JP2001016759A - Short-circuit detecting method, and circuit breaking method and alarm outputting method using the short- circuit detecting method, and plug or socket using the circuit breaking method or the alarm outputting method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect the short-circuit current in a household electric appliance so as to discriminate it from the load current thereof, by processing adequately through an operating circuit the digital voltage values outputted from an A/D converter circuit to output plural deciding values, and by comparing the summed value of the plural deciding values with the threshold. SOLUTION: A microcomputer 11 has an A/D converter circuit 4, an operation circuit 12, a register circuit 13, and a circuit-break output circuit 6. After the division of the output voltage of a rectifier circuit 3, the A/D converter circuit 4 converts it into a digital voltage. The operation circuit 12 processes the digital voltage generated correspondingly to the half period of a commercial frequency voltage to add to the resultant a deciding value stored in the operation circuit 12. The register circuit 13 discards in every unit time its oldest decided value and reads in it its latest deciding value outputted from the operation circuit 12 to store always in it its plural new deciding values. The circuit-break output circuit 6 reads from the register circuit 13 the plural new deciding values to sum them, and when the summed value exceeds a threshold, the circuit-break output circuit 6 decides it as the occurrence of a short-circuit to output a sensing signal. Thereby, the fault current in a household electric appliance can be discriminated from its load current.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for detecting a short circuit,
In particular, a method for detecting a short circuit due to a code short circuit / tracking phenomenon, a circuit interruption method for interrupting an electric circuit using the method, an alarm output method for outputting an alarm, and a plug or outlet using the circuit interruption method or the alarm output method It is about.

[0002]

2. Description of the Related Art As shown in FIG. 1, a method of detecting a short circuit and a circuit breaker using the method are described as follows.
, The driving signal from the trip circuit 7
The trip coil 8 which is a driving unit is operated to open the contact 9. In the method for detecting a short circuit in FIG. 1 and the circuit breaker using the method, in order to disconnect the contact 9 by combining an electronic circuit, the current of the electric circuit 10 is detected by the current transformer 1 to detect the current-voltage. After being converted into a voltage value by the conversion circuit 2, it is converted into a digital value (absolute value) by the A / D conversion circuit 4 inside the microcomputer 11, and the digital value is integrated by the integration circuit 5 for a predetermined time to obtain an integrated value. When the value exceeds a predetermined reference value, a trip signal is output from the cutoff output circuit 6 to the trip circuit 7, and the electric circuit is cut off.

[0003]

2. Description of the Related Art However, in the above-mentioned conventional technology,
There were the following inconveniences.

The conventional circuit breaker shown in FIG. 1 integrates a current value for a predetermined time in the integrating circuit 5, so that a relatively low value fault current, particularly a short circuit current due to a tracking phenomenon, is generated. To detect, it is necessary to keep the predetermined reference value small.However, due to the rush current of home electric appliances, if the reference value is reduced to a certain value or more, erroneous shutoff occurs, and it is difficult to detect a low fault current. .

[0005] Further, the circuit breaker shown in FIG. 1 detects a short circuit due to a code short circuit or tracking phenomenon, and performs a breaking operation at a portion of the circuit breaker. Circuits other than outlets,
For example, when a lighting circuit and the like were connected in parallel, the power supply to circuits other than the specific outlet was cut off even though the accident occurred at a specific outlet.

[0006]

SUMMARY OF THE INVENTION Accordingly, the present invention has been made in view of the above-described circumstances, and does not operate with a current flowing waveform of a home appliance, and a short-circuit current due to a short-circuit due to a cord having a low fault current value or a tracking phenomenon occurs. A short-circuit due to a short-circuit due to a code short-circuit or a tracking phenomenon is generated by reliably detecting a short-circuit, a circuit breaking method using the detection method, an alarm output method, and incorporating the method into an outlet or a plug. It is an object of the present invention to provide a plug or an outlet that can cut off only a necessary minimum electric circuit.

