JP2021092402A - Partial disconnection detector - Google Patents

Abstract

To provide a partial disconnection detector which can detect the occurrence of partial disconnection without detecting an electric circuit current.SOLUTION: The partial disconnection detector includes a measuring unit 2 which acquires waveform information of an AC voltage applied to an electric wire L and divides one cycle into 200 parts to output voltage value information at respective division points, a determination unit 3 which determines the occurrence of partial disconnection of the electric wire L on the basis of the voltage value information at the division points which is outputted by the measuring unit 2, and a display unit 5 which, when the determination unit 3 determines the occurrence of partial disconnection, indicates the occurrence of partial disconnection. The determination unit 3 calculates variation between voltages at adjacent division points in accordance with the voltage value information at the division points and, if an absolute value of the variation exceeds a prescribed threshold, determines the occurrence of partial disconnection.SELECTED DRAWING: Figure 1

Description

The present invention relates to a half-break detection device that detects a half-break of an electric wire.

As a conventional technique for detecting a half-break of an electric wire, there is one disclosed in Patent Document 1. In Patent Document 1, information on the current flowing through the electric wire is obtained, and a change peculiar to the half-break of the current waveform is detected to determine the occurrence of the half-break.

Japanese Unexamined Patent Publication No. 2008-8859

However, since the technique of Patent Document 1 makes a judgment based on the waveform of the electric circuit current, a zero-phase current transformer which is a sensor for detecting the electric circuit current is required, and a large installation space for that is required. It was.

Therefore, in view of such a problem, an object of the present invention is to provide a half-breakage detecting device capable of detecting the occurrence of half-breakage without detecting the electric circuit current.

In order to solve the above problem, the invention of claim 1 obtains waveform information of the AC voltage applied to the electric wire, divides one cycle into at least 100, and outputs voltage value information of each division point. A measurement unit, a half-break judgment unit that determines the occurrence of a half-break of an electric wire based on the dividing point voltage value information output by the measurement unit, and a notification unit that notifies the occurrence of a half-break when the half-break judgment unit determines that a half-break has occurred. The half-breakage determination unit calculates the amount of change in the adjacent division point voltage from the division point voltage value information, and determines that half-breakage has occurred when the absolute value of this change amount exceeds a predetermined threshold value. And.
According to this configuration, since the normal voltage waveform is a sinusoidal waveform, the adjacent voltage values of the dividing point voltage values do not change beyond a predetermined value, so that the voltage fluctuation exceeding the predetermined value occurs in the energized state. If it changes, it can be judged that a half disconnection has occurred. Therefore, the occurrence of a half-break can be detected without monitoring the current.

The invention of claim 2 is a measuring unit that obtains waveform information of the AC voltage applied to the electric wire, divides one cycle into at least 100, and outputs voltage value information of each division point, and the measuring unit outputs the waveform information. It has a half-breakage determination unit that determines the occurrence of a half-breakage of an electric wire based on the voltage value information at the dividing point, and a notification unit that notifies the occurrence of a half-breakage when the half-breakage determination unit determines that a half-breakage has occurred. Is to divide one cycle of the voltage waveform into four and monitor the waveform of at least one quarter cycle rising from the zero cross point and one quarter cycle falling from the zero cross point, and the voltage change between the dividing points in the rising waveform. If shows a negative value, or if the voltage change between the dividing points shows a positive value in the falling waveform, it is determined that a half disconnection has occurred.
According to this configuration, it is known that the fluctuation of the voltage waveform due to the occurrence of the half-break occurs mainly in the range from the rising edge to the peak from the voltage waveform zero crossing point, or in the range from the falling edge to the peak. .. Therefore, the voltage waveform in each section of at least one quarter cycle is monitored, and if the polarity of the slope is reversed in that section, it is judged that half-breakage has occurred. Therefore, the occurrence of half-breakage can be detected with high accuracy. , The occurrence of half-break can be detected without monitoring the current.

According to the present invention, when the amount of change of the adjacent voltage value of the dividing point voltage value changes beyond a predetermined value, or at least in the range where the voltage rises from the zero cross point to reach the peak, or falls to the peak. Since it is determined that a half-break occurs when the voltage gradient is reversed, the occurrence of a half-break can be detected without monitoring the current.

