JP2017009548A - Abnormality detection system, and abnormality detection method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently detect an abnormality of an electric wire by a simple configuration.SOLUTION: A pulse application part 101 applies a voltage pulse between one ends of a pair of electric wires. A waveform measurement part 102 measures a voltage waveform showing variation of voltage between the one ends of the pair of electric wires in a period including rise time of the voltage pulse. A resistance value measurement part 103 measures a resistance value between the one ends of the pair of electric wires. An information output part 104 outputs information showing that detects an abnormality of the pair of electric wires when difference between a theoretical value of loop resistance of the pair of electric wires to be calculated from a voltage waveform measured in a period in which the other ends of the pair of electric wires are short-circuited and a voltage waveform measured in a period in which the other ends of the pair of electric wires are opened, and an actual value of the loop resistance of the pair of electric wires based on a resistance value measured in the period in which the other ends of the pair of electric wires are short-circuited exceeds a predetermined threshold.SELECTED DRAWING: Figure 3

Description

  The present invention relates to an abnormality detection system and an abnormality detection method for detecting an abnormality in an electric wire.

  Equipment such as air conditioning equipment is mutually connected to a power supply device and other equipment using electric wires such as power lines and signal lines. If an abnormality such as disconnection, poor contact, short circuit, or oxidation occurs in such an electric wire, the equipment may not operate normally. Therefore, various techniques for detecting such an abnormality in the electric wire are currently known.

  For example, Patent Document 1 includes a loop resistance measurement unit, an impedance measurement unit, a TDR (Time Domain Reflectometry) measurement unit, an insulation resistance measurement unit, a switching device unit, a controller, and a data storage unit. An abnormality detection device for an electric wire / cable system is disclosed. In the abnormality detection device disclosed in Patent Document 1, the switching device unit switches the connection between the electric wire / cable system and each measuring unit according to the switching operation signal output from the controller, and the measurement data of each measuring unit is stored in the data storage unit. Saved. In the abnormality detection device disclosed in Patent Document 1, a plurality of types of measurements are sequentially performed, and an abnormality in the electric wire / cable system is detected based on the plurality of types of measurement results.

JP-A-6-194401

  However, the abnormality detection device disclosed in Patent Document 1 has a complicated configuration in order to realize many types of measurements, and often performs measurements that are not necessary to be performed in vain. . For this reason, the technique which detects the abnormality of an electric wire efficiently with a simple structure is desired.

  The present invention has been made in view of the above problems, and an object thereof is to provide an abnormality detection system and an abnormality detection method for efficiently detecting an abnormality of an electric wire with a simple configuration.

In order to achieve the above object, an abnormality detection system according to the present invention includes:
Pulse applying means for applying a voltage pulse between one end of a pair of electric wires;
A waveform measuring means for measuring a voltage waveform indicating a change in voltage between one ends of the pair of electric wires in a period including a rising time of the voltage pulse;
Resistance value measuring means for measuring a resistance value between one end of the pair of electric wires;
The voltage waveform measured by the waveform measuring means during a period in which the other end of the pair of electric wires is short-circuited and the voltage measured by the waveform measuring means in a period during which the other end of the pair of electric wires is open The theoretical value of the loop resistance of the pair of electric wires obtained from the waveform and the resistance of the pair of electric wires based on the resistance value measured by the resistance value measuring means during a period in which the other end of the pair of electric wires is short-circuited And an information output means for outputting information indicating that an abnormality of the pair of electric wires is detected when a difference between the measured value of the loop resistance exceeds a predetermined threshold value.

  In the present invention, a pair of electric wires obtained from a voltage waveform measured during a period in which the other ends of the pair of electric wires are short-circuited and a voltage waveform measured in a period during which the other ends of the pair of electric wires are open The difference between the theoretical value of the loop resistance and the measured value of the loop resistance of the pair of wires based on the resistance value measured during the period in which the other ends of the pair of wires are short-circuited exceeds a predetermined threshold. In this case, information indicating that an abnormality of the pair of electric wires has been detected is output. Therefore, according to the present invention, it is possible to efficiently detect an abnormality in the electric wire with a simple configuration.

It is a block diagram of the abnormality detection system which concerns on embodiment of this invention. It is a block diagram of the processing apparatus which concerns on embodiment of this invention. It is a functional block diagram of the abnormality detection system which concerns on embodiment of this invention. It is a figure which shows the voltage pulse which a pulse generator generates. (A) is a figure which shows the waveform at the time of the short circuit measured by a waveform measuring apparatus. (B) is a figure which shows the waveform at the time of an opening measured by a waveform measuring apparatus. (C) is a figure which shows a correlation coefficient waveform. It is a flowchart which shows the abnormality detection process which the abnormality detection system which concerns on embodiment of this invention performs. It is a figure which shows the example which applies the abnormality detection system which concerns on embodiment of this invention to the detection of the abnormality of the electric wire contained in the cable with a shield.

  Embodiments of the present invention will be described below with reference to the drawings. First, an abnormality detection system 1000 according to an embodiment of the present invention will be described with reference to FIG. The abnormality detection system 1000 is a system that detects an abnormality of a pair of electric wires included in the cable 500. More specifically, the anomaly detection system 1000 is based on the difference between the theoretical value of the loop resistance of the electric circuit constituted by the pair of electric wires and the actual measurement value of the loop resistance of the electric circuit, This system detects abnormalities such as half-breaks, poor contacts, short circuits, and oxidation.

  In addition, as a case where the measured value of the loop resistance is higher than the theoretical value of the loop resistance, a case where disconnection, half disconnection, poor contact, or oxidation occurs in the pair of electric wires can be considered. In addition, as a case where the measured value of the loop resistance is lower than the theoretical value of the loop resistance, a case where a short circuit or oxidation occurs in the pair of electric wires can be considered. In this embodiment, the abnormality detection system 1000 calculates the theoretical value of the loop resistance of this electric circuit by TDR (Time Domain Reflectometry) measurement. The theoretical value of the loop resistance can be considered as the rated value of the loop resistance.