[0007]

According to a first aspect of the present invention, there is provided a current transformer for detecting a current flowing in an electric circuit, and a current for converting an AC current output from the current transformer into an AC voltage. A voltage conversion circuit, a rectification circuit for rectifying the AC voltage and converting the pulsation voltage to a pulsating voltage, and an A / D conversion circuit for converting the pulsating voltage to a digital voltage value at predetermined time intervals of several milliseconds or less. And the digital voltage value is processed for each unit time corresponding to the length of a half-wave of the commercial frequency, and a determination value U inside the arithmetic circuit is added according to the processing result. An arithmetic circuit for outputting the value U and clearing the judgment value U inside the arithmetic circuit at the same time; and discarding the oldest judgment value U inside the register circuit for each predetermined unit time and simultaneously outputting the value from the arithmetic circuit. Read the latest judgment value U By using a register circuit that always stores the latest plurality of judgment values U and a shut-off output circuit that compares a threshold value B with the sum of each past judgment value U stored in the register circuit, When the sum of the past determination values U stored in the register circuit becomes larger than the threshold value B at every predetermined unit time corresponding to the length of a half wave of the frequency, the cutoff output circuit outputs the detection signal. It provides a judgment method of outputting.

According to a second aspect of the present invention, in the arithmetic circuit of the first aspect, the magnitude of the digital voltage value exceeds the threshold value A during a predetermined unit time corresponding to a half-wave length of the commercial frequency. A method is provided in which when there is something, a judgment value U inside the arithmetic circuit is added.

According to a third aspect of the present invention, there is provided the arithmetic circuit according to the first aspect, wherein the second digital voltage among the three consecutive digital voltage values converted into the digital voltage value at every time width of several milliseconds or less is provided. Value is smaller than the other two digital voltage values,
Also, a method is provided in which, when the magnitude of the second digital voltage value is larger than the threshold value C, the judgment value U inside the arithmetic circuit is added.

According to a fourth aspect of the present invention, the maximum value of the digital voltage value within the unit time is registered in the arithmetic circuit of the first aspect every predetermined unit time corresponding to the length of a half-wave of the commercial frequency. At the same time, the register circuit reads and stores the maximum value of the digital voltage value of the arithmetic circuit at the unit time, and at the same time, at least the latest five digital voltage values stored in the register circuit have the maximum value. When the difference between the value and the minimum value is larger than the threshold value D, a method of adding a determination value U inside the arithmetic circuit is provided.

According to a fifth aspect of the present invention, in the determining means according to the first aspect, the latest digital voltage value stored in the register circuit for each predetermined unit time corresponding to the length of a half-wave of the commercial frequency. If the difference between the second to at least the fifth newest digital voltage value stored in the register circuit and the maximum value is larger than the threshold value E and smaller than the threshold value F, the judgment value U inside the arithmetic circuit is added. Offers a way to do that.

According to a sixth aspect of the present invention, there is provided the arithmetic circuit according to the first aspect, wherein the second digital voltage value among the three consecutive digital voltage values converted into the digital voltage value at every time width of several milliseconds or less. Is smaller than the other two digital voltage values and the magnitude of the second digital voltage value is larger than the threshold value C, and a predetermined unit corresponding to the length of a half-wave of the commercial frequency At each time, the maximum value of the digital voltage value of the arithmetic circuit is read and stored in a register, and at the same time, the difference between the maximum value and the minimum value of the latest five digital voltage values stored in the register circuit is a threshold value D.
And the difference between the latest maximum digital voltage value stored in the register circuit and the second to at least fifth highest digital voltage value stored in the register circuit. Is larger than the threshold value E and smaller than the threshold value F, when all of the first to third conditions are satisfied, the sum of the past determination values U stored in the register circuit is equal to the threshold value B. There is provided a method of substituting a larger numerical value into a determination value U inside an arithmetic circuit.

A seventh aspect of the present invention relates to a method for selectively adding all of the second to sixth aspects or the second to sixth aspects with respect to the method of adding the judgment value U in the arithmetic circuit. providing.

[0014] Claim 8 is Claim 1 to Claim 7
In response to the detection signal of the cut-off output circuit of any of the short-circuit detection methods shown in (1), the trip circuit receives the detection signal, outputs a drive signal to the trip coil, opens the contacts, and cuts off the electric circuit. A circuit interruption method is provided.

[0015] Claim 9 is Claim 1 to Claim 7
In response to the detection signal of the cut-off output circuit in any of the short-circuit detection methods shown in (1), the alarm circuit provides an alarm output method of receiving the detection signal and outputting an alarm to the outside.

According to a tenth aspect of the present invention, there is provided a plug incorporating the circuit shut-off method according to the eighth aspect and the alarm output method according to the ninth aspect.

An eleventh aspect of the present invention provides an outlet incorporating the circuit shut-off method according to the eighth aspect and the alarm output method according to the ninth aspect.