It is a block diagram which shows an example of the half disconnection detection apparatus which concerns on this invention. It is a waveform explanatory view which shows the 1st mode which determines the half disconnection. It is explanatory drawing which enlarged the part A of FIG. It is a waveform explanatory view which shows the 2nd form of a half disconnection detection apparatus.

Hereinafter, embodiments embodying the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram showing an example of a half disconnection detection device according to the present invention. The half-breakage detection device 10 includes a voltage dividing circuit 1 that divides the voltage detected from the electric wire L, and a measuring unit 2 that divides one cycle of the divided voltage waveform into 200 and outputs voltage value information of 200 points per cycle. Judgment unit 3 that calculates the amount of voltage change (inclination) from the divided voltage value information output by the measurement unit 2 to determine the occurrence of a half-break, and output unit 4 that shuts off the electric circuit when a half-break occurs. A display unit 5 for displaying and notifying voltage information is provided. Further, 6 indicates a cutoff portion provided with an opening / closing contact for cutting off the electric wire L from the power source.
Here, the blocking unit 6 is configured to shut off when a half-break is detected.

The determination unit 3 includes an A / D conversion circuit (not shown), a storage unit that stores a determination threshold value, a determination CPU, and the like, and operates as follows.
First, the first embodiment will be described with reference to the waveform explanatory diagram of FIG.
FIG. 2 shows one cycle of a voltage waveform having an effective value of 100 V and 60 Hz applied to the electric wire L. W1 is a waveform shown for comparison, and shows a voltage waveform in a normal state in which half-breakage does not occur. W2 shows the waveform in which the half-break occurs only in the half cycle, and shows the division point voltage of 100 points for the half cycle out of 200 divisions in one cycle. The normal waveform W1 indicates a division point voltage obtained by dividing one cycle into 40 parts.

It can be seen that a large voltage fluctuation occurs in the section M1 from the division point P1 to Q1 shown in FIG. 2, and the voltage is significantly reduced as compared with the normal waveform. Therefore, it can be determined that a discharge phenomenon peculiar to half-breakage occurs in this range. The determination unit 3 detects this voltage drop and determines that a discharge has occurred (half-breakage has occurred).
Specifically, the maximum value of the voltage change amount in the case of the 100V effective value occurs in the vicinity of zero cross, and is about 33V / msec. Here, the determination unit 3 stores this value as a threshold value, and if the absolute value of the amount of change in the dividing point voltage value exceeds this threshold value in the energized state, it is determined that a half disconnection has occurred.

FIG. 3 is an enlarged view of part A of FIG. 2, and as shown in FIG. 3, the voltage v1 at the dividing point P1 is about 73V, and the voltage v2 at the next dividing point P2 is about 64V. Since the elapsed time is 0.083 ms, the amount of change (slope) of the voltage is Δv = 108 V / msec, which is a value that greatly exceeds the set threshold value.
The determination unit 3 calculates the amount of change Δv of this voltage, and determines that a half disconnection has occurred because this is a numerical value exceeding the threshold value. When it is determined that a half disconnection has occurred, a drive signal is output to the output unit 4, and the output unit 4 shuts off the cutoff unit 6. In addition, the display unit 5 displays the occurrence of a half disconnection.
Since the determination unit 3 determines by the absolute value, the voltage drop in the negative half cycle is also detected in the same manner.

In this way, since the normal voltage waveform is a sinusoidal waveform, the adjacent voltage values of the dividing point voltage values do not change beyond a predetermined value. Therefore, if the voltage fluctuation exceeding the predetermined value changes in the energized state, It can be judged that a half disconnection has occurred. Therefore, the occurrence of a half-break can be detected without monitoring the current.

