KR20100048742A - An apparatus to measure a tension of steel cable using an ac magnetism - Google Patents

Abstract

PURPOSE: A tension measurement device of a steel cable using the alternating current magnetism is provided to effectively compensate surrounding environmental factors which can affect the tension of the steel cable. CONSTITUTION: A tension measurement device of a steel cable comprises a steel cable(1), a tension sensor(2), a steel cable(3), a tension sensor(4) and a power amplifier(5). The steel cable for measurement keeps structure. The tension sensor for measurement measures the tension applied to the steel cable for measurement. The steel cable for compensation makes up for something the environmental factor added in the steel cable for measurement. The tension sensor for compensation measures the tension applied to the steel cable for compensation. The power amp adds the fixing bias magnetic field or the AC magnetic field to the tension sensor for compensation.

Description

Tension measuring device of steel cable using alternating magnetism {AN APPARATUS TO MEASURE A TENSION OF STEEL CABLE USING AN AC MAGNETISM}

The present invention relates to a tension measuring device of a steel cable using an alternating magnetism capable of measuring the tension of the steel cable mounted on a large bridge, and more particularly, according to the tension of the steel cable on one side circumferential surface of the steel cable The present invention relates to an apparatus for measuring tension of a steel cable using alternating magnetism, in which a sensor capable of changing a magnetic field is attached to enable easy measurement of the tension of the steel cable within a range in which the steel cable is not damaged.

In general, large bridges, such as cable-stayed bridges and suspension bridges, are more likely to damage structures of large bridges due to excessive displacement of bridges due to wind loads and corrosion of bridges against seawater.

Therefore, a steel cable is installed in a structure for supporting a large bridge placed in a harsh environment as described above, and a load cell or an acceleration sensor is directly connected to the steel cable to measure a tension applied to the steel cable. It is supposed to be.

However, as the structure of the load cell or acceleration sensor directly connected to the steel cable as described above, as the structure is gradually enlarged, it is expensive to install a load cell or tension sensor between the structure and the steel cable, the steel cable connected to the large structure There is a limit to measure the tension of the, there was a problem that the reliability of the result of the tension measurement for the large structure is poor.

On the other hand, in order to overcome the limitations of the method such as a load cell or an acceleration sensor directly connected to the cable as described above, when tension is applied to the steel cable, only by surrounding the sensor on the circumferential surface of the steel cable using a physical property that changes the permeability In addition, research on the EM (Electro Magnetic) sensor that can measure the tension of the steel cable has been actively conducted.

However, the method of measuring the tension of the steel cable for the EM sensor as described above, there was a problem that the temperature requirement as an environmental condition that may affect the length of the steel cable in addition to the tension applied to the steel cable, can not be overlooked. The temperature requirement has a problem that even if the tension applied to the steel cable is substantially the same, the result value output from the tension sensor may be different due to the temperature parameter.

Therefore, in order to solve this problem, the conventional method is applied to the temperature compensation circuit or other method in addition to the EM sensor method, but still requires additional work to calculate the actual tension is excluded the temperature influence, As a result, there is a problem in that it is impossible to continuously calculate the tension, and there is a limitation in that the exact characteristic change of the EM sensor cannot be solved according to the change of the surrounding environment.

In order to solve the problem according to the conventional tension sensor as described above, the present invention can not only measure the tension of the cable within the range that does not damage the cable connected to the structure, but also acts as a variable to the tension of the cable It is an object of the present invention to provide an apparatus for measuring tension of steel cables using alternating magnetism that can effectively compensate for possible environmental requirements.

An apparatus for measuring tension of a steel cable using alternating magnetism according to the present invention for achieving the above object is to measure the tension applied to a steel cable for measurement and a steel cable for measurement, which hold a specific structure as a first embodiment. A measurement tension sensor for measuring, a compensation steel cable in a no-load state for compensating for environmental requirements applied to the measurement steel cable, a compensation tension sensor for measuring tension applied to the compensation steel cable, And a power amplifier for applying a fixed bias magnetic field or an alternating magnetic field to the measuring tension sensor and the compensating tension sensor, wherein the measuring tension sensor, the compensating tension sensor, and the power amplifier include the measuring tension sensor. And monitoring the information collected from the compensating tension sensor and at the same time, A tension controller of the measuring steel cable is derived by using a resultant value of a tension sensor, and a central controller is provided to control the power amplifier, and the central controller is connected to the central controller and is connected to the central controller. The analog signal input from the sensor and the compensation tension sensor is converted into a digital signal and transmitted to the central control device, and the digital control signal transmitted from the central control device to the power amplifier is converted into an analog signal and transmitted to the power amplifier. It can be configured as a DAQ board.

In addition, the apparatus for measuring the tension of a steel cable using alternating magnetism according to the present invention is a measuring steel cable for supporting a specific structure as a second embodiment, and for measuring the tension applied to the measuring steel cable. A tension sensor, a power amplifier for applying a fixed bias magnetic field or an alternating magnetic field to the measurement tension sensor, and a temperature sensor capable of measuring the temperature of the measurement steel cable, collected from the measurement tension sensor and the temperature sensor And a central control device capable of deriving the tension of the steel cable for measurement and controlling the power amplifier by monitoring the measured information and using the resultant values of the measurement tension sensor and the temperature sensor. Is connected to the analog signal input from the tension sensor and the temperature sensor for conversion into a digital signal And a DAQ board for converting the digital control signal transmitted from the central control device to the power amplifier and converting the digital control signal into an analog signal to the power amplifier.

