Wire break detection method and apparatus

Abstract

To provide a disconnection detection method and device that can facilitate analyzing a cause of disconnection.SOLUTION: A disconnection detection method includes: providing a periodical movement to a cable 10 having a conductor 11a formed of a plurality of wires; measuring a value of resistance of the conductor 11a that changes in time sequence according to the movement; on the basis of a result of measurement of the resistance value, extracting an operating frequency corresponding to a period of the movement or a resistance value variation component of a high-order frequency of the operating frequency; and when a magnitude of the extracted resistance value variation component is larger than a preset threshold, stopping provision of the movement.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a disconnection detection method and apparatus.

Background Art

[0002] Disconnection detection in the conductor of a cable is generally performed based on the measurement result of the electrical resistance of the conductor in the cable. When a disconnection occurs in a part of the strands included in a conductor composed of a plurality of strands and the number of disconnected strands increases and the disconnection progresses, the resistance value of the conductor gradually increases. Therefore, for example, by measuring in advance the resistance value of the conductor in the initial state where no disconnection has occurred and detecting the disconnection of the conductor based on the rate of increase in the resistance value from the initial state of the resistance value. Conventionally, when the rate of increase in the resistance value from the initial state exceeds 20%, it is generally determined that there is a disconnection.

[0003] Note that as prior art document information related to the invention of this application, there is Patent Document 1.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] By the way, there are various causes for the disconnection of the strands for calibrating the conductor. For example, when operations such as bending are repeatedly performed on the cable, the cause of the strand disconnection is not only simple fatigue disconnection, but also disconnection due to the influence of friction between the strands, or disconnection due to damage to the strands. There are various failure modes leading to disconnection. When developing a cable in which disconnection is unlikely to occur in the conductor, there is a demand to analyze in what failure mode the disconnection has occurred in the conductor.

[0006] However, with conventional methods of determining wire breakage based on the rate of increase in resistance, wire breakage is only detected when the breakage has progressed (for example, when the rate of increase in resistance from the initial state exceeds 20%), that is, when a large number of strands have already broken. Therefore, even if an inspection is performed when a wire breakage is detected, it can be difficult to analyze the cause of the breakage because the broken part of the strand may be crushed by bending, etc.

[0007] Therefore, the present invention aims to provide a wire break detection method and apparatus that can facilitate the analysis of the cause of wire breakage. [Means for solving the problem]

[0008] The present invention aims to solve the above problems by providing a wire break detection method that involves applying a periodic operation to a cable having a conductor made up of multiple strands, measuring the resistance value of the conductor which changes in a time series due to the operation, extracting a resistance value fluctuation component at the operating frequency or a higher-order frequency corresponding to the period of the operation based on the measurement result of the resistance value, and stopping the application of the operation when the magnitude of the extracted resistance value fluctuation component is greater than a preset threshold.

[0009] Furthermore, the present invention provides a wire break detection device comprising: an action-applying mechanism for applying periodic motion to a cable having a conductor made up of multiple strands; a resistance value measuring instrument for measuring the resistance value of the conductor which changes in time series due to the motion; a frequency analysis processing unit for extracting resistance value fluctuation components of an operating frequency or higher-order frequencies corresponding to the period of the motion based on the resistance value measurement result by the resistance value measuring instrument; and an action stop processing unit for stopping the application of motion by the action-applying mechanism when the magnitude of the resistance value fluctuation component extracted by the frequency analysis processing unit is greater than a preset threshold. [Effects of the Invention]

[0010] According to the present invention, a wire break detection method and apparatus can be provided that facilitate the analysis of the cause of wire breakage. [Brief explanation of the drawing]

[0011] [Figure 1] This is a schematic diagram showing a wire break detection device according to one embodiment of the present invention. [Figure 2] This is a cross-sectional view showing a schematic example of the cable configuration that is subject to wire break detection. [Figure 3] (a) and (b) are diagrams illustrating a schematic configuration example of a resistance meter. [Figure 4] This is a flowchart of a wire break detection method according to one embodiment of the present invention. [Figure 5] This is a schematic diagram showing a wire break detection device according to one modified example of the present invention. [Modes for carrying out the invention]

[0012] [Embodiment] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

[0013] Figure 1 is a schematic diagram showing a wire break detection device 1 according to this embodiment. Figure 2 is a cross-sectional view showing a schematic example of the configuration of the cable 10 that is the target of wire break detection.