  In the present embodiment, it is assumed that the insulating member 560 included in the cable 500 is not deteriorated due to aging or the like, and the relative dielectric constant of the insulating member 560 remains at the rated value. Similarly, in this embodiment, it is assumed that the effective relative dielectric constant of the cable 500 determined by the relative dielectric constant, cross-sectional shape, cross-sectional area, etc. of the insulating member 560 remains the rated value. As shown in FIG. 1, the abnormality detection system 1000 includes a processing device 100, a pulse generation device 200, a waveform measurement device 300, and an open / close switching device 400.

  The abnormality detection system 1000 executes an abnormality detection process for the four electric wires (the electric wire 510, the electric wire 520, the electric wire 530, and the electric wire 540) included in the cable 500. Here, the abnormality detection system 1000 detects the abnormality of the electric wire by measuring the loop resistance and physical length of an electric circuit constituted by a pair of electric wires (two electric wires). This loop resistance is the resistance for the reciprocation of a pair of electric wires, and this physical length is the physical length for one way of a pair of electric wires. The abnormality detection system 1000 repeatedly executes a process of simultaneously checking appropriate two wires selected from the four wires until all the four wires are checked.

  The method of selecting two electric wires to be checked simultaneously from the four electric wires can be appropriately adjusted. However, the abnormality detection system 1000 performs TDR measurement on an electric circuit constituted by a pair of electric wires. For this reason, it is preferable to select a pair of electric wires on which TDR measurement is easily performed appropriately. In the present embodiment, the equipment device 610 and the equipment device 620 are connected to each other via the electric wire 510 and the electric wire 520, and the equipment device 630 and the equipment device 640 are connected to each other via the electric wire 530 and the electric wire 540. Shall be. In this case, as shown in FIG. 1, the equipment 610 is connected to one end of the electric wire 510 and one end of the electric wire 520, and the equipment 620 is connected to the other end of the electric wire 510 and the other end of the electric wire 520. 630 is connected to one end of the electric wire 530 and one end of the electric wire 540, and the equipment 640 is connected to the other end of the electric wire 530 and the other end of the electric wire 540.

  Here, when the same equipment is connected to each of the pair of electric wires, the pair of electric wires are not completely opened due to the influence of the capacitance component inside the equipment. Therefore, there is a high possibility that TDR measurement cannot be performed correctly for such a pair of wires. Therefore, it is preferable that a pair of electric wires configured by two electric wires that are not connected to the same equipment is selected. In this embodiment, the same equipment (equipment 610, equipment 620) is connected to the electric wire 510 and the electric wire 520, and the same equipment (equipment 630, equipment 640) is connected to the electric wire 530 and the electric wire 540. It is connected. Therefore, it is preferable to avoid the combination of the electric wire 510 and the electric wire 520 and the combination of the electric wire 530 and the electric wire 540. In other words, a combination of the electric wire 510 and the electric wire 530, a combination of the electric wire 510 and the electric wire 540, a combination of the electric wire 520 and the electric wire 530, and a combination of the electric wire 520 and the electric wire 540 are preferable.

  In the present embodiment, the abnormality detection system 1000 will be described as executing abnormality detection processing on a pair of electric wires configured by a combination of the electric wires 510 and 530. And if the detection result with respect to this pair of electric wires is abnormal, it turns out that at least one of electric wires 510 and 530 is abnormal. Further, the abnormality detection system 1000 performs an abnormality detection process on a pair of electric wires configured by a combination of the electric wires 520 and 540, thereby detecting an abnormality in at least one of the electric wires 520 and 540. It can be determined whether or not there is. That is, in the present embodiment, the abnormality detection system 1000 can determine whether or not an abnormal wire exists in the four wires by performing the abnormality detection process twice.

  The processing device 100 is a device that processes information acquired from the waveform measuring device 300 and detects an abnormality in a pair of electric wires. The processing device 100 has a function of communicating with the pulse generator 200 and the waveform measuring device 300. Specifically, the processing apparatus 100 causes the pulse generator 200 to generate a voltage pulse. In addition, the processing apparatus 100 causes the waveform measurement apparatus 300 to acquire a voltage waveform, and acquires information indicating the voltage waveform (hereinafter referred to as “waveform information”) from the waveform measurement apparatus 300. The processing device 100 is a personal computer, a tablet terminal, a smartphone, or the like. Hereinafter, the configuration of the processing apparatus 100 will be described with reference to FIG.

  As shown in FIG. 2, the processing device 100 includes a CPU (Central Processing Unit) 11, a ROM (Read Only Memory) 12, a RAM (Random Access Memory) 13, a flash memory 14, an RTC (Real Time Clock) 15, a touch screen. 16, a measuring instrument interface 17, and a telecommunication network interface 18. The components included in the processing apparatus 100 are connected to each other via a bus.

  The CPU 11 controls the overall operation of the processing apparatus 100. The CPU 11 operates according to a program stored in the ROM 12 and uses the RAM 13 as a work area. The ROM 12 stores programs and data for controlling the overall operation of the processing apparatus 100. The RAM 13 functions as a work area for the CPU 11. That is, the CPU 11 temporarily writes programs and data in the RAM 13 and refers to these programs and data as appropriate.

  The flash memory 14 is a nonvolatile memory that stores various types of information. For example, information acquired by an operation on the touch screen 16, information acquired by the measuring instrument interface 17, information acquired by the telecommunications network interface 18, and the like are stored in the flash memory 14. The RTC 15 is a time measuring device. The RTC 15 incorporates a battery, for example, and keeps timing while the processing apparatus 100 is powered off. The RTC 15 includes an oscillation circuit including a crystal oscillator, for example.

  The touch screen 16 detects a touch operation performed by the user and supplies a signal indicating the detection result to the CPU 11. The touch screen 16 displays an image based on the image signal supplied from the CPU 11 or the like. As described above, the touch screen 16 functions as a user interface of the processing apparatus 100. Note that the processing apparatus 100 may include a liquid crystal display, a mouse, a keyboard, and the like instead of the touch screen 16.

