JP4921868B2 - Wet deterioration detector - Google Patents

Description

The present invention relates to a wet degradation detection equipment for detecting the wetting deterioration such plug connected to an electrical outlet.

  If moisture adheres between the plug blades of the home appliance due to condensation, a minute discharge occurs between the plug blades (pre-tracking phenomenon). When this discharge phenomenon is repeated, deterioration of the plug (wet deterioration) proceeds, and a phenomenon in which the plug blades are carbonized (tracking phenomenon) eventually appears, and discharge is finally generated even during drying (tracking short circuit). Since this phenomenon causes a fire, various devices for detecting this phenomenon have been proposed and incorporated in outlets and circuit breakers.

In such a phenomenon, it is known that the current generated by the pre-tracking phenomenon, which is the first stage, is relatively small, 50 to 400 mA. However, since a load current much larger than the discharge current flows through the plug, it is difficult to detect this discharge current, and further, the discharge expands and tracking is generated to increase the discharge current. It was detected. Specifically, conventional discharge detection between plug blades is usually performed by detecting the current flowing through the plug by CT, removing the load current component using a high-pass filter, and extracting the high-frequency component peculiar to tracking discharge. By detecting, the state where the discharge was repeated and the carbonization phenomenon occurred was detected.
In order to increase the tracking detection sensitivity, the present applicants determine the charge amount, generation frequency, and frequency level of the discharge current, and determine the occurrence of tracking by setting a threshold value for them. A method for detecting the occurrence of tracking before exceeding amperage has been proposed (see Patent Document 1).

JP 2004-279205 A

However, even in the method of the above-mentioned Patent Document 1, it is difficult to detect until the plug surface is sufficiently carbonized due to repeated discharge, and there remains a problem in that it prevents fire. Further, when the load includes an inverter circuit, a current waveform similar to the discharge current is generated, and thus erroneous detection may occur.
The present invention has been made in view of such problems, it is possible to detect the wetting degradation before the plug and outlet are carbonized, also load the wet deterioration detection equipment is not erroneously detected even inverter The purpose is to provide.

In order to solve the above problems, a wet deterioration detecting device according to the invention of claim 1 includes a current detecting means for detecting an electric circuit current waveform, a voltage detecting means for detecting an electric circuit voltage waveform, and a load connected to the electric circuit. Stop / standby detection means for detecting a stop / standby state, a peak value of a waveform having a frequency higher than the power supply frequency in the detected current waveform, and a current peak value calculation means for calculating the phase thereof, and the current peak value calculation Counting means that counts the number of peak occurrences when the absolute value of the peak value calculated by the means is equal to or greater than a preset value, and outputs the count number during the voltage half cycle, and when the connected load is in the stop / standby state, and a deterioration determining means and the count is to determine the wet deterioration occurs reaches the predetermined number of more than 10 times, the counting means, the peak voltage level to be further preset value or more 0 degrees 120 degrees, and Once generated only between 300 degrees 180 degrees, and outputs the carbonized path generation signal to the deterioration determining means.

  As described above, it is known that the pre-tracking phenomenon that occurs when moisture adheres has a small peak value of 50 to 400 mA and a frequency of 60 to 1000 Hz. Also, home appliances such as air conditioners and refrigerators do not continue to operate for 24 hours, and always have a stopped state or a standby state. Against this background, the above-described configuration makes it possible to detect a pre-tracking phenomenon using a stand-by state that is not affected by the load current, so that the current characteristics peculiar to wet conditions before the plug or outlet is carbonized can be obtained. It can be detected reliably and the pre-tracking phenomenon can be detected with high accuracy. Even if the load includes an inverter circuit, it is not determined when the load is driven, so that no erroneous detection is caused.

In addition, tracking deterioration due to carbonization can be detected as the wet deterioration progresses, and both pre-tracking and tracking can be detected separately.

According to the present invention, the current characteristic peculiar to the wet state before the plug or the outlet is carbonized can be reliably detected, and the pre-tracking phenomenon can be detected with high accuracy. Even if the load includes an inverter circuit, it is not determined when the load is driven, so that no erroneous detection is caused.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, embodiments of the invention will be described in detail with reference to the drawings. FIG. 1 is a circuit block diagram showing an example of a wet deterioration detecting device according to the present invention, and shows a shut-off device that cuts off an electric circuit when wet deterioration is detected. In the figure, 1 is a current transformer as current detecting means for detecting the current waveform of the electric circuit 10, 2 is a transformer as voltage detecting means for detecting the voltage waveform of the electric circuit 10, 3 is a blocking means for interrupting the electric circuit 10, Reference numeral 5 denotes a wet deterioration detection device, and reference numeral 6 denotes a load.

  The wet deterioration detection device 5 includes a first A / D conversion circuit 11, a stop / standby detection unit 12 that determines a stop / standby state of the load 6, a second A / D conversion circuit 13, a current peak value calculation unit 14, and a count unit 15. , A deterioration determination unit 16, a register 17, a determination output unit 18 that performs a blocking operation of the blocking unit 3, and an alarm circuit 19 that performs a notification operation. The stop / standby detection unit 12, the current peak value calculation unit 14, the count unit 15, and the deterioration determination unit 16 are configured by one CPU, and predetermined determination and control are performed by a program. The register 17 stores the number of peak value detections and the like.

  Specifically, the stop / standby detection unit 12 has a threshold value set to 50 mA, and if the electric current is 50 mA or less continues for 5 minutes, the stop / standby detection unit 12 determines that the device is stopped or in a standby state, and deteriorates that effect. Output to the decision unit. Further, the current peak value calculation unit 14 calculates and outputs the peak value and the phase of the circuit current waveform from the circuit current information and the circuit voltage information.

