JPH1014094A - Breaker for wiring - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to detect even an intermittent current and cut off the operation by letting a tripping coil make a attracting operation and tripping a contact switching mechanism open a contact device only when the current of a commercial frequency component is in an overload or short-circuit state and a high frequency component is a specified value or above. SOLUTION: A filter circuit 13 passes current of a commercial frequency component through and a filter circuit 23 passes current of a high frequency component through. Threshold value circuits 12, 22 output H-level signals only when the outputs of amplifier circuits 11, 21 are specified threshold values and an AND circuit 3 outputs an H-level signal only when the outputs of the amplifier circuits 11, 21 are both H-level. When a thyristor 4 is turned on, a tripping coil 5 is excited by current rectified by a diode 6 and opens a contact device 7. By this method, the contact device is opened instantly and thereby a fire is prevented when a cord accident occurs wherein such discharing short circuit current as to include a high frequency component appears.

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 the present invention relates to a circuit breaker for breaking a circuit with a discharge-like short-circuit current generated by insulation breakdown of an insulator that cannot be detected by a conventional circuit breaker. Related to the vessel.

[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, the detection current of the instantaneous cutoff (detection cutoff current in a half cycle) is made smaller than that of the overflow or rush current in order to avoid a malfunction due to the overflow or rush current as shown in FIG. I couldn't do that. Generally, the operating current of the instantaneous interruption is one of the rated current of the circuit breaker for the reason described above.
000%. For example, the rated current of a circuit breaker used in a general house is 20 A, and the operating current for instantaneous interruption is about 200 A effective value. However, insulation deterioration of the film of the cord used to connect to the outlet, short-circuiting of the core due to melting of the film due to overheating,
In the discharge-type short circuit due to tracking, the short circuit current is from several tens to about 200 A. Further, the short circuit current is not a continuous sine wave but a discontinuous intermittent current as shown in FIG. In the case of the circuit breaker, no instantaneous shut-off operation was performed, and it took a long time to shut off. In the worst case, a short-circuit could cause a fire or fire.

The object of the present invention is shown in FIG.
, The magnitude of the short-circuit current is about several tens to 200 A, and even a discontinuous intermittent current, not a sine wave, can be instantaneously detected and cut off, and the above-mentioned overflow or rush current can be prevented. An object of the present invention is to provide a circuit breaker that does not malfunction.

[0004]

In order to achieve the above object, according to the present invention, first, a commercial frequency component of a short-circuit current generated by a discharge-type short circuit caused by insulation breakdown of an electric wire and , Both high frequency components are detected by the two current detectors, respectively, and the trip coil is attracted only when the commercial frequency component current is overloaded or short-circuited and the high frequency component is above a certain level. hand,
The contact opening / closing mechanism is pulled off to open the contact device. As a result, the two independent current detectors respectively provide a commercial frequency component as shown in FIG. 2A and a commercial frequency component as shown in FIG. Each of high frequency components is detected, and a series of operations after the trip coil is performed only when the commercial frequency component of a is in an overload or short circuit state and the high frequency component of b exceeds a predetermined fixed value. The circuit breaker does not operate with a current having a waveform having no high-frequency component such as an overflow or an inrush current as shown in FIG. Therefore, even if the sensitivity of the current detection unit on the commercial frequency side is set to be equal to or less than the overflow and the inrush current, the overcurrent without the high frequency component does not malfunction due to the inrush current and includes the current of the high frequency component. In the case of the above-mentioned insulation deterioration of the cord film, core short circuit due to melting of the film due to overheating, or discharge-type short circuit due to tracking, even a short circuit current smaller than the overflow or inrush current can be detected and cut off instantaneously. I can do it.