  The measuring instrument interface 17 is an interface for connecting the processing apparatus 100 to the pulse generator 200, the waveform measuring apparatus 300, and the like. The measuring instrument interface 17 controls the pulse generator 200 according to an instruction from the CPU 11. The measuring instrument interface 17 supplies the waveform information acquired from the waveform measuring apparatus 300 to the CPU 11, RAM 13, flash memory 14, and the like. The measuring instrument interface 17 includes, for example, interfaces such as a local area network (LAN), a universal serial bus (USB), and an institute of electrical and electronic engineers (IEEE) 1394.

  The telecommunication network interface 18 is an interface for connecting the processing device 100 to a telecommunication network (not shown). This telecommunications network may be a LAN or a WAN (Wide Area Network) such as the Internet. The telecommunication network interface 18 includes a LAN interface such as a NIC (Network Interface Card). The CPU 11 downloads information stored in a server connected to the telecommunications network or uploads various types of information to the server via the telecommunications network interface 18.

  The pulse generator 200 generates voltage pulses for TDR measurement in accordance with instructions from the processing device 100. TDR measurement is a measurement technique in which a fast rising voltage pulse is applied to a two-terminal sample, and the internal structure of the sample is grasped from a temporal change in voltage applied to the sample. In the present embodiment, the sample is a circuit including an electric circuit composed of the electric wire 510 and the electric wire 530. The pulse generator 200 includes an output terminal connected to one end of the electric wire 510 and an output terminal connected to one end of the electric wire 530. That is, the pulse generator 200 applies a voltage pulse between one end of the electric wire 510 and one end of the electric wire 530. The pulse generator 200 has a function of communicating with the processing device 100.

  Waveform measuring apparatus 300 measures a voltage waveform indicating a temporal change in voltage between one end of electric wire 510 and one end of electric wire 530. Specifically, the waveform measuring apparatus 300 sets the voltage between one end of the electric wire 510 and one end of the electric wire 530 to a sampling period (e.g., sufficiently short with respect to the time required for the electric signal to reciprocate the cable 500) (Several nsec). The waveform measuring apparatus 300 has an edge trigger function, and measures a voltage waveform in a period including the time when the edge trigger occurs (hereinafter referred to as “waveform measurement period”). The edge trigger occurs when the voltage between one end of the electric wire 510 and one end of the electric wire 530 exceeds a predetermined threshold value.

  The waveform measurement period is a period of a predetermined time length, and the start time of the waveform measurement period is a time that is a predetermined time before the time when the edge trigger occurs. The waveform measurement period is set to a time longer than the predicted value of the time (hereinafter referred to as “pulse reciprocation time”) for the voltage pulse to reciprocate through the electric circuit constituted by the electric wires 510 and 530. The waveform measuring apparatus 300 transmits waveform information indicating the measured voltage waveform to the processing apparatus 100.

  Moreover, the waveform measuring apparatus 300 measures the resistance value between one end of the electric wire 510 and one end of the electric wire 530 in a state where the other end of the electric wire 510 and the other end of the electric wire 530 are short-circuited. That is, the waveform measuring apparatus 300 measures the resistance value of the electric circuit (loop) composed of the electric wires 510 and 530. The waveform measuring apparatus 300 transmits resistance value information indicating the measured resistance value to the processing apparatus 100. The waveform measuring apparatus 300 has a function of communicating with the processing apparatus 100. The waveform measuring apparatus 300 is, for example, an oscilloscope or a digital multimeter.

  The opening / closing switching device 400 switches between the two output terminals between a short circuit state and an open state at a predetermined cycle (for example, about several seconds). The opening / closing switching device 400 includes a control circuit 410 and a relay 420. The control circuit 410 switches the state of the relay 420 every time a predetermined period elapses. The control circuit 410 includes, for example, an RTC. The relay 420 is switched between a short circuit and an open state in accordance with an instruction from the control circuit 410. One end of the relay 420 is connected to one output terminal provided in the open / close switching device 400, and the other end of the relay 420 is connected to the other output terminal provided in the open / close switching device 400. One output terminal included in the opening / closing switching device 400 is connected to the other end of the electric wire 510, and the other output terminal included in the opening / closing switching device 400 is connected to the other end of the electric wire 530.

  The cable 500 is a cable including a pair of electric wires to be subjected to abnormality detection processing. The cable 500 is, for example, a cable that is laid in equipment such as a building and used for supplying power and transmitting electrical signals. The abnormality detection process for the pair of electric wires is executed in a state where the cable 500 is laid in the facility. The cable 500 includes a wire 510, a wire 520, a wire 530, a wire 540, and an insulating member 560, and is a four-core cable configured by covering the wire 510, the wire 520, the wire 530, and the wire 540 with the insulating member 560. is there.

  Each of the electric wire 510, the electric wire 520, the electric wire 530, and the electric wire 540 is a core wire for transmitting electric power and an electric signal, and is made of, for example, copper. Each of the electric wire 510, the electric wire 520, the electric wire 530, and the electric wire 540 is covered with an insulating member 560 and insulated from other electric wires and external space.

  The insulating member 560 is an insulator that covers the electric wire 510, the electric wire 520, the electric wire 530, and the electric wire 540. The insulating member 560 is made of, for example, vinyl chloride resin. In the present embodiment, the insulating member 560 does not deteriorate due to aging or the like, and the relative dielectric constant of the insulating member 560 is maintained at the rated value (for example, the relative dielectric constant when new). The rated value of the relative dielectric constant of the insulating member 560 is, for example, about 3.0.

