JP2001324529A - Disconnection detecting method, device using this method, and plug or outlet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a disconnection detecting method, a device using this method, and a plug or an outlet. SOLUTION: A routine means is composed of a current detecting part 2 for detecting current flowing through a cable way 1; a current-voltage conversion part 3 for converting the current outputted from the current detecting part 2 into voltage; a filter part 4 for filtering the voltage outputted from the current-voltage conversion part 3; an A/D conversion part 5 for converting the voltage outputted from the filter part 4 into a digital value; a maximum value detecting part 6 for detecting the maximum value of the absolute values of the digital values converted at the A/D conversion part 5 during a semi-cycle of the commercial frequency; a first register part 7 for storing the maximum digital values from past several cycles outputted from the maximum value detecting part 6 to the latest cycle; and a processing part 8 for processing the maximum digital values stored in the first register part 7 and outputting detected signals, and this routine means is used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for detecting a disconnection, an apparatus using the method, and a plug or an outlet.

[0002] In recent years, electric fires have been increasing gradually. Due to aging of electrical equipment etc., improper use and maintenance,
It is believed that the internal wiring was broken and insulation deteriorated, leading to ignition due to overheating or short circuit. With the remarkable increase in electric equipment, electric fires generated from electric equipment and the like may increase in the future.

[0003]

2. Description of the Related Art In order to prevent such an electric fire, a disconnection detecting device as shown in FIG. 2 has conventionally been devised. In the figure, a current detection unit 2 detects a current flowing through an electric circuit 1, a current-voltage conversion unit 3 converts the current into an AC voltage, a filter unit 4 removes high-frequency noise included in the AC voltage, The / D conversion unit 5 converts the AC voltage into a digital value, and the arithmetic processing unit 8 integrates the number of occurrences of the digital value exceeding a threshold every predetermined time, and the integrated value falls within a predetermined range. If the detection signal is received, the detection unit 11 outputs a detection signal, the trip unit 11 receives the detection signal, outputs a cutoff signal to the trip coil, and the trip coil is connected to the contact 12.
Was opened to cut off the electric circuit.

[Problems to be solved by the invention]

[0004] However, this device can detect when the current is interrupted or interrupted at a very short cycle due to poor contact or when a pulse-like current flows between the phases at a very short cycle due to insulation deterioration. However, a very slow phenomenon, such as a complete disconnection and a re-contact and current flowing, could not be detected.

[0005]

SUMMARY OF THE INVENTION Accordingly, the present invention has been made in view of the above circumstances, and has been made in consideration of such a situation that the wiring is completely disconnected and the contact and disconnection are repeated at a relatively slow cycle. It is an object of the present invention to provide a method and an apparatus for detecting a state in which moisture is attached between the broken lines and that tracking is occurring.

[0006]

In view of the above, according to the present invention, a current detector for detecting a current flowing in an electric circuit, a current-voltage converter for converting a current output from the current detector into a voltage, A filter for filtering the voltage output from the converter, an A / D converter for converting the voltage output from the filter to a digital value, and an A / D converter that converts the voltage during a half cycle of the commercial frequency. A maximum value detection unit that detects the maximum value of the absolute value of the digital value, a first register unit that stores the maximum digital value from the past several cycles to the latest cycle output by the maximum value detection unit, An arithmetic processing unit that arithmetically processes the maximum digital value stored in the register unit and outputs a detection signal; and the arithmetic processing unit includes, among the maximum digital values stored in the first register unit, old And less than the threshold value B is the maximum digital value to the A + 1 th from th, A + 2 th maximum digital value exceeds the threshold value B, and greater than the maximum digital value is a threshold value B from A + 3 th to A + 3 + C th, and A + 4 + C
When the second maximum digital value is less than the threshold value B, a detection signal is output, and a disconnection detection method is provided.

According to the present invention, there is provided a disconnection detecting method for detecting a short-time contact between core wires due to an external force such as vibration applied to the electric wiring itself at a disconnection portion generated in the electric wiring of the electric device. it can.

According to a second aspect, the arithmetic processing unit according to the first aspect does not output a detection signal when any of the maximum digital values stored in the first register unit exceeds a threshold value D. The disconnection detecting method according to claim 1 is provided.

