JP6211865B2 - Cord short circuit detection circuit and outlet device - Google Patents

Description

  The present invention relates to a cord short-circuit detection circuit for detecting a cord short-circuit, and an outlet device having a function of interrupting an electric circuit when a cord short-circuit occurs.

2. Description of the Related Art Conventionally, there is an outlet device that has a function of detecting an occurrence of a short-circuiting of a cord on an electric path from a plug inserted into an outlet to a load and interrupting the electric circuit.
It is known that this cord short circuit starts from a so-called beard cord short circuit in which an electric wire of about one stranded wire is first short-circuited. At this time, when looking at the voltage waveform of the electric circuit, a unique shape as shown in FIG. This has been confirmed by experiments. As shown in FIG. 7, when a beard code short-circuit occurs, the waveform is greatly cut out from the vicinity of the peak indicated by S.
The present inventor proposed in Patent Document 1 an outlet device that detects the occurrence of a cord short circuit by detecting the characteristics of the voltage waveform and interrupts the electric circuit.

JP 2012-186653 A

However, in the technique of Patent Document 1, the voltage waveform rectified in the rectifier circuit does not drop to the zero point (0 volt) and the next half cycle starts (shown in FIG. 2A). For this reason, there is a limitation on the setting of specific binary values for detecting a mustache code short circuit, and it has been difficult to detect a beard code short circuit with high accuracy. This is caused by a capacitor provided in the power supply circuit, but it is impossible to omit this because it affects other circuits.
In addition, when the inrush current generated when the load device is turned on is extremely large, the electric circuit voltage is greatly reduced, and this voltage change may be determined as the occurrence of a whisker code short circuit.

  Therefore, in view of this problem, the present invention can detect a whisker cord short circuit with high accuracy without losing the capacitor of the power circuit, and further, a cord short circuit detection circuit that does not malfunction due to an inrush current, and an electric circuit when a code short circuit occurs. The object is to provide an outlet device that shuts off.

In order to solve the above problem, a cord short-circuit detection circuit according to the invention of claim 1 includes a rectifier circuit that obtains a voltage waveform of an electric circuit that supplies commercial power to a load and performs full-wave rectification, and a voltage rectified by the rectifier circuit. A specific distortion detection circuit that detects specific waveform distortion from a waveform, a determination circuit that determines the occurrence of a cord short circuit, and a rectifier circuit that obtains power from an electric circuit and supplies power to each circuit And the specific distortion detection circuit compares the rectified voltage waveform with a predetermined first threshold value that is lower than the peak value of the commercial voltage and a second threshold value that is lower than the first threshold value. A window comparator circuit that detects a state in which the instantaneous value is between two threshold values; and a waveform distortion determination circuit that determines that waveform distortion has occurred when a time period between the two threshold values exceeds a predetermined time. Distortion detection circuit is waveform distortion And outputs the code short circuit signal if it is determined that generation.
According to this configuration, since the rectifier circuit is provided independently of the power supply circuit, the output voltage waveform can reach 0 volts every half cycle without being affected by the capacitor. Therefore, even if the second threshold value is provided near 0 point, the waveform distortion determination circuit does not malfunction, and it is possible to detect a cord short-circuit with high accuracy.

A cord short-circuit detection circuit according to a second aspect of the invention detects a specific waveform distortion from a rectifier circuit that obtains a voltage waveform of a circuit that supplies commercial power to a load and performs full-wave rectification, and a voltage waveform rectified by the rectifier circuit. Specific distortion detection circuit, an inrush voltage detection circuit that detects a voltage change due to an inrush current of the load from the rectified voltage waveform of the output of the rectifier circuit, a determination circuit that determines the occurrence of a cord short circuit, A rectifier circuit for supplying power to the circuit and a power circuit provided independently, and the specific distortion detection circuit has a predetermined first threshold value lower than a peak value of the commercial voltage and a first value smaller than the first threshold value. A window comparator circuit that compares the threshold value of 2 with the rectified voltage waveform and detects a state where the instantaneous value of the rectified voltage waveform is between the two threshold values, and waveform distortion occurs when the time between the two threshold values exceeds a certain time Judge A waveform distortion determination circuit, and the inrush voltage detection circuit compares a voltage waveform with a predetermined third threshold value that is lower than the peak value of the commercial voltage and exceeds the first threshold value. When the specific distortion detection circuit determines that waveform distortion has occurred and the inrush voltage detection circuit determines that the peak value of the voltage waveform is greater than the third threshold value, it determines that a code short circuit has occurred and outputs a code short circuit occurrence signal. It is characterized by doing.
According to this configuration, since the rectifier circuit is provided independently of the power supply circuit, the output voltage waveform can reach 0 volts every half cycle without being affected by the capacitor. Therefore, even if the second threshold value is provided near 0 point, the waveform distortion determination circuit does not malfunction, so that it is possible to detect a cord short-circuit with high accuracy. And since the inrush current is detected, even if a large drop in the circuit voltage occurs instantaneously due to the occurrence of the inrush current, it is possible to prevent a situation in which it is erroneously detected that a cord short circuit has occurred. It becomes possible to detect.