  The effective relative dielectric constant of the cable 500 depends on the relative dielectric constant of the insulating member 560 and the cross-sectional shape of the cable 500. Here, if the shape of the cross section of the cable 500 is unchanged and the relative dielectric constant of the insulating member 560 is unchanged, the effective relative dielectric constant of the cable 500 is also unchanged. Note that the insulating member 560 does not fill all spaces in which an electric field is generated due to a current flowing through the electric wires 510, 520, 530, 540, and the like. For this reason, the effective relative dielectric constant of the cable 500 is smaller than the relative dielectric constant of the insulating member 560. For example, when the relative dielectric constant of the insulating member 560 is 3.0, the effective relative dielectric constant of the cable 500 is about 1.5 to 1.7.

  In the present embodiment, it is assumed that the processing apparatus 100 acquires cable information from a server or the like (not shown) via the telecommunication network interface 18. The cable information is information that correlates, for example, the cable model number, the effective relative dielectric constant (rated value) of the cable, the resistivity of the electric wire included in the cable, and the cross-sectional area of the electric wire included in the cable. . The cable information is appropriately stored in the flash memory 14 or the like.

  The facility device 610, the facility device 620, the facility device 630, and the facility device 640 are devices such as an air conditioner installed in a factory or the like. In this embodiment, the equipment 610 and equipment 630 are indoor units, the equipment 620 is an outdoor unit corresponding to the equipment 610, and the equipment 640 is an outdoor unit corresponding to the equipment 630. To do.

  Next, functions of the abnormality detection system 1000 will be described with reference to FIG. Functionally, the abnormality detection system 1000 includes a pulse application unit 101, a waveform measurement unit 102, a resistance value measurement unit 103, an information output unit 104, a physical length calculation unit 105, a theoretical value calculation unit 106, an actual measurement value determination unit 107, An opening / closing unit 108 is provided.

  The pulse application unit 101 applies a voltage pulse between one ends of a pair of electric wires. Specifically, the pulse application unit 101 includes a period in which the other end of the electric wire 510 and the other end of the electric wire 530 are short-circuited (hereinafter referred to as “short-circuit period”), and the other end of the electric wire 510 and the electric wire 530. A voltage pulse is applied between one end of the electric wire 510 and one end of the electric wire 530 in both periods in which the other end of the electric wire is open (hereinafter referred to as “opening period”). The function of the pulse application unit 101 is realized by the function of the pulse generator 200, for example.

  The waveform measurement unit 102 measures a voltage waveform indicating a change in voltage between one end of a pair of electric wires in a period (waveform measurement period) including the rising time of the voltage pulse. Specifically, the waveform measurement unit 102 measures a voltage waveform indicating a change in voltage between one end of the electric wire 510 and one end of the electric wire 530 during the waveform measurement period. The function of the waveform measuring unit 102 is realized by the function of the waveform measuring apparatus 300, for example.

  The resistance value measuring unit 103 measures the resistance value between one end of the pair of electric wires. Specifically, the resistance value measuring unit 103 measures the resistance value between one end of the electric wire 510 and one end of the electric wire 530 in both the short circuit period and the open period. Note that the resistance value measured by the resistance value measuring unit 103 is regarded as the resistance value measured in the short-circuit period when it is lower than the predetermined threshold value, and in the open period when it is higher than the predetermined threshold value. It is regarded as the measured resistance value. The function of the resistance value measuring unit 103 is realized by the function of the waveform measuring apparatus 300, for example.

  The information output unit 104 indicates that the abnormality of the pair of wires has been detected when the difference between the theoretical value of the loop resistance of the pair of wires and the measured value of the loop resistance of the pair of wires exceeds a predetermined threshold. Is output. The theoretical value of the loop resistance of the pair of electric wires is the period during which the voltage waveform measured by the waveform measuring unit 102 and the other end of the pair of electric wires are open while the other end of the pair of electric wires is short-circuited. It is obtained from the voltage waveform measured by the waveform measuring unit 102. The measured value of the loop resistance of the pair of electric wires is a value based on the resistance value measured by the resistance value measuring unit 103 during a period in which the other ends of the pair of electric wires are short-circuited. For example, the information output unit 104 displays an image notifying that an abnormality of the pair of electric wires has been detected, or outputs information indicating that an abnormality of the pair of electric wires has been detected to the flash memory 14. The function of the information output unit 104 is realized by the cooperation of the CPU 11 and the touch screen 16, for example.

The physical length calculation unit 105 calculates the physical length of the pair of electric wires based on the short circuit waveform and the open circuit waveform. The short-circuit waveform is a voltage waveform measured by the waveform measuring unit 102 during a period in which the other ends of the pair of electric wires are short-circuited (short-circuit period). The open waveform is a voltage waveform measured by the waveform measuring unit 102 during a period in which the other end of the pair of electric wires is open (open period). The physical length calculation unit 105 calculates the physical length of a pair of electric wires using, for example, an expression Lp = Tc × c ÷ (2 × √ε _es ) (hereinafter referred to as “expression (1)”). Here, Lp is the physical length (m) of the pair of wires, Tc is the pulse reciprocation time (sec), c is the speed of light (m / sec) in vacuum, and ε _es is the cable 500. Is the effective relative dielectric constant. Tc is obtained based on the correlation coefficient between the comparison waveform extracted from the short-circuit waveform and the comparison waveform extracted from the open-circuit waveform, which will be described in detail later. The function of the physical length calculation unit 105 is realized, for example, when the CPU 11 executes a program stored in the ROM 12.

The theoretical value calculation unit 106 calculates the theoretical value of the loop resistance of the pair of electric wires based on the physical length calculated by the physical length calculation unit 105 and the rated value of the resistance value per unit physical length of the pair of electric wires. . The rated value of the resistance value per unit physical length of the pair of electric wires is calculated from the resistivity of the pair of electric wires and the cross-sectional area of the pair of electric wires. In the present embodiment, the resistivity of the four wires is the same, and the cross-sectional areas of the four wires are the same. The theoretical value calculation unit 106 calculates the theoretical value of the loop resistance of the pair of electric wires using, for example, an equation of Rloop = 2 × Lp × ρ ÷ A (hereinafter referred to as “expression (2)”). Here, Rloop is the theoretical value (Ω) of the loop resistance, ρ is the electric resistivity (Ω · m) of the electric wire, and A is the cross-sectional area (m ² ) of the electric wire. The function of the theoretical value calculation unit 106 is realized, for example, when the CPU 11 executes a program stored in the ROM 12.

