JP4146063B2 - Circuit breaker for wiring - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a circuit breaker for wiring that shuts off the wiring path from the electric circuit when an abnormal current flows in the wiring path. Specifically, the circuit breaker detects the heat generation and tracking short circuit of the terminal part of the circuit breaker. It is related with the circuit breaker for wiring which carries out interruption | blocking operation.
[0002]
[Prior art]
Equipment that intervenes in the power line, such as a circuit breaker for wiring, generates heat due to the growth of cuprous oxide when terminals for connecting external conductors such as power supply terminals or load terminals are incomplete. The case may be burned out, and when the mold case is significantly burned out, a power supply short circuit may be induced. In addition, there is a case where a wire short circuit in which the film melts due to an electric wire flaw or heating, or a tracking short circuit generated when dust and moisture adhere to the terminal generate heat to induce a power short circuit and cause a fire.
For this reason, there is a technique disclosed in Japanese Utility Model Publication No. 63-6833 as a circuit breaker that shuts off the circuit against such heat generation. This is because a thermistor is attached to the power supply side terminal and the load side terminal, a heater element is interposed in each phase, a thermistor is also attached to the heater element, and the temperature rise between the thermistors attached to each phase and the heater element The temperature rise is compared and detected, and the abnormality is detected and the shut-off operation is performed.
[0003]
[Problems to be solved by the invention]
However, in the above circuit breaker, although it is possible to detect the cuprous oxide growth exothermic phenomenon that occurs when the terminal connection is incomplete, six or more thermistors are required. In addition, heat generation or short circuit due to other causes, that is, heat generation due to tracking short circuit or scar damage, short circuit current from coating melting to complete short circuit is a discontinuous current as shown in FIG. Is a discontinuous discharge current of several amperes to about 200 amperes, so that the interruption operation cannot be instantaneously performed, it takes time until the interruption, and in the worst case, a fire breaks out from the short circuit portion.
This is because the detection current for instantaneous interruption cannot be made smaller than these currents in order to avoid malfunction due to overflow or inrush current as shown in FIG. For example, since the rating of a circuit breaker used for a general house is at least 20A, it is impossible to end up with a current that is 10 times or more of that as a breaking current. On the other hand, the shut-off operation cannot be performed.
[0004]
SUMMARY OF THE INVENTION In view of the above problems, the present invention has an object to provide a circuit breaker for detecting a short circuit current of 200 amperes or less as well as heat generated by a cuprous oxide proliferation phenomenon in a terminal portion. .
[0005]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, the invention of claim 1 is a circuit breaker for wiring which operates a tripping circuit to open a contact when an abnormal current flows in the wiring path, and disconnects the wiring path from the power supply circuit. Te, comprising: a current detecting means for detecting a current of the wiring path, a voltage detector for detecting a power supply voltage, and a control means for operating the trip circuit receives the output of said voltage detecting means and said current detecting means and, said control means, when the peak value of the wiring path current waveform exceeds the set value over a predetermined time, or nitrous distortion voltage by a copper oxide growth behavior, zero point of the supply voltage waveform without distortion waveform as a reference When the amount of phase shift that occurs at the rise from 0 or the fall from the zero point exceeds a set value for a predetermined time, a cutoff signal is output and the trip circuit is activated.
[0006]
The invention of claim 2 is a circuit breaker for operating a trip circuit when an abnormal current flows in a wiring path to open a contact, and disconnecting the wiring path from the power supply circuit. current detecting means for detecting a voltage detecting means for detecting a power supply voltage, a temperature detecting means for detecting the temperature of the terminal portion, the pull receives an output of said current detecting means and said voltage detecting means and the temperature detecting means and control means for actuating the circuit off, said control means, when the peak value of the wiring path current waveform exceeds the set value over a predetermined time, the temperature of the terminal portion exceeds the set value over a predetermined time In this case, the voltage is distorted due to the cuprous oxide proliferation phenomenon, and the amount of phase shift that occurs at the rise from the zero point of the power supply voltage waveform or the fall from the zero point with respect to the waveform without distortion is a set value for a predetermined time. If it exceeds, It outputs a cutoff signal either, characterized in that to operate the trip circuit.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, embodiments of the invention will be described in detail with reference to the drawings. FIG. 1 is a circuit block diagram showing an example of a circuit breaker according to the present invention, in which 2 is a contact for opening the wiring path 16 from the electric circuit 15, 3 is a tripping coil for performing a tripping operation of the contact, 4 is A trip circuit. In addition, 5 is a current transformer for detecting the wiring current, 6 is a current-voltage conversion circuit for converting the detected current into voltage, 13 is a voltage detection circuit, and 7 is a control unit. The control unit 7 is configured by a microcomputer including a threshold circuit 10, an integration circuit 11, a calculation unit 8 having an output circuit 12, and an A / D conversion circuit 9 that inputs a control signal to the calculation unit 8.
