JP2011171244A - Circuit breaker - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a circuit breaker including a cord short circuit detection circuit for detecting only cord short circuit. <P>SOLUTION: The circuit breaker includes: sensor wiring 9 detecting one circuit voltage of an outlet 4; a peak value detection circuit 20 detecting a peak value of a voltage drop amount from a detected voltage of the sensor wiring 9; an average value circuit 21 averaging detected peak values; and a determination circuit 22 determining that the cord short circuit occurs when the averaged peak value falls below a predetermined value. When the determination circuit 22 outputs a cord short circuit detection signal, trip operation of a trip coil 12 is carried out to interrupt a circuit, and a display part 16 indicates that interruption is caused by the cord short circuit. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a circuit breaker having a function of detecting a cord short circuit.

  Conventionally, there is a device that cuts off the electric circuit when a short circuit is detected. For example, Patent Document 1 discloses an outlet in which a cord short circuit detection circuit and a cutoff circuit including an absolute value circuit and a comparison circuit are provided in an outlet, and an electric circuit is cut off in the outlet when a cord short is detected.

JP 2004-327180 A

However, the cord short circuit detection circuit uses a resistor in the electric circuit to determine the code short circuit from the magnitude of the voltage drop, that is, from the current flowing through the electric circuit. Not only the detection but also the overload condition may react to shut off. Therefore, it was not possible to determine whether the cause of the interruption was due to a cord short circuit or an overcurrent.
Therefore, in view of such a problem, an object of the present invention is to provide a circuit breaker including a cord short circuit detection circuit that detects only a cord short circuit.

In order to solve the above problem, the invention of claim 1 is a circuit breaker in which an electric wire leading to an outlet is connected to a load-side terminal, and an abnormal current such as an overcurrent flows through the electric wire, and the circuit breaker is interrupted. Sensor means for detecting the voltage of one electric circuit in the outlet or the vicinity of the outlet, and a cord short circuit detecting circuit for detecting a cord short circuit based on a voltage drop amount of the electric circuit, the code short circuit detecting circuit being the sensor A peak value detection circuit for detecting the peak value of the voltage drop amount from the detection voltage of the means, an average value circuit for averaging the detected peak values, and a determination for determining the occurrence of a cord short circuit when the average peak value falls below a predetermined value When the cord short circuit detecting circuit detects a cord short circuit, the circuit is cut off.
The cord short circuit occurs in the electric wire leading to the load connected to the outlet, and occurs from the outlet. Therefore, with such a configuration, highly accurate cord short-circuit information can be obtained by detecting the voltage of the outlet near the place where the cord short-circuit occurs. And the peak value detection circuit monitors the voltage drop (peak value) of the circuit voltage and averages the detected peak value to judge the code short-circuit, so that a steady large current such as when overcurrent is applied However, it can be operated so as to be cut off when a cord short-circuit is detected, and the cause of the cut-off operation can be easily determined.

According to a second aspect of the present invention, in the configuration according to the first aspect of the present invention, there is provided display means for displaying the occurrence of a cord short circuit, and the output signal of the determination circuit drives an output circuit for operating the cutoff means, The display means is operated to display.
According to this configuration, when the cause of the interruption is a cord short-circuit, it is displayed, so that the cause can be easily specified.

  According to the present invention, highly accurate cord short-circuit information can be obtained by detecting the voltage of the outlet near the place where the cord short-circuit occurs. The peak value detection circuit monitors the instantaneous beard-like voltage drop (peak value) of the circuit voltage, and averages the detected peak values to determine the code short-circuit. It does not react to a large current and can be operated so as to be cut off when a short-circuiting of the cord is detected.

It is a circuit diagram showing an example of an embodiment of a circuit breaker concerning the present 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 diagram showing an example of a circuit breaker according to the present invention, mainly showing a cord short circuit detection circuit, omitting the overcurrent detection circuit, the short circuit current detection circuit, etc., which are the original functions of the circuit breaker. is there. In FIG. 1, 1 is a circuit breaker, 2 is a power supply side circuit, 3 is a load side circuit, 4 is an outlet, 5 is a load, and 6 is an electric wire (cord) from the outlet 4 to the load 5. Further, S indicates a place where a cord short circuit occurs.

  The load-side circuit 3 is connected to the outlet 4, and a single sensor wiring 9 for detecting the circuit voltage at the outlet 4 is connected to the circuit breaker 1 in parallel with the load-side circuit 3. It extends from. As a result, the wiring from the circuit breaker 1 to the outlet 4 is composed of three electric wires.