According to a third aspect of the present invention, there is provided an outlet device in which a load is connected, an electric circuit for supplying commercial power to the electric outlet, an opening / closing means provided on the electric circuit for opening and closing the electric circuit, and an opening / closing means. It is characterized by having the interruption | blocking means to operate | move, the cord short circuit detection circuit of Claim 1 or 2, and the output circuit which drives the interruption | blocking means based on the code | cord | chord short circuit generation | occurrence | production signal which a code short circuit detection circuit outputs.
According to this configuration, when a cord short-circuit occurs, it is detected and the electric circuit is interrupted to stop the outlet output. Therefore, it is possible to reliably prevent the occurrence of a fire due to the cord short-circuit.

  According to the present invention, since the rectifier circuit is provided independently of the power supply circuit, the voltage waveform to be output can reach zero point every half cycle without being affected by the capacitor. Therefore, even if the second threshold value is provided near 0 point, the waveform distortion determination circuit does not malfunction, so that it is possible to detect a cord short-circuit with high accuracy. And, since the occurrence of inrush current is detected, it is possible to prevent a situation in which a short-circuiting of the cord is erroneously detected even if a large drop in the circuit voltage occurs instantaneously, and the short-circuiting of the cord can be detected with high accuracy in any environment. Is possible.

It is a circuit diagram which shows an example of the outlet apparatus which concerns on this invention. The rectification waveform of an electric circuit voltage is shown, (a) is a conventional waveform, (b) is a waveform of the rectifier circuit of FIG. It is a principal part waveform diagram of the specific distortion detection circuit at the time of code | cord short circuit generation | occurrence | production, (a) is an output waveform of a rectifier circuit, (b) is a 1st window comparator circuit output waveform, (c) is an integration circuit output waveform, ( d) shows the first one-shot pulse circuit output. It is an output waveform explanatory diagram of the inrush voltage detection circuit, (a) shows the output waveform of the rectifier circuit 13, (b) shows the output waveform of the inrush voltage detection circuit, (c) shows the output waveform of the determination circuit. It is a principal part waveform diagram of the specific distortion detection circuit at the time of inrush current generation, (a) is an output waveform of a rectifier circuit, (b) is a 1st window comparator circuit output waveform, (c) is an integration circuit output waveform, ( d) shows the first one-shot pulse circuit output. It is output explanatory drawing of the inrush voltage detection circuit at the time of inrush current generation, (a) shows the output waveform of a rectifier circuit, (b) has shown the output waveform of the specific waveform detection circuit. It is an electric circuit voltage waveform diagram at the time of a beard code short circuit occurrence.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments embodying the present invention will be described below in detail with reference to the drawings. FIG. 1 is a circuit diagram showing an example of an outlet device according to the present invention, where 1 is an outlet device, 2 is a commercial power source, 3 is a load such as a television or a heating appliance, 4 is an outlet, and L1 is an outlet device from the commercial power source 2. 1 is a load circuit extending from a plug (not shown) connected to the outlet 4 to the load 3. The outlet device 1 is usually used by being installed on a wall surface.

  As shown in FIG. 1, the outlet device 1 includes an opening / closing contact 7 provided on an electric path L3 from the power supply connecting portion connecting the electric circuit L1 to which the commercial power supply 2 is connected to the outlet 4, and a plunger 8a for opening the opening / closing contact 7. An electromagnetic coil 8, an output circuit 9 for driving the electromagnetic coil 8, and a cord short-circuit detecting circuit 11 for detecting a cord short-circuit.

