conversion means 1 and the differentiation circuit 2 in the middle.

Reference numeral 21 in FIG. 9 denotes a voltage dividing resistor for dividing the voltage generated by the current transformer 20 between the gate and the cathode of the thyristor 22. For example, two carbon film resistors are used. A voltage equal to or higher than a predetermined value is generated at both ends of the resistance between the gate and the cathode.

In FIG. 9, reference numeral 22 denotes a thyristor A, to which an output of the current transformer A is connected via a voltage dividing resistor 21 to a gate and a cathode. At the time of connection, taking the cathode side of the thyristor A22 as a reference of potential, for example, when a short-circuit current of the polarity (a) in FIG. When the waveform is divided into the first half of the waveform starting from zero and reaching the peak, and the second half of the waveform from the peak to returning to zero, the output voltage of the current transformer during the period from the peak to returning to zero is properly determined. The connection polarity between the secondary winding of the current transformer and the gate-cathode of the thyristor A22 is selected so that the thyristor A22 can be turned on when the threshold value is exceeded. That is, it corresponds to the functions of the threshold circuit 3, the polarity determination circuit 4, and the AND circuit 5 in FIG. In addition,
In FIG. 9, under the condition that a short-circuit current of the polarity (a) flows, the voltage of one pole 34 of the main circuit of the circuit breaker is 0 V, and the voltage of the other pole 35 is positive.

The thyristor A22 applies the voltage generated by the current transformer A between the cathode and the gate, and when receiving a voltage equal to or higher than a predetermined value, short-circuits between the anode and the cathode to turn on.

When the thyristor 22 is turned on and the voltage of the commercial AC voltage is at a voltage at which the trip coil 7 can be attracted at the timing when the thyristor 22 is turned on, the trip coil 7 is rectified by the diode A23. When it is excited by a power supply, it acts on a contact opening / closing mechanism (not shown) to open the contact device 10. Even if the thyristor A22 is turned on, if the voltage between the two poles of the circuit breaker is equal to or less than the trip coil trip operation voltage at that timing, the trip coil is energized and the energized voltage value is low, and the attraction operation is not performed. The contact device 10 is not opened. That is, it also has the functions of the voltage detection circuit 8, the voltage threshold circuit 9, and the AND circuit in FIG.

The current transformer A20 shown in FIG. 9 detects, for example, a short-circuit current having a polarity in the direction (a) shown in FIG. 6 and operates the trip coil 7 by the thyristor A22.
Although the contact device 10 is opened, the gate-cathode voltage of the thyristor 22 does not become a forward voltage (a state in which the gate side is high) with a short-circuit current having a polarity opposite to that shown in FIG. Since the voltage polarity of one pole 34 of the circuit breaker becomes + and the voltage polarity of the other pole 35 becomes 0 V, the thyristor 22 does not operate and the trip coil 7 cannot operate.

Therefore, the current transformer B30, the voltage dividing resistor 31, and the thyristor B3 shown in FIG.
2. The diode B33 detects a short-circuit current of the opposite polarity to that shown in FIG. 6A, and the thyristor 32 operates the trip coil 7 to open the contact device 10.

As a result, a short-circuit current of the opposite polarity to that shown in FIG. 6A can be detected, and detection and interruption can be performed with the same operation time regardless of the polarity.

The current transformers A20 and B30 are means for converting a short-circuit current into a voltage, and correspond to the function of the current / voltage conversion means 1 in FIG. Further, the output voltage is proportional to the time derivative of the current, and also has the function of a differentiating circuit.

The current transformers A20 and B30 are connected via the voltage dividing resistors 21 and 31, respectively, so that the output of the current transformer until the short-circuit current of the detected polarity returns from the current peak to zero, respectively. Thyristor A20,
Since the polarity is selected so as to trigger B30 between each gate and cathode, it functions in the same manner as the threshold circuit 3, the polarity determination circuit 4 and the AND circuit 5 in FIG.

Even if each thyristor is turned on, the trip coil 7 is turned on when the sine wave voltage is just before the end of the sine wave voltage and the voltage between both poles of the circuit breaker has not reached the coil trip voltage. , Contact device 10
Does not open. That is, it functions similarly to the voltage detection circuit 8, the voltage threshold circuit 9, and the AND circuit 5 in FIG.