[0018]

According to the first aspect of the present invention, a digital voltage value output from the A / D conversion circuit is appropriately processed by an arithmetic circuit to output a judgment value U, and a total value of the plurality of judgment values U is set to a threshold value. By comparing with B, it is possible to distinguish and detect the load current of the home electric appliance and the short-circuit current due to the low current value flowing when the cord is short-circuited or short-circuited due to the tracking phenomenon.

According to the method described in claim 2, when a transition is made from a rush current waveform at the time of power input to a home appliance having a similar current waveform to a steady current waveform and when a short-circuit current waveform due to a short-circuit is compared, It is possible to determine a short-circuited cord from the characteristic that a higher current is continuously generated in the short-circuit current waveform than in the steady-state current waveform of the home electric appliance.

According to the third aspect of the present invention, even if the short-circuit current waveform due to the tracking phenomenon and the current waveform in which noise is superimposed on the load current waveform of the home electric appliance are similar, two out of three consecutive digital voltage values are obtained. By focusing on the third magnitude, it is possible to distinguish the load current waveform of the home electric appliance from the short-circuit waveform due to the tracking phenomenon.

By utilizing the fact that the fluctuation width of the short-circuit current due to the tracking phenomenon is larger than the fluctuation width of the load current of the home electric appliance, the load current waveform of the home electric appliance and the tracking phenomenon are utilized. Can be distinguished from each other by the short-circuit waveform.

By utilizing the fact that the fluctuation width of the short-circuit current due to the tracking phenomenon is smaller than the fluctuation width of the load current when the home electric appliance is stopped, the method described in claim 5 utilizes the load when the home electric appliance is stopped. The current and the short-circuit current due to the tracking phenomenon can be distinguished.

When a plurality of waveforms specific to the short-circuit current due to the tracking phenomenon are detected by the method described in claim 6,
By substituting a numerical value such that the sum of the past determination values U stored in the register circuit becomes larger than the threshold value B as the determination value U of the arithmetic circuit, it is determined that a short circuit due to the tracking phenomenon has occurred in a short time. be able to.

According to the method described in claim 7, a short circuit due to a code short circuit and tracking can be detected more reliably.

When it is determined by the method described in claim 8 that a short circuit due to a code short circuit or tracking has occurred,
The electric circuit can be cut off.

According to the ninth aspect, when it is determined that a short circuit has occurred due to a code short circuit or tracking,
An alarm can be output.

According to the means described in the tenth aspect, it is possible to cut off or output an alarm limited to the minimum necessary electric circuit on the load device connection side of the plug.

According to the eleventh aspect, it is possible to cut off or output an alarm limited to the minimum necessary electric circuit on the load device connection side of the outlet.

[0029]

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

FIG. 2 shows an embodiment of the present invention.
FIG. 2 is a block diagram of the first embodiment of the present invention, in which a current transformer 1, a current-voltage conversion circuit 2, a rectification circuit 3, A
This is a combination of a tripping circuit 7, a tripping coil 8 and a contact 9 with respect to a short-circuit detection method including the / D conversion circuit 4, the arithmetic circuit 12, the cutoff output circuit 6, and the register circuit 13.

Although the electric circuit 10 is shown as a single-phase two-wire system, it is not particularly limited to the single-phase two-wire system. Further, a circuit breaker or a relay is used as a contact switching device including the trip coil 8 and the contact 9.

The current transformer 1 detects an electric current flowing through the electric circuit 10 and outputs an alternating current. The current transformer 1 detects, for example, a current waveform as shown in FIG.

The current-voltage conversion circuit 2 converts the AC current output from the current transformer 1 into an AC voltage, and specifically converts the voltage into a voltage value through a resistor.

The rectifier circuit 3 rectifies the output voltage of the current-voltage converter circuit 2 into a waveform as shown in FIG. 5 using a diode or the like, so that the monitored voltage range can be reduced to half that of the case where no rectification is performed. The resolution of the digital voltage value after digitizing the input voltage of the / D conversion circuit 4 can be increased.

Next, the inside of the microcomputer 11 will be described. The microcomputer 11 has an A / D conversion circuit 4, an arithmetic circuit 12, a register circuit 13, and a cutoff output circuit 6.

The A / D conversion circuit 4 divides the output voltage of the rectification circuit 3 by a predetermined time width of several milliseconds or less and converts it into a digital voltage value. For example, the output voltage is digitized every 1 ms, which is the sampling time.