Thus, a disconnection detection method can be obtained in which erroneous detection due to an inrush current flowing when a power switch of an electric device is turned on is reduced.

According to a third aspect of the present invention, the arithmetic processing unit according to the first or second aspect is configured such that, among the maximum digital values stored in the first register, the oldest maximum digital value is equal to or more than the threshold value H and less than the threshold value B, and 3. The disconnection detection method according to claim 1 or 2, wherein a detection signal is output when the maximum digital value monotonically decreases from the first to the (2 + E) th oldest one and the (2 + E) th digital value is smaller than the threshold value F. Is provided.

[0011] Thereby, in the broken portion generated in the electric wiring of the electric equipment, it is possible to detect the energization via moisture or moisture generated between the broken core wires, and even if the core wires do not directly contact. It is possible to obtain a disconnection detection method that enables disconnection detection.

According to a fourth aspect of the present invention, a second register unit and a tracking detection unit are added to the configuration of the disconnection detection method according to any one of the first to third embodiments, and the tracking detection unit is provided with the A for a half cycle of a commercial frequency. Among the absolute values of the digital values converted by the / D conversion unit, those that exceed the threshold value G are consecutively I or more.
If less than this occurs, a tracking detection signal is output,
The second register section stores a tracking detection signal output by the tracking detection section from the past several cycles to the latest cycle, and the arithmetic processing section calculates the total number of tracking detection signal occurrences of the second register section. A detection signal is output when a threshold value K is exceeded within a predetermined range.

[0013] Thereby, it is possible to detect the energization by tracking caused by moisture and moisture, dust and dirt generated between the broken core wires of the electric wiring generated in the electric equipment,
It is possible to obtain a disconnection detection method capable of detecting a disconnection without directly touching the core wires.

According to a fifth aspect of the present invention, there is provided a disconnection detecting apparatus having an alarm function of receiving a detection signal of the disconnection detecting method according to the first to fourth aspects and outputting an alarm.

[0015] Thus, it is possible to obtain a device that outputs an alarm when disconnection of electric wiring generated in an electric device is detected.

According to a sixth aspect of the present invention, there is provided a disconnection detecting apparatus having a function of receiving a detection signal of the disconnection detecting method according to the first to fourth aspects and interrupting an electric circuit.

[0017] Thus, it is possible to obtain a device for interrupting an electric path for supplying electricity to an electric device when disconnection of electric wiring generated in the electric device is detected.

According to a seventh aspect of the present invention, there is provided a plug or an outlet having the device according to the fifth or sixth aspect.

Thus, by incorporating the device into a plug or an outlet of an electric device, a plug or an outlet that issues an alarm or shuts off when a disconnection occurs can be obtained.

[0020]

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

FIG. 1 is a block diagram showing an embodiment of the present invention. The current detection unit 2, the current-voltage conversion unit 3, the filter unit 4, the A / D conversion unit 5, the maximum value detection unit 6, the first register unit 7, and the arithmetic processing unit 8 are combined. It was done.

The electric circuit 1 is of a single-phase two-wire system.

The current detector 2 uses a current transformer.

The current-voltage converter 3 converts the current waveform output from the current detector 2 into a voltage waveform.
Specifically, it is converted into a voltage value via a resistor.

The filter unit 4 performs low-pass filtering on the voltage waveform output from the current-voltage conversion unit 3 to remove high-frequency noise superimposed on the voltage waveform that hinders disconnection detection.

The A / D conversion section 5 sets the voltage value of the output voltage of the filter section 4 to several hundred μsec or less (400 μsec as an example).
Is converted into a digital value for each time width of.

If the input voltage range of the A / D converter 5 is 0 V to 5 V and the resolution of the digital conversion is 10 bits, the digital value output from the A / D converter 5 is 0 V
-128 for V, 0 for 2.5V, 1 for 5V
27. Here, one bit at the time of A / D conversion is 100
When the current-voltage converter is adjusted to correspond to mA,
The performance of the A / D converter 5 is from about -12.8 A to about 1
Current waveforms up to 2.8 A can be measured.

The maximum value detector 6 detects the maximum value among the absolute values of the digital values converted by the A / D converter during a half cycle of the commercial frequency.

