JP2001157355A - Wiring breaker - Google Patents

Abstract

PROBLEM TO BE SOLVED: To cut off a wiring route instantaneously when a discharge-type short circuit such as a short circuit between cord conductors, a tracking short circuit, etc., occurs while the wiring route is not cut off when an overflow current or a rush current is applied. SOLUTION: A current transformer 2 which detects a wiring route current, a filter circuit 3 which extracts a commercial frequency component from the current detected by the current transformer 2, a peak value conversion circuit 6 which detects the peak value of the extracted commercial frequency component and holds the peak value, a peak detection circuit 7 which detects the peak value of the current containing a discharge-type short circuit current from the current detected by the current transformer 2, and a comparison circuit 8 which outputs the operation signal of a thyristor drive circuit 9 when the output of the peak detection circuit 7 exceeds a threshold which is the output of the peak value conversion circuit 6 are provided. When a thyristor 10 is turned on, a trip coil 11 is made to operate to open contact devices 13.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a circuit breaker for breaking a wiring path when a short-circuit current or an overcurrent flows, and more particularly to a wiring breaker that detects and detects a discharge-like short-circuit current caused by tracking. About the vessel.

[0002]

2. Description of the Related Art A conventional circuit breaker for wiring uses a dashpot type electromagnetic coil for short-circuit current and a bimetal for overcurrent so as to respond to both short-circuit current and overcurrent. When one of them is detected, the cutoff operation is performed.

[0003]

However, in order to avoid a malfunction due to an overflow current or an inrush current generated when the load is turned on as shown in FIG. The detected current is set to a value larger than the expected inrush current, and is usually set to about 1000% of the rated current of the circuit breaker. In the case of a residential circuit breaker, the operating current for instantaneous interruption is set to 200 A because the rating is usually 20 A (ampere).

[0004] However, in the short circuit, in addition to the state in which a large current is generated as described above, the insulation of the insulation film of the cord connected to the outlet is deteriorated, or the film is melted by heating or the like. In some cases, a short circuit in the form of a discharge may occur.
It is known that it is about 0A. Since such a short-circuit current waveform is not a sine wave but a discontinuous discharge-like current waveform as shown in FIG. 7 (b), it cannot be detected by a conventional electromagnetic coil or bimetal. On the other hand, there was no interruption operation. However, it has been confirmed that a fire may occur even by such a short-circuit current, and there has been a demand for a wiring breaker that can perform a breaking operation even for such a short-circuit current.

In view of the above problems, the present invention does not operate with an overflow current or an inrush current, and instantaneously establishes a wiring path against a discharge-like short-circuit current such as a cord short circuit or a tracking short circuit. It is an object to provide a disconnecting circuit breaker for wiring.

[0006]

In order to solve the above-mentioned problems, a first aspect of the present invention is a wiring interrupter that opens a wiring path from a power line by opening a contact device when an abnormal current flows. A commercial waveform extracting means for extracting a current waveform of a commercial frequency flowing through the wiring path, a first peak detecting means for detecting a peak value thereof, and a peak of a current waveform including a discharge-like short-circuit current flowing through the wiring path. Second peak detecting means for detecting a value, a comparing means for outputting a signal when a detected value of the second peak detecting means exceeds a detected value of the first peak detecting means, and receiving an output of the comparing means. Operating means for opening the contact device.

According to a second aspect of the present invention, in the first aspect of the present invention, the operating means includes a thyristor which operates by receiving an output of the comparing means, and a trip coil which is driven by the operation of the thyristor. .

According to a third aspect of the present invention, in the first or second aspect of the invention, the comparing means uses the detected value of the first peak detecting means as a threshold value and the detected value of the second peak detecting means exceeds the threshold value. During that time, a signal is output.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a circuit block diagram of a circuit breaker according to the present invention, in which 1 is a main circuit of a circuit breaker connected to a wiring path, 2 is a current transformer provided in a main circuit 1, The wiring path current detected by the filter circuit 3
After passing through an absolute value circuit 4, an integration circuit 5, and a peak value conversion circuit 6, a detection value of a detection circuit 7 for detecting a peak value from a detection current of the current transformer 2 is compared with a detection value of a detection circuit 7 by a comparison circuit 8. The thyristor 10 is turned on via the drive circuit 9, the trip coil 11 is operated, and the contact device 13 is opened by the action of a contact opening / closing mechanism (not shown).