As described above, the circuit configuration of the third embodiment shown in FIG. 9 has the same functional effects as those of the second embodiment shown in FIG.

FIG. 10 shows a fourth embodiment of the present invention, which is different from the third embodiment shown in FIG. 9 in that the current transformers A20 and B30 in FIG. In the embodiment of FIG. 10, the current transformer A4
0 and the current transformer B50, two secondary windings are wound around the same core arranged at one pole of the circuit breaker, one of which is a current transformer A40, and the other winding is This is a current transformer B50. The other configuration is the same, and the operation of the circuit is the same as that of the third embodiment.

The operation of the third and fourth embodiments will be described below in detail with reference to a waveform time chart.

FIG. 11 is a time chart when the current flowing through the circuit breaker is a sine wave.

(B) is a waveform of a voltage generated at both ends of the secondary winding of the current transformer A20. When the waveform of the short-circuit current (a) flowing on the primary side is a sine wave, (b) Waveform is s
In the first half before the waveform of (a) reaches the peak value from zero, it becomes the same polarity as the waveform of (a), and the second half of the waveform of (a) returns from the peak value to zero in the first half until the waveform of (a) reaches the peak value. Then, the polarity is opposite to that of the waveform (a).

(C) shows the secondary winding output line of the current transformer A20 and the thyristor so that the output of the current transformer A20 triggers the thyristor 22 in the latter half from the peak of the sine wave to return to zero. This is the gate-cathode voltage of the thyristor A22 when the gate-cathode of A22 is connected.

(E) shows the operation of the thyristor, and when the waveform (c) reaches the appropriately determined threshold level a, the thyristor turns on. In this example, the thyristor is set by setting the threshold level a to a level slightly higher than the peak of the waveform of (c) in the latter half of (c) (the range where the waveform of (c) has a positive polarity). Does not perform the ON operation as in (e).

Next, the case where the sine wave short circuit current becomes larger than that of the example of FIG. 11 and the thyristor is triggered will be described.
This will be described with reference to FIG. 13A shows a sine-wave short-circuit current larger than that of FIG. 11A. (C)
Is the gate-cathode voltage of the thyristor A22 corresponding to (c) of FIG. 11, and since the short-circuit current of (a) is larger than that shown in FIG. 11, the gate-cathode voltage is increased at the last part of the half-wave waveform. Exceeds trigger voltage a, thyristor A22
Operates ON as shown in (e). However, at that time, the power supply voltage (at the timing when the thyristor is turned on) is lower than the level c at which the trip coil can operate, as shown in (h), and the trip coil does not perform the suction operation. Therefore, the contact device 10 does not perform the opening operation.

FIG. 12 is an operation time chart of the third and fourth embodiments when the current flowing through the circuit breaker is a short circuit due to a code fault with a peak value of 280 A. The waveform of the short-circuit current in this case is different from the case of the sine wave shown in FIG.
It is characterized in that the conduction time width of each half-wave current is shortened.

In the figure, the waveform (a) is the current waveform of the short-circuit current flowing through the circuit breaker.

In the figure, (b) shows the current transformer A2 in FIG.
This is a voltage waveform generated at 0, and generates a voltage proportional to the time differential value of the short-circuit current. In the first half of the waveform (a) from the zero to the peak value, the polarity is the same as that of the waveform (a), and in the second half where the peak value of the waveform (a) returns to zero, the waveform of the (a) It has the opposite polarity.

The secondary winding of the current transformer A20 is connected to the thyristor A of 22 in the latter half of the period from the peak of the short-circuit current to zero.
Is connected between the gate and the cathode of the thyristor 22 with a polarity that turns on the thyristor 22, and the gate voltage to the cathode of the thyristor A22 has a waveform as shown in FIG.

(E) is an operation waveform of the thyristor A22. In this example, since the width of the current is narrower than that of the example of FIG. 11, if the peak value is the same as that of the example of FIG.
The slope (differential value) from time to time becomes larger than that in the example of FIG. 11 and can exceed the level of the threshold value a defined in FIG. 11, and therefore, is applied between the gate and the cathode of the thyristor. The thyristor A22 is turned on at the falling portion of the short-circuit current where the voltage exceeds the threshold a as shown in FIG.