According to a second aspect of the present invention, a commercial frequency component and a high frequency component of a short-circuit current generated by a discharge-type short circuit caused by insulation breakdown of an electric wire are both converted into voltages and output. And two current detecting units for high frequency, two amplifying units for amplifying each voltage from each current detecting unit, and under the condition that each of the amplified voltages is equal to or more than a predetermined threshold value, A gate circuit section for closing the circuit,
A trip coil that is energized when the gate circuit is closed, a rectifier circuit that supplies power to the trip coil, and a contact switching mechanism that opens a contact device by energizing the trip coil; The threshold of
This value is selected as a value for determining whether or not an overload or a short circuit occurs. As a result, the current detecting unit for detecting the commercial frequency component and the current detecting unit for detecting the high frequency component detect a short-circuit current generated by a short-circuit due to insulation breakdown of an electric wire having a waveform as shown in FIG. 2 and a high-frequency component such as b in FIG. 2 are respectively detected, and a signal obtained by amplifying the detected signal is amplified by a threshold circuit at a threshold value which is equal to or greater than a threshold value respectively determined by both. Only when there is a current, the trip coil is energized by the gate circuit and the contact device is opened by the trip coil, so that high frequency components such as overflow and rush current as shown in FIG. The circuit breaker does not operate with a current having no waveform. Therefore, even if the sensitivity of the current detector on the commercial frequency side is set to be equal to or less than the overflow and the inrush current,
In case of the above-mentioned insulation deterioration of the cord film that contains high frequency component current without malfunction due to inrush current, core short circuit due to melting of the film due to overheating, or discharge short circuit due to tracking, overflow Even a short circuit current smaller than the inrush current can be instantaneously detected and cut off.

Third, according to the third aspect, two current transformers A and B penetrating the main circuit of the circuit breaker, and A which passes only the commercial frequency component from the voltage generated at both ends of the current transformer of A.
A filter circuit for passing only high frequency components from a voltage generated at both ends of the current transformer for B;
The output voltage of the A amplification unit for amplifying the output voltage of the A filter circuit, the B amplification unit for amplifying the output voltage of the B filter circuit, and the output voltage of the A amplification unit are not less than a predetermined fixed value. If the output voltage of the threshold circuit of A which makes the output an H level and the output voltage of the amplifying part of B are higher than a predetermined constant value, the output is made H level.
When both the output of the B threshold circuit and the outputs of the A and B threshold circuits are at H level, an AND circuit for operating the thyristor, and a gate connected to the output of the AND circuit, A thyristor with the anode connected to the trip coil and the cathode connected to one pole of the circuit breaker; a trip coil connected at one end to the anode of the thyristor; and the other end of the trip coil and the other pole of the circuit breaker. And a mechanism for opening the contact device when the trip coil is energized. The threshold value of the threshold circuit of A is such that the current of the commercial frequency component is overloaded or short-circuited. It is also selected as a value for determining whether or not there is. As a result, for the voltage A generated when the two current transformers A and B detect the current, for example, FIG.
A commercial frequency component such as a in FIG.
These high-frequency components are passed through a filter circuit, and a series of operations after the amplification unit are performed. As shown in FIG. 1, high-frequency components such as overflow and rush current are present. The circuit breaker does not operate with a current having a waveform that does not occur. Therefore, the sensitivity of the current detector on the commercial frequency side is
Even if it is set below the overflow or inrush current, there is no malfunction due to the overflow or inrush current, and the insulation of the above-mentioned cord film that contains high frequency component current is deteriorated, or the core wire is short-circuited due to melting of the film due to overheating. In the case of a discharge short circuit caused by tracking, even a short circuit current smaller than an overflow or an inrush current can be instantaneously detected and cut off.