The first register section 7 stores the maximum digital value output from the maximum value detection section 6 for several past cycles to the latest cycle.

The arithmetic processing unit 8 determines that among the maximum digital values stored in the first register unit, the oldest first to A + 1st maximum digital values are less than the threshold value B,
A detection signal is output when the A + 2th largest digital value exceeds the threshold B, the A + 3th to A + 3 + Cth largest digital values exceed the threshold B, and the A + 4 + Cth largest digital value is less than the threshold B. I do.

The above processing will be described with reference to FIGS. 3 and 4 show waveforms in which the absolute value of the digital value output from the A / D converter 5 is taken. When a break occurs in a circuit to which a resistive load such as a heater is connected and the core wire comes into contact again, a digital value exceeding a threshold value B as shown in FIG. 3 is measured.

When the power of the electric equipment is turned on / off, two half-wave sine wave arcs having the maximum digital value exceeding the threshold B at the fourth and the fifth are consecutive as shown in FIG.
There are cases where only one arc is measured, but by setting the value of the threshold C to 1 or more, unless three or more arcs of a half cycle of a sine wave having a maximum digital value exceeding the threshold B are continuously measured, No false detection.

However, when the threshold value C is set to 2 and the threshold value A is set to 1, as shown in FIG. If the arc of the half cycle of the sine wave having the maximum digital value not exceeding is measured at the sixth and twelfth points, five arcs of the half wave of the sine wave having the maximum value exceeding the threshold B are consecutive. In the case where it is determined that the malfunction occurs, the threshold A may be set to 2 or more.

The threshold value A is preferably an integer value of 1 to 5, and the threshold value B is preferably an arbitrary integer corresponding to about 80% of a peak value of a current flowing in an electric circuit in which a disconnection occurs. In addition, C is an arbitrary integer value in a range that does not operate due to ON / OFF of the power supply of the electric device, but the size of C is limited to the number A + 4 + C of the maximum digital value that can be stored in the first register.

Next, a second embodiment will be described. Claim 2
Does not output a detection signal when any of the maximum digital values stored in the first register unit exceeds the threshold value D in the arithmetic processing unit 8.

The above processing will be described with reference to FIG. FIG. 5 shows a waveform in which the absolute value of the digital value output from the A / D converter 5 is taken. When a load with a large current consumption is connected in parallel with the disconnected circuit, a large digital value exceeding the threshold value D is measured as shown in FIG.

In this case, no detection signal is output because the operation of the load consuming a large amount of current and the occurrence of disconnection cannot be distinguished. Note that the threshold value D is larger than the threshold value B, and may be set to an integer of about 80% of the maximum digital value of the load current having a large current consumption and connected in parallel to the disconnected circuit.

Next, a third embodiment will be described. Claim 3
In the arithmetic processing unit 8, among the maximum digital values stored in the first register unit, the oldest maximum digital value is greater than or equal to the threshold B and less than the threshold D, and the maximum digital value ranges from the second to the 2 + E-th oldest digital value. Monotonically decreasing, 2 + E
If the digital value is smaller than the threshold value F, a detection signal is output.

The above processing will be described with reference to FIG. FIG. 6 shows a waveform obtained by taking the absolute value of the digital value output from the A / D converter 5. If there is moisture between the broken cores, when the moisture between the cores dries, a current smaller than the contact of the cores flows before the drying, and almost no current flows when the drying is performed.

Therefore, the oldest maximum digital value is equal to or higher than the threshold value H, so that the current which is in the stage before drying flows, and the threshold value is set to eliminate the influence of the fluctuation of the load current operating in parallel with the disconnected circuit. B, and monotonically decreases from the oldest maximum digital value to the 2 + Eth maximum digital value, and the 2 + Eth maximum digital value that is 1 + Eth newer than the oldest maximum digital value becomes smaller than the threshold value F. Then, it is sufficient to detect that almost no current flows.

In this case, the constant E determines the optimum value of the time required for drying from an experiment, the threshold F is set to a value that does not detect the standby current of the electric equipment, and the threshold H is smaller than the threshold B and smaller than the threshold B. Set within a range that does not malfunction due to standby current or the like.