  The actual measurement value determination unit 107 calculates an actual measurement value of the loop resistance of the pair of wires based on a resistance value equal to or less than a predetermined threshold among a plurality of resistance values obtained by a plurality of measurements by the resistance value measurement unit 103. decide. That is, the actual measurement value determination unit 107 determines the actual measurement value of the loop resistance of the pair of electric wires based on the resistance value measured by the resistance value measurement unit 103 during the open period. For example, the actual measurement value determination unit 107 determines the average value or median value of the resistance values measured by the resistance value measurement unit 103 during the open period as the actual measurement value of the loop resistance of the pair of electric wires. The function of the actual measurement value determination unit 107 is realized by the CPU 11 executing a program stored in the ROM 12, for example.

  The opening / closing part 108 switches the short circuit / open state between the other ends of the pair of electric wires every time a predetermined time elapses. Specifically, the opening / closing unit 108 short-circuits the other end of the electric wire 510 and the other end of the electric wire 530 during the short-circuit period, and connects the other end of the electric wire 520 and the other end of the electric wire 540 during the open period that does not overlap with the short-circuit period. Open. It is desirable that the length of the short circuit period or the open period is sufficiently long with respect to the width of the voltage pulse. The function of the opening / closing unit 108 is realized by the function of the opening / closing switching device 400, for example.

  Next, voltage pulses generated by the pulse generator 200 will be described with reference to FIG. As shown in FIG. 4, the voltage pulse generated by the pulse generator 200 is a pulse having a voltage of V1 and a width of T1. V1 is, for example, 5V. T1 is a time sufficiently longer than the pulse reciprocation time (the time required for the electric signal to reciprocate the cable 500). T1 is, for example, a time of about several milliseconds. A frame Fr1 in FIG. 4 indicates a waveform measurement period. T2 indicates the time length of the waveform measurement period, and is a time corresponding to the width of the frame Fr1. T2 is shorter than T1 and longer than the pulse round-trip time.

  Next, a voltage waveform measured by the waveform measuring apparatus 300 will be described with reference to FIG. The terminal to which the pulse generator 200 applies a voltage pulse and the terminal from which the waveform measuring apparatus 300 measures the voltage waveform are the same terminals (one end of the electric wire 510 and one end of the electric wire 530). However, the voltage measured at this terminal is a voltage in which the voltage reflected at the other end of the electric wire 510 (the other end of the electric wire 530) is superimposed on the voltage applied to this terminal. For this reason, the voltage waveform measured by the waveform measuring apparatus 300 does not completely match the waveform of the voltage pulse generated by the pulse generating apparatus 200.

  More specifically, negative reflection occurs at a location where the characteristic impedance decreases, and positive reflection occurs at a location where the characteristic impedance increases. That is, when the other end of the electric wire 510 and the other end of the electric wire 530 are short-circuited, negative reflection occurs at the other end of the electric wire 510 (the other end of the electric wire 530). On the other hand, when the other end of the electric wire 510 and the other end of the electric wire 530 are open, positive reflection occurs at the other end of the electric wire 510 (the other end of the electric wire 530).

  FIG. 5A is a diagram showing a short-circuit waveform measured when the open / close switching device 400 is in a short-circuit state. As shown in FIG. 5A, the short-circuit waveform is a waveform in which the voltage is 0 V from t10 to t11, the voltage increases to V11 at t11, and the voltage decreases by V12 at t12 due to negative reflection. . V11 is basically equal to V1 that is the voltage of the voltage pulse, and is a voltage of about 5V. V12 is basically smaller than V11. In FIG. 5A, t10 is the start time of the waveform measurement period, t11 is the time when the edge trigger occurs (time when the pulse voltage rises), and t12 is the other end of the wire 510 (other than the wire 530). End) is the time when the negative reflection generated at the end reaches the one end of the electric wire 510 (one end of the electric wire 530), and t13 is the end time of the waveform measurement period. The time from t11 to t12 is the pulse round trip time. The time from t10 to t13 is equal to T2 which is the time length of the waveform measurement period.

  FIG. 5 (B) is a diagram showing an open waveform measured when the open / close switching device 400 is in the open state. As shown in FIG. 5B, the open waveform is a waveform in which the voltage is 0 V from t20 to t21, the voltage rises to V21 at t21, and the voltage rises to V22 due to the influence of positive reflection at t22. . V21 is basically equal to V1 that is the voltage of the voltage pulse, and is a voltage of about 5V. V22 is basically smaller than V21. In FIG. 5B, t20 is the start time of the waveform measurement period, t21 is the time when the edge trigger is generated (rising time of the pulse voltage), and t22 is the other end of the electric wire 510 (the other end of the electric wire 530). ) Is the time at which the positive reflection that occurred at one end of the electric wire 510 (one end of the electric wire 530) has arrived, and t23 is the time at the end of the waveform measurement period. The time from t21 to t22 is the pulse reciprocation time. The time from t20 to t23 is equal to T2, which is the time length of the waveform measurement period.

  Here, the pulse round-trip time can be obtained from the voltage waveform of either the short-circuit waveform or the open-circuit waveform, but it is more accurately obtained from the voltage waveform of both the short-circuit waveform and the open-circuit waveform. It becomes possible. For example, when the time axis of the short-circuit waveform and the open-circuit waveform are combined, the time when the polarity of the voltage change is reversed between the short-circuit waveform and the open-circuit waveform from the rise time of the pulse voltage (hereinafter “polarity mismatch time”) It is preferable that the time until the above is a pulse round trip time. In this case, for example, the time axis of the short-circuit waveform and the time waveform of the open waveform are combined, and a partial waveform (hereinafter referred to as “comparison waveform”) in the relatively same period from each of the short-circuit waveform and the open-time waveform. Extract). The correlation coefficient between the comparison waveform extracted from the short circuit waveform and the comparison waveform extracted from the open waveform is obtained while shifting the period for extracting the comparison waveform backward, and this correlation coefficient is negative. The time corresponding to the extraction position as a value can be set as the polarity mismatch time. Note that T3, which is the time length of the comparative waveform, is shorter than T2, which is the time length of the short circuit waveform and the open waveform. In FIGS. 5A and 5B, a frame Fr2 indicates a region where a comparative waveform is extracted.