At the timing when the thyristor A22 is turned on, the trip coil 7 includes the diode A23.
And a voltage is applied to both ends of the trip coil. In the case of FIG. 12, the conduction time width of the short-circuit current waveform (a) is narrower than the half-wave of the sine wave.
The turn-on timing of the thyristor A22 is also earlier than in the case of FIG. 11, and the power supply voltage waveform shown in (h) corresponds to the operating voltage level C of the trip coil 7.
Because of the above range, the trip coil 7 performs the suction operation by turning on the thyristor A22, and the contact device 10
Can be opened.

As described above, in FIG. 11, when the threshold a is set to a level slightly higher than the peak value of the waveform (c), when the magnitude of the current flowing through the circuit breaker is a constant value, A circuit breaker that does not operate reliably with a sine wave but operates with a discharge short-circuit current due to a code fault as shown in FIG. 12 can be configured.

【effect】

As described above, according to the present invention, the short-circuit current value is smaller than the sine wave and the inrush current or the rush current does not malfunction, and the conduction time width of the half-wave current is changed to the sine wave. On the other hand, in the case of a discharge short-circuit current caused by a short-circuit accident of the cord, the contact device is instantaneously opened to obtain a circuit breaker for wiring that prevents the occurrence of fire.

[Brief description of the drawings]

FIG. 1 is a diagram of a first embodiment of the present invention.

FIG. 2 is an operation time chart when a sine wave is short-circuited in the first embodiment.

FIG. 3 is an operation time chart in the case of a short circuit in a code accident of the first embodiment.

FIG. 4 is an operation time chart of the first embodiment when the phase at which the current starts to flow in FIG. 2 is delayed.

FIG. 5 is a diagram of a second embodiment of the present invention.

FIG. 6 is an operation time chart when a sine wave is short-circuited in the second embodiment.

FIG. 7 is an operation time chart in the event of a short circuit caused by a code according to the second embodiment.

FIG. 8 is an operation time chart in the case of a sine wave short circuit of the second embodiment.

FIG. 9 is a diagram of a third embodiment of the present invention.

FIG. 10 is a diagram of a fourth embodiment of the present invention.

FIG. 11 is an operation time chart in the case of a sine wave short circuit of the third and fourth embodiments.

FIG. 12 is an operation time chart in the case of a code fault short-circuit of the third and fourth embodiments.

FIG. 13 is an operation time chart in the case of a sine wave short-circuit of the third and fourth embodiments.

FIG. 14 Waveform of overflow current

FIG. 15 is a waveform of a discharge short circuit current due to a code fault.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Current-voltage conversion means 2 Differentiating circuit 3 Threshold circuit 4 Polarity judgment circuit 5 AND circuit 6 Thyristor 7 Trip coil 8 Voltage detection circuit 9 Voltage threshold circuit 10 Contact device 20 Current transformer A 21 Voltage dividing resistor 22 Thyristor A 23 Diode A 30 Current transformer B 31 Voltage dividing resistor 32 Thyristor B 33 Diode B 40 Current transformer A 50 Current transformer B ************ Fig. 8 Explanation Manuscript (draft) ***
************

Next, a case where the sine-wave short-circuit current becomes larger than that in the example of FIG. 6 will be described with reference to FIG.

FIG. 8A shows a sine-wave short-circuit current larger than FIG. 11A. (C) is the absolute value of the output of the differentiating circuit 2 corresponding to (c) in FIG.
Since the absolute value of the short-circuit current is larger than the current shown in FIG. 6, the gate-cathode voltage exceeds the threshold value a at the beginning and end of the half-wave waveform, and the thyristor A22 is turned on as shown in FIG. Operate. The voltage detection circuit 8 detects the voltage between the two poles of the circuit breaker as shown in (h). At the timing when the thyristor is turned on as shown in (e), the threshold value b determined by the voltage threshold circuit 9 is used. The voltage between both electrodes is lower,
Therefore, the output of the AND circuit remains at the L level, the trip coil does not perform the attraction operation, and the contact device 10 does not perform the opening operation.