A fourth aspect of the present invention provides a current transformer A for detecting only a commercial frequency component current that passes through a main circuit of a circuit breaker.
A current transformer B for detecting only a high-frequency component current that passes through the main circuit of the circuit breaker; an amplifier A for amplifying the output of the current transformer A; and an amplifier for the output of the current transformer B. A threshold circuit for outputting an H level when the output voltage of the A amplification section becomes higher than a predetermined value, and the output voltage of the B amplification section becomes higher than a predetermined value. When both the output from the B threshold circuit that outputs an H level and the outputs from the A and B threshold circuits are at the H level, an AND circuit that activates the thyristor, and a gate connected to the output of the AND circuit Thyristor with the anode side connected to the trip coil, the cathode side connected to one pole of the circuit breaker, the trip coil connected to the thyristor anode at one end, the other end of the trip coil and the other end of the circuit breaker. A diode connected between the A contact opening / closing mechanism for opening the contact device by energizing the lip coil is provided. The threshold value of the threshold circuit (A) determines whether the commercial frequency component is overloaded or short-circuited. I chose the value.
Thus, by providing the current transformer itself with the frequency characteristic, the filter circuit can be omitted, the circuit can be simplified, and the discharge caused by the insulation breakdown of the electric wire as shown in the waveform of FIG. Since a short-circuit current generated by a short circuit is detected, for example, a commercial frequency component as shown in FIG. 2A and a high frequency component as shown in FIG. 6B, a series of operations after the amplification unit are performed. The circuit breaker does not operate with a current having a waveform having no high frequency component such as an overflow or an inrush current as shown in FIG. Therefore, even if the sensitivity of the current detection unit on the commercial frequency side is set to be equal to or less than the overflow and the inrush current, the above-described code film including the high-frequency component current does not malfunction at the overflow and the inrush current. In the case of core short circuit due to insulation deterioration, melting of the film due to overheating, or discharge short circuit due to tracking, even a short circuit current smaller than an overflow or an inrush current can be detected and cut off instantaneously.

A fifth aspect of the present invention relates to a voltage generating section proportional to a current caused by two internal impedances A and B arranged in a main circuit of a circuit breaker, and a voltage generated at both ends of the voltage generating section of A, and A filter circuit for passing only a frequency component, A filter circuit for passing only high frequency components from a voltage generated at both ends of a voltage generator of B, and A
An amplification unit for amplifying the output voltage of the filter circuit of
Amplifying section of B for amplifying the output voltage of the filter circuit of B; a threshold circuit of A for setting the output to the H level if the output voltage of the amplifying section of A is higher than a predetermined value; If the output voltage of the unit is equal to or higher than a predetermined fixed value, the thyristor is turned on when the outputs from the B threshold circuit and the A and B threshold circuits are both at the H level. An AND circuit to be operated, a thyristor having a gate connected to the output of the AND circuit, an anode side connected to a trip coil, a cathode side connected to one pole of a circuit breaker, and a trip coil connected to the anode of the thyristor at one end. A diode connected between the other end of the trip coil and the other pole of the circuit breaker, and a mechanism for opening the contact device by energizing the trip coil, and the threshold circuit of the threshold circuit A Values are commercial laps The number component of the current, it also chose a value for determining whether a state of overload or short circuit. Thereby, a voltage generator proportional to the current due to the two internal impedances arranged in the main circuit of the circuit breaker,
For example, a commercial frequency component as shown in FIG. 2A and a high frequency component as shown in FIG. Are detected and a series of operations after the amplifying unit are performed. Therefore, the circuit breaker does not operate with a current having a waveform having no high-frequency component such as an overflow or an inrush current as shown in FIG. Therefore, even if the sensitivity of the current detector on the commercial frequency side is set to be equal to or less than the overflow and the inrush current,
In case of the above-mentioned insulation deterioration of the cord film that contains high frequency component current without malfunction due to inrush current, core short circuit due to melting of the film due to overheating, or discharge short circuit due to tracking, overflow In addition, a breaking operation can be performed instantaneously even with a short-circuit current smaller than the inrush current.

[0009]

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

FIG. 1 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, but the frequency component is commercial. It contains only frequency components.

FIG. 2 shows a short-circuit current waveform in the case of insulation deterioration of a film of a cord connected to an outlet, a short circuit of a core wire due to melting of the film due to overheating, or a discharge-type short circuit caused by tracking. At tens to hundreds of amps,
It is a current waveform characterized by including a basic commercial frequency component a and a high frequency component b.

FIG. 3 is a diagram of a first embodiment of the present invention.

In FIG. 3, reference numeral 1 denotes a current transformer A, which detects a current flowing in a main circuit of the circuit breaker.

In FIG. 3, reference numeral 2 denotes a current transformer B, which detects a current flowing in a main circuit of the circuit breaker.

In FIG. 3, reference numeral 13 denotes a filter circuit of A,
In this circuit, only the commercial frequency component (a in FIG. 2) of the current flowing through the main circuit detected by one current transformer A is passed.