The operation of each circuit block will be described in detail with reference to the waveform explanatory diagram of FIG. 2. When the current transformer 2 flows into the main circuit 1, for example, a discharge-like short-circuit current as shown in FIG. When the superimposed current waveform is detected, the filter circuit 3 removes high-frequency components such as a discharge-like short-circuit current and noise, and FIG.
Only the commercial frequency waveform shown in (b) is extracted and passed. Then, the absolute value circuit 4 performs full-wave rectification as shown in FIG. 2C, integrates and amplifies with the integration circuit 5, and the peak value conversion circuit 6 converts the peak of the full-wave rectification waveform into a DC voltage value. . In FIG. 2C, L is the output waveform of the absolute value circuit, M is the output waveform of the integration circuit, and N is the output waveform of the peak value conversion circuit.

The peak detection circuit 7 sequentially detects the peak value of the detected current waveform, that is, the peak value of the discharge-like short-circuit current waveform superimposed on the commercial frequency current waveform as shown in FIG. Output a triangular wave with the peak value at the top. The comparison circuit 8 compares the output of the peak detection circuit 7 with the peak value N, which is the DC voltage value converted by the peak value conversion circuit 6, as a threshold (FIG. 2E). As shown in e), the times t1, t2
, A high-level output is generated (FIG. 2 (g)). Then, the thyristor drive circuit 9 sends a trigger signal to the thyristor 10 when the output voltage of the comparison circuit 8 is at a high level.

When the trigger signal of the thyristor drive circuit 9 exceeds a certain value, the thyristor 10 is turned on by short-circuiting between the anode and the cathode, and is activated by flowing a current from the main line 1 to the trip coil 11 via the diode 12. The contact device 13 is opened. In addition, thyristor,
Actuating means for opening the contact device by the trip coil, the diode, and the contact switching mechanism is formed.

As described above, the filter circuit is provided as the commercial waveform extracting means, the absolute value circuit, the integrating circuit, and the peak value converting circuit are provided as the first peak detecting means, and are compared with the peak detecting circuit as the second peak detecting means. Difference, so even if a discharge-like short-circuit current such as tracking short-circuit or cord short-circuit occurs, it is instantaneously detected and the wiring path is opened, thus ensuring the occurrence of fire. Can be prevented. And for overflow current and inrush current,
Since the waveform does not change even after passing through the filter circuit, there is no difference between the output value of the peak value conversion circuit 6 and the output value of the peak detection circuit 7, the output of the comparison circuit does not become high level, and the contact device opens. Never do. Further, by making the output waveform of the peak detection circuit a triangular wave, it is possible to more reliably detect a short-circuit current having a narrow discharge-like time width.
It should be noted that short-circuit current and overcurrent may be dealt with by using a known dashpot-type electromagnetic coil or bimetal.

FIG. 3 shows a second embodiment, in which the first embodiment is used.
This embodiment is different from the first embodiment in that an absolute value circuit, an integration circuit and a peak value conversion circuit are not provided, but a high-frequency component is deleted by a filter circuit 3 to output a current waveform of a commercial frequency, and the peak value is detected. The point that the commercial peak detection circuit 15 is provided and the peak detection circuit are different, and the other configuration is the same.

The operation of this embodiment will be described with reference to the waveform explanatory diagram of FIG. When a circuit current on which a discharge-like short-circuit current is superimposed as shown in FIG. 4A flows through the main circuit 1, the commercial peak value detection circuit 15 determines the peak value P of the current waveform of the commercial frequency shown in FIG. The peak value P of the waveform including the discharge short-circuit current detected by the second peak detection circuit 16 whose output waveform is sharpened by the peak detection circuit 7 is sequentially compared by the comparison circuit 8, and the peak value P is set as a threshold value. If the peak value Q exceeds this threshold value, a high-level output as shown in FIG.
Send to Then, the thyristor drive circuit 9 receives the signal and outputs a thyristor drive signal to turn on the thyristor 10. When the thyristor 10 is turned on, a current flows from the main line 1 to the trip coil 11 via the diode 12 to operate, and the contact device 13 is opened.

As described above, since the peak is directly detected by the commercial peak detecting circuit, even if the absolute value circuit, the integrating circuit, and the peak value converting circuit are omitted, the discharge short circuit current can be detected and the cutoff operation can be performed. Can be simplified. Further, like the second peak detection circuit 16, the peak detection waveform including the discharge short-circuit current may be narrowed in accordance with the operation characteristics of the operation means.