FIG. 7 is a block diagram of a fourth embodiment. A fourth aspect of the present invention provides the configuration of the disconnection detection method according to any one of the first to third aspects,
In addition, the tracking detection unit 15 determines that the absolute value of the digital value converted by the A / D conversion unit for a half cycle of the commercial frequency that exceeds the threshold value G is continuously I or more.
If less than this occurs, a tracking detection signal is output,
The second register unit 14 stores a tracking detection signal output by the tracking detection unit 15 from the past several cycles to the latest cycle, and the arithmetic processing unit 8 stores the tracking detection signal of the second register unit 13. When the total number of occurrences exceeds a threshold value K within a predetermined range, a function of outputting a detection signal is provided.

The above processing will be described with reference to FIG. FIG. 8 shows a waveform obtained by taking the absolute value of the digital value output from the A / D converter 5. As shown in FIG. 8, when tracking occurs, digital values exceeding the threshold G are concentrated in a specific phase range.

Therefore, when the number exceeding the threshold value G occurs continuously from I to J, the tracking is detected by outputting the tracking detection signal.

Further, in order to prevent a malfunction, the second register section 14 stores a tracking detection signal output from the tracking detecting section 15 from several past cycles to the latest cycle, and the arithmetic processing section 8 stores the tracking detection signal. When the total number of occurrences of the tracking detection signal of the second register section 13 exceeds the threshold value K within a predetermined range, a detection signal is output.

Since the current flowing when the tracking occurs is smaller than the current caused by the contact of the core wire, the threshold G is set to a value smaller than the threshold B. Since the predetermined time and the threshold value K vary depending on the material used for the electric equipment and the magnitude of the current value of the monitoring circuit, a numerical value that does not malfunction is determined experimentally.

FIG. 9 shows a fifth embodiment of the present invention. FIG.
In the example, the alarm output means 13 is added to the disconnection detection method shown in FIG. 7, and an apparatus which outputs an alarm when a disconnection is detected can be obtained.

Next, an embodiment according to claim 6 is shown in FIG. In the example of FIG. 10, means for interrupting an electric circuit, that is, a trip unit 11, a trip coil 10, a contact 1
With the addition of 2, it is possible to obtain a device that cuts off the electric circuit when disconnection is detected.

Next, an embodiment according to claim 7 is shown in FIG. In the example of FIG. 11, a plug or an outlet incorporating the device of FIG. 9 or 10 can be obtained.

It should be noted that the present invention is not limited to the above embodiment, but can be applied without departing from the scope of the claims of the present invention, and these are not excluded from the scope of the present invention.

[0051]

As described above, according to the present invention, a wire in which a wire is completely disconnected and contact and disconnection are repeated at a relatively slow cycle, or a completely disconnected wire. It is possible to obtain a method and device for detecting the state where moisture is attached in between, and that tracking is occurring.Also, it is possible to output an alarm when disconnection occurs and to cut off only the minimum necessary electric circuit. This has the effect that a possible plug or outlet can be obtained.

[Brief description of the drawings]

FIG. 1 is a block diagram of an embodiment according to claims 1 to 3;

FIG. 2 is a block diagram of an embodiment of a conventional disconnection detection method.

FIG. 3 is a waveform showing the absolute value of a digital value output from an A / D converter when a disconnection occurs.

FIG. 4 is a waveform showing the absolute value of a digital value output from an A / D converter when the power of an electric device is turned on.

FIG. 5 is a waveform showing the absolute value of a digital value output from an A / D converter during a load operation with a large current consumption connected in parallel to a disconnected circuit;

FIG. 6

FIG. 7 is a block diagram of an embodiment of a disconnection detection method according to claim 4;

FIG. 8 is a waveform showing an absolute value of a digital value output from an A / D converter when tracking occurs.

