JP7314039B2 - Half disconnection detector - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a half-break detection device for detecting 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 Japanese Patent Laid-Open No. 2004-100000, information about the current flowing through the electric wire is obtained, and a change in the current waveform peculiar to the half-break is detected to determine the occurrence of the half-break.

JP-A-2008-8859

However, since the technique of Patent Document 1 makes a determination based on the waveform of the circuit current, it requires a zero-phase current transformer, which is a sensor for detecting the circuit current, and requires a large installation space.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a half-disconnection detection device capable of detecting the occurrence of a half-disconnection without detecting the electric circuit current.

In order to solve the above-mentioned problems, the invention of claim 1 obtains waveform information of an AC voltage applied to a wire, divides one cycle into at least 100, and outputs voltage value information of individual division points, a partial wire break determination unit that determines occurrence of a partial wire breakage based on the division point voltage value information output by the measurement unit, and a notification unit that notifies the occurrence of a partial wire breakage when the partial wire breakage determination unit determines that a partial wire breakage has occurred. It is characterized by calculating the amount of change in the voltage at the dividing point, and determining that a half disconnection has occurred when the absolute value of this amount of change exceeds a predetermined threshold value.
According to this configuration, since the normal voltage waveform is a sinusoidal waveform, the voltage values adjacent to the division point voltage value do not change by exceeding a predetermined value. Therefore, if the voltage fluctuation exceeds a predetermined value in the energized state, it can be determined that a half-break has occurred. Therefore, it is possible to detect the occurrence of a half disconnection without monitoring the current.

The invention of claim 2 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 individual division points, a partial disconnection determination unit that determines the occurrence of partial disconnection based on the division point voltage value information output by the measurement unit, and a notification unit that notifies the occurrence of the partial disconnection when the disconnection determination unit determines that a partial disconnection has occurred. A quarter cycle and a quarter cycle waveform falling from a zero crossing point are monitored, and if the voltage change between the division points shows a negative value in the rising waveform, or if the voltage change between the division 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 a half-break occurs mainly in the range from the rise to the peak of the voltage waveform zero cross point, or in the range from the fall to the peak. Therefore, the voltage waveform of at least each quarter cycle section is monitored, and if the polarity of the slope is reversed in that section, it is determined that the partial disconnection has occurred. Therefore, the occurrence of the partial disconnection can be detected with high accuracy, and the occurrence of the partial disconnection can be detected without monitoring the current.

According to the present invention, when the amount of change in the voltage value adjacent to the voltage value at the division point changes beyond a predetermined value, or at least when the slope of the voltage is reversed in the range from the zero-crossing point to the peak, or from the fall to the peak, it is determined that the half-break has occurred, so the occurrence of the half-break can be detected without monitoring the current.

1 is a block diagram showing an example of a half-break detection device according to the present invention; FIG. FIG. 4 is a waveform explanatory diagram showing a first form for judging a half-break. FIG. 3 is an explanatory view enlarging part A of FIG. 2 ; FIG. 4 is a waveform explanatory diagram showing a second form of the half-break detection device;

BEST MODE FOR CARRYING OUT THE INVENTION 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-break detection device according to the present invention. The partial disconnection detection device 10 includes a voltage dividing circuit 1 that divides the voltage detected from the electric wire L, a measurement unit 2 that divides one cycle of the divided voltage waveform into 200 points and outputs voltage value information of 200 points per cycle, a determination unit 3 that calculates the voltage change amount (slope) from the divided voltage value information output by the measurement unit 2 and determines the occurrence of a partial disconnection, an output unit 4 that cuts off the electric circuit when a partial disconnection occurs, and a display unit 5 that displays and notifies the measured voltage information. are Reference numeral 6 denotes a breaker having opening/closing contacts for breaking the electric wire L from the power supply.
Here, it is configured such that the cutoff unit 6 cuts off when a half-break is detected.

The determination unit 3 includes an A/D conversion circuit (not shown), a storage unit for storing threshold values for determination, a CPU for determination, and the like, and operates as follows.
First, the first mode will be described with reference to the explanatory diagram of waveforms in FIG.
FIG. 2 shows one cycle of a voltage waveform with an effective value of 100 V and 60 Hz applied to the wire L. FIG. W1 is a waveform shown for comparison, and shows a voltage waveform in a normal state in which no half disconnection has occurred. W2 indicates only a half cycle of the waveform in which a half disconnection occurs, and indicates 100 division point voltages for half a cycle out of 200 divisions of one cycle. A normal waveform W1 indicates a division point voltage obtained by dividing one period into 40 parts.