  The cord short circuit detection circuit 11 starts the rectifier circuit 13 composed of a diode bridge circuit that full-wave rectifies the voltage waveform of the commercial power flowing through the electric circuit L3, the specific distortion detection circuit 14 that detects a waveform peculiar to the mustache cord short circuit, and the load 3. A second comparison circuit 15 as an inrush voltage detection circuit for detecting a voltage drop caused by the occurrence of an excessive inrush current at the time, and a second one-shot pulse circuit 16 as a determination circuit for determining the occurrence of a code short circuit, The power supply circuit 17 supplies power to each circuit.

  The rectifier circuit 13 is provided independently of the rectifier circuit 17a provided in the power supply circuit 17, and no capacitor is disposed in the vicinity thereof. The rectified waveform output from the rectifier circuit 13 is shown in FIG. FIG. 2A shows a waveform output from the rectifier circuit of Patent Document 1. As shown in FIG. 2, the rectified waveform output from the rectifier circuit 13 rises after decreasing to 0 volts every half cycle.

  The specific distortion detection circuit 14 compares a rectified voltage waveform with a predetermined binary value (a first threshold value and a second threshold value smaller than the first threshold value) (hereinafter simply referred to as “comparator circuit”). ) 20, a waveform shaping circuit 21 that shapes the output waveform of the comparator circuit 20, an integration circuit 22 that integrates the output waveform of the waveform shaping circuit 21, and a waveform distortion determination circuit that compares the output of the integration circuit 22 with a predetermined threshold value. 1 comparison circuit 23 and a first one-shot pulse circuit 24 that receives the output of the first comparison circuit 23 and outputs a pulse signal.

The inrush voltage detection circuit 15 is configured by a comparison circuit (second comparison circuit) that compares the instantaneous value of the rectified circuit voltage with a predetermined third threshold value. H "signal is output.
The third threshold value is set between the peak value of the circuit voltage and the first threshold value.

  The second one-shot pulse circuit 16 determines the occurrence of a code short circuit based on the outputs of the specific distortion detection circuit 14 and the second comparison circuit 15.

  Hereinafter, the operation of the cord short-circuit detection circuit 11 will be specifically described. FIG. 3 shows the waveform of the main part of the cord short-circuit detection circuit 11 when a cord short-circuit occurs, which will be described with reference to FIG. 3, (a) is the output waveform of the rectifier circuit 13, (b) is the output waveform of the comparator circuit 20, (c) is the output waveform of the integrating circuit 22, and (d) is the first one-shot pulse circuit. 24, that is, the output of the specific distortion detection circuit 14 is shown.

The comparator circuit 20 compares the rectified voltage waveform output from the rectifier circuit 13 with a predetermined threshold value (a higher first threshold value EH and a lower second threshold value EL), and an electric circuit between the two threshold values. A specific signal is output while there is an instantaneous voltage value.
The circuit circuit voltage is divided and inputted to the comparator circuit 20, for example, a voltage divided by 1/10 is inputted. As a result, a voltage having a peak value of about 14 volts is input. For this value of voltage, for example, EH = 5 volts and EL = 1 volt are set. FIG. 3A shows a relationship between the voltage waveform of the electric circuit L3 and the specific binary values EH and EL in the comparator circuit 20 set as described above.

  When a whisker code short circuit occurs, a voltage waveform having a notch as shown by S in FIG. 7 is generated. Therefore, the generation of this waveform takes several ms from several volts to about 70 volts, which is about 50% of the peak value. It can be judged from the characteristics that remain. This feature is greatly different from the voltage waveform at the time of overcurrent occurrence such as inrush current.In the present invention, by detecting the occurrence of this characteristic waveform, the whisker cord short circuit which is a small cord short circuit is detected, and the electric circuit is connected. It is a thing to cut off.

Therefore, the first threshold value EH is about 50% or less with respect to the crest value of the circuit voltage (70 V or less if the crest value of the circuit voltage is about 140 V), and the second threshold value EL is 3% or more (wave circuit voltage). If the high value is about 140V, set it to 4V or higher).
This range may be further limited, and even when the first fixed value EH = 50V and the second fixed value EL = 10V, the cord short circuit can be detected well.

