JP2008151575A - Disconnection detection method and apparatus - Google Patents

Abstract

Disclosed is a disconnection detection method capable of accurately estimating a disconnection position even when the propagation speed of a high-frequency pulse is not uniform.
A reflection member for reflecting a high frequency pulse is attached to an electric wire cable, a high frequency pulse is injected into the electric wire cable, a waveform of a reflected wave returning from the electric wire cable is received, and the reflected wave is received. A partial waveform due to the reflection member 10 and a partial waveform due to the disconnection of the electric cable are extracted from the waveform, and the partial waveform due to the disconnection is evaluated on the basis of the partial waveform due to the reflection member 10 to estimate the disconnection position. To do.
[Selection] Figure 6

Description

  The present invention relates to a disconnection detection method and apparatus capable of accurately estimating the disconnection position even when the propagation speed of a high-frequency pulse is not uniform.

  The electric cable is formed by twisting a plurality of strands. Even if the wire is slightly broken, the electric cable is not completely broken, which is called partial breakage. It is desirable that the disconnection detection of the electric cable can detect not only complete disconnection but also partial disconnection (= element wire disconnection).

  As a conventional disconnection detection method, a method of measuring the electrical resistance of an electric cable is generally used.

  Of these, the first method applies a DC voltage across the cable, measures the DC resistance from the current flowing through the cable and the applied voltage, and the DC resistance is the initial value (value when there is no disconnection). ) To detect that a partial disconnection has occurred.

  The second method is described in Patent Document 1, in which an AC voltage is applied between both ends of the cable, the AC resistance is measured from the current flowing through the cable and the applied voltage, and the AC resistance is an initial value ( It is detected that a partial disconnection has occurred by changing from the value when there is no disconnection.

Japanese Examined Patent Publication No. 7-69375

  In the conventional disconnection detection method, since a DC voltage or an AC voltage is applied between both ends of the electric cable, the electric cable cannot be performed in a live line state (a state in which a voltage for use is applied). Therefore, the present applicant is researching a disconnection detection method that can be performed even in a live line state.

  That is, according to the applicant's research, a high frequency pulse is injected into an electric wire cable, a waveform of a reflected wave returning from the electric wire cable is received, and a partial waveform due to disconnection of the electric wire cable is obtained from the reflected wave waveform. Can be extracted to detect disconnection. This method can be implemented not only in a live line state, but also because the time of the partial waveform due to disconnection in the entire waveform of the reflected wave is proportional to the distance from the reception position to the disconnection position, the disconnection position can be estimated. .

  However, this method is based on the premise that the propagation speed of the high frequency pulse is uniform everywhere in the electric cable. If the propagation speed of the high-frequency pulse is different in the longitudinal direction of the electric cable, the disconnection position is not accurately estimated.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve the above problems and provide a disconnection detection method and apparatus capable of accurately estimating the disconnection position even if the propagation speed of the high frequency pulse is not uniform.

  In order to achieve the above object, the method of the present invention attaches a reflection member that reflects a high frequency pulse to an electric cable, injects the high frequency pulse into the electric cable, and receives the waveform of the reflected wave returning from the electric cable. And extracting the partial waveform due to the reflection member and the partial waveform due to the disconnection of the electric cable from the waveform of the reflected wave, and evaluating the partial waveform due to the disconnection based on the partial waveform due to the reflection member, The position is estimated.

  In order to achieve the above object, the apparatus of the present invention includes a reflecting member that reflects a high-frequency pulse attached to an electric cable, high-frequency pulse injection means that injects the high-frequency pulse into the electric cable, and a reflection that returns from the electric cable. Based on the reflected wave receiving means for receiving the wave, the partial waveform extracting means for extracting the partial waveform by the reflecting member and the partial waveform by the disconnection of the electric cable from the waveform of the reflected wave, and the partial waveform by the reflecting member And a disconnection position estimating means for estimating the disconnection position by evaluating the partial waveform due to the disconnection.

  The reflection member may be attached by dividing the electric wire cable into a plurality of partial cables in the longitudinal direction and joining the partial cables, and inserting the partial cables into the joining portion.

  The reflecting member may be an inductor inserted in series between the partial cables.

  The reflection member may be attached by providing a plurality of the electric cable in parallel and spanning between the electric cables.

  The reflecting member may be a capacitor inserted between the plurality of electric cables.

  The reflection member may be a ferrite core that covers the outer periphery of the electric cable.

  The present invention exhibits the following excellent effects.

