JP2008164460A - Cable electroscope - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cable electroscope that can easily and certainly determine each of a dead cable and a live cable without requiring experience and skill, and can rapidly detect them. <P>SOLUTION: This cable electroscope formed of a receiver body comprises a sensor 16 formed of a search coil that is butted on a cable to be detected and detects electromagnetic wave, a signal current detection mechanism 17 for detecting a signal current having a predetermined frequencies other than the commercial frequency emitted from a signal transmitter via the sensor 16, a commercial current detection mechanism 18 for detecting a commercial current having commercial frequency via the sensor 16. The signal current detection mechanism 17 and commercial current detection mechanism 18 comprise band path filters 20 and 26, level detectors 21 and 27, and current displaying means 24 and 29. A shielding plate for disturbing the transmission of the electromagnetic wave is disposed on the side surface opposite to the abutting side on at least the cable of the receiver body. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to electric power and other cable voltage detectors for detecting a target cable or checking a cable alive state in manholes, caves, and the like.

  Conventionally, when detecting the target cable in a manhole or a sinus and checking the cable alive status, the electromagnetic field of the cable is detected by a sensor consisting of a search coil, and it is performed by the galvanometer shake and the sound from the earphone through the amplifier. It was. This electromagnetic field is generated by attaching an oscillator for flicker adjustment by changing the output current with a variable resistor to the cable head and injecting intermittent current at a commercial frequency into the cable. The sensor detects an electromagnetic field of the flicker current.

  Such cable detection and life / death line discrimination are carried out when the cable is cut in a manhole or a sinus. However, a lot of cables are laid in manholes and caves, and a lot of dead line cables and live line cables are mixed. For this reason, a live wire cable exists in the vicinity of the dead line cable to be detected, and the galvanometer needle is swung under the influence of the electromagnetic field of the live wire cable. Therefore, in the past, the sensitivity of the galvanometer shake was adjusted, and the life / death line of the cable was determined while paying attention to the flicker current. However, since this requires the experience and skill of the worker, it is not certain and cannot be performed without the work of an experienced and skilled worker, which hinders rapid work. Yes.

  On the other hand, Patent Document 1 discloses a power cable power detection device for preventing erroneous detection of cable life and death, and a method of determining a life and death line of a power cable using the same.

Japanese Patent No. 3009144

  However, since the power cable voltage detection device described in Patent Document 1 and the life and death line determination method for a power cable using the power cable detection device are surely easy to operate, it is possible to determine the life and death line without requiring experience or skill. Although it is possible, it does not have a mechanism for detecting a live cable through which a commercial frequency current flows. It is convenient and preferable to have a mechanism capable of detecting a dead line and a live line in the life and death line determination work in the field.

  The present invention is based on the above-described prior art, and can easily and surely distinguish each of a dead line cable and a live line cable without requiring experience or skill, and can be quickly detected. The purpose is to provide a voltage detector.

  In order to achieve the above object, according to the first aspect of the present invention, there is provided a sensor comprising a search coil for detecting electromagnetic waves by contacting a cable to be detected, and a commercial frequency generated from a signal transmitter via the sensor. A cable voltage detector comprising a receiver main body having a signal current detection mechanism for detecting a signal current having a predetermined frequency and a commercial current detection mechanism for detecting a commercial current having a commercial frequency via the sensor. The signal current detection mechanism includes a signal current band-pass filter that passes only the signal current, a signal current level detector that measures a detection level of the signal current that has passed through the signal current band-pass filter, and the signal Signal current display means for indicating that the current detection level is equal to or higher than a predetermined value is provided, and the commercial current detection mechanism passes only the commercial current. A commercial current band-pass filter, a commercial current level detector that measures the detection level of the commercial current that has passed through the commercial current band-pass filter, and a commercial that indicates that the detection level of the commercial current is greater than or equal to a predetermined value Provided is a cable voltage detector, comprising: a current display means; and a shielding plate for preventing transmission of the electromagnetic wave on at least a side surface of the receiver main body that is in contact with the cable.

  According to a second aspect of the present invention, in the first aspect of the invention, the commercial current detection mechanism is provided with a sensitivity adjustment mechanism capable of adjusting a sensitivity for detecting the commercial current.

  According to a third aspect of the invention, in the first or second aspect of the invention, the frequency and current value of the signal current are 500 Hz to 1 kHz and 1 to 5 amperes.

