JP3847919B2 - Cable monitoring device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a cable monitoring device for grasping a disconnection of a cable.
[0002]
[Prior art]
Generally, a cable has a plurality of core wires insulated from each other. Conventionally, the following method has been known as a method for grasping that the insulation between the core wires of the cable has been lowered. That is, two pilot lines are provided in the cable insulator, the ends of both pilot lines are open, and a voltage is applied between the ends. The current flowing at this time is measured, and if the current value exceeds a predetermined current threshold value, it is determined that the insulation of both pilot lines is defective. When it is determined that both pilot wires are poorly insulated, the core wires of the cables are also or may be poorly insulated.
[0003]
[Problems to be solved by the invention]
However, although the method for grasping the insulation failure between the core wires of the cable as described above has been known, the method for grasping the disconnection of the cable has not been known.
Therefore, as illustrated in FIG. 4, the present inventor connects a terminal resistance Re between the terminal terminals 13 and 14 of both pilot lines L1 and L2, and connects the terminal terminals 11 and 12 of both pilot lines L1 and L2. A device was devised in which a voltage was applied between them and the current flowing at that time was detected by a current detector. In this case, a current flows unless both the pilot lines L1 and L2 are disconnected, and a current does not flow if at least one of the pilot lines L1 and L2 is disconnected. Here, if at least one of the pilot lines L1 and L2 is disconnected, the core wire (signal line) of the cable may be disconnected or may be disconnected. For this reason, based on the detection signal (current value) of the current detector, it is possible to grasp the disconnection status of the core wire of the cable.
[0004]
By the way, if the place where the cable is laid is a noisy place such as in a railway vehicle station, for example, the cable picks up the noise and the current value flowing through the pilot lines L1 and L2 cannot be measured accurately. . In order to avoid this inconvenience, it is conceivable to incorporate a capacitor as a noise cutting filter circuit (see FIG. 5).
[0005]
However, when sequentially inspecting disconnection for a plurality of cables as shown in FIG. 5, if such a filter circuit is present, if at least one of the pilot lines L1 and L2 that were previously inspected is disconnected, Since the capacitor of the filter circuit remains charged without being discharged, the current flowing through the pilot lines L1 and L2 of the cable to be inspected this time is covered by the capacitor at the beginning of the inspection. For this reason, since the current detected by the current detector is small, there is a possibility that it is erroneously determined that both of the pilot lines L1 and L2 are not disconnected.
[0006]
The present invention has been made in view of the above problems, and provides a cable monitoring device capable of accurately grasping the disconnection state even when the disconnection is sequentially monitored for a plurality of cables laid in a place susceptible to noise. The purpose is to do.
[0007]
[Means for Solving the Problems and Effects of the Invention]
In order to solve the above-described problems, the present invention provides a plurality of first pilot lines having a first tip terminal and a first end terminal, and a second pilot line having a second tip terminal and a second end terminal. A cable monitoring device for sequentially monitoring the cables of
A terminal resistor connected between the first and second terminal terminals;
Cable connecting means for connecting each of the first and second tip terminals to each of the first and second input terminals;
A power source in which one of the two power terminals is connected to the first input terminal;
It has first and second detection terminals, and measures the current flowing between the two detection terminals, and the first detection terminal is connected to the power supply terminal opposite to the first input terminal of the two power supply terminals Current detection means,
Terminal switching means for selectively connecting one of the first and second detection terminals of the current detection means to the second input terminal;
The terminal switching means-connected between the signal path connecting the second input terminal and the first input terminal-signal path connecting the power supply terminal connected to the first input terminal of the two power supply terminals. And a capacitor.
[0008]
In this cable monitoring device, a terminal resistance is connected between the ends of both pilot lines provided in the cable, a voltage is applied between the ends of both pilot lines by a power source, and the current flowing through the current detection means Detect with. In this case, if neither of the pilot lines is disconnected, current flows, and if at least one of the pilot lines is disconnected, current does not flow. Here, if at least one of the pilot lines is disconnected, the core wire (signal line) of the cable is also disconnected or may be disconnected. For this reason, based on the detection signal (current value) of the current detection means, the disconnection state of the core wire of the cable can be grasped.