Claims (7)

[Claims] A contact of a contact switching device is opened when a differential value of a short-circuit current is detected and a differential value of a polarity opposite to a polarity direction of the short-circuit current becomes equal to or more than an appropriately determined threshold value. A circuit breaker for wiring. 2. A current transformer for converting a short-circuit current into a voltage and outputting the voltage, a first half of a waveform of a half-wave of the short-circuit current starting from zero and reaching a peak, and a second half of returning from the peak to zero. When the output voltage of the current transformer during the period from the peak to the return to zero exceeds the threshold, the contact is opened by the detector that drives the trip coil and the suction drive of the trip coil. Circuit breaker composed of a switching mechanism. 3. A current-voltage conversion means for converting a short-circuit current into a voltage, a differentiation circuit for outputting a differential value of an output signal of the current-voltage conversion means, and an absolute value of an output voltage of the differentiation circuit being appropriately determined. If the output voltage is equal to or higher than the threshold value, a threshold circuit that sets the output to the H level is compared with the polarity of the voltage output by the current-voltage converter and the polarity of the voltage output by the differentiating circuit. A polarity determining circuit for setting the output to the H level if the polarities of the differential values of the current are different; and an AND circuit for operating the thyristor when the outputs from the differentiating circuit and the polarity determining circuit are both at the H level. A thyristor in which the gate is connected to the output of the AND circuit, the anode side is connected to the trip coil, the cathode side is connected to one pole of the circuit breaker, and the trip coil has one end connected to the anode of the thyristor The circuit breaker is composed of a contact switching mechanism for the contact device and opened by energization of the trip coil. 4. A current-voltage conversion means for converting a short-circuit current into a voltage, a differentiation circuit for obtaining a differential value of a signal output from the current-voltage conversion means, and an absolute value of an output voltage of the differentiation circuit being appropriately determined. If the threshold value is equal to or higher than the threshold value, the polarity of the voltage output by the current-to-voltage converter and the polarity of the voltage output by the differentiating circuit are compared with a threshold circuit that sets the output to the H level. If the polarity and the polarity of the differential value of the short-circuit current are different polarities, a polarity determination circuit that sets the output to H level, a voltage detection circuit that detects the voltage between both electrodes of the circuit breaker, and a signal output by the voltage detection circuit If the outputs from the voltage threshold circuit that sets the output to the H level if it is equal to or more than a predetermined value, and the outputs from the differentiating circuit, the polarity determination circuit, and the voltage threshold circuit are all at the H level, AN for operating thyristor Circuit, a gate connected to the output of the AND circuit, a thyristor with the anode connected to the trip coil and a cathode connected to one pole, a trip coil with one end connected to the anode of the thyristor, A circuit breaker comprising a contact switching mechanism for opening a contact device. 5. A current transformer for converting a short-circuit current into a voltage and outputting the voltage, a thyristor receiving an output of the current transformer at a gate, a trip coil supplied with current by turning on the thyristor, and a current supplied to the trip coil. It consists of a switching mechanism that opens and closes contacts, and the connection between the current transformer and the thyristor consists of the first half of the half-wave waveform of the short-circuit current starting from zero and reaching the peak, and the second half of the waveform until the peak returns to zero. A circuit breaker characterized in that the output voltage in the latter half, which returns to zero from the peak when divided into two, is connected to the polarity that triggers the thyristor. 6. A current transformer A which converts a short-circuit current into a voltage and outputs the voltage. An output of the current transformer A is connected to a gate and a cathode via a voltage dividing resistor, and the cathode is connected to one pole of the circuit breaker. A thyristor A connected thereto; a diode B having an anode connected to the cathode of thyristor A and a cathode connected to the anode of thyristor A;
A current transformer B that converts a short-circuit current into a voltage and outputs the voltage; and a thyristor B that connects the output of the current transformer B to a gate and a cathode via a voltage dividing resistor and connects the cathode to the other pole of the circuit breaker. A diode A having an anode connected to the cathode of thyristor B and a cathode connected to the anode of thyristor B; a trip coil having a coil winding connected between the anode of thyristor A and the anode of thyristor B; The current transformer A and the connection of the thyristor A and the connection of the current transformer B and the thyristor B have a half-wave waveform of the short-circuit current starting from zero and having a peak. The output voltage of each current transformer in the first half before reaching the peak and the latter half from the peak to zero is divided by each thyristor. Circuit breaker, characterized in that formed by connecting the trigger polarity. 7. The current transformer A and the current transformer B are formed by winding two secondary windings around the same core, one of the windings being a current transformer A, and the other winding being a current transformer. 7. The circuit breaker according to claim 6, wherein the circuit breaker is a circuit breaker. [0001]