The tension measuring device of the steel cable using the alternating magnetism of the present invention having such a structure is provided with a tension sensor for measuring the magnetic field can be changed in accordance with the tension applied to the steel cable on one side of the steel cable mounted on a large bridge If only the cycle, it is possible to measure the tension of the steel cable within a range that does not damage the steel cable.

Such a device for measuring the tension of a steel cable using alternating magnetism according to the present invention can not only measure the tension of the steel cable by simply wrapping and fixing the outer circumferential surface of the steel cable connected to the structure, but also to the tension of the steel cable. A more accurate and reliable tension measurement of the structure, since it can actively respond to changes in the surrounding environment, such as ambient temperature and humidity, and aging of the support, and can automatically compensate for changes in the surrounding environment. There is an advantage to get it.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.

In addition, the terms to be described later are terms defined in consideration of functions in the present invention, which may vary according to intention or custom of a user or an operator, and the definitions refer to a device for measuring tension of a steel cable using alternating magnetism according to the present invention. It should be made based on the contents throughout the specification to be described.

1 is a control block diagram of a first embodiment of the tension measuring device of the steel cable using the alternating current magnet according to the present invention, Figure 2 is a second embodiment of the tension measuring device of the steel cable using the alternating current magnet according to the present invention 3 is a control block diagram of an example, and FIG. 3 is a cross-sectional view of a measurement tension sensor and a compensation tension sensor according to the present invention.

4 is a state diagram in which a tension sensor and a steel cable are mounted on a standard tensile tester, and FIG. 5 is a state diagram showing a result measured from a component provided in the present invention in a central control device equipped with the present invention. 6 is a graph showing an output value of the measurement tension sensor according to the temperature of the measurement steel cable from the measurement tension sensor provided in the second embodiment.

7 is a graph showing the tension applied to the measurement steel cable to the voltage output from the measurement tension sensor provided in the second embodiment.

As shown in these figures, the first embodiment of the tension measuring device of the steel cable using the alternating magnetism according to the present invention, as shown in Figure 1, and the measuring steel cable (1) holding a specific structure and , A measurement tension sensor 2 for measuring the tension applied to the measurement steel cable 1, and a steel cable for compensation in a no-load state to compensate for environmental requirements applied to the measurement steel cable 1 (3) a fixed bias to the compensation tension sensor 4 capable of measuring the tension applied to the compensation steel cable 3, the measurement tension sensor 2 and the compensation tension sensor 4; A power amplifier 5 for applying a magnetic field or an alternating magnetic field is provided, and the measurement tension sensor 2, the compensation tension sensor 4, and the power amplifier 5 have the measurement tension sensor 2. Collected from the tension sensor (4) Simultaneously with monitoring the beam, the tension of the measuring steel cable 1 is derived using the resultant values of the measuring tension sensor 2 and the compensating tension sensor 4, and the power amplifier 5 is controlled. The central control device 6 is provided, and the central control device 6 is connected to the central control device 6 and is input from the measurement tension sensor 2 and the compensation tension sensor 4. Converts an analog signal into a digital signal and transmits it to the central control unit 6, and converts a digital control signal transmitted from the central control unit 6 to the power amplifier 5 into an analog signal to convert the analog signal into the power amplifier 5 DAQ board (7) to be delivered to the) is further equipped.

In addition, the present invention, as in the second embodiment shown in Figure 2, a measurement capable of measuring the tension applied to the measurement steel cable (1) and the measurement steel cable (1) supporting a specific structure Temperature sensor capable of measuring a temperature of the tension sensor 2, a power amplifier 5 that applies a fixed bias magnetic field or an alternating magnetic field to the measurement tension sensor 2, and the measurement steel cable 1 ( 8), the measurement tension sensor 2 and the temperature sensor 8 monitors the information collected from the measurement tension sensor 2 and the temperature sensor 8, and at the same time the tension sensor for measurement A central control unit 6 is provided which can derive the tension of the measurement steel cable 1 by using the resultant values of (2) and the temperature sensor 8 and control the power amplifier 5, The central control unit 6 is connected to the central control unit 6 The analog signal input from the static tension sensor 2 and the temperature sensor 8 is converted into a digital signal and transmitted to the central control device 6, and transmitted from the central control device 6 to the power amplifier 5. The structure may be changed to the DAQ board 7 which converts the digital control signal into an analog signal and transfers the converted digital control signal to the power amplifier 5.

In addition, a control start switch 9 may be additionally installed between the power amplifier 5 and the DAQ board 7 provided in the first and second embodiments so that the central control apparatus 6 and the DAQ The power amplifier 5 may be controlled according to a control signal input from the board 7, and 1 of the measurement tension sensor 2 or the compensation tension sensor 4 directly connected to the power amplifier 5 may be controlled. A shunt 10 may be directly connected to the primary coil 14 so that the current flowing through the primary coil 14 may be accurately detected.

