JPH0827263B2 - Corrosion degradation determination method for three-layer metal wire - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for determining corrosion deterioration of a three-layer metal wire rod such as a steel-core aluminum stranded wire (hereinafter referred to as ACSR) in which the circumference of the core wire is covered with a dissimilar metal. It is an object of the present invention to provide a method capable of individually detecting the residual amount of the coating layer and the coating layer after corrosion for the three types of metals.

[0002]

2. Description of the Related Art ACSR (Aluminium Cable Steel Rein)
forced) is an aluminum wire wound in a stranded state around a galvanized steel wire to form a single electric wire. The aluminum wire is the main conductor and the galvanized steel wire is corrosion resistant. Gives tensile strength. This ACSR is widely used for power transmission and distribution facilities including electric railways, and especially in tunnels of train lines, early detection of power supply feeders, feeder suspension wires, and ground faults of these feeders. It is used for AT protection line, ground fault line and so on. This ACS
Since R is exposed to the outside air, it is necessary to periodically or as needed inspect the degree of corrosion to determine the replacement time in order to prevent a wire disconnection accident due to corrosion.

An eddy current flaw detection test method (Japanese Patent Laid-Open No. 2-54166, etc.) is known as a method for inspecting corrosion deterioration of metal wires.
However, conventional inspection targets are limited to those made of a single material such as aluminum or copper, and cannot be used for a product in which dissimilar metals are laminated like ACSR.

Therefore, the applicant of the present invention has applied and developed the principle of this eddy current flaw detection test method to invent a method for judging the corrosion deterioration of a double-layer metal wire, and filed a prior application (Japanese Patent Application Laid-Open No. Hei 3).
-72506).

A method for determining the corrosion deterioration of the two-layer metal wire will be briefly described. In the eddy current flaw detection test method, generally, an alternating magnetic field is applied to a test object to generate a vortex, and the impedance of the test object is known from the size of the vortex, and the size of the scratch or the like is determined from this. Specifically, the induced voltage generated in the detection coil by the eddy current is phase-detected at a predetermined phase and used as a detection output. In this detection circuit, for example, positive and negative FETs (field effect transistors) are alternately turned on every half cycle (180 °) at a predetermined phase where the signal component has a maximum value at the same frequency as the frequency of the acting magnetic field. Calculate the average value of the passing voltage. It should be noted that this phase has a value unique to the material of the test piece (eg zinc, steel).

As shown in FIG. 10, the output obtained by measuring the double-layer metal wire by the flaw detection test method is shown in FIG.
Expressed as a vector L on a two-dimensional plane represented by a phase and an amplitude, this vector L is a composite of the vectors M and N when different metal parts of this laminated metal wire rod are individually taken out and individually detected. Has become.

Therefore, if the phase detection is performed at the phase m'or n '(the phase having the phase difference of 90 ° with the maximum output of the component) where the detected component of one metal becomes zero, the laminated state is obtained. Even if there is, only the component of the other metal can be taken out, and by performing such phase detection for each of the two types of metals, the two types of metals can be individually measured in the laminated state, and the corrosion deterioration of each can be determined. It This is the method previously proposed by the applicant.

[0008]

However, this method is
This is a method for determining the corrosion deterioration of a double-layer metal wire,
It cannot be used to determine the corrosion deterioration of a three-layer metal wire such as SR. For this reason, double-layer metal wire rods such as galvanized steel wires have become able to be subjected to highly accurate actual inspections instead of visual inspections. However, as for ACSR, human ladders, towers, maintenance vehicles, etc. There was no choice but to get on the line and approach the line in a live or blackout state to visually check for corrosion deterioration.

In this visual inspection, the time to replace the ACSR is estimated by estimating the corrosion amount of the aluminum stranded wire portion through which the current flows, the corrosion amount of the galvanized layer applied to the surface of the steel wire, and the steel wire portion maintaining strength. It is necessary to make a comprehensive judgment based on the amount of corrosion. However, since the visual inspection method is judged by the external appearance, it is difficult to grasp the progress of corrosion to the inside, and it is easy to make an error in estimating the replacement time. For example, even if no damage is found in the aluminum stranded wire on the surface, the corrosion-preventing galvanized layer is broken inside, and the steel wire for strength retention is greatly corroded, resulting in a large decrease in the tensile strength of ACSR. There is a case. As a result of this erroneous recognition, there were problems such as a wire breakage accident and replacement of a wire that was still sufficiently usable. Therefore, the electric railway performs inspections about once every four days and inspections every two years, but proper management was difficult.