Assuming that the maximum input voltage of the A / D conversion circuit 4 is 5 V and the resolution of digital conversion is 8 bits, A / D conversion
The output of the conversion circuit 4 is 0 at 0 V, 127 at 2.5 V, and 255 at 5 V. Where A / D
When the current-voltage conversion circuit is adjusted so that the 1-bit current value at the time of conversion corresponds to 1 A, the performance of the A / D conversion circuit 8 can measure a current waveform from 0 A to +255 A. Further, a microcomputer 11 having the A / D conversion circuit 4 may be used.

The arithmetic circuit 12 processes a digital voltage value generated per unit time corresponding to a half-wave length of the commercial frequency, and determines a judgment value U inside the arithmetic circuit 12 according to the processing result. to add.

The register circuit 13 discards the oldest judgment value U for each unit time and simultaneously reads and stores the newest judgment value U output from the arithmetic circuit 12, and preferably sets T to 10 or more. The determination values U for the past T new values are always stored as numbers.

Although the number T of past judgment values U to be stored is required to be 10 or more as much as possible in order to increase the judgment accuracy, it is preferable to store as many judgment values U as possible in accordance with the memory capacity inside the microcomputer. Good.

The cutoff output circuit 6 reads out each judgment value U stored in the register for each unit time and obtains the sum, and when the sum becomes larger than the threshold value B, judges that a short circuit has occurred. Outputs a detection signal.

In the short-circuit detecting method according to the first embodiment of the present invention, the digital voltage value output from the A / D conversion circuit is compared with the arithmetic circuit 12 in comparison with the conventional integration type determination method shown in FIG. The threshold value B is summed by the cutoff circuit 6 and compared with the threshold value B. Therefore, the arithmetic circuit captures the characteristics of the current waveform and determines the determination value U. U can be weighted. Thereby, the load current and the fault current of the home electric appliance can be distinguished. The rectifier circuit 3 can be omitted. In this case, since both the positive and negative digital voltage values output from the A / D conversion circuit are output, they may be converted into absolute values thereafter.

Next, a second embodiment of the present invention will be described. The description will be made based on the block diagram of FIG. 2 and the waveform when the cord is short-circuited as shown in FIG. Claim 2 is an embodiment of the arithmetic circuit 12. The arithmetic circuit 12 compares the magnitude of the digital voltage value generated per unit time corresponding to the length of a half-wave of the commercial frequency with the threshold value A. If the digital voltage value is larger than the threshold value A, the judgment value U inside the arithmetic circuit 12 is added. The adding method may include comparing the magnitude of the digital voltage value generated per unit time with a threshold value A, and adding the number of occurrences of the digital voltage value that is larger than the threshold value A to the determination value U. The magnitude of the digital voltage value generated per unit time is compared with the threshold value A, and if the digital voltage value is larger than the threshold value A, the judgment value U
Alternatively, a method of adding 1 to may be used. FIG. 6 shows an example of the latter addition method. .

The set value of the threshold value B with respect to the sum of the threshold value A of the current and the past judgment value U of the register circuit is set to a magnitude of a current that operates with a short-circuited cord and does not malfunction due to a rush current of a home electric appliance or the like. Set the corresponding numerical value. For example, the threshold value A of the current can be arbitrarily set to a current value of about 100 A, and the threshold value B can be set arbitrarily within a range not exceeding T.

The above processing will be described in a concrete example. For example, in the case of a code short-circuit waveform as shown in FIG. 6, a half-wave waveform exceeding the threshold value A among the T half-wave waveforms is generated. Assuming that 1 has been added to the determination value U of the portion where there is, each of the past T determination values U stored in the register circuit.
Is equal to the threshold value B, so that the cutoff output circuit determines that a code short circuit has occurred. As a result, it is possible to determine a waveform that gradually decreases from a large current due to a rush current or the like of the home electric appliance to a steady current and a case where a short-circuit current that is not large up to the rush current such as a cord short-circuit continuously flows.

Next, a third embodiment of the present invention will be described. The description will be made based on the block diagram of FIG. 2, the load current waveform of the home electric appliance of FIG. 7, and the short-circuit current waveform due to the tracking phenomenon of FIG. The third embodiment is an embodiment of the arithmetic circuit 12. The arithmetic circuit 12 updates the digital voltage values one by one at every predetermined time width, and always stores three new continuous digital voltage values. .

The waveform in which the second digital voltage value among the three consecutive digital voltage values is smaller than the other two digital voltage values frequently appears in the short-circuit current waveform due to the tracking phenomenon, and is characterized by other waveforms. However, when noise is superimposed on the current waveform of only a home appliance having an inverter, it is difficult to distinguish the noise.