[0008]
The circuit operation will be described. When a current as shown in FIG. 3A is detected by the current transformer 5, for example, the detected current waveform is converted into a voltage waveform by the current / voltage conversion circuit 6, and the A / It is input to the D conversion circuit 9. The A / D conversion circuit 9 time-divides the input voltage waveform at a predetermined time and outputs it to the calculation unit 8. The calculation unit 8 receives the signal from the A / D conversion circuit 9 in the threshold circuit 10 and compares it with a predetermined threshold value. For example, as shown in FIG. If it exceeds, a digital signal corresponding to the time exceeding the threshold as shown in FIG. The integrating circuit 11 integrates the signal for a predetermined time, and the output circuit 12 receives the calculation result of the integrating circuit, outputs a signal when the integrated value exceeds a predetermined set value, and operates the tripping coil 3. I am letting.
[0009]
The current waveform in FIG. 3 (a) schematically shows a waveform when a cord short circuit or tracking occurs. Thus, from the current detection means and the microcomputer comprising a current transformer and a current-voltage conversion circuit. The control means holds the current peak value, compares it with the threshold value as shown in FIG. 3B, and generates a pulse as shown in FIG. 3C when the current waveform exceeds the threshold value. By detecting when the state exceeding the threshold value continues for a predetermined time, a discontinuous whisker-like discharge can be detected, and a discharge short-circuit of 200 amperes or less that occurs due to insulation deterioration or destruction of the cord coating occurs. In such a case, a tracking phenomenon caused by dust or moisture in the outlet socket portion can be instantly interrupted to protect the outlet socket and the socket and prevent a fire from occurring.
[0010]
Further, the detection waveform by the voltage detection circuit 13 is normally the A waveform shown in FIG. 2A, but when a cuprous oxide growth phenomenon occurs, a B wave that is a harmonic component thereof is generated, particularly in the C portion. Large distortion occurs. Therefore, for example, a voltage waveform as shown in FIG. 2B is obtained. When the voltage detection circuit 13 detects this waveform, the A / D conversion circuit 9 divides the voltage waveform into a digital value by dividing the voltage waveform by a predetermined time width. 2, the threshold circuit 10 detects a zero point phase shift due to the distortion, and outputs a pulse waveform corresponding to the magnitude of the phase shift as shown in FIG. The integrating circuit 11 integrates the pulse wave for a predetermined time in the same manner as the signal from the current transformer 5, and outputs an output signal from the output circuit 12 when the integrated value exceeds a predetermined reference value, and the trip coil 3 is connected. It is operating.
[0011]
In this way, the voltage detection circuit (voltage detection means) and the control means can perform a shut-off operation against a cuprous oxide proliferation phenomenon that occurs due to poor tightening or poor contact due to loose screws. Burnout and power supply short-circuit accidents can be prevented in advance.
It should be noted that the cuprous oxide growth phenomenon and tracking phenomenon may be judged from both the information obtained from the current waveform and the information obtained from the voltage waveform. It is possible to detect anomalies in time.
[0012]
FIG. 4 shows another embodiment of the present invention, in which 20 is a thermistor provided in the power supply side terminal section, 21 is a temperature-voltage conversion circuit for converting temperature information from the thermistor into an electrical signal, and is the same as FIG. Components are given the same reference numerals. The voltage distortion caused by the generation of harmonic components in the fundamental wave is generated in addition to the heat generation due to the cuprous oxide growth phenomenon in the terminal section. And the temperature is also detected.
[0013]
The operation of this circuit will be described. The temperature-voltage conversion circuit 21 changes the temperature into a voltage, and the A / D conversion circuit 9 divides each divided voltage into a digital value by dividing it by a predetermined time width. The digital output is compared with the set value by the threshold circuit 10, and if it exceeds the set value, it is integrated by the integrating circuit 11, and when the integrated value exceeds the predetermined value, the output circuit 12 outputs the operation signal of the trip circuit. The removal coil 3 is operated.