[0014] The cable 10 shown in Figure 2 is constructed by twisting together five electric wires 11 and a thread-like interlining 12 to form a cable core 13, then spirally wrapping a retaining tape 14 around it, and providing a sheath 15 to cover the retaining tape 14. Each electric wire 11 has a conductor 11a made up of multiple strands and an insulator 11b provided to cover the conductor 11a. The conductor 11a is, for example, a stranded conductor made by twisting together 19 strands of soft copper wire with an outer diameter of 0.08 mm. The insulator 11b is, for example, made of a fluororesin such as ETFE (tetrafluoroethylene-ethylene copolymer). The interlining 12 is, for example, made of jute or rayon. Note that the number of electric wires 11 used in the cable 10 is not limited to five. The retaining tape 14 is, for example, made of a tape material such as nonwoven fabric, paper, or resin. The sheath 15 is, for example, made of PE (polyethylene), PP (polypropylene), PVC (polyvinyl chloride), etc. Note that the cable 10 is not limited to the configuration shown in the figure, and may have various configurations as long as it includes a conductor 11a consisting of at least stranded conductors. In other words, the electric wire 11 may be one, several, or dozens or more. Note that when there is only one electric wire 11, the intervening material 12, the retaining tape 14, and the sheath 15 are often omitted. In this case, the cable 10 and the electric wire 11 refer to the same thing.

[0015] As shown in Figure 1, the wire break detection device 1 is a device that detects wire breaks in the strands of a cable 10 having a conductor 11a consisting of multiple strands, and comprises an action-giving mechanism 2, a resistance value measuring instrument 3, a calculation device 4, and a stop device 6.

[0016] The motion-granting mechanism 2 is a device that imparts periodic motion to the cable 10. In this embodiment, the case where the motion-granting mechanism 2 is a test device is described, but equipment such as an industrial robot to which the cable 10 is wired may be used as the motion-granting mechanism 2 as is.

[0017] Regarding the operation imparted to the cable 10 by the operation imparting mechanism 2, there is no particular limitation in this embodiment. For example, it may be a bending operation that repeatedly bends the cable 10, a twisting operation that periodically twists the cable 10 in its circumferential direction (the direction along the outer circumference of the cable 10 shown in FIG. 2), a U-shaped bending operation in which the cable 10 is bent in a U shape and one end of the cable 10 is periodically slid in a predetermined stroke along the longitudinal direction of the cable at that end, and the like. The data of the operation by the operation imparting mechanism 2 (= operation data 51) is input to the arithmetic unit 4 and stored in the storage unit 42. The operation data 51 is, for example, data such as the number of times the operation is imparted. Note that the operation data 51 may be input to the arithmetic unit 4 by an input device (not shown) or the like.

[0018] The resistance value measuring device 3 measures the resistance value of the conductor 11a that changes in time series. The data of the resistance value of the conductor 11a that changes in time series measured by the resistance value measuring device 3 (= resistance value data 50) is input to the arithmetic unit 4 and stored in the storage unit 42. Details of the resistance value measuring device 3 will be described later.

[0019] The arithmetic unit 4 includes a control unit 41 and a storage unit 42. Details of these control unit 41 and storage unit 42 will be described later. Although the specific hardware configuration is not shown in FIG. 1, the arithmetic unit 4 is, for example, configured by a personal computer, and includes an arithmetic element such as a CPU, a memory such as a RAM and a ROM, a storage device such as a hard disk, and a communication interface that is a communication device such as a LAN card. Each component is connected by a bus.

[0020] A display 43 is connected to the arithmetic unit 4, and various data such as resistance value data 50 and the result of open circuit detection can be displayed on the display 43. Although not shown, an input device such as a keyboard is provided in the arithmetic unit 4, and various settings and operations of the display content of the display 43 can be performed by input from the input device. Note that the display 43 may be configured as a touch panel display so that the display 43 also serves as an input device. Further, the display 43 may not be connected to the arithmetic unit 4 by wire, but may be connected wirelessly. In this case, the display 43 may be, for example, a display of a smartphone or a tablet.