  (1) The disconnection position can be accurately estimated even if the propagation speed of the high-frequency pulse is not uniform.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

  First, the disconnection detection method studied by the present applicant as the basis of the present invention will be described.

  As shown in FIG. 1, a moving cable 3 that connects between a moving device 1 and a commercial frequency power supply 2 that supplies power to the device 1 is used as a wire cable 3 that is a disconnection detection target. The high frequency pulse from the high frequency pulse generator 5 is injected through the high frequency pulse injection capacitor 4, and the waveform of the reflected wave returning from the moving cable 3 is received by the high frequency CT 6 through the high frequency pulse injection capacitor 4. Record in waveform recording measuring instrument 7. Since the high frequency blocking inductor 8 is attached to the moving cable 3 at the end on the device 1 side and the end on the commercial frequency power supply 2 side, the high frequency pulse damages the device 1 or the commercial frequency power supply 2 and causes malfunction. There is no adverse effect, and the commercial frequency component is blocked by the high-frequency pulse injection capacitor 4, so that it does not hinder disconnection detection.

  Briefly describing the principle of disconnection detection, the same waveform can be obtained each time the injection of the high frequency pulse and the recording of the waveform of the reflected wave are repeated at an appropriate time interval. Different waveforms can be obtained. When a partial disconnection occurs, a partial waveform due to pulse reflection from the disconnection location appears, so the partial waveform is extracted from the difference from the previous waveform, and an event that a partial disconnection occurs can be detected, The disconnection position can be estimated from the temporal position of the partial waveform in the entire waveform.

  More specifically, the high-frequency pulse is a signal that does not adversely affect the device 1 or the commercial frequency power supply 2 such as damage or malfunction and can be easily separated from the commercial frequency component. Further, it is also a condition of the high frequency pulse that electronic devices such as partial waveform extraction means, disconnection position estimation means, and high frequency waveform recording / measuring instrument 7 constituted by a CPU built-in device such as a personal computer do not malfunction.

  When propagating through a propagation path, the high-frequency pulse is greatly affected by the impedance of the LC of the propagation path. For this reason, the disconnection detection method using a high-frequency pulse improves the detection sensitivity with respect to LC change at the time of disconnection compared with the method based on the measurement of the resistance R using a direct current or a commercial frequency signal. The disconnection detection method using the high frequency pulse detects the change in the impedance of the LCR when the resistor R is disconnected. Therefore, the disconnection detection method using only a change in the resistance R using a direct current or a commercial frequency signal is detected. Sensitivity is improved.

  On the other hand, the disconnection due to the bending of the cable occurs from the outermost periphery of the cable conductor formed by assembling the strands, and the high-frequency signal flows on the outer surface of the cable conductor due to the skin effect. Is suitable for detecting disconnection, and detection sensitivity is improved by using a high-frequency pulse.

  In the configuration of FIG. 1, the high-frequency pulse generated by the high-frequency pulse generator 5 passes through the high-frequency CT 6 and is injected into the moving cable 3 through the high-frequency pulse injection capacitor 4. This high-frequency pulse propagates through the cable conductor of the moving cable 3, and at the impedance changing portion due to insertion of the high-frequency blocking inductor 8 at the end portion on the device 1 side and the end portion on the commercial frequency power supply 2 side, respectively. reflect. The reflected wave returning from the moving cable 3 is received by the high frequency CT 6 via the high frequency pulse injection capacitor 4. The high-frequency waveform recording / measuring instrument 7 continues the recording for a sufficient time so that the reflected waves returned from the respective high-frequency blocking inductors 8 can be recorded.

  The reflected waveform is recorded at regular intervals, and the initial recorded waveform (which can be any waveform without disconnection) and the waveform after the passage of time are compared with the waveform change. Can be extracted as a partial waveform. The occurrence of a partial disconnection (wire disconnection) can be determined from the presence or absence of a significant partial waveform (for example, if there is a partial waveform larger than a predetermined reference value, the partial waveform is present). Furthermore, since the position where the partial waveform exists on the time axis represents the time when the high-frequency pulse propagates to the location where the disconnection occurs and is reflected and returned, the disconnection position can be estimated from that time. it can.

  In the initial waveform, since the moving cable 3 has been used, there may be a possibility that a partial disconnection has already occurred. At this time, if there is a difference in waveform with another moving cable 3 having the same structure, or if there are a plurality of independent wires in parallel in one moving cable 3 as shown in FIG. The partial disconnection can be determined from the difference in the waveform of the reflected wave obtained with the electric wire.