[0009]
Further, in this cable monitoring apparatus, the first and second tip terminals of both pilot lines of the predetermined cable and the first and second input terminals are connected by the cable connecting means. Before or at the same time as making this connection, the terminal switching means connects the measurement pause state (the first detection terminal and the second input terminal of the current detection means are connected to each other) for a time sufficient to discharge the capacitor. State in which no current is passed through the detection means). Here, when at least one of the two pilot lines of the cable that was inspected last time is disconnected, the capacitor of the filter circuit remains in a charged state without being discharged. Is switched to the measurement state (the state in which the second detection terminal and the second input terminal of the current detection means are connected and the current is supplied to the current detection means) and the current flowing in both pilot lines of the cable to be tested this time is discharged. For detection, the detected current value is not affected by the capacitor. Even if the cable picks up noise, the noise is cut by the capacitor, so that the detected current value is not affected by the noise.
[0010]
Therefore, according to this cable monitoring apparatus, even when the disconnection is sequentially monitored for a plurality of cables laid in a place susceptible to noise, an effect of accurately grasping the disconnection state can be obtained.
The cable monitoring device of the present invention is
When each of the first and second tip terminals and each of the first and second input terminals are connected by the cable connecting means, a time sufficient to instruct the terminal switching means to discharge the capacitor Only connecting the first detection terminal and the second input terminal of the current detection means, and then instructing the terminal switching means to connect the second detection terminal and the input terminal of the current detection means Switching control means;
After the terminal switching means connects the second detection terminal of the current detection means and the input terminal in accordance with a command from the terminal switching control means, the first or the second signal is detected based on the detection signal detected by the current detection means. Determining means for determining whether or not the second pilot line is disconnected;
An informing means for informing outside when it is judged by the judging means that the first or second pilot line is disconnected may be provided.
[0011]
In this case, the terminal switching control means instructs the terminal switching means to switch between the measurement pause state and the measurement state so that the detected current value is not affected by the capacitor, and the judgment means is detected in the measurement state. Based on the current value, it is determined whether or not the first or second pilot line is disconnected. If the first or second pilot line is disconnected, the notification means notifies the outside. For this reason, it is not necessary for the operator to check the current value detected by the current detecting means to determine the presence or absence of disconnection by himself / herself, and an effect of reducing the work load can be obtained. The determining means may compare the detected current value with the current threshold value for disconnection determination and determine whether or not the disconnection is made according to the result. A resistance (interline resistance) may be obtained, the interline resistance value may be compared with a resistance threshold for disconnection determination, and it may be determined whether or not the disconnection has occurred according to the result.
[0012]
Here, the determination means further determines whether insulation failure has occurred between the first pilot line and the second pilot line based on the detection signal detected by the current detection means, The notification means may be configured to notify the outside when the determination means determines that insulation failure has occurred between the first pilot line and the second pilot line. In this case, the judging means also judges the insulation failure between the two pilot lines, and in the case of insulation failure, the notification means notifies the outside. For this reason, it is possible to grasp the disconnection status of the cable with a single device and also grasp the insulation status of the cable. In this case, the measurement pause state is set to the longer one of the time sufficient for discharging the capacitor and the time sufficient for charging the capacitor. The determination means may compare the detected current value with a current threshold value for determining insulation failure, and may determine whether there is insulation failure according to the result, or may determine between the pilot lines from the detected current value. It is also possible to determine the resistance (interline resistance) and compare this line resistance value with a resistance threshold value for determining insulation failure, and determine whether or not there is insulation failure according to the result.
[0013]
In the cable monitoring device of the present invention, one cable is sequentially selected from the plurality of cables, and each of the first and second tip terminals of the selected cable is first and second by the cable connecting means. You may provide the cable connection control means connected to each of an input terminal. In this case, since the cable connection control means sequentially switches the cables, the operator's work load is further reduced.
[0014]
Furthermore, it is preferable that the first and second pilot lines are provided outside the core line of the cable. In this case, for example, even if either one of the two pilot lines is disconnected, both pilot lines are arranged outside the core wire (signal line), so that the inner core wire is also disconnected. Not exclusively. For this reason, in addition to the case where the core wire of the cable is disconnected, it is possible to grasp the situation that the core wire of the cable will be disconnected soon. For example, even if the insulation between both pilot lines is poor, the core line is not necessarily poorly insulated. For this reason, in addition to when the insulation between the cores of the cable becomes defective, it is possible to grasp the situation where the insulation between the cores of the cable will soon become defective.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Preferred embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a schematic configuration diagram of this embodiment, and FIG. 2 is a cross-sectional view of a cable.