However, by adding a condition for determining whether or not the magnitude of the second digital voltage value is larger than the threshold value C, the short-circuit current waveform due to the tracking phenomenon shown in FIG. 8 and the inverter as shown in FIG. It is possible to distinguish the case where noise is superimposed on the current waveform depending on the home electric appliance having the same.

When the magnitude of the digital voltage value is larger than the threshold value C, the second arithmetic circuit judges that a waveform specific to short circuit due to the tracking phenomenon as shown in FIG. The judgment value U is added. further,
The interruption output circuit 6 reads out each determination value U stored in the register as needed and calculates the sum. When the sum exceeds the threshold B, it is determined that a short circuit due to the tracking phenomenon has occurred.

The threshold value C shown in FIGS. 7 and 8 is large enough to operate with the short-circuit current due to the tracking phenomenon shown in FIG. 8 and not to malfunction by a home electric appliance having the inverter shown in FIG. Set the value corresponding to the value. For example, the set value of the threshold C is set to a numerical value such as 20A. There is an upper limit on the load capacity of home electric appliances having an inverter, and therefore, an upper limit can also be set for the threshold value C. By appropriately selecting the threshold value C, a short-circuit current waveform due to a normal tracking phenomenon and a current waveform of a home electric appliance having an inverter can be distinguished.

Next, a fourth embodiment of the present invention will be described. The description will be made based on the block diagram of FIG. 3, the load current of the home electric appliance of FIG. 9, and the short-circuit current due to the tracking phenomenon of FIG. Claim 4 is an embodiment of the arithmetic circuit 12, wherein the maximum value of the digital voltage value within the unit time is output to the register circuit 13 at each unit time, and the register circuit 13 calculates at every predetermined unit time. The maximum value of the newest digital voltage value of the circuit is read and stored, and at the same time, the maximum value of the oldest digital voltage value is discarded, and the latest maximum value of the digital voltage value of at least the past S is always stored.

If the difference between the maximum value and the minimum value of the first to at least fifth newest digital voltage values stored in the register circuit 13 is larger than the threshold value D, the operation circuit 12 Is added.
Further, the cutoff output circuit 6 reads out each determination value U stored in the register as needed and calculates the sum. When the sum exceeds the threshold value B, it is determined that a short circuit due to tracking has occurred.

Note that the threshold value D is larger during the fluctuation of the short-circuit current due to the tracking phenomenon as shown in FIG. 10 than the fluctuation width of the maximum value of the load current of the home electric appliance as shown in FIG. A value corresponding to the magnitude of the current that operates with the short-circuit current due to the tracking phenomenon as shown in FIG. 10 and does not malfunction due to the current of the home electric appliance or the like as shown in FIG. 9 is set. For example, the threshold value D is set to a current value of about 10 A which is larger than the amount of change in the load current during normal use of the home electric appliance. Further, it is necessary to store more than ten judgment values for the past S values, and it is preferable to increase the number that can be stored according to the internal memory capacity of the microcomputer.

Next, a fifth embodiment of the present invention will be described. The description will be made based on the block diagram of FIG. 2, the load current waveform of the home electric appliance of FIG. 11, and the current waveform by tracking shown in FIG. Claim 5 is an embodiment of the arithmetic circuit 12, wherein the latest digital voltage value stored in the register circuit 13 and the second to at least fifth newest digital voltage values stored in the register circuit are included. When the difference from the maximum value is larger than the threshold value E and smaller than the threshold value F, it is determined that the short-circuit current due to the tracking phenomenon as shown in FIG. 12 has occurred, and the determination value U of the arithmetic circuit 12 is added. . Further, the cutoff output circuit 6 reads out each determination value U stored in the register as needed and calculates the sum. When the sum exceeds the threshold value B, it is determined that a short circuit due to tracking has occurred.

The threshold value E can be set for the reason described with reference to FIGS. 9 and 10, and the set value of the threshold value F is a large change in the load current when the home electric appliance is stopped as shown in FIG. Since the amount of change in the short-circuit current due to the tracking phenomenon as shown in FIG. 12 is smaller than the amount of the short-circuit current due to the tracking phenomenon as shown in FIG. It is possible to set a digital voltage value corresponding to the magnitude of the current that does not cause a malfunction due to an operation such as turning on / off the power.