  FIG. 5C shows a correlation coefficient waveform. The correlation coefficient waveform is a waveform indicating the relationship between the time corresponding to the extraction position of the comparison waveform and the correlation coefficient between the comparison waveform extracted from the short-circuit waveform and the comparison waveform extracted from the open waveform. is there. As shown in FIG. 5C, the correlation coefficient waveform is a waveform in which the correlation coefficient is 1 from t30 to t32, and the correlation coefficient becomes −1 at t32. 5C, t30 is the start time of the waveform measurement period, t31 is the time when the edge trigger is generated (rising time of the pulse voltage), and t32 is the other end of the electric wire 510 (the other end of the electric wire 530). ) Is the time when the reflection generated at the end of the electric wire 510 reaches one end of the electric wire 510 (one end of the electric wire 530). Then, T31, which is the time from t31 to t32, is regarded as the pulse reciprocation time, thereby increasing the physical length calculation accuracy.

  Next, the abnormality detection processing executed by the abnormality detection system 1000 will be described with reference to the flowchart shown in FIG. The CPU 11 starts the abnormality detection process after receiving an instruction to start the abnormality detection process from the user. On the other hand, as shown in FIG. 1, the user connects the pulse generator 200, the waveform measuring device 300, and the open / close switching device 400 to the cable 500, and switches between the processing device 100, the pulse generator 200, the waveform measuring device 300, and the open / close switching. After powering on the apparatus 400, the start of the abnormality detection process is instructed. In the present embodiment, it is assumed that the open / close switching device 400 automatically switches between the short circuit / open state when the power is turned on.

  First, the CPU 11 accepts designation of a cable model number (step S101). For example, the CPU 11 controls the touch screen 16 to present a screen prompting the user to input the cable model number. Then, the CPU 11 acquires the model number of the cable input via the touch screen 16.

  CPU11 will acquire cable information, if the process of step S101 is completed (step S102). For example, the CPU 11 acquires cable information corresponding to the cable model number acquired in step S <b> 101 from a server (not shown) via the telecommunication network interface 18. The CPU 11 stores the acquired cable information in the flash memory 14.

  CPU11 will measure resistance value over the period more than the opening / closing period of the opening / closing switching apparatus 400, if the process of step S102 is completed (step S103). For example, the CPU 11 controls the waveform measuring apparatus 300 to cause the waveform measuring apparatus 300 to start measuring a resistance value. Then, the CPU 11 continues the process of receiving the resistance value information periodically transmitted from the opening / closing switching device 400 and storing it in the flash memory 14 for a period equal to or longer than the opening / closing cycle of the opening / closing switching device 400.

  CPU11 will determine the measured value of loop resistance, if the process of step S103 is completed (step S104). For example, the CPU 11 specifies the resistance value measured during the short circuit period among the resistance values indicated by the resistance value information stored in the flash memory 14. Then, the CPU 11 determines the average value or the median value of the identified resistance values as the actually measured value of the loop resistance.

  CPU11 will start the measurement of a voltage waveform, if the process of step S104 is completed (step S105). Specifically, the CPU 11 controls the waveform measuring apparatus 300 to start measuring the voltage waveform. On the other hand, the waveform measuring apparatus 300 starts measuring the voltage waveform according to the control by the processing apparatus 100. Thereafter, each time the voltage waveform is acquired, the waveform measuring apparatus 300 transmits waveform information indicating the acquired voltage waveform to the processing apparatus 100.

  CPU11 will start the output of a voltage pulse, if the process of step S105 is completed (step S106). For example, the CPU 11 controls the pulse generator 200 to start outputting voltage pulses. On the other hand, the pulse generator 200 starts outputting voltage pulses in accordance with control by the processing device 100. The pulse generator 200 outputs voltage pulses periodically.

  CPU11 will discriminate | determine whether the waveform at the time of a short circuit and the waveform at the time of open have been acquired, if the process of step S106 is completed (step S107). For example, when the waveform information is acquired from the waveform measurement device 300 over a period equal to or longer than the opening / closing cycle of the opening / closing switching device 400, the CPU 11 determines that the short-circuit waveform and the open waveform have been acquired. Or CPU11 may discriminate | determine whether the voltage waveform of both the waveform at the time of a short circuit and the waveform at the time of an open | release has been acquired with reference to the waveform information acquired from the waveform measuring apparatus 300. FIG. For example, when the waveform information indicating the voltage waveform in which the voltage decreases after the voltage increases has been acquired, the CPU 11 determines that the short-circuit waveform has been acquired. And CPU11 discriminate | determines that the waveform at the time of an open is already acquired, when the waveform information which shows the voltage waveform which a voltage rises further after a voltage rise is already acquired.

When determining that the short-circuit waveform and the open-circuit waveform have not been acquired (step S107: NO), the CPU 11 returns the process to step S107. On the other hand, when determining that the short-circuit waveform and the open-circuit waveform have been acquired (step S107: YES), the CPU 11 calculates the physical length of the electric wire (step S108). For example, as described above, the CPU 11 obtains Tc that is the pulse round trip time based on both the short-circuit waveform and the open-circuit waveform. Further, the CPU 11 specifies ε _es that is an effective relative dielectric constant of the cable 500 with reference to the cable information acquired in step S102. And CPU11 calculates Lp which is the physical length of the electric wire 510 (or electric wire 530) by applying the calculated | required Tc and the specified (epsilon) _es to Formula (1) mentioned above.