As shown in FIG. 1, the cable monitoring device includes a plurality (n) of cables CA _{1 to} CA _n , a cable connection switch 20, a current measurement circuit 30, a controller 40, an alarm device 41, and a resistance display device 42. .
[0016]
As shown in FIG. 2, the cable CA _k (k is an integer of 1 to n) includes a plurality of core wires 15, 15,..., And first and second pilots provided outside the core wires 15. Lines L 1 and L 2, inclusions 16 surrounding them, a sheath 17 surrounding the outer periphery of the inclusions 16, and a steel strip 18 provided in the sheath 17 are provided. The core wire 15 has a structure in which a conductive wire 15a is covered with an insulator 15b, and the first and second pilot lines L1 and L2 have the same structure. As shown in FIG. 1, the first pilot line L1 includes a first tip terminal 11 and a first end terminal 13, and the second pilot line L2 includes a second tip terminal 12 and a second end terminal 14. ing. A terminal resistance Re (2 MΩ in this case) is connected between the first and second terminal terminals 13 and 14.
[0017]
Cabling switch as cable connection means 20, respectively of the first and second input terminals 21 and 22, first and second distal terminal 11 of the one cable CA _k of the plurality of cables CA ₁ to CA _n , 12 are connected to each other. The cable connection switch 20 is operated by a command from the outside, and in this embodiment, by a command signal from the controller 40.
[0018]
Current measuring circuit 30 is a circuit for measuring the current flowing through the first pilot line L1- terminal resistor Re- second pilot line L2 in the cable CA _k. In the current measurement circuit 30, the first input terminal 21 is connected to one (minus) power supply terminal 24 of the DC power supply 23. A current detector 26 as a current detection means measures a current flowing between the first and second detection terminals 28 and 29, and the first detection terminal 28 is the other (plus) power supply terminal 25 of the DC power supply 23. It is connected to the.
[0019]
A terminal changeover switch 27 serving as a terminal changeover means is a switch that alternatively connects one of the first and second detection terminals 28 and 29 of the current detector 26 to the second input terminal 22. The terminal changeover switch 27 is actuated by a command from the outside, and in this embodiment, by a command signal from the controller 40. The state in which the first detection terminal 28 of the current detector 26 is connected to the second input terminal 22 by the terminal changeover switch 27 is the measurement pause state, and the second detection terminal 29 of the current detector 26 is changed to the second input terminal 22. The connected state is referred to as a measurement state.
[0020]
The capacitor C is connected between a signal path Lb connecting the terminal changeover switch 27 and the second input terminal 22 and a signal path La connecting the first input terminal 21 and one power supply terminal 24 of the DC power supply 23. Resistors R2 and R4 for limiting the current flowing into the capacitor C are provided in the signal path La, and resistors R1 and R3 are also provided in the signal path Lb. These capacitors C and resistors R1 to R4 are used to cut noise when the first and second pilot lines L1 and L2 of the cable CAk (k is an arbitrary integer of 1 to n) pick up ambient noise. The filter circuit 31 is configured. That is, the filter circuit 31 prevents the current detector 26 from erroneously detecting due to noise. Such a filter circuit 31 is useful when monitoring a cable provided in a noisy location such as in a railway station. A plurality of filter circuits 31 may be provided depending on the magnitude of noise.
[0021]
The controller 40 is a device including a known CPU, ROM, RAM, clock, counter, and the like, and is connected so that a detection signal from the current detector 26 can be input. The control signal is connected to the device 41 and the resistance display device 42 so as to be output. Alarm apparatus 41 is used for displaying the monitoring status of the cable CA ₁ to CA _n to a display (not shown), the resistance display 42 is the line resistance of the first and second pilot lines L1, L2 of the cable CA _k during the measurement Is displayed. The controller 40 corresponds to cable connection control means, terminal switching control means, and determination means, and the alarm device 41 corresponds to notification means.