On the other hand, this visual inspection work is an aerial work for riding on a maintenance vehicle or the like because a person needs to approach the ACSR at a high position, and it is necessary to look from the opposite side to inspect the entire surface. Yes, it takes time. Furthermore, maintenance personnel and the like of the maintenance vehicle are also required, and since this ACSR is laid over a considerable distance, a lot of manpower is required and the work cost is very high.

Therefore, an object of the present invention is to provide a method for easily and reliably determining corrosion deterioration of a laminated wire made of three kinds of metal such as ACSR for each metal portion.

[0012]

According to the present invention, there is provided a method for judging corrosion deterioration of a three-layer metal wire rod, which comprises a three-layer metal wire rod in which a ferromagnetic metal and two kinds of non-magnetic metal are laminated, A low-frequency excitation coil that applies a low-frequency magnetic field, and a low-frequency detection circuit that has a detection coil for detecting a change in magnetic field due to an induced current generated by this excitation, a high-frequency excitation coil that applies a high-frequency magnetic field, and an overcurrent generated by this excitation. The detector that has a high-frequency detection circuit that has a detection coil for the magnetic field change due to is moved, and the induced voltage generated in the detection coil of the low-frequency detection circuit is detected at a predetermined phase, and the residual amount of ferromagnetic metal is detected from the output. Knowing that the output of the detection coil of the high-frequency detection circuit is phase-detected at a phase that is 90 ° different from the phase at which the maximum output is obtained when phase detection is performed on one (other) non-magnetic metal element From the vector composite value of the output corresponding to the other (one) non-magnetic metal and the output corresponding to the ferromagnetic metal, the remaining amount of the ferromagnetic metal is vectorically subtracted from this composite value, and the other It is characterized in that the remaining amounts of the three kinds of metals are individually calculated by knowing the remaining amount of the (one) non-magnetic metal.

[0013]

In the above method, when the phase detection is performed by the low frequency detection circuit, the secondary output due to the electromagnetic induction of the ferromagnetic metal portion becomes extremely larger than the output component due to the overcurrent, and the amount of non-magnetic metal present is increased. The remaining amount of the ferromagnetic metal can be detected regardless of the above.

When phase detection is performed in the high frequency detection circuit, if the phase is set to an appropriate angle, one (other)
The output component due to the non-magnetic metal of is cut, and the secondary composite vector output according to the remaining amount of the other (one) non-magnetic metal and ferromagnetic metal can be obtained. Therefore, the remaining amount of the three kinds of metals is calculated individually by subtracting the remaining amount of the ferromagnetic metal detected earlier from the detected value of each non-magnetic metal including the output component of the ferromagnetic metal. You can

Incidentally, the correspondence between the output of the detector and the remaining amount of each metal shall be measured in advance, and the above subtraction is
The conversion is performed by using the inner product of the reference vector of each metal (a vector of length 1 having a phase angle at which the maximum output is obtained) and the phase component subjected to the phase detection.

[0016]

EXAMPLES Next, specific measuring devices and measuring methods will be described. The circuit configuration of the detector 1 used for measurement is shown in FIG.
Shown in This configuration has both a high frequency detection circuit 2 which mainly measures using an overcurrent and a low frequency circuit 3 which measures an output component due to an overcurrent as small as possible. In order to improve accuracy, each of the detection circuits 2 and 3 uses a mutual induction type coil instead of the self induction type coil used in a general eddy current flaw detection test method.