  FIG. 2 shows an example of the recorded waveform. In this figure, a waveform 21 obtained from a sound product (one electric wire without partial disconnection) and a waveform 22 obtained from a partial disconnection product (the other electric wire with partial disconnection) are drawn. The relationship between these waveforms can be regarded as equivalent to the relationship between the initial waveform and the waveform after change (disconnection) in the same wire. Since the two waveforms 21 and 22 are almost the same, most of them overlap like one, but it can be seen that a partial waveform 23 having a difference between them appears.

  This partial waveform 23 is generated by the impedance change at the disconnection portion. The high-frequency pulse was reflected and returned at the impedance change location, that is, the disconnection location, and the partial waveform 23 that was not found in the waveform of the healthy product was generated. On the horizontal axis from the vicinity of the time 50 ns to the partial waveform 23 near the time 100 ns, the round-trip propagation time tX from the high frequency CT 6 to the disconnection point appears. On the other hand, a round-trip propagation time tY from the high frequency CT 6 to the high frequency blocking inductor 8 on the device 1 side appears on the horizontal axis from about 50 ns to about 130 ns. Since the propagation speed of the high-frequency pulse can be obtained from the round-trip propagation time tY and the length of the moving cable 3 (the distance traveled by the high-frequency pulse), the position of the broken line can be estimated from the round-trip propagation time tX. The formula for calculating the distance from the high-frequency CT 6 is propagation speed × round-trip propagation time tX / 2.

  By the way, the position estimation is based on the premise that the detected electric wire cable 3 such as the moving cable 3 has a uniform high-frequency pulse propagation speed in the longitudinal direction of the electric wire cable. If the propagation speed of the high frequency pulse is different in the longitudinal direction of the electric cable, an error occurs in position estimation. As examples in which the propagation speed is different in the longitudinal direction as described above, when a wire cable is configured by connecting a plurality of types of electric wires having different structures in series, or even if the structure is a uniform electric cable in the longitudinal direction, There may be a temperature difference in the direction. In addition, when comparing the initial waveform and the waveform after change with time, if there is a difference in the cable temperature when both waveforms are recorded, the propagation speed is different even for the same cable.

  The electric wire cable 31 shown in FIG. 3 is obtained by connecting n electric wires in series from the left incident end 32, and in order from the incident end 32, the electric wire 33a, the relay portion 34a, the electric wire 33b,. The part 34m and the electric wire 33n are arranged, and the right end is a terminal end 35. In the relay portions 34a to 34m, when the electric wires 33a to 33n are not impedance matched, a reflected wave is generated. A reflected wave is not generated from the relay section where the impedance is matched.

  Here, assuming that a partial disconnection 36 occurs in the vicinity of the relay portion 34m in the electric wire 33n, a time chart of the reflected wave waveform recorded at that time is shown in FIG. In this figure, the high-frequency pulse 41 injected to the incident end 32 at time 0 is indicated by a solid line, and for reference, the partial waveforms 42a and 42m due to the reflected waves from the relay portions 34a and 34m and the reflection from the terminal end 35 are shown. A partial waveform 43 due to the waves is shown by broken lines at times ta, tm and tn. In addition, a partial waveform 44 due to a reflected wave from the partial disconnection 36 is shown at time tx.

  Actually, when the impedance is matched by the relay units 34a to 34m and the termination is matched by the terminal 35, there is no broken partial waveform, and times ta, tm, and tn are defined as time measurement standards. Only. At this time, since the time tx is behind the time tm in time, it is determined that the partial disconnection 36 has occurred farther than the relay unit 34m, that is, the electric wire 33n.

  Next, consider a case where the propagation speed of the high-frequency pulse in the wires 33a to 33m changes because the ambient temperature of the wires 33a to 33m has become extremely different from the ambient temperature of the wire 33n. FIG. 5 shows a time chart of the reflected wave waveform recorded at that time. Partial waveforms 42a, 42m, and 43 shown by broken lines are obtained when the same ambient temperature as shown in FIG. 4 is uniform in the longitudinal direction, and define times ta, tm, and tn as time measurement standards. is there. On the other hand, the time indicated by the vertical bars is the time of a partial waveform (not shown) when the reflected wave is virtually returned from the relay units 34a and 34m and the terminal 35 when the ambient temperature is different (for example, Time tmα).