  According to the first aspect of the present invention, since the signal current is detected using a predetermined frequency other than the commercial frequency as a transmission signal, it is possible to reliably detect or discriminate the target cable. In addition, since both the signal current detection mechanism and the commercial current detection mechanism are provided, the target cable can be discriminated as a dead-line cable through which signal current flows, and it can also be reliably discriminated whether the target cable is a live cable through which commercial current flows. Can do. In addition, since the sensor, the signal current detection mechanism, and the commercial current detection mechanism are integrally formed in the receiver main body, the apparatus is downsized and the operation is quick and easy. In addition, since a shielding plate is provided at least on the side opposite to the surface to be in contact with the cable, it is possible to shield the electromagnetic waves of the cable near the target cable, and only the electromagnetic field of the target cable is reliably detected by the sensor to detect the voltage. Work can be done. This contact includes not only physical contact of the sensor with the cable but also non-contact but very close proximity.

  According to the invention of claim 2, since the commercial current detection mechanism is provided with a sensitivity adjustment mechanism capable of adjusting the sensitivity for detecting the commercial current, it depends on the level of the detection level depending on the magnitude of the magnetic field of the commercial current. Therefore, the target cable can be reliably identified. That is, the sensor can be brought into contact with the target cable and the sensitivity of the commercial frequency from the nearby cable can be manipulated during the detection of the target cable to ensure the determination. Further, even when the electromagnetic wave permeability varies depending on the type of cable, it can be reliably detected by adjusting the sensitivity.

  According to the invention of claim 3, since the predetermined frequency other than the commercial frequency emitted from the signal transmitter is 500 Hz to 1 kHz, it is almost 10 times the commercial frequency of 50 Hz or 60 Hz, and the signal current It is possible to reliably prevent erroneous recognition of the commercial current. Further, even if a CV cable that is generally easy to pass electromagnetic waves is a target, since the current value is as small as 1 to 5 amperes, the influence of the signal current can be reduced during detection of the cable through which the commercial current passes. Further, in such a case, since the receiver body is provided with a shielding plate, it is possible to prevent the electromagnetic wave from the cable from being erroneously detected by the sensor.

  The present invention provides a sensor for detecting an electromagnetic field of a cable to be detected, a signal current detection mechanism for detecting a signal current having a predetermined frequency other than a commercial frequency emitted from a signal transmitter, and a commercial current having a commercial frequency. It has a receiver body with a commercial current detection mechanism to detect it, can reliably determine the target cable, and even if a power cable other than the power detection target is detected, it is a live line through which the commercial current flows This is a cable voltage detector that can reliably identify the cable.

  FIG. 1 is a schematic diagram showing a voltage detection state by a cable voltage detector according to the present invention. FIG. 2 is a schematic diagram of a signal transmitter.

  A number of power cables 2 are laid in the sinus 1 (only one is shown except for the head and the terminal portion in FIG. 1). A signal transmitter 4 is connected to the cable head 3 at one end of the power cable 2. The other end of the power cable 2 is short-circuited to ground. A manhole 5 is formed at any intermediate point of the sinus 1. The electric detection work is performed when an operator who has entered the sinus 1 from the manhole 5 brings the electric detector 6 into contact with the power cable 2 in the sinus 1. The voltage detector 6 identifies the power cable 2a (see FIG. 3) to which the signal transmitter 4 is connected and the power cable 2b (see FIG. 3) through which a commercial current flows. Although this example shows an example of identifying a power cable, it can also be used for identifying a communication cable or the like.

  The signal transmitter 4 transmits an output current having a predetermined frequency other than the commercial frequency as a signal current output intermittently. As shown in FIG. 2, the signal transmitter 4 includes a power switch 10, a no-fuse breaker 11 that operates at, for example, twice the rated current, an energization start switch 12 for flowing a signal current, and an output of the signal current. An output current meter 13 for displaying is provided. A storage unit 15 is also provided for storing a connection cable 14 for connecting the signal transmitter 4 and the cable head 3.

  The voltage detector 6 detects this signal current with a filter circuit described later. Therefore, the operator can confirm the power cable through which the signal current flows from among the power cables 2 laid in the tunnel 1 at a position away from the signal transmitter 4 such as the manhole 5. it can.

  FIG. 3 is a cross-sectional view showing an outline of a voltage detection state of the cable.

  As described above, the voltage detection of the power cable 2 is performed by bringing the voltage detector 6 into contact with the outer periphery of the power cable 2. In the figure, as an example, an example in which contact is made at four locations (positions A, B, C, and D) is shown. In the figure, a signal current flows through the power cable 2a. For example, when the power cable 2a is a three-core cable as shown in the figure, a reciprocal signal current flows through the two wires, and the magnetic flux 7 leaking outside the power cable 2a is detected by the voltage detector 6 (position A in the figure). Thus, since this signal current is detected using a predetermined frequency other than the commercial frequency as a transmission signal, it is possible to reliably determine the target cable.