[0021] (Principle of open circuit detection) First, when a periodic operation such as bending is applied to the conductor 11a in a state where a strand of the conductor 11a is broken, the broken portion will periodically repeat approaching and separating in response to the operation, and a resistance value fluctuation will occur at the operation period, which is the period of the applied operation, or a period that is an integer multiple of the operation period. Therefore, by using the resistance value measuring device 3 to measure the resistance value of the conductor 11a that changes over time, and monitoring the magnitude of the component of the operation frequency, which is the frequency corresponding to the operation period, or the component of its higher-order frequency in the obtained resistance value data, it becomes possible to detect that a strand of the conductor 11a has broken (that is, the progress state of the open circuit of the conductor 11a). By using this method, it becomes possible to accurately detect the open circuit of the strand excluding the influence of factors such as resistance value fluctuations due to temperature, etc. For example, it becomes possible to detect at the initial stage of open circuit where one to several strands have broken. In the present embodiment, by stopping the operation of the operation applying mechanism 2 at the time when an initial open circuit occurs, it becomes possible to observe the conductor 11a at the time when the initial open circuit occurs, and it becomes possible to analyze the cause of the open circuit of the strand, such as in what open circuit mode the strand has broken. Note that the cause of the open circuit can be specified, for example, by observing the cross section of the strand with a microscope or the like and looking at differences in the shape of the cross section, etc.

[0022] (Details of the resistance value measuring device 3) Figure 3(a) shows a schematic configuration example of the resistance meter 3. As shown in Figure 3(a), the resistance meter 3 includes a resistance measuring unit 35 having a DC signal source (e.g., a DC constant voltage source) 35a, an input resistor 35b, and a resistance detector 35c. Note that if a DC constant current source is used as the DC signal source 35a, the input resistor 35b is not required. The DC signal source 35a applies a DC signal (in this case, a DC voltage) to the cable 10 (conductor 11a) via the input resistor 35b. In response, the cable 10 (conductor 11a) outputs a modulated signal (e.g., a voltage signal) containing a component of the operating frequency (e.g., f=1Hz) due to the repeatedly applied operation. The resistance detector 35c detects the resistance value of the conductor 11a, which changes over time, by amplifying this modulated signal with a predetermined gain, for example. The signal from the resistance detector 35c is converted into a digital signal by the A / D converter 37 and output to the arithmetic unit 4 as resistance value data 50.

[0023] Note that the configuration of the resistance meter 3 shown in Figure 3(a) is merely an example and can be modified as appropriate. For example, as shown in Figure 3(b), the resistance meter 3 may have an integrated frequency analysis unit 36. In this case, the frequency analysis processing unit 411 (see Figure 1) of the calculation unit 4, which will be described later, can be omitted.

[0024] The frequency analysis unit 36 ​​includes, for example, a carrier signal generator 36a, a mixer 36b, and a low-pass filter (LPF) 36c. The carrier signal generator 36a generates a carrier signal with the same carrier frequency (ωc, for example, 1Hz) as the operating frequency (e.g., f=1Hz), i.e., the resistance fluctuation frequency due to a broken wire, and with the same phase as the resistance fluctuation frequency. The mixer 36b multiplies this carrier signal with the output signal from the resistance detector 35c (in other words, performs synchronous detection) to output a signal in which a DC component signal and a "2×ωc" component signal are superimposed. In the carrier signal generator 36a shown in Figure 5(b), sin(ωct) can extract the resistance fluctuation component at the operating frequency f when ωc=2πf. That is, the resistance fluctuation component is the amplitude when the resistance value changes.

[0025] The low-pass filter 36c receives the output signal from the mixer 36b, blocks the "2 × ωc" component of the signal, and allows the DC component of the signal to pass through. This DC component of the signal represents the magnitude of the resistance fluctuation component at the operating frequency f (= ωc). In this way, by using the frequency analysis unit 36 ​​which has the carrier signal generator 36a, the mixer 36b, and the low-pass filter 36c, it is possible to detect resistance fluctuation components at predetermined frequencies (for example, resistance fluctuation components at the operating frequency f and resistance fluctuation components at predetermined higher-order frequencies, which will be described later). The signal from the low-pass filter 36c is converted into a digital signal by the A / D converter 37 and output to the arithmetic unit 4.

[0026] In the configuration examples shown in Figures 3(a) and 3(b), a DC signal is applied to the cable 10 (conductor 11a). However, it is not limited to a DC signal; an AC signal of a predetermined frequency (e.g., around 10 kHz) may be applied using an AC signal source. In this case, the cable 10 outputs a signal that is amplitude-modulated by this AC signal with a modulation signal of operating frequency f. By multiplying this output signal with a carrier signal of the same frequency as the AC signal source using a mixer, the modulated signal of operating frequency f can be demodulated. Using this method allows for measurements at higher frequencies (e.g., around 10 kHz), resulting in less interference from noise components.