First, the high frequency detection circuit 2 will be described. In this circuit, L ₁ and L ₂ are primary coils connected in series, and connected to an exciting AC power supply e having a predetermined frequency selected according to the three-layer metal wire to be inspected. L ₃ and L ₄ are secondary detection coils connected in series, and are two resistors R ₁ and R ₁ .
It is bridge-connected to R ₂ and a variable resistor R ₃ for balancing. L ₁ and L ₃ are overlapped and wound inside the saddle type bobbin 4 for detection shown in FIGS. 2 and 3, and are magnetically coupled to each other by using the ACSR 5 which is a three-layer metal wire to be detected as a magnetic circuit. The coils L ₂ and L ₄ are wound and overlapped on the inside of the saddle type bobbin 6 which is always in the air core state for zero point adjustment, and are magnetically coupled to each other in the air core state. The output of the bridge circuit 7 is taken out from the middle point of the secondary side detection coils L ₃ , L ₄ and the movable contact of the balancing resistor R ₃ and output to the processing circuit 8. The processing circuit 8 generates a phase signal having a predetermined phase difference from the AC power supply e from the exciting AC power supply e by a phase shift circuit (not shown) and performs phase detection. This detection output is output to the arithmetic circuit 9 common to the low frequency detection circuit 3 for calculating the remaining amount of each metal. The calculation result is displayed on the display 10. Since this high-frequency detection circuit 2 is mainly intended to detect the remaining amount of the non-magnetic metal, the frequency of the exciting AC power supply e is set to, for example, 1 kHz to ensure that the eddy current sufficiently flows through the non-magnetic metal. It is selected as high as 250 kHz, and the resonance frequency of each coil L ₁ , L ₂ , L ₃ , L ₄ is made to coincide with this frequency. In addition, the phase of the phase detection performed for each non-magnetic metal was detected for the other (one) non-magnetic metal so that the output component of the other (one) non-magnetic metal would be zero. Sometimes the phase detection output is selected as a phase having a difference of 90 ° from the maximum phase.

Next, the low frequency detection circuit 3 will be described.
Since the low frequency detection circuit 3 also has the same circuit configuration as the high frequency detection circuit 2, a dash (') is added to the corresponding components.
Is attached. The coils L ₁ ′, L ₂ ′, L ₃ ′ and L ₄ ′ are provided on the saddle type bobbin 4 for detection and the saddle type bobbin 6 for zero point adjustment,
Like the high frequency coil, it is wound on the outside of the coils L ₁ , L ₂ , L ₃ , and L ₄ of the high frequency detection circuit 2 in the same manner. Since this low frequency detection circuit 3 is intended to detect only the remaining amount of the ferromagnetic metal, the primary coil L
Degree ₁ ', L _2' frequency of excitation AC power supply e to be connected to 'is the relative secondary output by the induction current in the ferromagnetic metal, the secondary output due to the turbulence of the non-magnetic metal is negligible Low frequency (eg 1Hz-100)
The detection phase selected for Hz) and used in the processing circuit 8'is the phase that maximizes the detection sensitivity of the ferromagnetic metal.

FIGS. 4 to 6 show examples of the mechanical construction of the detector 1 incorporating the above circuit. 11 shown in FIG. 4 and FIG.
Is a sensor part of the detector 1, and is a low frequency coil and a high frequency coil L _{1 to} L ₄ and L ₁ ′ to a box type case 12.
The saddle type bobbins 4 and 6 having L ₄ ′ wound therein are housed.
Further, the case 12 is provided with two guide rollers 13 and 14 for traveling on the ACSR 5.
A long insulating rod 15 allows the inspector to tow and move on the ACSR 5. Further, pinch rollers 17 and 18 for pressing the ACSR 5 against the guide rollers 13 and 14 are provided, and the saddle type bobbin 4 around which the coils L ₁ , L ₃ , L ₁ ′ and L ₃ ′ are wound keeps a constant distance from the ACSR 5. This ensures that detection errors due to changes in this interval are prevented.

Reference numeral 19 shown in FIG. 6 is a detector main body which an inspector can hang on his shoulder and carry.
e ', a transfer circuit, a phase detection circuit, and the like, the processing units 8 and 8', a display 10 for each of the three metals, and the like, and are connected to the sensor unit 11 by a stretchable spiral wire 20. With such a configuration, workability is significantly improved. Depending on the location, it is also possible for the inspector to carry out the corrosion deterioration inspection simply by walking under the overhead line without using a ladder, a tower, a maintenance car, or the like.

Next, a specific method of use will be described. Prior to the inspection, the outputs of the bridge circuits 7 and 7 ′ of the high frequency detection circuit 2 and the low frequency detection circuit 3 can be changed to 0 with no metal inside and around the saddle type bobbins 4 and 6. Move resistors R ₃ and R ₃ ′ to adjust the zero point. After that, the sensor unit 11 is lowered from above and suspended on the ACSR 5. At this time, the pinch rollers 17 and 18 are automatically pressed against the ACSR 5 from below by a rotary support mechanism (not shown). In this state, the coils L ₂ , L ₄ and L ₂ ′,
The magnetic circuit portion of L ₄ ′ is always in an air-core state, and the other coils L ₁ , L ₃ and L ₁ ′ _, L ₃ ′ are in close proximity to the ACSR 5
Is a magnetic circuit.