  In addition to the detection of the signal current, the voltage detector 6 can also detect a commercial current having a commercial frequency. Therefore, the voltage detector 6 is brought into contact with the power cable 2b through which the commercial current flows (for example, positions B, C, and D in the figure), and it can be confirmed that the cable 2b is the power cable 2b through which the commercial current flows. That is, it is possible to reliably determine whether the power cable is alive or dead by the voltage detector 6 including both the signal current detection mechanism and the commercial current detection mechanism.

  The voltage detector 6 includes a receiver body 8 and a shielding plate 9. The receiver body 8 is provided with a sensor (not shown) for detecting the leakage magnetic flux 7. A shielding plate 9 is provided on the side of the receiver body 8 opposite to the sensor that contacts at least the power cable 2. The shielding plate 9 is made of a silicon steel plate and shields electromagnetic waves. As described above, the power cable 2a through which the signal current flows and the power cable 2b through which the commercial current flows are laid close to each other. Even in such a situation, it is possible to prevent the leakage flux of other power cables from being erroneously detected by the shielding plate 9 while the leakage flux of the target cable is being detected by the voltage detector 6. Therefore, the electric field can be detected by reliably detecting the electromagnetic field of only the target cable with the sensor. For example, in a state where the voltage detector 6 is disposed between the adjacent cables 2a and 2b (positions A and B in the figure), the shielding plate 9 faces the adjacent cables 2a or 2b other than the target cable. The electromagnetic wave of the adjacent cable 2a or 2b is shielded. As a result, the electromagnetic wave of the other cable is blocked or the difference between the strengths of the detection levels becomes large, and the target cable and the non-target cable can be easily detected.

  FIG. 4 is a schematic configuration diagram of a cable voltage detector according to the present invention, and FIG. 5 is an external view thereof.

  In the voltage detector 6, a signal current detection mechanism 17 and a commercial current detection mechanism 18 are connected in parallel to a sensor 16 including a search coil for detecting leakage magnetic flux. The signal current detection mechanism 17 includes an amplifier 19, a signal current bandpass filter 20 that passes only the signal current, and a signal current level detector 21 that measures the detection level of the signal current that has passed through the signal current bandpass filter 20. And a signal current display means 24 including a buzzer 22 and a lamp 23 indicating that the detection level of the signal current by the signal current level detector 21 is equal to or higher than a predetermined value. The commercial current detection mechanism 18 also includes an amplifier 25, a commercial current bandpass filter 26 that passes only the commercial current, and a commercial current level detection that measures the detection level of the commercial current that has passed through the commercial current bandpass filter 26. And a commercial current display means 29 comprising a buzzer 30 and a lamp 31 indicating that the commercial current level detected by the commercial current level detector 27 is equal to or higher than a predetermined value, and a level meter 28 for displaying the detected level. Composed. Thus, since the sensor 16, the signal current detection mechanism 17, and the commercial current detection mechanism 18 are integrally formed in the receiver main body 8, the apparatus is downsized, and the operation is quick and easy.

  When the target cable is a power cable through which a signal current flows, first, the sensor 16 detects the leakage magnetic flux 7 (see FIG. 3) from the target cable. The detected signal current is amplified by an amplifier 19 in the voltage detector 6. Next, the signal current band-pass filter 20 that passes only the signal current is passed. At this time, even if the detected signal current passes through the amplifier 25 in the commercial current detection mechanism 18, it cannot pass through the commercial current band-pass filter 26, so that the signal current is subjected to subsequent processing in the commercial current detection mechanism 18. Never happen. The signal current that has passed through the signal current band-pass filter 20 is detected by the signal current level detector 21 if the detection level is equal to or higher than a predetermined level, and the lamp is assumed to be a power cable through which the signal current flows. 23 or the like. The lamp 23 blinks in accordance with the flicker output of the signal current.

  The signal current is preferably 500 Hz to 1 kHz and 1 to 5 amperes. By doing in this way, it becomes about 10 times or more with respect to the commercial frequency of 50 Hz or 60 Hz, and it can prevent reliably recognizing a signal current and a commercial current accidentally. In addition, by reducing the current value to 1 to 5 amperes, the influence of the signal current can be reduced during the detection of the cable through which the commercial current passes even if the target is a CV cable through which electromagnetic waves generally pass easily. it can. Further, in such a case, since the receiver main body 8 is provided with the shielding plate 9 (see FIG. 3), it is possible to prevent the sensor 16 from erroneously detecting electromagnetic waves from the CV cable. Such an effect is particularly prominent when the voltage detector 6 in FIG.