  As shown in FIG. 5, when the ambient temperature is different, the time tmα that would be actually taken from the injection of the high frequency pulse 41 to the incident end 22 until the partial waveform by the relay unit 34m returns is initially assumed. The time tx of the partial waveform 54 due to the reflected wave from the partial disconnection 36 also moves to the left along with the movement of the time tx to the left of the time axis. Therefore, it is erroneously detected that a partial disconnection occurs in the electric wire 33m instead of the electric wire 33n.

  Therefore, in the disconnection detection method according to the present invention, as shown in FIG. 6, a reflection member 10 that reflects a high-frequency pulse is attached to the electric cable 3, and a portion due to partial disconnection is based on the partial waveform of the reflection member 10. The disconnection position was estimated by evaluating the waveform. The reflection member 10 may be any member as long as it has a reflection capability sufficient to obtain a significant partial waveform in the reflected wave waveform received by the high frequency CT 6 and recorded in the high frequency waveform recording / measuring instrument 7. Will be described later.

  In FIG. 6, the same reference numerals as those in FIG.

  The partial waveform extraction means and the disconnection position estimation means (not shown) can be constituted by a personal computer connected to the high-frequency waveform recording measuring instrument 7, a dedicated computer, or the like. In the present invention, the disconnection position is basically estimated by the method described with reference to FIG. 2, but the partial waveform extracting means extracts the partial waveform due to the reflecting member 10 and the partial waveform due to the disconnection of the electric cable from the waveform of the reflected wave. The disconnection position estimation means estimates the disconnection position by evaluating the partial waveform due to disconnection with reference to the partial waveform by the reflecting member 10.

  Only one reflecting member 10 may be provided at an arbitrary position in the longitudinal direction of the electric cable 3 or two or more reflecting members 10 may be provided in a distributed manner. Therefore, an embodiment in which a plurality of reflecting members are attached to the electric cable 31 shown in FIG. 3 will be described with reference to FIG.

  As shown in FIG. 7, a reflective member 37a is attached in the immediate vicinity of the relay portion 34a (meaning substantially the same position; it may be the same position immediately before or immediately after), and a reflective member 37m is attached in the immediate vicinity of the relay portion 34m. A reflective member 38 is attached in the immediate vicinity of the terminal end 35.

  In this electric wire cable 31, the case where the propagation speed of the high frequency pulse in the electric wires 33a to 33m changes because the ambient temperature of the electric wires 33a to 33m has become extremely different from the ambient temperature of the electric wire 33n will be considered. FIG. 8 shows a time chart of the reflected wave waveform recorded at that time. In FIG. 8, as in FIG. 5, a partial waveform when the ambient temperature is uniform in the longitudinal direction is indicated by a broken line, and times ta, tm, and tn are added.

  As shown in FIG. 8, when the ambient temperature is different, the time tmα that would actually be taken from the time when the high frequency pulse 81 is injected into the incident end 32 until the partial waveform by the relay unit 34m returns is initially assumed. The time tx of the partial waveform 84 due to the reflected wave from the partial disconnection 36 also moves to the left along with the movement to the left of the time axis from tm. However, at this time, as shown by the solid lines, partial waveforms 82a, 82m, and 83 are obtained from the reflecting members 37a, 37m, and 38. These partial waveforms are not imaginary like the partial waveforms shown by broken lines in FIGS. 5 and 4, but are actually obtained.

  As shown in FIG. 8, when the ambient temperature is different, the time tmα of the partial waveform by the relay unit 34m (reflecting member 37m) moves to the left of the time axis rather than the time tm when the ambient temperature is uniform in the longitudinal direction. Yes.

  Comparing the time of the partial waveform 84 due to the partial break 36 and the partial waveform 82m due to the reflecting member 37m, it can be seen that the time tx is to the right of the time tmα, that is, the partial break 36 is at a position farther than the reflecting member 37m. It can be correctly determined that a partial disconnection has occurred in the electric wire 33n.

  The electric cable 91 shown in FIG. 9 is formed by dividing a plurality of partial cables 91a, 91b,... (Not shown below) in the longitudinal direction and joining the partial cables 91a, 91b,. It is. The reflection member 93 is inserted and attached to the joint portion 92. The reflecting member 93 is composed of an inductor and is inserted in series between the conductors of the partial cables 91a and 91b. Since the reflection member 93 made of the inductors connected in series in this way has impedance different from that of the partial cables 91a, 91b,..., It can reflect a high frequency pulse. The reflecting member 93 preferably reflects high-frequency pulses well and transmits commercial frequency components and other signal components.