In this way, the terminal block temperature and voltage waveform are used to determine the shut-off operation. Therefore, it is possible to reliably detect and stop the cuprous oxide growth phenomenon in the terminal section, and to detect current with a current transformer. In addition, it is possible to detect and block discharge short-circuit due to insulation deterioration of the cord film and tracking phenomenon of the outlet.
FIG. 5 shows the thermistor temperature-output voltage characteristics. By reducing the threshold temperature from t 3 to t 2, t 1 , the cuprous oxide growth phenomenon at the terminal can be predicted early. Moreover, although the thermistor is provided in the power supply side terminal in FIG. 4, you may provide in a load side terminal and may provide in both.
[0014]
【The invention's effect】
As described above in detail, according to the present invention, when a cuprous oxide multiplication phenomenon occurs due to poor tightening or poor contact due to loose screws, the terminal portion can be burned out or a power supply short circuit accident occurs. Can be prevented in advance, and can be instantaneously interrupted even with a short-circuit current of 200 ampere or less due to a tracking phenomenon caused by dust or moisture in the outlet socket part due to a short-circuiting of the cord sheath due to insulation deterioration or destruction of the cord coating. Yes, it can protect cords, outlets and sockets and prevent fires.
[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.
FIG. 2 shows a detected voltage waveform and a processed waveform thereof; (a) shows a fundamental voltage waveform and a harmonic component waveform generated when a cuprous oxide proliferation phenomenon occurs; (b) shows a cuprous oxide proliferation phenomenon. (C) is a threshold circuit output waveform.
FIGS. 3A and 3B show waveforms of respective blocks due to occurrence of a tracking short circuit, in which FIG. 3A shows a detected current waveform, FIG. 3B shows a peak hold explanatory waveform and threshold in the threshold circuit, and FIG. 3C shows a threshold circuit output waveform;
FIG. 4 is a circuit block diagram showing another embodiment of the present invention.
5 is an explanatory diagram of output voltage-temperature characteristics of the thermistor section of FIG. 4. FIG.
6A is an explanatory diagram of a discontinuous discharge-like short-circuit current, and FIG. 6B is an explanatory diagram of an inrush current.
[Explanation of symbols]
2 .... Contact, 3 .... Trip coil, 4 .... Trip circuit, 5 .... Current transformer, 6 .... Current-voltage conversion circuit, 7 .... Control unit, 8 .... Calculation unit, ... A / D conversion circuit, 10 .... threshold circuit, 11 .... accumulation circuit, 12 .... output circuit, 13 .... voltage detection circuit, 15 .... electric circuit, 16 .... wiring route, 20 .... thermistor, 21 ... Temperature-voltage conversion circuit.

Claims (2)

A circuit breaker for disconnecting the wiring path from the power circuit by operating the trip circuit when an abnormal current flows in the wiring path, opening the contact,
Comprising a current detector for detecting a current of the wiring path, a voltage detector for detecting a power supply voltage, and a control means for operating the trip circuit receives the output of said voltage detecting means and said current detecting means,
When the peak value of the wiring current waveform exceeds the set value for a predetermined time or when the voltage is distorted due to a cuprous oxide proliferation phenomenon , the control means starts from the zero point of the power supply voltage waveform on the basis of the waveform without distortion. A circuit breaker for wiring, which outputs a cut-off signal and activates a trip circuit when the amount of phase shift occurring at the rise or the fall from the zero point exceeds a set value for a predetermined time. A circuit breaker for disconnecting the wiring path from the power circuit by operating the trip circuit when an abnormal current flows in the wiring path, opening the contact,
Current detecting means for detecting a current of the wiring path, a voltage detector for detecting a power supply voltage, and temperature detection means for detecting a temperature of the terminal portion, an output of said current detecting means and the voltage detecting means and the temperature detecting means And a control means for operating the trip circuit in response to
When the peak value of the wiring current waveform exceeds a set value for a predetermined time, or when the temperature of the terminal exceeds the set value for a predetermined time, the control means distorts the voltage due to a cuprous oxide proliferation phenomenon. If the amount of phase shift that occurs at the rising edge from the zero point of the power supply voltage waveform or the falling edge from the zero point exceeds the set value for a predetermined time with reference to the waveform without distortion , the cutoff signal is sent either A circuit breaker for output, which operates and operates a tripping circuit.

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