Then, pulling with the insulating rod 15, the ACSR5
While the sensor unit 11 is moving at a low speed, the detection by the high frequency detection circuit 2 and the detection by the low frequency detection circuit 3 are performed at the same time. Even if they are performed at the same time, the frequencies of the circuits 2 and 3 are significantly different, for example, about 1000 times, and mutual interference does not occur.

The phase detection by the low frequency is performed at the phase where the maximum output is obtained when the single steel wire is detected as described above. This output, as shown in FIG.
This is the same as when the steel wire portion of the CSR alone is taken out and inspected. That is, the output vector F of the phase detection
The amplitude decreases in-phase as the steel wire decreases due to corrosion, and goes to zero when the steel wire disappears.
At this time, the output of non-magnetic metal zinc and aluminum is negligibly small because it is excited at a low frequency. Therefore, if a correspondence table between the remaining amount of the steel wire and the magnitude f of the output vector F is created and stored in a storage device, the output value of the phase detection is calculated and A
The remaining amount of the steel wire in the CSR 5 can be displayed on the display 10.

The phase detection by high frequency is 90 ° with respect to the phase (zinc axis a) at which the maximum output is obtained when one non-magnetic metal (zinc) of ACSR is taken out and phase detected as shown in FIG. Phase b with a phase difference of (phase that cuts output by zinc) and ACSR as shown in FIG.
The phase where the maximum output is obtained when the other non-magnetic metal (aluminum) of 5 is independently extracted and subjected to phase detection (aluminum shaft c)
Phase detection with a phase difference of 90 ° with respect to (a phase that cuts the output of aluminum). The respective detection outputs are separately taken out and processed / processed by the processing circuit 8.

The phase detection by the phase shifter 2 and the phase shifter 2 by the high-frequency detection circuit 2 as described above is non-existent among the three kinds of metals of ferromagnetic metal (steel wire) and two kinds of non-magnetic metal (zinc, aluminum). It is intended to perform phase detection so that the output component of one of the magnetic metals (zinc or aluminum) does not appear.

The principle and procedure for calculating the remaining amount of aluminum are
Next, a description will be given. Regarding the new ACSR, the output when the steel wire portion only, the aluminum portion only, and the zinc portion only are respectively extracted and phase-detected is represented by the phase and amplitude on the two-dimensional plane shown in FIG. It becomes like vector B and vector C. These vectors A,
The magnitudes of B and C approach zero with the same phase as the respective quantities decrease. When phase detection is performed on a new ACSR, the phase and amplitude of its output are
It becomes a composite vector D of B and C, and as each part of steel wire, aluminum, and zinc decreases, the respective vector components decrease,
The composite vector D also changes accordingly.

In order to cut the output component due to zinc, consider a reference vector α for phase detection of size 1 in the direction orthogonal to the vector A of zinc, and phase-detect the ACSR at that phase. The size g is the inner product of the composite vector D and the reference vector α, which is the inner product of the vector B and the reference vector α (B · cos θ = i),
Inner product of vector C and reference vector α (C · cos φ =
It is the sum of h). Therefore, in order to convert the output voltage value f of the ferromagnetic metal (steel wire) previously detected at a low frequency into the output voltage value c when detected by the high frequency detection circuit 2, the same steel wire has a low voltage value in advance. Ratio p of output voltage obtained by phase detection at the same phase by the frequency detection circuit 3 and the high frequency detection circuit 2
c ′ / f ′ is multiplied and cosφ is further multiplied to convert into the magnitude in the reference vector α direction to obtain the magnitude of the component in the detection direction h = f · p · cosφ, which is subtracted from the phase detection output g. Then, the output component i of aluminum can be calculated. further,
By dividing this by cos θ, the size on the aluminum shaft C can be obtained. Then, in the same manner as described above for measuring the remaining amount of steel wire, if a correspondence table between the remaining amount of aluminum and the size of the output vector B is created and stored in the storage device,
The remaining amount of aluminum can be immediately displayed on the display 10 after the calculation is performed by the calculation circuit 9.