  When completing the process in step S108, the CPU 11 calculates a theoretical value of the loop resistance (step S109). For example, the CPU 11 refers to the cable information acquired in step S102, ρ that is the electrical resistivity of the electric wire 510 (or electric wire 530), A that is the cross-sectional area of the electric wire 510 (or electric wire 530), and Is identified. Then, the CPU 11 calculates Rloop, which is a theoretical value of the loop resistance, by applying Lp calculated in step S108 and the specified ρ and A to the above-described equation (2).

  When completing the process in step S109, the CPU 11 determines whether or not the difference between the measured value of the loop resistance determined in step S104 and the theoretical value of the loop resistance calculated in step S109 is greater than or equal to a threshold value (step S110). . This threshold can be, for example, several tens of percent of the theoretical value of the loop resistance.

  If CPU11 discriminate | determines that the difference of an actual value and a theoretical value is more than a threshold value (step S110: YES), it will alert | report that the abnormality of the electric wire was detected (step S111). For example, the CPU 11 controls the touch screen 16 to display on the touch screen 16 a screen for notifying that an electric wire abnormality has been detected.

  On the other hand, when the CPU 11 determines that the difference between the actual measurement value and the theoretical value is not equal to or greater than the threshold value (step S110: NO), the CPU 11 notifies that an abnormality of the electric wire has not been detected (step S112). For example, the CPU 11 controls the touch screen 16 to display on the touch screen 16 a screen for notifying that an abnormality of the electric wire has not been detected. When completing the process in step S111 or the process in step S112, the CPU 11 completes the abnormality detection process.

  As described above, in this embodiment, the voltage waveform measured during a period in which the other ends of the pair of electric wires are short-circuited and the voltage waveform measured in a period during which the other ends of the pair of electric wires are opened. The difference between the theoretical value of the loop resistance of the pair of wires obtained from the above and the measured value of the loop resistance of the pair of wires based on the resistance value measured while the other ends of the pair of wires are short-circuited is When the predetermined threshold value is exceeded, information indicating that an abnormality of the pair of electric wires has been detected is output. Therefore, according to this embodiment, it is possible to efficiently detect an abnormality in the electric wire with a simple configuration. In addition, according to the present embodiment, if both ends of the pair of electric wires are arranged in a place where the user can confirm, even if the middle part of the pair of electric wires is arranged in a place where the user cannot confirm. It becomes possible to determine whether or not there is an abnormality in the pair of electric wires.

  In the present embodiment, the physical length of the pair of wires is calculated based on the voltage waveform measured in the short circuit period and the voltage waveform measured in the open period, and the calculated physical length and the unit physics of the pair of wires are calculated. The theoretical value of the loop resistance of the pair of electric wires is calculated based on the rated value of the resistance value per length. Therefore, according to the present embodiment, it is possible to improve the accuracy of detecting the abnormality of the electric wire.

  Moreover, in this embodiment, the measured value of the loop resistance of a pair of electric wires is determined based on the resistance value below a predetermined threshold among a plurality of resistance values obtained by a plurality of measurements. Therefore, according to the present embodiment, synchronization between the waveform measuring device 300 and the open / close switching device 400 is not necessary, and the system configuration can be simplified.

  In the present embodiment, the short-circuit / open state between the other ends of the pair of electric wires is automatically switched every time a predetermined time elapses. Therefore, according to this embodiment, the user can eliminate the trouble of manually switching the short circuit / open state between the other ends of the pair of electric wires.

  Moreover, in this embodiment, a pair of electric wire is comprised by two electric wires which are not connected to the same installation apparatus among the some electric wires contained in a cable. Therefore, according to the present embodiment, it is possible to improve the accuracy of detecting the abnormality of the electric wire.

(Modification)
As mentioned above, although embodiment of this invention was described, when implementing this invention, a deformation | transformation and application with a various form are possible.

  In the present invention, which part of the configuration, function, and operation described in the above embodiment is adopted is arbitrary. Further, in the present invention, in addition to the configuration, function, and operation described above, further configuration, function, and operation may be employed.

  In the above-described embodiment, the example in which the target for detecting abnormality is a pair of electric wires including electric wires included in a cable that does not include a shielded wire has been described. In this invention, it is good also considering the object which detects abnormality as a pair of electric wire containing the electric wire contained in the cable containing a shield wire. Hereinafter, an example in which the abnormality detection system 1000 is applied to detection of an abnormality in an electric wire included in a shielded cable will be described with reference to FIG.

  As shown in FIG. 7, the cable 501 is a two-core cable including an electric wire 510, an electric wire 520, a shield wire 550, an insulating member 560, and an insulating member 570. Each of the electric wire 510 and the electric wire 520 is a core wire for transmitting electric power and an electric signal, and is made of, for example, copper. Each of the electric wires 510 and 520 is covered with an insulating member 560, insulated from other electric wires and shield wires 550, and shielded by the shield wires 550. The shield wire 550 shields the electric wire 510 and the electric wire 520. The shield wire 550 is sandwiched between the insulating member 560 and the insulating member 570. The insulating member 560 is an insulator that covers the electric wire 510 and the electric wire 520. The insulating member 570 is an insulator that covers the shield wire 550. Each of the insulating member 560 and the insulating member 570 is made of, for example, vinyl chloride resin.

  Here, the shield wire 550 is not connected to any equipment. For this reason, it is preferable to include the shield wire 550 in a pair of electric wires to be detected for abnormality. As described above, when the shield wire 550 is included in the pair of electric wires, the pair of electric wires are not connected to the same equipment, and a decrease in accuracy of the theoretical value of the loop resistance can be suppressed.

  In FIG. 7, the pulse generator 200 and the waveform measuring device 300 are connected to one end of the electric wire 510 and one end of the shield wire 550, respectively, and the open / close switching is performed between the other end of the electric wire 510 and the other end of the shield wire 550. The example which connects the apparatus 400 is shown. According to such a configuration, the abnormality of the electric wire 510 or the abnormality of the shield wire 550 can be accurately detected by the abnormality detection process shown in FIG. Similarly, by configuring the pair of electric wires to be detected for abnormality by the electric wire 520 and the shield wire 550, the abnormality of the electric wire 520 or the abnormality of the shield wire 550 can be detected with high accuracy.