  When the target cable is a power cable through which a commercial current flows, the sensor 16 detects the leakage magnetic flux and is amplified by the amplifier 25. The commercial current passes only through the commercial current band-pass filter 26 in the commercial current detection mechanism 18, and the detection level is measured by the commercial current level detector 27. As a result, the image is displayed by the lamp 31, the level meter 28, or the like.

  The commercial current detection mechanism 18 further includes a sensitivity adjustment function 32. This sensitivity adjustment function 32 adjusts the detection level of the commercial current. For example, in the case where the voltage detection operation is performed at the position A in FIG. 3, when both the lamp 23 indicating the signal current and the lamp 31 indicating the commercial current are turned on, by reducing the sensitivity of the detection level of the commercial current, It can be determined that the signal current is flowing through the target cable when the lamp 31 is turned off or the level meter 28 is strong or weak. That is, since the frequency of the commercial current has a level of detection depending on the magnitude of the magnetic field, the circuit configuration is configured to accurately detect the frequency of the signal current by using the level of the commercial current. Further, the sensitivity adjustment function 32 can cope with an over-detection level of the commercial current.

  In the voltage detector 6 shown in FIG. 5, reference numeral 33 denotes a battery check button for checking the battery state of the voltage detector 6. Reference numeral 34 denotes a detection switch for detecting leakage magnetic flux while being pressed. If the standby current is zero, the battery capacity can be saved.

  Further, even when the signal transmitter 4 shown in FIG. 1 is not connected to a power cable, if the power detector 6 according to the present invention is used, the power cable through which the commercial current flows can be determined. Can do.

It is the schematic which shows the electric power detection state by the cable voltage detector which concerns on this invention. It is the schematic of a signal transmitter. It is sectional drawing which shows the outline of the electric detection state of a cable. It is a schematic block diagram of the cable voltage detector which concerns on this invention. It is an external view of the cable voltage detector which concerns on this invention.

Explanation of symbols

1: sinus road, 2: power cable, 3: cable head, 4: signal transmitter, 5: manhole, 6: voltage detector, 7: leakage magnetic flux, 8: receiver body, 9: shielding plate, 10: power switch 11: No-fuse breaker, 12: Energization start switch, 13: Output current meter, 14: Connection cable, 15: Storage section, 16: Sensor, 17: Signal current detection mechanism, 18: Commercial current detection mechanism, 19: Amplifier 20: Signal current band-pass filter, 21: Signal current level detector, 22: Buzzer, 23: Lamp, 24: Signal current display means, 25: Amplifier, 26: Commercial current band-pass filter, 27: Commercial current Level detector, 28: level meter, 29: commercial current display means, 30: buzzer, 31: lamp, 32: sensitivity adjustment function, 33: battery check button, 34 Detection switch

Claims (3)

A sensor consisting of a search coil that detects electromagnetic waves by contacting the cable to be detected;
A signal current detection mechanism for detecting a signal current having a predetermined frequency other than the commercial frequency emitted from the signal transmitter via the sensor;
A cable voltage detector comprising a receiver body having a commercial current detection mechanism for detecting a commercial current having a commercial frequency via the sensor,
The signal current detection mechanism includes a signal current band-pass filter that passes only the signal current, a signal current level detector that measures a detection level of the signal current that has passed through the signal current band-pass filter, and the signal current Comprising a signal current display means indicating that the detection level is equal to or higher than a predetermined value,
The commercial current detection mechanism includes a commercial current band-pass filter that passes only the commercial current, a commercial current level detector that measures a detection level of the commercial current that has passed through the commercial current band-pass filter, and the commercial current A commercial current display means indicating that the detection level is equal to or higher than a predetermined value,
A cable voltage detector characterized in that a shielding plate for preventing transmission of the electromagnetic wave is provided on at least a side surface of the receiver main body that is in contact with the cable.   The cable voltage detector according to claim 1, wherein the commercial current detection mechanism includes a sensitivity adjustment mechanism capable of adjusting sensitivity for detecting the commercial current.   The cable voltage detector according to claim 1 or 2, wherein a frequency and a current value of the signal current are 500 Hz to 1 kHz and 1 to 5 amperes.

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