Next, a sixth embodiment of the present invention will be described. A description will be given based on FIG. Claim 6 is an embodiment of the arithmetic circuit 12, wherein the second digital voltage value among the three consecutive digital voltage values described in claim 3 is smaller than the other two digital voltage values, and The first condition that the magnitude of the second digital voltage value is larger than the threshold value C and the maximum value of the first to at least fifth newest digital voltage values stored in the register circuit described in claim 4. A second condition that the difference is larger than the threshold value D, and the latest digital voltage value stored in the register circuit and the second to at least fifth newest digital value stored in the register circuit. When all of the third conditions that the difference between the digital voltage value and the maximum value is larger than the threshold value E and smaller than the threshold value F are satisfied, a short circuit occurs due to the tracking phenomenon. The phenomenon of chromatic results in which a plurality detected, since a short circuit due to the tracking phenomenon is very likely generated interruption circuit 6
Each past judgment value U stored in the register circuit
Is added to the arithmetic circuit 12 with a function of substituting a numerical value such that the sum of the values becomes larger than the threshold value B into the arithmetic circuit U.
In such a case, when the interruption output circuit 6 reads out the respective judgment values U stored in the register at any time and obtains the sum, the sum becomes larger than the threshold value B and the short circuit due to tracking occurs immediately. You can judge.

Next, a seventh embodiment of the present invention will be described. Claim 7 relates to the operation of the judgment value U of the operation circuit 12 in which all of the methods according to Claims 2 to 6 are performed or selectively performed in combination. In addition, it is possible to detect a short circuit caused by a code and a tracking phenomenon.

Next, an eighth embodiment of the present invention will be described. This will be described with reference to FIG. FIG. 3 is a block diagram showing a configuration of a means for realizing an interruption method when a short circuit occurs due to a code short circuit / tracking phenomenon, and includes a current transformer 1, a current-voltage conversion circuit 2, a rectification circuit 3, an A / D converter. Circuit 4,
The arithmetic circuit 12, the register circuit 13, and the cutoff output circuit 6 are the same as those in FIG. 2, and include a trip circuit 7, a trip coil 8,
The contact 9 is added. In this embodiment, a detection signal from the shut-off output circuit according to any one of claims 1 to 7 is output to a trip circuit, and the trip circuit 7 receives the detection signal and outputs a drive signal to the trip coil 8. Thus, the electric circuit can be cut off.

Next, a ninth embodiment of the present invention will be described. This will be described with reference to FIG. FIG. 3 is a block diagram showing a configuration of means for realizing an alarm output method when a short circuit occurs due to a code short circuit / tracking phenomenon. The current transformer 1, the current-voltage conversion circuit 2, the rectification circuit 3, and the A / A D conversion circuit 4, cut-off output circuit 6, arithmetic circuit 12, register circuit 1
3 is the same as that of FIG.
It is connected to the. This embodiment is a block diagram showing a configuration of a means for realizing a method of outputting an alarm when a short circuit due to a code short-circuit / tracking phenomenon is detected. The alarm output circuit 17 shown in FIGS. Is added, an alarm can be output when a short circuit occurs due to a code short circuit and a tracking phenomenon.

The alarm means of the alarm output circuit 17 may be provided with an alarm lamp display, audio output, or external contact output.

Next, claims 10 and 11 of the present invention will be described.
The following shows an example. This will be described with reference to FIGS.
In this embodiment, the plug 19 or the outlet 16 is connected to the circuit shut-off method or the alarm output method according to claim 8 or claim 9. Provide a plug or outlet that can shut off the circuit due to a short circuit due to the tracking phenomenon, or output an alarm, and separate only the circuit where an accident has occurred from other circuits to generate an interrupt or generate an alarm. it can.

[0062]

As described above, according to the first aspect of the present invention,
The arithmetic circuit appropriately processes the digital voltage value output from the A / D conversion circuit to output a determination value U, and a plurality of determination values U
Is compared with the threshold value B, it is possible to distinguish and detect the load current of the home electric appliance and the short-circuit current due to a low current value flowing when the cord is short-circuited or short-circuited due to the tracking phenomenon.

According to the second aspect of the present invention, the waveform at the time of transition from the rush current waveform at the time of power supply input to the home appliance having a similar current waveform to the steady current waveform and the short-circuit current waveform due to the short-circuit of the cord are compared. In this case, it is possible to determine the short-circuit of the cord from the characteristic that the short-circuit current waveform due to the short-circuit of the cord continuously generates a higher current than the steady current of the home electric appliance.