[0027] (Arithmetic unit 4) The control unit 41 of the arithmetic unit 4 is equipped with a frequency analysis processing unit 411, a wire break progression estimation processing unit 412, an operation stop processing unit 413, and an alarm processing unit 414. The details of each part will be described below.

[0028] The frequency analysis processing unit 411 performs frequency analysis on the resistance value data 50 measured by the resistance value measuring instrument 3 (i.e., data on the resistance value of the conductor 11a that changes over time). The results of the frequency analysis are stored in the storage unit 42 as frequency analysis data 52. Frequency analysis means analyzing the magnitude of each frequency component contained in the resistance value data 50 and obtaining frequency analysis data 52, which is data in which the magnitude of the component for each frequency is extracted.

[0029] The frequency analysis processing unit 411 then extracts resistance fluctuation components of higher frequencies, which are the operating frequency f or n times the operating frequency f (where n is a natural number greater than or equal to 2), from the frequency analysis data 52 obtained by the frequency analysis. The choice of which frequency resistance fluctuation components to extract is best determined according to the operation to be performed by the operation application mechanism 2, and it is preferable to conduct experiments in advance and set the parameters based on the results of those experiments.

[0030] The wire break progression estimation processing unit 412 estimates the wire break progression state by comparing the resistance value fluctuation component extracted by the frequency analysis processing unit 411 with a preset threshold. In this embodiment, the wire break progression estimation processing unit 412 determines whether the magnitude of the resistance value fluctuation component extracted by the frequency analysis processing unit 411 is greater than the preset threshold. The determination result is stored in the storage unit 42 as determination data 53. The preset threshold is, for example, the magnitude of the resistance value fluctuation component at the operating frequency or a higher frequency when n strands (n: an integer of 1 or more) among the multiple strands constituting the conductor 11a are broken. By appropriately setting the threshold used for determination in accordance with when a wire break occurs, it is possible to estimate that a desired wire break progression state has been reached, such as the stage when the initial break occurs, or the stage when the break has progressed further from the initial break (i.e., when one of the multiple strands is broken). It is preferable to conduct experiments in advance and set the specific value to be set as the threshold based on the results of those experiments.

[0031] The operation stop processing unit 413 stops the operation of the operation granting mechanism 2 when a desired disconnection progression state is reached (when the resistance value fluctuation component extracted by the frequency analysis processing unit 411 becomes larger than a threshold). In this embodiment, the operation stop processing unit 413 is configured to stop the operation of the operation granting mechanism 2 by sending a stop signal to the stop 6 and having the stop 6 cut off the power supply. However, this is not the only option; for example, if the operation granting mechanism 2 has a function to stop itself in response to an externally input signal, the operation stop processing unit 413 may be configured to stop the operation of the operation granting mechanism 2 by directly sending a stop signal to the operation granting mechanism 2.

[0032] The operation stop processing unit 413 automatically stops the operation of the operation granting mechanism 2 when the desired wire break progression state is reached, making it possible to observe the cross-section of the conductor 11a in the desired wire break progression state and to analyze the cause of wire breakage.

[0033] The alarm processing unit 414 issues an alarm to the operator performing the operation using the operation mechanism, the administrator managing various data and devices, etc., when the desired wire break progression state occurs (when the resistance value fluctuation component at the operating frequency or a higher-order frequency extracted by the frequency analysis processing unit 411 becomes larger than a threshold). The alarm issued by the alarm processing unit 414 may be an alarm using light or sound, or it may be done by displaying an alert on the display unit 43 or notifying the administrator, etc., via email, etc.

[0034] The presence of the alarm processing unit 414 makes it possible to notify administrators, etc., when a desired wire break progression state has been reached, and to notify them at a stage when the conductor 11a has not yet broken (a stage when the rate of increase in resistance from the initial state has not exceeded 20%), i.e., to notify them of a wire break in advance. This makes it possible for administrators, etc., to recognize that the wire breakage is in progress and to take measures such as proceeding with the replacement of the cable 10 before the cable 10 is completely broken.

[0035] In this embodiment, the arithmetic unit 4 is configured as a personal computer, but it is not limited to this, and the arithmetic unit 4 may be, for example, a server device. In this case, the resistance value data 50 measured by the resistance meter 3 will be transmitted to the arithmetic unit 4, which is the server device, via the network. Furthermore, the control unit 41 and the storage unit 42 may be configured as separate devices. This reduces the load on the arithmetic unit 4 and allows for the preservation of data such as the resistance value data 50 stored in the storage unit 42 installed in another device if the device equipped with the control unit 41 fails, and this preserved data can be transmitted to a new device equipped with the control unit 41 to perform wire break detection. For example, the resistance value data 50 stored in the storage unit 42 of the server device can be downloaded by a control unit 41 installed in another server device or personal computer, etc., to perform wire break detection.