  The circuit breaker 1 includes a contact portion 11 for turning on / off the electric circuit, a trip coil 12 for opening the contact portion 11, an output circuit 13 for tripping the trip coil 12, and a circuit for supplying power to the circuit inside the circuit breaker 1. A power supply circuit 14 to be supplied, a cord short-circuit detecting circuit 15 for detecting the occurrence of a cord short-circuit, a display unit 16 for displaying the occurrence of a cord short-circuit, and the like are provided.

The cord short-circuit detection circuit 15 includes a peak value detection circuit 20, an average value circuit 21, and a determination circuit 22. The peak value detection circuit 20 obtains voltage information of one electric circuit at the outlet 4 through the sensor wiring 9, and A beard-like voltage drop caused by a short-circuited cord is monitored from the changing voltage waveform, and the peak value is detected.
The average value circuit 21 calculates and outputs an average value in consideration of the occurrence frequency based on the peak value information output from the peak value detection circuit 20.
The determination circuit 22 compares the voltage value output from the average value circuit with a threshold value, and if it falls below the threshold value, determines that a code short circuit has occurred and outputs a code short circuit occurrence signal.

  The display unit 16 is configured to perform a display operation by a mechanical operation similar to the operation of the trip coil 12 in response to the determination of the determination circuit 22, and the trip operation is performed to interrupt the electric circuit and stop the supply of power. Is also configured to maintain the display state.

In response to the output of the cord short-circuit generation signal, the circuit breaker operates as follows. When the determination circuit 22 outputs a code short-circuit occurrence signal, the output circuit 13 is activated and a trip current flows through the trip coil 12 to perform a trip operation. As a result, the contact portion 11 opens and the electric circuit is interrupted.
On the other hand, in response to the cord short-circuit occurrence signal, the display unit 16 performs a display operation and displays that the electric circuit is cut off due to the cord short-circuit.

For example, it is assumed that a cord short-circuit occurs and a whisker-like voltage drop occurs in an electric circuit rated at 20 amps. When such a cord short-circuit occurs, the electric circuit voltage of the outlet 4 is instantaneously greatly reduced to, for example, 50 volts due to the electric wire conductor resistance in the load side electric circuit 3. Note that the electric circuit voltage instantaneously drops to near 0 volts at the cord short-circuit occurrence point.
The sensor wiring 9 detects this voltage fluctuation in the vicinity of the outlet 4, and the cord short circuit detection circuit 15 determines the cord short circuit.
However, depending on the connected load, an inrush current of, for example, 300 amperes, which is larger than the current generated by the cord short circuit, may occur. Therefore, the peak detection circuit 20 does not react to such inrush current.

Thus, highly accurate cord short-circuit information can be obtained by detecting the voltage of the outlet 4 near the place where the cord short-circuit occurs. Since the peak value detection circuit 20 monitors the beard-like voltage drop (peak value) of the circuit voltage and averages the detected peak values to determine the code short circuit, the peak value detection circuit 20 determines a steady large current when overcurrent is applied. It does not react to current and can be operated to shut off when a cord short is detected.
And when the cause of interruption | blocking is a code short circuit, since it displays on the display part 16, it is easy to pinpoint a cause.

  In the above embodiment, the voltage information is obtained by connecting the sensor wiring 9 to the tip of the load side electric circuit 3 connected to the outlet 4, but it may be in the vicinity of the outlet 4, from the middle of the load side electric circuit. Voltage information may be obtained.

  1 .... Circuit breaker 2 .... Power supply side circuit 3 .... Load side circuit 4 .... Outlet 5 .... Load 6 .... Wire (cord) 9 .... Sensor wiring (sensor means) 11 ..Contact part, 12 ..trip coil, 13 ..output circuit, 14 ..power supply circuit, 15 ..code short circuit detection circuit, 16 ..display unit (display means), 20 ..peak value detection circuit, 21・ ・ Average circuit, 22 ・ ・ Determination circuit.

Claims (2)

A circuit breaker that cuts off the electrical circuit when an abnormal current such as an overcurrent flows through the wire when the wire leading to the outlet is connected to the load side terminal,
Sensor means for detecting the voltage of one electrical circuit near the outlet or the outlet, and a cord short circuit detection circuit for detecting a cord short circuit based on the voltage drop amount of the electrical circuit,
The cord short circuit detection circuit includes a peak value detection circuit that detects a peak value of a voltage drop amount from a detection voltage of the sensor means, an average value circuit that averages the detected peak values, and an average peak value that is a predetermined value. It has a judgment circuit that judges the occurrence of a short circuit when it falls below,
The circuit breaker, wherein when the cord short circuit detection circuit detects a cord short circuit, the circuit is cut off. 2. The display device according to claim 1, further comprising display means for displaying the occurrence of a cord short circuit, wherein the output signal of the determination circuit drives an output circuit for operating the shut-off means and causes the display means to perform display operation. Circuit breaker.

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