[0022]
Next, the operation of the cable monitoring device of this embodiment will be described. FIG. 3 is a flowchart of cable monitoring processing executed by the controller of the cable monitoring apparatus.
Various control programs are recorded in a ROM (not shown) of the controller 40, one of which is a cable monitoring program. When a monitoring execution switch (not shown) is turned on, the CPU (not shown) of the controller 40 executes the cable monitoring process shown in FIG. 3 based on the cable monitoring program.
[0023]
When this process is executed, first, in S201, the controller 40 resets a value k of a cable number counter (not shown), and then in S202, increments the value k of this cable number counter.
In subsequent S203, the controller 40 sends a signal to the terminal change-over switch 27 to electrically connect the first detection terminal 28 and the second input terminal 22 of the current detector 26 (that is, to make the measurement inactive state) and to connect the cable. It sends a signal to the connection switch 20, to connect the respective first and second distal terminal 11, 12 of the cable CA _k to each of the first and second input terminals 21 and 22.
[0024]
In subsequent S204, the controller 40 determines whether or not a predetermined time ta (a time sufficient for charging the capacitor C or a time sufficient for discharging, whichever is longer) has elapsed. If the predetermined time ta has elapsed in S204, a signal is sent to the terminal changeover switch 27 in S205 to electrically connect the second detection terminal 29 and the second input terminal 22 of the current detector 26 (that is, Go to S206). On the other hand, if the predetermined time ta has not elapsed in S204, the process waits until the predetermined time ta elapses.
[0025]
If the disconnection is determined in S206, in the subsequent S207, the controller 40 sends a signal to the alarm device 41 so that the alarm device 41 notifies the outside. For example, the alarm device 41, indicating that at least one of the cable CA first or second pilot lines _k L1, L2 is disconnected (or core of the cable CA _k is broken, or that there is the possibility) Is displayed on a display (not shown) or an alarm is sounded. Then, the process proceeds to S208. On the other hand, if it is determined in S206 that there is no disconnection, the process proceeds directly to S208.
[0026]
In S208, the controller 40 based on a detection signal of the current detector 26, in turn determines whether insulation failure between the first and second pilot lines L1, L2 of the cable CA _k. Specifically, the current value Im detected by the current detector 26 is compared with the current threshold value It2 for determining insulation failure. If the current value Im is equal to or smaller than the current threshold value It2, the insulation is good and the current is passed. If the threshold value It2 is exceeded, it is determined that the insulation is defective. Alternatively, the line resistance value Rm of the pilot lines L1 and L2 is obtained from the current value Im detected by the current detector 26, and the line resistance value Rm is compared with the resistance threshold value Rt2 for determining insulation failure. It may be determined that the insulation is good if the resistance threshold value Rt2 is exceeded, and that the insulation is defective if the resistance threshold value Rt2 or less.
[0027]
If it is determined in S208 that the insulation is defective, in S209, the controller 40 sends a signal to the alarm device 41 so that the alarm device 41 notifies the outside. For example, the alarm device 41, or the insulation between that insulation between the first and second pilot lines L1, L2 of the cable CA _k is defective (or cable CAk core is defective, or there is the possibility ) Is displayed on a display (not shown) or an alarm is sounded. Then, the process proceeds to S210. On the other hand, if it is determined in S208 that the insulation is good, the process proceeds to S210 as it is.
[0028]
In S210, it is determined whether or not the value k of the cable number counter matches a predetermined number n (total number of cables). If they do not match, the processing from S202 is repeated, and if they match, the processing from S201 is repeated. .
The controller 40 in this embodiment calculates the line-to-line resistance value Rm of the first and second pilot lines L1, L2 of the cable CA _k from the current value Im from the current detector 26, the line to the resistance display 42 The resistance value Rm is displayed. The line-to-line resistance value Rm displayed on the resistance display device 42 is a value calculated by the controller 40 by calculating the combined resistance Rs from the current value Im and 1 / Rs = 1 / Re + 1 / Rm. The operator determines that both pilot lines L1 and L2 are normal if the line resistance value Rm displayed on the resistance display device 42 is, for example, 1 to 3 MΩ, and if it is 1 MΩ or less, the insulation between the pilot lines L1 and L2 is poor. it is determined that (core wires of the cable CA _k there is or fear that a poor insulation), the core wire is broken in which at least one is disconnected (cable CA _k of both pilot line L1, L2 if more 3MΩ Or there is a risk of it).