[0036] (Method for detecting broken wires) Figure 4 is a flowchart of the wire break detection method according to this embodiment. As shown in Figure 4, first, in step S11, the cable 10 is set in the action-applying mechanism 2 and the action-applying mechanism 2 starts applying action to the cable 10, and in step S12, the resistance value measurement of the conductor 11a is started by the resistance value measuring instrument 3. The resistance value data of the conductor 11a measured in step S12 is transmitted to the arithmetic unit 4 as resistance value data 50 and stored in the storage unit 42 of the arithmetic unit 4.

[0037] Subsequently, in step S12, the frequency analysis processing unit 411 performs frequency analysis on the resistance value data 50. The results of the frequency analysis are stored in the storage unit 42 as frequency analysis data 52. Then, in step S13, the frequency analysis processing unit 411 extracts resistance value fluctuation components at a preset frequency (operating frequency or higher-order frequency) from the frequency analysis data 52. Then, in step S14, the wire breakage progression estimation processing unit 412 determines whether the magnitude of the resistance value fluctuation component extracted in step S13 is greater than or equal to a preset threshold. The determination result is stored in the storage unit 42 as determination data 53. If NO (N) is determined in step S14, in step S15, the operation of the operation granting mechanism 2 and the measurement of the resistance value by the resistance value measuring instrument 3 continue, and the process returns to step S12.

[0038] If the result in step S14 is YES (Y), the operation stop processing unit 413 determines that the desired disconnection progression state has been reached, sends a stop signal to the stopper 6 to stop the operation of the operation granting mechanism 2, and stops the resistance measurement by the resistance value measuring instrument 3. Subsequently, in step S17, the alarm processing unit 414 issues an alarm. After that, the process ends.

[0039] (Operation and Effects of the Embodiment) As described above, in the wire break detection method according to this embodiment, a periodic operation is applied to a cable 10 having a conductor 11a consisting of multiple strands, the resistance value of the conductor 11a which changes in a time series due to the operation is measured, and based on the resistance value measurement result, a resistance value fluctuation component at the operating frequency or a higher-order frequency corresponding to the period of the operation is extracted, and when the magnitude of the extracted resistance value fluctuation component is greater than a preset threshold, the application of the operation is stopped.

[0040] This allows the operation of the action-giving mechanism 2 to be stopped at a desired stage of wire breakage progression, by appropriately setting a threshold according to the stage of wire breakage progression for which analysis of the cause of breakage is desired. This makes it easier to analyze the cause of wire breakage, such as the mode of failure that led to the breakage of the conductor 11a. The results of the wire breakage cause analysis obtained can then be used in the design and development of the cable 10. For example, by accumulating data on the cause of wire breakage and associating it with other data such as operation data 51, it becomes possible to estimate the cause of wire breakage from arbitrary operation data 51. This makes it possible to estimate the cause of wire breakage without observing the cross-section of the wire strands.

[0041] (modified version) In the above embodiment, a case with one action-granting mechanism 2 was described, but it is not limited to this, and multiple action-granting mechanisms 2 may be provided, as in the wire break detection device 1a shown in Figure 5. A resistance value measuring instrument 3 and a stopper 6 are provided to correspond to each action-granting mechanism 2. This makes it possible to apply periodic motion to multiple cables 10 using multiple action-granting mechanisms 2. By making the periodic motion for each cable 10 the same motion (for example, bending motion) and making the threshold for stopping the action-granting mechanism 2 different for each cable 10, it is possible to obtain cables 10 in which the wire break progression state differs in stages for the same motion. This makes it possible to analyze, for example, the relationship between the position of the second broken strand and the position of the first broken strand, and to perform a more detailed analysis of the cause of wire breakage. Alternatively, the periodic motion for each cable 10 may be different motions (for example, one cable 10 may be a bending motion and the other cable 10 may be a twisting motion), and the threshold for stopping the action-granting mechanism 2 may be the same or different for each cable 10. This makes it possible to analyze differences in the progression of disconnection when different operations are applied to cables 10 with the same structure, and to analyze the cause of disconnection due to differences in operation. It also makes it possible to analyze differences in the progression of disconnection when different operations are applied to cables 10 with different structures. As a result, when combining multiple cables 10 with different structures to form a harness, it becomes possible to position each of the multiple cables 10 according to their durability for each operation.