Further, according to the third aspect of the present invention, even if noise is superimposed on the short-circuit current waveform due to the tracking phenomenon and the load current waveform of the home appliance and the current waveforms are similar, among the three continuous digital voltage values, By focusing on the second magnitude, it is possible to distinguish the load current waveform of the home electric appliance from the short-circuit waveform due to the tracking phenomenon.

According to the fourth aspect of the present invention, by utilizing the fact that the fluctuation width of the short-circuit current due to the tracking phenomenon is larger than the fluctuation width of the load current of the home electric appliance, the load current waveform of the home electric appliance is changed. It becomes possible to distinguish the short-circuit waveform due to the tracking phenomenon.

According to the fifth aspect of the present invention, the fact that the fluctuation width of the short-circuit current due to the tracking phenomenon is smaller than the fluctuation width of the load current when the home electric appliance is stopped is utilized. And the short circuit current due to the tracking phenomenon can be distinguished.

According to the invention of claim 6, when a plurality of waveforms specific to the short-circuit current due to the tracking phenomenon are detected, the judgment value U of the arithmetic circuit is replaced by the past judgment value U stored in the register circuit. By substituting a numerical value that makes the sum larger than the threshold value B, it can be determined that a short circuit due to the tracking phenomenon has occurred in a short time.

Further, according to the invention of claim 7, a short circuit due to a code short circuit / tracking can be detected more reliably.

According to the invention of claim 8, when it is determined that a short circuit due to a code short circuit / tracking has occurred, the electric circuit can be cut off.

According to the ninth aspect of the present invention, when it is determined that a short circuit has occurred due to a code short circuit or tracking, an alarm can be output.

According to the tenth aspect of the present invention, the cutoff is limited to the minimum necessary electric circuit on the load device connection side of the plug.
Alternatively, an alarm can be output, and an electric fire due to a short circuit due to a code short circuit or tracking phenomenon can be prevented beforehand, and at the same time, other necessary power sources such as lighting can be secured.

According to the eleventh aspect of the present invention, the means described in the eleventh aspect can cut off or output an alarm only for the minimum necessary electric circuit on the load device connection side of the outlet. As a result, it is possible to prevent an electric fire due to a short circuit due to a code short circuit or a tracking phenomenon, and to secure other necessary power sources such as lighting.

[Brief description of the drawings]

FIG. 1 is a schematic circuit example of a conventional electronic circuit breaking method equipped with a microcomputer.

FIG. 2 is a schematic circuit example of the present invention.

FIG. 3 shows an embodiment of the present invention.

FIG. 4 shows an example of a current waveform.

FIG. 5 is an example of a voltage waveform obtained by rectifying the output voltage of the current-voltage conversion circuit 2 using a diode.

FIG. 6 shows an example of a code short-circuit waveform.

FIG. 7 is a load current waveform of a home appliance.

FIG. 8 is a short-circuit current waveform obtained by tracking.

FIG. 9 is a load current waveform of a home appliance.

FIG. 10 shows a short-circuit current waveform by tracking.

FIG. 11 is a load current waveform of a home appliance.

FIG. 12 shows a short-circuit current waveform by tracking.

FIG. 13 shows a plug using a circuit interruption method or an alarm output method.

FIG. 14 shows an outlet using a circuit interruption method or an alarm output method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Current transformer 2 Current-voltage conversion circuit 3 Rectifier circuit 4 A / D conversion circuit 5 Integration circuit 6 Contact 7 Tripping circuit 8 Tripping coil 9 Contact 10 Electric circuit 11 Microcomputer 12 Operation circuit 13 Register circuit 14 Wiring insertion connection Container 15 Relay 16 Outlet 17 Alarm circuit 18 Plug 19 Plug blade

Continued on the front page F term (reference) 5G004 AA01 AB02 BA03 BA04 CA04 DA01 DB01 DC04 DC07 EA04 FA01 5G030 FC08 XX00 YY13

Claims (11)