As for zinc, as shown in FIG. 9, phase detection is performed at a phase D orthogonal to the aluminum axis C, and a calculation is performed in the same manner as described above to subtract the steel wire component. The component of zinc on the vector A is obtained, and the remaining amount of zinc can be calculated and displayed.

The data obtained by the above-mentioned measurement and calculation can be displayed on the spot on the display 10 or can be recorded on a recorder. The prediction of the replacement time of the ACSR based on this data can This will be done in light of past data, taking into account the circumstances of overhead lines such as the surrounding environment.

The method of the present invention is to measure based on the above-mentioned principle. Means for applying an AC magnetic field to generate an induced current and an eddy current at the time of measurement, the structure of the detection coil and the processing of the secondary output. The method can be appropriately selected within a range in which the above method can be performed, depending on the three-layer metal wire rod (not limited to ACSR) to be detected.

[0031]

According to the present invention, the corrosion state of a three-layer metal wire rod such as ACSR can be accurately grasped by a simple operation. Therefore, the maintenance method of ACSR can be shifted from the inaccurate time-based maintenance by the visual inspection, which is conventionally adopted, to the accurate state-based maintenance standard using the equipment diagnostic equipment. Therefore, the inspection cycle can be extended and the ACS
ACS that can be used while reducing the number of R inspection personnel
The replacement cost of R is eliminated and the maintenance cost of ACSR can be reduced.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration example of an electric circuit of a detector of the present invention.

FIG. 2 is a diagram showing an arrangement example of an exciting coil and a detecting coil on a bobbin.

FIG. 3 is a diagram showing a state in which a sensor unit is guided by an ACSR.

FIG. 4 is an external configuration diagram of a sensor unit.

FIG. 5 is a diagram showing a state in which the sensor unit is moved on the ACSR by an insulating rod.

FIG. 6 is a diagram showing an external configuration example of the entire detector.

FIG. 7 is a diagram showing an output example of a low frequency detection circuit of the present invention.

FIG. 8 is a diagram showing an output example when aluminum is detected by a high frequency detection circuit according to the method of the present invention.

FIG. 9 is a diagram showing an output example when zinc is detected by the high frequency detection circuit of the method of the present invention.

FIG. 10 is a diagram illustrating a method for determining corrosion deterioration of a two-layer metal wire rod, which is a premise of the present invention.

[Explanation of symbols]

1 detector 2 high frequency detection circuit 3 low frequency detection circuit 4, 6 saddle type bobbin 5 three-layer metal wire (ACSR) 7, 7'bridge circuit 8, 8 'processing circuit 9 arithmetic circuit 10 indicator 11 sensor section L ₁ ~ L ₄ high-frequency coil L ₁ '~L _4' low-frequency coil

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Goro Yokota, 1-13 13 Midodencho, Yamanouchi, Ukyo-ku, Kyoto Prefecture, Kyoto Electronics Co., Ltd. (56) Reference JP-A-63-212804 (JP, A) Japanese Patent Sho 63-41502 (JP, B2)

Claims (1)

[Claims] 1. A low-frequency magnetic field is applied along the outer circumference of a three-layer metal wire rod in which two kinds of non-magnetic metal are laminated on a ferromagnetic metal, and vortexes to the ferromagnetic metal inside.
A low-frequency excitation coil that flows a current, and a low-frequency detection circuit that has a detection coil for detecting the change in magnetic field due to the induced current generated by this excitation, and the eddy current concentrates in the upper non-magnetic metal.
RF excitation coil and the action of high-frequency magnetic field so,
By moving a detector that has a high-frequency detection circuit that has a detection coil for the magnetic field change due to the overcurrent generated by this excitation, the induced voltage generated in the detection coil of the low-frequency detection circuit is detected at a specified phase, and the Knowing the remaining amount of magnetic metal, phase-detect the output of the detection coil of the high-frequency detection circuit at a phase that is 90 ° different from the phase at which the maximum output is obtained when phase detection is performed on one (other) non-magnetic metal unit. One hand (other
The output corresponding to the remaining amount of non-magnetic metal of
By knowing the vector composite value of the output corresponding to the other (one) non-magnetic metal and the output corresponding to the ferromagnetic metal, the residual amount of the ferromagnetic metal is vectorically subtracted from this composite value. Then, the remaining amount of the other (one) non-magnetic metal is known, and the remaining amount of the three kinds of metals is calculated individually.