Reference numeral 23 in FIG. 3 denotes a B filter circuit.
In this circuit, only the high frequency component (b in FIG. 2) of the current flowing through the main circuit detected by one current transformer B is passed.

In FIG. 3, reference numeral 11 denotes an amplifier circuit A, which is composed of, for example, an operational amplifier, and amplifies the output voltage from the filter circuit 13.

In FIG. 3, reference numeral 21 denotes a B amplifier circuit, which is composed of, for example, an operational amplifier and amplifies the output voltage from the filter circuit 23.

In FIG. 3, reference numeral 12 denotes a threshold value circuit for determining whether or not the output of the amplifier circuit 11 is equal to or greater than a predetermined threshold value. Occurs and holds the output for one cycle from about a half cycle of the commercial frequency.

In FIG. 3, reference numeral 22 denotes a threshold value circuit for determining whether or not the output of the amplifier circuit 21 is equal to or more than a predetermined threshold value. Occurs and holds the output for one cycle from about a half cycle of the commercial frequency.

In FIG. 3, reference numeral 3 denotes an AND circuit.
The output is set to the H level only when both outputs are at the H level.

In FIG. 3, reference numeral 4 denotes a thyristor which short-circuits between the anode and cathode when the output voltage of 3 receives a voltage equal to or higher than a predetermined value.

In FIG. 3, reference numeral 5 denotes a trip coil. When the thyristor 4 is turned on, it is excited by a power supply rectified by the diode 6, and when excited, it acts on a contact opening / closing mechanism (not shown) to activate the contact device 7. Open.

FIG. 4 shows a second embodiment. The difference from the first embodiment shown in FIG. 3 is that, instead of having the filter circuits 13 and 23, the main circuit of the circuit breaker passes through the main circuit of the circuit breaker. Only 10 current transformers A that detect and output the current and the main circuit of the circuit breaker detect only the high frequency component current,
This is provided with 20 current transformers B for outputting, and the other configuration is the same.

The 10 current transformers A penetrate the main circuit of the circuit breaker by a method such as selecting a core or the like, and the commercial frequency components (FIG.
Only the current component a) is detected.

The 20 current transformers B pass through the main circuit of the circuit breaker by a method such as selecting a core or the like, and the commercial frequency components (FIG.
Only the current component of b) is detected.

By using these current transformers 10 and 20, the outputs of the current transformers can be directly input to the amplifier circuits 11 and 21, whereby the filter circuit can be omitted and the circuit can be simplified. Can be

The circuit operation after the amplifier circuit is the same as that of the first embodiment. When the output of the threshold circuit becomes H level and the output of the AND circuit becomes H level, the operation of the thyristor 4 and
When it is excited by a power supply rectified by the diode 6 and operates, it acts on a contact opening / closing mechanism (not shown) to operate the contact device 7.
Release of.

FIG. 5 shows a third embodiment. The difference from the first embodiment shown in FIG. 3 is that instead of the current transformers 1 and 2, a voltage generating section 100 proportional to the current caused by the internal impedance of the circuit breaker is used. The other configuration is the same, and the operation is the same.

The voltage generator 100 can use the impedance existing in the main circuit of the circuit breaker as it is. For example, a bimetal used as an overcurrent trip element of a conventional circuit breaker for wiring, or the impedance of an electromagnet coil can be used.

In the above-described first to third embodiments, the current detection level of the commercial frequency component, that is, the current of the commercial frequency component flowing through the main circuit so that the output of the threshold circuit 12 becomes H level. The level is set to a range that is smaller than the magnitude of the overflow that flows when the incandescent lamp is turned on or the rush current that flows when the motor starts, and is several times larger than the rated current of the circuit breaker for wiring. That is, the current is set to the current in the overload or short-circuit area of the conventional circuit breaker for wiring. Specifically, 20
In the case of the circuit breaker A, the circuit breaker is selected to be about 40 to 200 A. Therefore, the output voltage characteristics of the current transformers 1 and 10, the amplification factor of the amplifier 11, and the threshold level of the threshold circuit 12 are adjusted. .