[Claims] 1. A current transformer for detecting a current flowing in an electric circuit, a current-voltage conversion circuit for converting an AC current output from the current transformer into an AC voltage, and rectifying the AC voltage into a pulsating voltage. A rectifier circuit for converting, an A / D converter circuit for converting the pulsating voltage into a digital voltage value for each predetermined time width of several milliseconds or less, and for each unit time corresponding to a half-wave length of the commercial frequency And a decision value U inside the arithmetic circuit is added according to the processing result, and a decision value U inside the arithmetic circuit is calculated.
And an arithmetic circuit for clearing the judgment value U inside the arithmetic circuit at the same time as outputting the oldest judgment value U inside the register circuit for each unit time and the newest output from the arithmetic circuit at the same time. From a register circuit that always stores the latest plurality of judgment values U by reading and storing the judgment value U, and a shutoff output circuit that compares a threshold value B with the sum of each past judgment value U stored in the register circuit. When the sum of the past determination values U stored in the register circuit is greater than the threshold value B for each unit time corresponding to the length of a half wave of the commercial frequency, the cutoff output circuit A short-circuit detection method that outputs a detection signal. 2. The arithmetic circuit according to claim 1, wherein the digital voltage value exceeds a threshold value A during a unit time corresponding to a half-wave length of a commercial frequency. 2. The short-circuit detection method according to claim 1, wherein the determination value U is added. 3. The arithmetic circuit according to claim 1, wherein the second digital voltage value of the three consecutive digital voltage values converted into the digital voltage value for each time width of several milliseconds or less is the other two digital voltage values. 2. The short-circuit detection method according to claim 1, wherein when the value of the second digital voltage value is smaller than the threshold value and the magnitude of the second digital voltage value is larger than the threshold value C, the judgment value U inside the arithmetic circuit is added. 4. The arithmetic circuit outputs a maximum value of a digital voltage value within the unit time to a register circuit for each unit time corresponding to a half-wave length of a commercial frequency, and the register circuit outputs the maximum value. The maximum value of the digital voltage value of the arithmetic circuit is read and stored for each unit time, and at the same time, the difference between the maximum value and the minimum value of the latest five digital voltage values stored in the register circuit is greater than the threshold value D. 2. The short-circuit detection method according to claim 1, further comprising adding a judgment value U inside the arithmetic circuit when the difference is larger. 5. The arithmetic circuit outputs a maximum value of a digital voltage value in a unit time corresponding to a length of a half-wave of a commercial frequency to a register circuit, and the register circuit outputs the arithmetic circuit every unit time. At the same time as reading and storing the maximum value of the digital voltage values, the latest digital voltage value stored in the register circuit and the maximum of the second to at least fifth newest digital voltage values stored in the register circuit. 2. The short-circuit detection method according to claim 1, wherein when the difference from the value is larger than the threshold value E and smaller than the threshold value F, the judgment value U inside the arithmetic circuit is added. 6. The arithmetic circuit according to claim 1, wherein the second digital voltage value of the three consecutive digital voltage values converted into the digital voltage value at every time width of several milliseconds or less is the other two digital voltage values. And the second digital voltage value is larger than a threshold value C, and the digital voltage value of the arithmetic circuit is changed every unit time corresponding to a half-wave length of the commercial frequency. A second condition that the difference between the maximum value and the minimum value is larger than the threshold value D in at least the last five digital voltage values stored in the register circuit at the same time as reading and storing the maximum value of The difference between the digital voltage value that is the latest maximum value stored in the register circuit and the maximum value among the second to at least fifth newest digital voltage values stored in the register circuit is a threshold E. When all of the first to third conditions among the third conditions that are larger than the threshold value F and are smaller than the threshold value F are satisfied, the sum of the past determination values U stored in the register circuit becomes larger than the threshold value B. 2. The short-circuit detection method according to claim 1, wherein a numerical value is substituted for a judgment value U inside the arithmetic circuit. 7. The method according to claim 1, wherein the method of adding the judgment value U in the arithmetic circuit selectively includes all of claims 2 to 6, or any of claims 2 to 6. Short circuit detection method. 8. A trip circuit for outputting a drive signal to a trip coil in response to a detection signal of a shut-off output circuit in any one of the short-circuit detection methods according to claim 1, and a contact 9 for cutting off an electric circuit. The detection signal of any one of the cut-off output circuits according to any one of claims 1 to 7 is output to a trip circuit, and the trip circuit receives the detection signal and outputs a drive signal to a trip coil to contact the trip circuit. 9. A circuit interrupting method, comprising opening an electric circuit by opening a circuit 9. 9. An alarm circuit for outputting an alarm in response to a detection signal of a cut-off output circuit according to any one of claim 1 to claim 7, wherein the alarm circuit receives a detection signal of the cut-off output circuit. And outputting an alarm to the outside. 10. A plug incorporating the circuit shut-off method according to claim 8 or the alarm output method according to claim 9. 11. An outlet incorporating the circuit shut-off method according to claim 8 or the alarm output method according to claim 9.