[0042] Furthermore, although not mentioned in the above embodiment, the display unit 43 may display resistance value data 50, operation data 51, frequency analysis data 52, etc., in an appropriate format such as a graph, so that the changes in resistance value corresponding to the operation applied to the cable 10 and the results of the frequency analysis can be monitored. This makes it possible to visualize the progression of the break.

[0043] (Summary of the embodiments) Next, the technical concept understood from the embodiments described above will be described using the reference numerals and other symbols from the embodiments. However, the reference numerals and other symbols in the following description are not limited to the components in the claims that are specifically shown in the embodiments.

[0044] [1] A wire break detection method comprising: applying a periodic operation to a cable (10) having a conductor (11a) consisting of multiple strands; measuring the resistance value of the conductor (11a) which changes in a time series due to the operation; extracting a resistance value fluctuation component at the operating frequency or a higher-order frequency corresponding to the period of the operation based on the measurement result of the resistance value; and stopping the application of the operation when the magnitude of the extracted resistance value fluctuation component is greater than a preset threshold.

[0045] [2] The wire break detection method according to [1], wherein an alarm is issued when the magnitude of the extracted resistance value fluctuation component is greater than a preset threshold.

[0046] [3] The wire break detection method according to [1], wherein a periodic operation is applied to multiple cables (10) and the threshold value is different for each cable (10).

[0047] [4] A wire break detection device (1) comprising: an action-applying mechanism (2) for applying periodic motion to a cable (10) having a conductor (11a) consisting of multiple strands; a resistance value measuring instrument (3) for measuring the resistance value of the conductor (11a) which changes in time series due to the motion; a frequency analysis processing unit (411) for extracting resistance value fluctuation components of an operating frequency or higher-order frequencies corresponding to the period of motion based on the resistance value measurement results by the resistance value measuring instrument (3); and an action stop processing unit (413) for stopping the application of motion by the action-applying mechanism (2) when the magnitude of the resistance value fluctuation component extracted by the frequency analysis processing unit (411) is greater than a preset threshold.

[0048] Although embodiments of the present invention have been described above, the embodiments described above do not limit the invention as defined in the claims. Furthermore, it should be noted that not all combinations of features described in the embodiments are necessarily essential for solving the problem of the invention. In addition, the present invention can be implemented with appropriate modifications without departing from its spirit. [Explanation of symbols]

[0049] 1…Wire break detection device 2...Motion-granting mechanism 2a Industrial robots 3… Resistance meter 4...Arithmetic device 41... Control Unit 411…Frequency Analysis Processing Unit 412...Disconnection Progression Estimation Processing Unit 413... Operation Stop Processing Unit 414… Alarm Processing Unit 42...Storage section 43...Indicator 50…Resistance value data 51…Operation data 52…Frequency analysis data 53… Judgment Data 6…Stop device 10… Cable 11...Electric wire 11a...Conductor

Claims

1. By imparting periodic motion to multiple cables having conductors composed of multiple strands, The resistance value of the conductor, which changes over time as a result of the above operation, is measured. Based on the measurement results of the aforementioned resistance values, the resistance value fluctuation components at the operating frequency or higher-order frequencies corresponding to the period of the aforementioned operation are extracted. When the magnitude of the extracted resistance fluctuation component is greater than a preset threshold, the application of the operation is stopped. The aforementioned pre-set threshold is set to differ for each cable. Method for detecting wire breakage.

2. When the magnitude of the extracted resistance fluctuation component exceeds a preset threshold, an alarm is issued. The wire break detection method according to claim 1.

3. An action-applying mechanism that imparts periodic motion to multiple cables having conductors composed of multiple strands, A resistance measuring instrument for measuring the resistance value of the conductor which changes over time due to the aforementioned operation, A frequency analysis processing unit extracts resistance fluctuation components of the operating frequency or higher-order frequencies corresponding to the period of the operation, based on the resistance measurement results obtained by the resistance measuring instrument. The system includes an operation stop processing unit that stops the operation application by the operation application mechanism when the magnitude of the resistance value fluctuation component extracted by the frequency analysis processing unit is greater than a preset threshold, The aforementioned pre-set threshold is set to differ for each cable. Wire break detection device.

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