  The waveform shaping circuit 21 receives the output of the comparator circuit 20 and outputs an “H” signal when the instantaneous voltage value is between the first threshold value EH and the second threshold value EL. FIG. 3B shows this output, and while the voltage waveform of the electric circuit L3 to be monitored is a normal sine wave, a constant signal having a narrow width (short time) shown in T1 is output. Indicates a state in which a wide (long time) signal as shown in T2 is output.

  The integrating circuit 22 integrates the rectangular wave which is the “H” signal output from the waveform shaping circuit 21 and outputs a signal M having a waveform as shown in FIG. As shown in FIG. 3C, a waveform M1 having a small peak value is output with respect to a normal sine wave, but a large peak value is obtained as indicated by M2 in response to a rectangular wave of T2 generated by a cord short circuit. Is output.

The first comparison circuit 23 compares the output of the integration circuit 22 with a predetermined threshold value Th1, and outputs a signal N as shown in FIG. 3D when the threshold value Th1 is exceeded. As shown in FIG. 3D, the threshold value Th1 is set to a specific value that does not reach in the case of a normal sine wave and reaches when a distortion as shown in S occurs.
As a result, the signal N is output in response to the integral value M2 of the rectangular wave T2 when the cord is short-circuited. In this way, a case is detected in which the time for which the output of the comparator circuit 20 outputs a signal of “H” exceeds a certain time.

  The first one-shot pulse circuit 24 receives the output N of the comparison circuit 23, generates a one-shot pulse signal as an output signal of the specific distortion detection circuit 14, and outputs it from the point A shown in FIG.

4A and 4B are explanatory diagrams of the output waveform of the second comparison circuit 15. FIG. 4A is an output waveform of the rectifier circuit 13, FIG. 4B is an output waveform of the second comparison circuit 15, and FIG. Each output waveform is shown. As shown in FIG. 4, when the instantaneous value of the circuit voltage exceeds a predetermined threshold value Th2, the second comparison circuit 15 outputs an “H” signal from the point B shown in FIG. Specifically, a waveform indicated by U1 is output for a normal sine wave voltage, and a waveform indicated by U2 is output when a cord short-circuit occurs.
Note that N shown in FIG. 4B indicates the output N of the first comparison circuit 23.

When the second one-shot pulse circuit 16 outputs “H” based on the output of the first one-shot pulse circuit 24 and the output of the second comparison circuit 15, FIG. An “H” signal is output as shown in FIG.
As a result, the output circuit 9 receives the output of the determination circuit 16 to drive the electromagnetic coil 8, the plunger 8 a is pulled out, the open / close contact 7 is opened, and the supply of power to the load 3 is stopped.

Thus, since the rectifier circuit 13 is provided independently of the power supply circuit 17, the voltage waveform to be output can reach 0 volts every half cycle without being affected by the capacitor. Therefore, even if the second threshold value EL is provided near 0 point, the window comparator circuit 20
Therefore, it is possible to detect a cord short-circuit with high accuracy.
And since a code short circuit is detected from the waveform change of the circuit voltage regardless of the current change, the code short circuit can be detected with high accuracy. In addition, since a characteristic voltage waveform change when a whisker code short circuit occurs is detected, it is possible to determine that a code short circuit has occurred even if the code short circuit is as small as a beard code short circuit.
Also, if a cord short-circuit occurs, it is detected and the electrical circuit is shut off to stop the outlet output, so that a fire due to a cord short-circuit can be reliably prevented.

Next, the case where the circuit voltage is greatly changed due to the occurrence of inrush current will be described. FIG. 5 is a waveform diagram of the main part of the specific distortion detection circuit 14 when an inrush current is generated. (A) is an output waveform of the rectifier circuit 13, (b) is an output waveform of the comparator circuit 20, and (c) is an integration circuit 22. (D) shows the output of the first one-shot pulse circuit 24, that is, the output of the specific distortion detection circuit 14.
When an inrush current is generated, particularly when a large inrush current is generated, the circuit voltage is momentarily reduced and gradually recovered as shown by the voltage waveform V in FIG. As a result, the comparator circuit 20 outputs an “H” signal for a long time as shown in FIG. 5B, and the first one-shot pulse circuit 24 outputs a signal as shown in FIG. 5D. That is, the specific distortion detection circuit 14 may determine that specific distortion has occurred.