  The electric cable 91 may be a bundle of a plurality of electric wires 94 insulated from each other. The reflecting member 93 is inserted into the joining portion 92 of the appropriate electric wire 94 among them. In this case, by using the partial waveform of the reflected wave from the reflecting member 93 as a time reference, it can be used not only for detecting the breakage of not only the electric wire 94 but also another electric wire 94 in which the reflecting member 93 is not inserted.

  The electric wire cable 91 shown in FIG. 10 is divided into a plurality of partial cables 91a and 91b in the longitudinal direction and joined in series in the same manner as in FIG. It is a bundle of electric wires 94 of books. The reflective member 103 is installed between two appropriate electric wires 94 among them. The reflecting member 103 is formed of a capacitor, and is inserted between the connection portion between the conductors of the partial cables 91a and 91b in one electric wire 94 and the connection portion between the conductors of the partial cables 91a and 91b in the other electric wire 94. Thus, since the impedance of the reflecting member 103 and the partial cables 91a and 91b sandwiched between the electric wires 94 is different, the high-frequency pulse can be reflected.

  The electric wire cable 111 shown in FIG. 11 is not particularly divided in the longitudinal direction, but is regarded as the partial cables 111a and 111b with the reflecting member 113 as a boundary. The reflection member 113 is formed of a ferrite core that covers the outer periphery of the electric cable 111. In this case, there is an advantage that it is not necessary to divide the electric cable 111 in the longitudinal direction.

It is an apparatus block diagram for enforcing the disconnection detection method used as the foundation of the present invention. It is a graph of the waveform recorded by the apparatus of FIG. 1, a horizontal axis shows time and a vertical axis | shaft shows the magnitude | size of an electric current. It is a longitudinal direction block diagram of the electric wire cable made into a disconnection detection object. It is a time chart of the partial waveform of the reflected wave obtained from the electric wire cable of FIG. 3 when the propagation speed of a high frequency pulse is predetermined. It is a time chart of the partial waveform of the reflected wave obtained from the electric wire cable of FIG. 3 when the propagation speed of a high frequency pulse changes. It is an apparatus block diagram for enforcing the disconnection detection method of this invention. It is a longitudinal direction block diagram of the electric wire cable made into the disconnection detection object in this invention. It is a time chart of the partial waveform of the reflected wave obtained from the electric wire cable of FIG. 7 when the propagation speed of the high frequency pulse changes. It is a substantial circuit diagram which shows embodiment of the reflective member used for this invention. It is a substantial circuit diagram which shows embodiment of the reflective member used for this invention. It is a substantial circuit diagram which shows embodiment of the reflective member used for this invention.

Explanation of symbols

3 Electric wire cable 5 High frequency pulse generator 7 High frequency waveform recording measuring instrument 10 Reflective member

Claims (7)

  A reflection member that reflects a high-frequency pulse is attached to the electric wire cable, a high-frequency pulse is injected into the electric wire cable, and a waveform of a reflected wave returning from the electric wire cable is received. A disconnection detection method characterized in that a disconnection position is estimated by extracting a waveform and a partial waveform due to disconnection of the electric cable and evaluating the partial waveform due to the disconnection with reference to the partial waveform due to the reflection member.   Reflective member for reflecting high-frequency pulses attached to the electric cable, high-frequency pulse injection means for injecting high-frequency pulses into the electric cable, reflected wave receiving means for receiving the reflected wave returning from the electric cable, and the reflected wave A partial waveform extracting means for extracting a partial waveform due to the reflecting member and a partial waveform due to the disconnection of the electric cable from the waveform, and evaluating the partial waveform due to the disconnection based on the partial waveform due to the reflecting member. A disconnection detecting device comprising: a disconnection position estimating means for estimating a position.   The said reflecting member divides | segments the said electric wire cable into a some partial cable in a longitudinal direction, it comprises this partial cable, and it attaches it by inserting in the joint part, The attachment of Claim 2 characterized by the above-mentioned. Disconnection detection device.   The disconnection detecting device according to claim 3, wherein the reflecting member is an inductor inserted in series between the partial cables.   The disconnection detecting device according to claim 2, wherein the reflection member is attached by providing a plurality of the electric cables in parallel and spanning between the electric cables.   6. The disconnection detecting device according to claim 5, wherein the reflecting member is a capacitor inserted between the plurality of electric cables.   The disconnection detecting device according to claim 2, wherein the reflecting member is a ferrite core that covers an outer periphery of the electric cable.

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