The current detection level of the high-frequency component, that is, the current level of the high-frequency component flowing through the main circuit for causing the output of the threshold circuit 22 to go to the H level is set small enough to prevent malfunction due to noise. Specifically, the number A
For this purpose, the output voltage characteristics of the current transformers 2 and 20, the amplification factor of the amplifier 21, and the threshold level of the threshold circuit 22 are adjusted. The frequency range of the high-frequency component to be detected is selected from about 1 kHz to several tens of kHz, which is a high-frequency component actually generated at the time of the above-described short-circuit accident of the cord.

In the circuit breaker of the present invention configured as described above, the current of the commercial frequency component in the overflow or inrush current as shown in FIG. 1 exceeds the current detection level of the commercial frequency component of the present invention. Therefore, the output of the threshold circuit 12 is at the H level, but the overflow and the inrush current do not include high frequency components other than the commercial frequency component, so that the output of the threshold circuit 22 is at the L level. And the AND circuit 3
Is low, the thyristor 4 is not triggered, and the trip coil 5 is not attracted, so that the circuit breaker does not open.

Next, in the fault current of the code as shown in FIG. 2, the commercial frequency component a is several tens to several hundreds A, the output of the threshold circuit 12 becomes H level, and the high frequency component b, the output of the threshold circuit 22 also goes high, the output of the AND circuit 3 goes high,
The thyristor 4 is triggered, the trip coil 5 is attracted, and the circuit breaker opens instantaneously.

Therefore, the contact device does not open when an overflow or an inrush current occurs. However, even if the current value is smaller than the overflow or the inrush current, the contact device is opened because a specific high-frequency component is included even if the current value is smaller than the overflow or the inrush current. Can work. Although a conventional circuit breaker with a rating of 20 A can open a contact device in an overload short-circuit current range of several tens to several hundreds of A, it takes several seconds to several seconds from the occurrence of a short circuit to the opening operation of the contact device. It took ten seconds, and the contact device could not be instantaneously opened after the short circuit occurred as in the present invention.

If a conventional thermal overcurrent detection tripping device (bimetal) or an electromagnetic overcurrent detection tripping device (dashpot type electromagnet) is used in combination with the wiring breaker according to the present invention, the conventional overcurrent detection device can be used. While having the function to protect the wiring from the load and short-circuit current, it is also instantaneous due to deterioration of the insulation of the cord when the cord is connected to the outlet, melting of the cord film due to overheating, and discharge-like short circuit due to tracking. It is possible to provide a circuit breaker having a function capable of preventing a fire and a fire due to partial overheating of a cord by interrupting a circuit.

【effect】

As described above, according to the present invention, a code for generating a discharge-type short-circuit current having a smaller short-circuit current value and containing a high-frequency component without malfunctioning due to an overflow current or an inrush current. In the event of an accident, there is an effect that a contact breaker can be instantaneously opened to obtain a circuit breaker for wiring that prevents the occurrence of fire.

[Brief description of the drawings]

Fig. 1 Examples of overflow and inrush current waveforms

FIG. 2 shows an example of a discontinuous intermittent discharge-like short-circuit current waveform.

FIG. 3 is a diagram of a first embodiment of the present invention.

FIG. 4 is a diagram of a second embodiment of the present invention.

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

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Current transformer A 2 Current transformer B 3 AND circuit 4 Thyristor 5 Trip coil 6 Diode 7 Contact device 11 A amplifier circuit 12 A threshold circuit 13 A filter circuit 21 B amplifier circuit 22 B threshold Value circuit 23 B filter circuit 100 Voltage generator

Claims (5)