Next, a second mode of the semi-disconnection detection device will be described. Since the circuit configuration is the same as that in FIG. 1, the description thereof will be omitted, and the description will be made with reference to the waveform explanatory diagram of FIG.
In the above embodiment, the half disconnection is determined from all the dividing point voltage values, but not all the voltage information is used here, and the range M2 and M3 shown in FIG. 4, that is, from the negative of one voltage waveform cycle. Judgment is made based on the information of a quarter cycle from the zero cross point C1 in which the polarity changes positively and a quarter cycle from the zero cross point C2 in which the polarity changes from positive to negative. Also in FIG. 4, the voltage waveform in which the half-break occurs is shown only in the positive half cycle, and the negative half cycle is omitted.

When a half-break occurs, the voltage rises from the zero crossing point C1 and then reaches a positive peak, or after a half cycle, the voltage drops from the zero crossing point C2 and then reaches a negative peak. , A large voltage fluctuation (voltage drop) occurs in the electric wire due to the discharge generated at the half-disconnected part. By detecting this voltage drop in these two ranges, it is possible to determine a half disconnection.

The determination unit 3 grasps the range M2 of the rising quarter cycle and the range M3 of the falling quarter cycle from the voltage value information from the measuring unit 2, and the voltage increases in the range M2 and the slope of the voltage. Is positive, and in the range M3, the voltage increases negatively and the slope is negative.
Then, upon receiving the input of the dividing point voltage divided into 200, the amount of change between the dividing points is first calculated. If a change that suddenly becomes a negative inclination occurs in the range where the inclination is positive (division points P1 to P3 shown in FIG. 4), it is determined that a half disconnection has occurred. Further, if a positive inclination suddenly occurs in the range M3 where the inclination is negative, it is determined that a half disconnection has occurred.
In this way, if a decrease occurs in the area where the dividing point voltage value should increase, or an increase (absolute value decreases) occurs in the area where the dividing point voltage value should decrease, it is determined that a half disconnection has occurred.

As described above, it is known that the voltage fluctuation due to the occurrence of the half-break occurs in the range from the rising edge (or falling edge) from the voltage waveform zero cross point to the peak, and continues until it passes the peak. Therefore, by monitoring the voltage waveform in the section of at least one quarter cycle and determining that half-breakage has occurred if the polarity of the slope is reversed, the occurrence of half-breakage can be detected with high accuracy and the current. The occurrence of a half-break can be detected without monitoring.

In the second mode, it is judged from the information of the rising and falling quarter cycles, and the voltage information of the other half cycle is not seen, but the other half cycle does not rest. It may be added to the judgment factor.
Further, in each of the above embodiments, the determination is made by dividing one cycle of the voltage into 200, but it is possible to make the determination even with the information of the division point voltage of about 100 divisions. Further, the number of divisions may be more than 200 divisions.

2 ... Measurement unit, 3 ... Judgment unit (half disconnection judgment unit), 5 ... Display unit (notification unit), L ... Electric wire.

Claims (2)

A measuring unit that obtains waveform information of the AC voltage applied to the electric wire, divides one cycle into at least 100, and outputs voltage value information at each division point.
A half-breakage determination unit that determines the occurrence of a half-breakage of the electric wire based on the dividing point voltage value information output by the measurement unit,
When the half-breakage determination unit determines that a half-breakage has occurred, it has a notification unit for notifying the occurrence of the half-breakage.
The half-breakage determination unit calculates a change amount of an adjacent division point voltage from the division point voltage value information, and determines that a half-breakage has occurred when the absolute value of the change amount exceeds a predetermined threshold value. Half disconnection detector. A measuring unit that obtains waveform information of the AC voltage applied to the electric wire, divides one cycle into at least 100, and outputs voltage value information at each division point.
A half-breakage determination unit that determines the occurrence of a half-breakage of the electric wire based on the dividing point voltage value information output by the measurement unit,
When the half-breakage determination unit determines that a half-breakage has occurred, it has a notification unit for notifying the occurrence of the half-breakage.
The half-break determination unit divides one cycle of the voltage waveform into four and monitors at least a quarter cycle rising from the zero cross point and a quarter cycle falling from the zero cross point.
If the voltage change between the dividing points shows a negative value in the rising waveform, or if the voltage change between the dividing points shows a positive value in the falling waveform, it is judged that a half disconnection has occurred. Semi-disconnection detection device.

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