[0029]
In the above cable monitoring processing, in S203 to S205, the terminal changeover switch 27 is controlled so as to be in the measurement pause state before the predetermined time ta elapses and to enter the measurement state after the predetermined time ta elapses. The fluctuation of the detection value of the current detector 26 due to the influence of the capacitor C of the filter circuit 31 is eliminated.
[0030]
That is, for example, assuming that the cable CA _k-1 previously connected to the first and second input terminals 21 and 22 is short _- circuited and the current cable CA _k is normal, the connection is switched to the cable CA _k. Immediately after that, the capacitor C is charged from a state where it is not sufficiently charged. At this time, if the second detection terminal 29 and the second input terminal 22 are connected by the terminal changeover switch 27, that is, if a current flows through the current detector 26, the current detector 26 charges the capacitor C. Therefore, since the value of the flowing current is detected, a large current value is detected. Therefore, a large current value is detected even though the first and second pilot lines L1 and L2 of the cable CA _k are normal. Therefore, the first and second pilot lines L1 and L2 of the cable CA _k are detected. May be judged as a poor insulation. To overcome this fear, is immediately after switching is connected to the cable CA _k, a measurement hibernation is had to detect the current thereafter switched from lost the influence of the capacitor C to the measurement state.
[0031]
In addition, assuming that the cable CA _k-1 to which the first and second input terminals 21 and 22 were connected last time is disconnected and the current cable CA _k is normal, the connection is switched to the cable CA _k . immediately after, the capacitor C will be discharged from the fully charged state, than the current flowing through the first pilot line L1- terminal resistor Re- second pilot line L2 of the cable CA _k is covered by the DC power source 23 Without the capacitor C. At this time, if the second detection terminal 29 and the second input terminal 22 are connected by the terminal changeover switch 27, the current detector 26 detects a small current value. For this reason, although the first and second pilot lines L1 and L2 of the cable CA _k are normal, a small current value is detected. Therefore, the first and second pilot lines L1 and L2 of the cable CA _k are detected. There is a risk that one of the above is disconnected. To overcome this fear, is immediately after switching is connected to the cable CA _k, a measurement hibernation is to that to measure the current thereafter switched from lost the influence of the capacitor C to the measurement state.
[0032]
As described above in detail, according to the cable monitoring apparatus, the effect is obtained that the breakage situation of the cable CA _k can be easily grasped. The operator may determine the presence or absence of their disconnection while watching the line-to-line resistance value Rm of the resistance display 42, but the alarm device 41 when there is a risk of, or disconnected cable CA _k is broken Since it is notified, it is not necessary to determine the presence or absence of disconnection by itself, and the effect that the work burden is reduced can be obtained. Moreover, since both pilot line L1, L2 is provided outside the core 15, grasp of course when the core wire 15 of the cable CA _k is disconnected, even a situation where the core wire 15 of the cable CA _k will shortly break it can. Furthermore, since a so-called polling system (a system in which cables are sequentially switched) is adopted, an effect that the apparatus configuration becomes compact can be obtained. In addition, since the ends of the first and second pilot lines L1 and L2 are connected to each other, it is possible to obtain an effect that it is possible to grasp the disconnection state of the cable with one device and also to grasp the insulation state of the cable.
[0033]
In particular, according to the cable monitoring apparatus, the following effects can be obtained. That is, the detected current value is not affected by the noise because the noise is cut by the capacitor C of the filter circuit 31, and the capacitor is used to detect the current by switching to the measurement state after temporarily switching to the measurement state after switching the cable. It is not affected by C. Therefore, even in the case of monitoring the sequential breakage plurality of cables CA ₁ to CA _n laid in place susceptible to noise, the effect is obtained that the breakage situation can be accurately grasped.
[0034]
The embodiment of the present invention is not limited to the above-described embodiment, and it goes without saying that various forms can be adopted as long as it belongs to the technical scope of the present invention.