  The shield wire 550 needs to have an electrical resistivity and a cross-sectional area as in the case of the electric wires 510 and 520. Therefore, in this case, it is preferable that the cable information includes information indicating the electrical resistivity and the cross-sectional area of the shield wire.

  In the above-described embodiment, an example in which the generation timing of the voltage pulse by the pulse generator 200, the measurement timing of the voltage waveform by the waveform measuring device 300, and the switching timing of the open / close state by the open / close switching device 400 are not synchronized has been described. . In the present invention, these timings may be synchronized. In this case, for example, the processing apparatus 100 first controls the open / close switching device 400 so that the relay 420 is in a short-circuit state, and then controls the waveform measurement device 300 so as to measure the short-circuit waveform. The pulse generator 200 is controlled to generate a pulse. Then, the processing device 100 controls the open / close switching device 400 so that the relay 420 is in an open state, and then controls the waveform measuring device 300 to measure the open waveform, and then generates a voltage pulse. The pulse generator 200 is controlled.

  In the above-described embodiment, the example in which the cable information is acquired via the touch screen 16 has been described. In the present invention, the cable information may be acquired from a terminal device (not shown) connected to a telecommunication network (not shown).

  By applying an operation program that defines the operation of the processing apparatus 100 according to the present invention to an existing personal computer or information terminal device, the personal computer or the like can also function as the processing apparatus 100 according to the present invention.

  Further, such a program distribution method is arbitrary. For example, the program is stored and distributed in a computer-readable recording medium such as a CD-ROM (Compact Disk Read-Only Memory), a DVD (Digital Versatile Disk), or a memory card. Alternatively, it may be distributed via a communication network such as the Internet.

  Various embodiments and modifications can be made to the present invention without departing from the broad spirit and scope of the present invention. Further, the above-described embodiment is for explaining the present invention, and does not limit the scope of the present invention. That is, the scope of the present invention is shown not by the embodiments but by the claims. Various modifications within the scope of the claims and within the scope of the equivalent invention are considered to be within the scope of the present invention.

  The present invention is applicable to an abnormality detection system that detects an abnormality of an electric wire.

11 CPU, 12 ROM, 13 RAM, 14 Flash memory, 15 RTC, 16 Touch screen, 17 Measuring instrument interface, 18 Telecommunications network interface, 100 Processing device, 101 Pulse applying unit, 102 Waveform measuring unit, 103 Resistance measuring unit , 104 Information output unit, 105 Physical length calculation unit, 106 Theoretical value calculation unit, 107 Actual measurement value determination unit, 108 Opening / closing unit, 200 Pulse generator, 300 Waveform measuring device, 400 Open / close switching device, 410 Control circuit, 420 Relay, 500,501 Cable, 510,520,530,540 Electric wire, 550 Shielded wire, 560,570 Insulating member, 610,620,630,640 Equipment, 1000 Abnormality detection system

Claims (7)

Pulse applying means for applying a voltage pulse between one end of a pair of electric wires;
A waveform measuring means for measuring a voltage waveform indicating a change in voltage between one ends of the pair of electric wires in a period including a rising time of the voltage pulse;
Resistance value measuring means for measuring a resistance value between one end of the pair of electric wires;
The voltage waveform measured by the waveform measuring means during a period in which the other end of the pair of electric wires is short-circuited and the voltage measured by the waveform measuring means in a period during which the other end of the pair of electric wires is open The theoretical value of the loop resistance of the pair of electric wires obtained from the waveform and the resistance of the pair of electric wires based on the resistance value measured by the resistance value measuring means during a period in which the other end of the pair of electric wires is short-circuited When the difference between the measured value of the loop resistance and a predetermined threshold value is exceeded, information output means for outputting information indicating that the abnormality of the pair of electric wires has been detected, and
Anomaly detection system. The voltage waveform measured by the waveform measuring means during a period in which the other end of the pair of electric wires is short-circuited and the voltage measured by the waveform measuring means in a period during which the other end of the pair of electric wires is open A physical length calculating means for calculating a physical length of the pair of electric wires based on the waveform;
A theoretical value calculating means for calculating a theoretical value of a loop resistance of the pair of electric wires based on a physical length calculated by the physical length calculating means and a rated value of a resistance value per unit physical length of the pair of electric wires; , Further comprising
The abnormality detection system according to claim 1. Measured value determining means for determining the measured value of the loop resistance of the pair of electric wires based on a resistance value equal to or less than a predetermined threshold value among a plurality of resistance values obtained by a plurality of measurements by the resistance value measuring means. Further comprising
The abnormality detection system according to claim 1 or 2. An opening / closing means for switching a short circuit / open state between the other ends of the pair of electric wires each time a predetermined time elapses;
The abnormality detection system according to any one of claims 1 to 3. Apply a voltage pulse between one end of a pair of wires,
Measuring a voltage waveform indicating a change in voltage between one end of the pair of electric wires in a period including a rising time of the voltage pulse;
Measure the resistance value between one end of the pair of wires,
The pair of electric wires obtained from the voltage waveform measured during a period in which the other ends of the pair of electric wires are short-circuited and the voltage waveform measured in a period during which the other ends of the pair of electric wires are opened. A predetermined threshold is defined as a difference between a theoretical value of the loop resistance and an actual measurement value of the loop resistance of the pair of wires based on a resistance value measured during a period in which the other ends of the pair of wires are short-circuited. If it exceeds, output information indicating that the abnormality of the pair of wires has been detected,
Anomaly detection method. The pair of electric wires is composed of two electric wires that are not connected to the same equipment among a plurality of electric wires included in the cable.
The abnormality detection method according to claim 5. The pair of electric wires includes a shielded wire included in a shielded cable and any one of the plurality of electric wires included in the shielded cable and shielded by the shielded wire,
The abnormality detection method according to claim 5.

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