FIG. 9 is an embodiment of claim 5;

FIG. 10 is an embodiment of claim 6;

FIG. 11 shows an embodiment according to claim 7;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Electric circuit 2 Current detection part 3 Current-voltage conversion part 4 Filter part 5 A / D conversion part 6 Maximum value detection part 7 First register part 8 Arithmetic processing part 10 Tripping coil part 11 Tripping part 12 Contact 13 Alarm output Means 14 Second register unit 15 Tracking detection unit

[Procedure amendment]

[Submission date] June 14, 2000 (2006.1.
4)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Brief description of drawings

[Correction method] Change

[Correction contents]

[Brief description of the drawings]

FIG. 1 is a block diagram of an embodiment according to claims 1 to 3;

FIG. 2 is a block diagram of an embodiment of a conventional disconnection detection method.

FIG. 3 is a waveform showing the absolute value of a digital value output from an A / D converter when a disconnection occurs.

FIG. 4 is a waveform showing the absolute value of a digital value output from an A / D converter when the power of an electric device is turned on.

FIG. 5 is a waveform showing the absolute value of a digital value output from an A / D converter during a load operation with a large current consumption connected in parallel to a disconnected circuit;

FIG. 6 is a waveform showing the absolute value of a digital value output from an A / D converter.

FIG. 7 is a block diagram of an embodiment of a disconnection detection method according to claim 4;

FIG. 8 is a waveform showing an absolute value of a digital value output from an A / D converter when tracking occurs.

FIG. 9 is an embodiment of claim 5;

FIG. 10 is an embodiment of claim 6;

FIG. 11 shows an embodiment according to claim 7;

[Description of Signs] 1 Electric circuit 2 Current detection unit 3 Current-voltage conversion unit 4 Filter unit 5 A / D conversion unit 6 Maximum value detection unit 7 First register unit 8 Arithmetic processing unit 10 Tripping coil unit 11 Tripping unit DESCRIPTION OF SYMBOLS 12 Contact 13 Alarm output means 14 2nd register part 15 Tracking detection part

Claims (7)

[Claims] A current detection section for detecting a current flowing through an electric circuit, a current-voltage conversion section for converting a current output from the current detection section into a voltage, and a filter processing for a voltage output from the current-voltage conversion section. A filter unit, an A / D converter that converts a voltage output from the filter unit into a digital value, and a maximum value of an absolute value of the digital value converted by the A / D converter during a half cycle of the commercial frequency. A maximum value detection unit to be detected, a first register unit storing the maximum digital value from the past several cycles to the latest cycle output by the maximum value detection unit, and a maximum digital value stored in the first register unit Of the maximum digital value stored in the first register unit from the oldest first digital value to A +
The maximum digital value up to the first is less than the threshold B and A + 2
Outputting a detection signal when the third largest digital value exceeds the threshold value B, and the largest digital value from A + 3 to A + 3 + C exceeds the threshold value B, and the A + 4 + Cth largest digital value is less than the threshold value B; A disconnection detection method characterized by the following. 2. The arithmetic processing unit according to claim 1, wherein a detection signal is not output when one of the maximum digital values stored in the first register unit exceeds a threshold value D. The disconnection detection method according to claim 1. 3. The arithmetic processing unit according to claim 1, wherein, of the maximum digital values stored in the first register unit, the oldest maximum digital value is equal to or more than the threshold value H and less than the threshold value B, and from the second to the (2 + E) th. 3. The disconnection detecting method according to claim 1, wherein when the maximum digital value monotonically decreases over the oldest one and the 2 + E-th digital value is smaller than the threshold value F, a detection signal is output. 4. A disconnection detecting method according to claim 1, further comprising a second register section and a tracking detecting section, wherein said tracking detecting section comprises said A / D converter for a half cycle of a commercial frequency. When the absolute value of the digital value converted by the unit exceeds the threshold value G and the number of consecutive occurrences is I or more and less than J, the second register unit outputs the tracking detection signal from the past several cycles. A tracking detection signal output from the tracking detection unit up to a cycle is stored, and the arithmetic processing unit determines that the total number of occurrences of the tracking detection signal of the second register unit exceeds a threshold K in a predetermined range. And a function for outputting a detection signal. 5. A disconnection detecting device having an alarm function for receiving a detection signal of the disconnection detecting method according to claim 1 and outputting an alarm. 6. A disconnection detecting device having a function of interrupting an electric circuit in response to a detection signal of the disconnection detecting method according to any one of claims 1 to 4. 7. A plug or outlet comprising the device according to claim 5.