For example, the controller 40 is configured to switch the cable connection switch 20 and the terminal selector switch 27 at a predetermined timing, but the operator may manually switch the switches 20 and 27.
[0035]
Also, the cables CA _{1 to} CA _n to be monitored are not necessarily plural, and may be one.
Furthermore, in the cable CA _k used in the above embodiment, the first and second pilot lines L1 and L2 are provided outside the core wire 15, but any two of the plurality of core wires 15 are connected to the first and second pilots. It may be a line.
[0036]
Furthermore, to omit the cables CA _k per second pilot line L2 used in the above embodiment, it may be used in place of the steel strip 18 second pilot line L2. In this case, the cable monitoring device grasps the disconnection state of the first pilot line L1 or the steel strip 18, and the insulation state between the first pilot line L1 and the steel strip 18.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of an embodiment.
FIG. 2 is a cross-sectional view of a cable.
FIG. 3 is a flowchart of cable monitoring processing according to the present embodiment.
FIG. 4 is a schematic configuration diagram of a cable monitoring device capable of grasping cable disconnection.
FIG. 5 is a schematic configuration diagram of a cable monitoring device with a filter circuit.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 30 ... Current measurement circuit, 11 ... 1st tip terminal, 12 ... 2nd tip terminal, 13 ... 2nd end terminal, 14 ... 2nd end terminal, 15 ... Core wire, DESCRIPTION OF SYMBOLS 20 ... Cable connection switch, 21 ... 1st input terminal, 22 ... 2nd input terminal, 23 ... DC power supply, 24 ... One power supply terminal, 25 ... Other power supply terminal , 26 ... current detector, 27 ... terminal selector switch, 28 ... first detection terminal, 29 ... second detection terminal, 31 ... filter circuit, 40 ... controller, 41 · .. Alarm device, 42... Resistance display device, C... Capacitor, CA _{1 to} CA _n .. Cable, L1... First pilot line, L2. -Terminal resistance.

Claims (5)

Cable monitoring device for sequentially monitoring a plurality of cables including a first pilot line having a first tip terminal and a first end terminal, and a second pilot line having a second tip terminal and a second end terminal Because
A terminal resistor connected between the first and second terminal terminals;
Cable connecting means for connecting each of the first and second tip terminals to each of the first and second input terminals;
A power source in which one of the two power terminals is connected to the first input terminal;
It has first and second detection terminals, and measures the current flowing between the two detection terminals, and the first detection terminal is connected to the power supply terminal opposite to the first input terminal of the two power supply terminals Current detection means,
Terminal switching means for selectively connecting one of the first and second detection terminals of the current detection means to the second input terminal;
The terminal switching means-connected between the signal path connecting the second input terminal and the first input terminal-signal path connecting the power supply terminal connected to the first input terminal of the two power supply terminals. A cable monitoring device comprising a capacitor. The cable monitoring device according to claim 1,
When each of the first and second tip terminals and each of the first and second input terminals are connected by the cable connecting means, a time sufficient to instruct the terminal switching means to discharge the capacitor Only connecting the first detection terminal and the second input terminal of the current detection means, and then instructing the terminal switching means to connect the second detection terminal and the input terminal of the current detection means Switching control means;
After the terminal switching means connects the second detection terminal of the current detection means and the input terminal in accordance with a command from the terminal switching control means, the first or the second signal is detected based on the detection signal detected by the current detection means. Determining means for determining whether or not the second pilot line is disconnected;
A cable monitoring apparatus comprising: a notification unit configured to notify the outside when the determination unit determines that the first or second pilot line is disconnected. The cable monitoring device according to claim 2,
The determination means further determines whether or not insulation between the first and second pilot lines is defective based on a detection signal detected by the current detection means,
The cable monitoring device according to claim 1, wherein the notification unit further includes a notification to the outside when the determination unit determines that the first or second pilot line is defective in insulation. The cable monitoring device according to claim 1, wherein one cable is sequentially selected from the plurality of cables, and each of the first and second tip terminals of the selected cable is connected to the cable. A cable monitoring device comprising cable connection control means for connecting to each of the first and second input terminals by a connection means. The cable monitoring device according to claim 1,
The cable monitoring apparatus, wherein the first and second pilot lines are provided outside a core line of the cable.

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