[Claims] 1. A commercial frequency component and a high frequency component of a discharge-like short-circuit current generated by a short circuit due to insulation breakdown of an electric wire are both detected by two current detectors, and the commercial frequency component current is overloaded. Alternatively, the circuit breaker for wiring is characterized in that the trip coil is attracted only when the high frequency component is above a certain value in a short-circuit state, the contact switching mechanism is tripped, and the contact device is opened. 2. A current for commercial frequency and a current for high frequency, each of which converts both a commercial frequency component and a high frequency component of a discharge-like short-circuit current generated by a short circuit due to insulation breakdown of an electric wire and outputs the voltage. A detecting unit, two amplifying units for amplifying each voltage from each of the current detecting units, a gate circuit unit for closing the circuit under the condition that both of the amplified voltages are respectively equal to or more than predetermined threshold values, A trip coil that is energized when the gate circuit is closed, a rectifier circuit that supplies power to the trip coil, and a contact opening / closing mechanism that opens a contact device by energizing the trip coil; Wherein the threshold value is selected as a value for determining whether the current of the commercial frequency component is in an overload or short-circuit state. 3. Two current transformers A and B penetrating the main circuit of the circuit breaker, a filter circuit of A passing only commercial frequency components from a voltage generated at both ends of the current transformer of A, A filter circuit of B for passing only high frequency components from a voltage generated at both ends of the current transformer, an amplification section of A for amplifying the output voltage of the filter circuit of A, and an output voltage of the filter circuit of B for amplification A threshold voltage circuit of A for setting the output to an H level if the output voltage of the amplifier section of A is equal to or more than a predetermined constant value; and an output voltage of the amplifier section of B for a predetermined constant value. A threshold circuit of B for setting the output to the H level if the value is equal to or higher than the threshold value; an AND circuit for operating the thyristor when the outputs from the threshold circuits of A and B are both at the H level; Connect the gate to the output of the A thyristor with the cathode connected to one pole of the coil, a trip coil with one end connected to the anode of the thyristor, and a diode connected between the other end of the trip coil and the other pole of the circuit breaker And a contact opening / closing mechanism for opening the contact device by energizing the trip coil. The threshold value of the threshold circuit of A is determined by whether the current of the commercial frequency component is overloaded or short-circuited. A circuit breaker for wiring, characterized in that it has been selected as a value for judging. 4. A current transformer A for detecting only a commercial frequency component current passing through the main circuit of the circuit breaker, and a current transformer B for detecting only a high frequency component current passing through the main circuit of the circuit breaker. A amplifying section for amplifying the output of the current transformer of A, B amplifying section for amplifying the output of the current transformer of B, and H when the output voltage of the amplifying section of A exceeds a certain value. A threshold circuit of A that outputs a level, a threshold circuit of B that outputs an H level when the output voltage of the amplification section of B exceeds a certain value, and a threshold circuit of A and B When both outputs are at the H level, an AND circuit for operating the thyristor, a gate connected to the output of the AND circuit, a thyristor having the anode side connected to the trip coil, and the cathode side connected to one pole of the circuit breaker And a thyristor with one end connected to the anode And a diode connected between the other end of the trip coil and the other pole of the circuit breaker, and a contact opening / closing mechanism for opening the contact device by energizing the trip coil. A circuit breaker for a wiring, wherein the threshold value of the value circuit is selected as a value for determining whether or not the current of the commercial frequency component is in an overload or short-circuit state. 5. A voltage generating section disposed in a main circuit of a circuit breaker, the voltage generating section being proportional to a current due to an internal impedance, a filter circuit of A for passing only a commercial frequency component from a voltage generated at both ends of the voltage generating section, A filter circuit of B that passes only high-frequency components from a voltage generated at both ends of the voltage generation unit, an amplification unit of A that amplifies the output voltage of the filter circuit of A, and an output voltage of the filter circuit of B A threshold voltage circuit of A for setting the output to an H level if the output voltage of the amplifier section of A is equal to or more than a predetermined constant value; and an output voltage of the amplifier section of B for a predetermined constant value. A threshold circuit of B for setting the output to the H level if the value is equal to or higher than the threshold value; an AND circuit for operating the thyristor when the outputs from the threshold circuits of A and B are both at the H level; Output to the game Thyristor with the anode side connected to the trip coil and the cathode side connected to one pole of the circuit breaker; a trip coil connected at one end to the anode of the thyristor; the other end of the trip coil and the other side of the circuit breaker And a contact opening / closing mechanism for opening the contact device by energizing the trip coil. The threshold value of the threshold circuit of the above A is such that the current of the commercial frequency component is excessive. A circuit breaker for wiring, which is selected as a value for determining whether a load or a short circuit is present. [0001]