  On the other hand, if there is data having a peak value of an absolute value of 300 mA or more from the transmitted peak value information, the count unit 15 counts the number for each voltage half cycle and outputs it to the deterioration determination unit 16. In addition, when the occurrence of the current peak value occurs only between the voltage phases of 0 degrees to 120 degrees and between 180 degrees to 300 degrees, a carbonization path generation signal (tracking generation signal) is output separately.

  Then, when the load 6 is in the stop / standby state, the deterioration determination unit 16 determines that the wet deterioration has occurred when receiving the count information signal 20 times or more from the count unit 15, and sends the wet deterioration occurrence signal to the determination output unit 18. Output. At that time, if the carbonization path generation signal is also received, the carbonization path generation signal is output to the determination output unit 18.

The shut-off device configured as described above specifically operates as follows. The electric circuit current detected by the current transformer 1 is input to the wet deterioration detection device 5. In the wet deterioration detection device 5, the current signal is converted into a digital signal by the first A / D conversion circuit 11, and then connected to the electric circuit by the stop / standby detection unit 12. Detect if it is in a state.
On the other hand, the current converted into a digital signal by the second A / D conversion circuit 13 is input to the current peak value calculation unit 14, and the circuit voltage information detected by the transformer 2 is also input to the wet deterioration detection device 5.

The current peak value calculation unit 14 receives current information and voltage information, calculates the peak value and phase of the circuit current, and sends the peak value and phase information to the count unit 15.
The count unit 15 counts the number of peak value data having a value of 300 mA or more during a voltage half cycle from the received current peak value and phase information, and outputs the information to the degradation determination unit 16.
The deterioration determining unit 16 determines that the wet deterioration has occurred if the count number received from the counting unit 15 during stop / standby of the load 6 is 20 or more, and determines the wet deterioration occurrence signal as a determination output unit 18. Output to. When the determination output unit 18 receives the wet deterioration determination signal in this way, the blocking means 3 is operated to block the electric circuit 10, and the alarm circuit 19 having a buzzer or the like is alarmed.

  Further, if the counting unit 15 outputs the carbonization path generation signal, the carbonization path generation signal is output to the determination output unit 18, and the notification circuit 19 is notified by a notification operation different from the wet deterioration, so that the wet deterioration has progressed. To let you know.

As described above, since the pre-tracking phenomenon is detected by using the stand-by state that is not affected by the load current, the current characteristic peculiar to the wet state before the plug or outlet is carbonized can be reliably detected. The tracking phenomenon can be detected with high accuracy. Even if the load includes an inverter circuit, it is not determined when the load is driven, so that no erroneous detection is caused.
In addition, tracking discharge due to carbonization can be detected, and both pre-tracking and tracking can be detected separately.

  2 to 4 show the voltage waveform and current waveform of the electric circuit, FIG. 2 shows a state in which no wet deterioration or carbonization has occurred in the plug or the like, FIG. 3 shows a state in which the wet deterioration has progressed, and FIG. It shows a state in which deterioration (carbonization) has progressed. In each waveform diagram, two current waveforms are shown with different ranges. As shown in this waveform diagram, it can be seen that both the positive and negative peak values of the discharge current increase as the deterioration progresses, and that the voltage waveform concentrates on rising from 0 degrees and 180 degrees. From these characteristics, it can be seen that by detecting the number of peak values having a relatively large value and the generation phase thereof, it is possible to determine the state of occurrence of tracking and the degree of progress.

In addition, the threshold value of current (300 mA) and the number of peak detection times (20 times or more) in the voltage half cycle in the above embodiment can be changed. For example, if the threshold value is lowered, a minute discharge can be detected, but it contains a lot of noise. Also, if the number of peak detections is reduced, the sensitivity increases, but malfunctions easily occur. Therefore, it is preferable to determine that the moisture has deteriorated when it is detected at least 10 times or more.
In addition, when it is determined that the wet deterioration has occurred, the alarm circuit 19 is operated and the alarm circuit 19 is operated. Also good. For example, when the current having a peak of 300 mA or more is 20 times or less (10 times or more), only the alarm may be issued without interrupting the electric circuit 10.

It is a circuit block diagram which shows an example of embodiment of the wet deterioration detection apparatus which concerns on this invention. It is a wave form diagram of circuit current and circuit voltage without wet deterioration and tracking. It is a wave form diagram of the circuit current and circuit voltage in the state where the wet deterioration has occurred. It is a wave form diagram of the circuit current and circuit voltage in the state where the carbonization path was generated.

Explanation of symbols

  1 .. Current transformer (current detection means) 2 .... Transformer (voltage detection means) 5 .... Wet deterioration detection device 6 .... Load 10 .... Electric circuit 12 .... Stop / Standby detection unit, 14. Current peak value calculation section, 15. Count section, 16. Degradation determination section, 17. Register, 18. Determination output section, 19. Alarm circuit.

Claims (1)

Current detection means for detecting a circuit current waveform;
Voltage detection means for detecting the circuit voltage waveform;
A stop / standby detection means for detecting a stop / standby state of a load connected to the electric circuit;
A peak value of a waveform having a frequency higher than the power supply frequency in the detected current waveform, and a current peak value calculating means for calculating the phase thereof;
Counting means for counting the number of peak occurrences when the absolute value of the peak value calculated by the current peak value calculating means is equal to or greater than a preset value, and outputting the count number during a voltage half cycle;
When the connection load is in a stop / standby state, the deterioration determination means for determining that the wet deterioration has occurred when the count reaches a predetermined number exceeding 10 times,
The counting means further outputs a carbonization path generation signal to the deterioration determining means when the peak that is equal to or greater than a preset value occurs only in the voltage phase of 0 to 120 degrees and 180 to 300 degrees. Wetting deterioration detection device characterized by the above.

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