  On the other hand, the output of the second comparison circuit 15 at this time is shown in FIG. As shown in FIG. 6, since the peak value of the circuit voltage does not reach the threshold value Th2, the “H” signal is not output. Therefore, the second one-shot pulse circuit 16 does not output an “H” signal, and the electric circuit is not interrupted.

  In this way, the voltage change due to the inrush current is detected, so even if a large drop in the circuit voltage occurs instantaneously due to the occurrence of the inrush current, it is possible to prevent a false detection of the occurrence of a cord short-circuit. A cord short-circuit can be detected with accuracy.

In addition, although the said embodiment demonstrated the case where the cord short circuit detection circuit 11 was provided in the outlet, it may be incorporated in circuit interruptions, such as a branch breaker, or it may be incorporated in the tap outlet used by connecting to an outlet. May be.
In addition, the power outlet is provided with a shut-off function, and the power path is cut off. However, when a cord short-circuit occurs, a notification may be made by sound or LED light emission.

  1 .. Outlet device, 7 .. Open / close contact, 9 .. Output circuit, 11 .. Code short circuit detection circuit, 13 .. Rectifier circuit, 14 .. Specific distortion detection circuit, 15. Voltage detection circuit), 16 .... second one-shot pulse circuit (determination circuit), 17 .... power supply circuit, 20..window comparator circuit, 23..first comparison circuit (waveform distortion determination circuit), 24. A first one-shot pulse circuit.

Claims (3)

A rectifier circuit that obtains the voltage waveform of the electric circuit that supplies commercial power to the load and performs full-wave rectification,
A specific distortion detection circuit for detecting a specific waveform distortion from the voltage waveform rectified by the rectifier circuit;
A determination circuit for determining the occurrence of a cord short circuit;
A power supply circuit provided independently from the rectifier circuit for obtaining power from the electric circuit and supplying power to each circuit;
The specific distortion detection circuit compares a predetermined first threshold value lower than a peak value of a commercial voltage with a second threshold value smaller than the first threshold value and the rectified voltage waveform, and an instantaneous value of the rectified voltage waveform is obtained. A window comparator circuit for detecting a state between the two threshold values;
A waveform distortion determination circuit that determines that waveform distortion occurs when a time between the two thresholds exceeds a certain time,
The determination circuit outputs a code short-circuit occurrence signal when the specific distortion detection circuit determines that waveform distortion has occurred. A rectifier circuit that obtains the voltage waveform of the electric circuit that supplies commercial power to the load and performs full-wave rectification,
A specific distortion detection circuit for detecting a specific waveform distortion from the voltage waveform rectified by the rectifier circuit;
An inrush voltage detection circuit for detecting a voltage change due to an inrush current of the load from the rectified voltage waveform of the rectifier circuit output;
A determination circuit for determining the occurrence of a cord short circuit;
A power supply circuit provided independently from the rectifier circuit for obtaining power from the electric circuit and supplying power to each circuit;
The specific distortion detection circuit compares a predetermined first threshold value lower than a peak value of a commercial voltage with a second threshold value smaller than the first threshold value and the rectified voltage waveform, and an instantaneous value of the rectified voltage waveform is obtained. A window comparator circuit for detecting a state between the two threshold values;
A waveform distortion determination circuit that determines that a waveform distortion occurs when a time between the two thresholds exceeds a certain time;
The inrush voltage detection circuit is a circuit that compares the voltage waveform with a predetermined third threshold value that is lower than a peak value of a commercial voltage and that exceeds the first threshold value,
The determination circuit determines that a code short circuit has occurred when the specific distortion detection circuit determines that waveform distortion has occurred and the inrush voltage detection circuit determines that the peak value of the voltage waveform is greater than the third threshold value. A cord short-circuit detection circuit that outputs a cord short-circuit occurrence signal. An outlet to which a load is connected, an electric circuit for supplying commercial power to the outlet, an opening / closing means provided on the electric circuit for opening and closing the electric circuit, and a blocking means for opening the opening / closing means. An outlet device comprising: the cord short circuit detection circuit according to 1 or 2; and an output circuit that drives the blocking means based on a cord short circuit generation signal output from the cord short circuit detection circuit.

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