It can be seen that a large voltage fluctuation occurs in the section M1 from the dividing point P1 to Q1 shown in FIG. Therefore, it can be determined that a discharge phenomenon peculiar to the half disconnection occurs in this range. The determination unit 3 detects this voltage drop and determines that a discharge has occurred (occurrence of a half disconnection).
Specifically, the maximum value of the voltage change amount in the case of 100 V effective value occurs near the zero cross and is about 33 V/msec. Here, this value is stored as a threshold value in the determination unit 3, and if the absolute value of the change amount of the division 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 in FIG. 2. As shown in FIG. 3, the voltage v1 at the division point P1 is about 73 V, and the voltage v2 at the next division point P2 is about 64 V. Since the elapsed time is 0.083 ms, the voltage change amount (slope) Δv=108 V/msec, which greatly exceeds the set threshold value.
The determination unit 3 calculates the amount of change Δv in this voltage, and determines that a partial disconnection has occurred since this value exceeds the threshold value. When it is determined that a half disconnection has occurred, a drive signal is output to the output section 4, and the output section 4 operates the cutoff section 6 to cut off. Also, the display unit 5 displays occurrence of a half-break.
Note that the determination unit 3 also detects a voltage drop in the negative half cycle because the determination is based on the absolute value.

In this way, since the normal voltage waveform is a sinusoidal waveform, the voltage values adjacent to the division point voltage value do not change by exceeding a predetermined value. Therefore, if the voltage fluctuation exceeds a predetermined value in the energized state, it can be determined that a half-break has occurred. Therefore, it is possible to detect the occurrence of a half disconnection without monitoring the current.

Next, a second form of the half-break detection device will be described. Since the circuit configuration is the same as that of FIG. 1, description thereof will be omitted, and the description will be made with reference to the waveform diagram of FIG.
In the above embodiment, a half-break is determined from all division point voltage values. However, here, not all voltage information is used, and determination is made based on the information in the ranges M2 and M3 shown in FIG. Also in FIG. 4, only the positive side half cycle of the voltage waveform in which the half disconnection occurred is shown, and the negative side 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 the voltage falls from the zero-crossing point C2 after half a cycle and then reaches a negative peak. By detecting this voltage drop in these two ranges, it is possible to determine whether the wire is partially disconnected.

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 grasps that the voltage increases in the range M2 and the voltage slope is positive, and that the voltage increases negatively and the slope is negative in the range M3.
Then, upon receiving the input of the division point voltage divided by 200, first, the amount of change between the division points is calculated. If a change to a negative slope suddenly occurs in the positive slope range (division points P1 to P3 shown in FIG. 4), it is determined that a half-break has occurred. Also, if a positive slope suddenly occurs in the range M3 where the slope is negative, it is determined that a half disconnection has occurred.
In this way, when the division point voltage value decreases in an area where it should increase, or when it increases (decrease in absolute value) in an area where it should decrease, it is determined that a half disconnection has occurred.

In this way, it is known that the voltage fluctuation due to the occurrence of a half disconnection occurs in the range from the rise (or fall) from the voltage waveform zero cross point to the peak, and continues until the peak is passed. Therefore, by monitoring the voltage waveform in at least one-fourth period of each section and judging that the occurrence of a partial disconnection occurs if the polarity of the gradient is reversed, the occurrence of a partial disconnection can be detected with high accuracy, and the occurrence of a partial disconnection can be detected without monitoring the current.

In the second mode, determination is made from the information of the 1/4 period of rising and falling, and the voltage information of the other 1/2 period is not looked at, but the other 1/2 period may also be added to the judgment elements without rest.
In the above-described embodiments, determination is made by dividing one cycle of voltage into 200. However, it is possible to make a determination even with information on division point voltages of approximately 100 divisions. Also, the number of divisions may be more than 200 divisions.

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

Claims (2)

a measurement unit that obtains waveform information of an alternating voltage applied to a wire, divides one cycle into at least 100, and outputs voltage value information of each division point;
a partial disconnection determination unit that determines occurrence of a partial disconnection of the electric wire based on division point voltage value information output by the measurement unit;
a notification unit that notifies when the half-break determination unit determines that a half-break has occurred,
The half-broken wire detection device, wherein the half-broken wire determination unit calculates a change amount of an adjacent division point voltage from the division point voltage value information, and judges that a half-broken wire has occurred when the absolute value of the change amount exceeds a predetermined threshold value. a measurement unit that obtains waveform information of an alternating voltage applied to a wire, divides one cycle into at least 100, and outputs voltage value information of each division point;
a partial disconnection determination unit that determines occurrence of a partial disconnection of the electric wire based on division point voltage value information output by the measurement unit;
a notification unit that notifies when the half-break determination unit determines that a half-break has occurred,
The half-disconnection determination unit divides one cycle of the voltage waveform into four and monitors at least one quarter cycle rising from the zero cross point and one quarter cycle falling from the zero cross point,
A partial disconnection detection device characterized by determining that a partial disconnection occurs when a voltage change between dividing points in a rising waveform indicates a negative value, or when a voltage change between dividing points indicates a positive value in a falling waveform.

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