FIG. 5 shows a third embodiment. The first embodiment differs from the first embodiment in that a pulse classification circuit 18 is provided after a comparison circuit.
And the other configuration is the same. The pulse classification circuit 18 is a circuit that classifies and removes a waveform having an extremely narrow pulse width such as a noise or a discharge waveform that may be superimposed on a waveform of a commercial frequency. The pulse width is output by setting the width of the waveform to a pulse width. The pulse classification circuit 18 separates this signal to remove a waveform having an extremely narrow pulse width such as noise.

The operation of this embodiment will be described with reference to the waveform explanatory diagram of FIG. When a discharge-like short-circuit current or a current on which noise is superimposed as shown in FIG. 6A occurs in the main circuit 1, the comparison circuit 8 sets the peak value of the commercial frequency current as a threshold value as shown in FIG. Fig. 6 for waveforms beyond that
A high-level signal as shown in (c) is output. Then, a signal having a narrow pulse width is deleted by the pulse classification circuit, and the waveform shown in FIG. 6D is output. Subsequent circuit operations are the same as those of the first embodiment, and the thyristor drive circuit 9 turns on the thyristor 10 to release the trip coil 1.
1 is excited to open the contact device 13.

As described above, by providing the pulse classification circuit after the comparison circuit, even if the comparison circuit operates due to noise or the like having a frequency higher than the discharge short-circuit current, the thyristor does not operate according to the signal. A highly accurate operation can be performed.

[0020]

As described in detail above, according to the present invention,
It does not operate with an overflow current or an inrush current, and when a short-circuit current in the form of a discharge having a short-circuit current value smaller than these flows is detected, the wiring path can be instantaneously released from the power line.

[Brief description of the drawings]

FIG. 1 is a circuit block diagram of a circuit breaker showing an example of an embodiment of the present invention.

FIGS. 2A and 2B show waveforms of respective parts in FIG. 1, wherein FIG. 2A shows a detection waveform of a current transformer, FIG. 2B shows a filter circuit output waveform, and FIG. 2C shows an absolute value circuit, an integration circuit, and a peak value conversion circuit (D) is the output waveform of the peak detection circuit, (e) is the comparison waveform of the comparison circuit, (f) is the comparison result waveform exceeding the threshold value, (g) is the output waveform of the comparison circuit and the output waveform of the thyristor drive circuit. It is.

FIG. 3 is a circuit block diagram showing a second embodiment of the present invention.

4A and 4B show waveforms of main parts of FIG. 3, wherein FIG. 4A shows a detected waveform of a current transformer, FIG.
The output value of the peak detection circuit, and (c) is the output waveform of the comparison circuit.

FIG. 5 is a circuit block diagram showing a third embodiment of the present invention.

6A and 6B show waveforms of main parts in FIG. 5, wherein FIG. 6A shows a detection waveform of a current transformer, FIG. 6B shows a comparison waveform of a comparison circuit, FIG. 6C shows an output waveform of the comparison circuit, and FIG. It is an output waveform of a classification circuit.

FIG. 7A is an explanatory diagram of an overflow / inrush current waveform,
(B) is an explanatory view of a discharge-like short-circuit current waveform.

[Explanation of symbols]

1. Main circuit, 2. Current transformer, 3. Filter circuit, 4
..Absolute value circuit, 5 ... Integration circuit, 6 ... Peak value conversion circuit, 7 ... Peak detection circuit, 8 ... Comparison circuit, 9 ...
Thyristor drive circuit, 10 thyristor, 11 trip coil, 13 contact device, 15 commercial peak detection circuit, 16 second peak detection circuit, 18 pulse separation circuit.

Claims (3)

[Claims] 1. A circuit breaker for opening a wiring path from a power line by opening a contact device when an abnormal current flows, and a commercial circuit for extracting a current waveform of a commercial frequency flowing through the wiring path. Waveform extracting means, first peak detecting means for detecting a peak value thereof, second peak detecting means for detecting a peak value of a current waveform including a discharge-like short-circuit current flowing in the wiring path, and second peak detecting means. A comparator for outputting a signal when the detected value exceeds a detected value of the first peak detecting unit; and an operating unit for receiving the output of the comparing unit and opening the contact device. Breaker for wiring. 2. The circuit breaker according to claim 1, wherein the actuating means includes a thyristor that operates in response to an output of the comparing means, and a trip coil that is driven by the operation of the thyristor. 3. The wiring according to claim 1, wherein the comparison means outputs a signal while the detection value of the second peak detection means exceeds the threshold value, using the detection value of the first peak detection means as a threshold value. Circuit breaker.