The output signal branched from the shunt 10 is connected to the pre-amp 11 shown in FIGS. 1 and 2 to receive a very small current signal input from the shunt 10. Amplified to a suitable size, and then transmitted to the DAQ board (7).

In addition, the digital input / output terminal of the DAQ board 7 provided in the first and second embodiments is equipped with a measurement start switch 12 capable of driving the tension measuring device according to the present invention according to a specific operation signal. Can be.

Before explaining the operation of each of the first embodiment or the second embodiment according to the present invention having the structure as described above, the principle that the measuring tension sensor 2 or compensation tension sensor 4 is operated Reference will be made in detail to 3 and a plurality of equations.

First, the measuring tension sensor 2 and the compensating tension sensor 4 provided in the first and second embodiments are the measuring steel cable 1 or the compensation as shown in FIG. A sensor capable of measuring the tension of the steel steel cable (3), wherein the measurement steel cable (1) or compensation for maintaining while maintaining a constant gap with the measuring steel cable (1) or compensation steel cable (3) The bobbin 13 which can wrap the circumferential surface of the steel cable 3, and the primary coil 14 wound on the outer circumferential surface of the bobbin 13 a predetermined number of times, the circumference of the bobbin 13 The surface is provided with a secondary coil mounting hole 15 recessed to a predetermined depth in the circumferentially inward direction of the bobbin 13 to the bobbin 13 and the primary coil 14 through the secondary coil mounting hole 15. The secondary coil 16 can be interposed in between.

In this case, the primary coil 14 is a coil applying a magnetic field, the secondary coil 16 is a tension applied to the measuring steel cable (1) or the compensation steel cable (3), the primary coil A sensing coil whose output changes in accordance with the magnetic field applied to (14), or the ambient temperature at which the measuring steel cable 1 and the compensating steel cable 3 are placed.

At this time, the precaution should be made that the measurement tension sensor 2 and the compensation tension sensor 4 provided in the first embodiment have the same characteristics.

In the measuring tension sensor 2 and the compensating tension sensor 4, instead of inputting a conventional pulsed magnetic field, an AC magnetic field is input to set the center value of the magnetic field section to a fixed bias magnetic field (= operating point). In addition, a small signal AC magnetic field is applied to the primary coil provided in the measurement tension sensor 2 and the compensation tension sensor 4.

Next, in order to explain the driving principle of the measurement tension sensor 2 and the compensation tension sensor 4 having the above structure by using the equation, the symbols shown in FIG. 3 are defined as follows.

는 1차/2차 권선수이고,

는 1차/2차 코일(14,16)의 단면적이며,

는 측정용 강재 케이블(1) 또는 보상용 강재 케이블(3)의 단면적이다. First, shown in Figure 3

Is the number of primary and secondary turns,

Is the cross-sectional area of the primary and secondary coils 14 and 16,

Is the cross-sectional area of the measuring steel cable 1 or the compensating steel cable 3.

는 1차/2차 코일(14,16)의 직경이고,

는 측정용 강재 케이블(1) 또는 보상용 강재 케이블(3)의 직경이며,

은 솔레노이드의 길이이다. Also,

Is the diameter of the primary and secondary coils 14 and 16,

Is the diameter of the measuring steel cable (1) or the compensating steel cable (3),

Is the length of the solenoid.

In general, an alternating magnetic field is applied to the primary coil 14 of the measuring tension sensor 2 and the compensating tension sensor 4 as a sine wave, and the alternating magnetic field is expressed by Equation 1 below.

는 다음 수학식 3과 같다.In addition, when Faraday's law is applied to the voltage induced in the secondary coil 16 of the measurement tension sensor 2 or the compensation tension sensor 4, the following equation (2),

Is as shown in Equation 3 below.

는 1차 코일에서 2차 코일로 유도된 자속으로 케이블 내의 자속과 2차 코일 내부 에어갭(

)에 흐르는 자속으로 구성된다. At this time,

Is the magnetic flux induced from the primary coil to the secondary coil and the magnetic flux in the cable and the air gap inside the secondary coil (

It consists of magnetic flux flowing in

는 투자율이고,

은 비투자율이며,

는 진공 투자율로서

이다. In addition, the equation (2)

Is the permeability,

Is the specific permeability,

Is the vacuum permeability

to be.

Using the above equation, the equation (2) is applied to the tension sensor with a cable, as shown in the following equation (4).

은

값이 0이므로 다음 수학식 5와 같다. In addition, there is no cable in the tension sensor, the output voltage of the tension sensor exposed to the air

silver

Since the value is 0, the following Equation 5 is obtained.

에 대해 정리한다. At this time, after dividing Equation 4 by Equation 5, the specific permeability

To summarize.

로 표현하고 정리하면 다음 수학식 6과 같다. In addition, the permeability and the output voltage of the tension sensor may vary depending on the tension applied to the cable, the temperature, and the magnetic field.

When expressed and summarized as in the following equation (6).

는

의 실효값이고,

는 (장력, 온도, 자기장)이

에서의

의 실효값이다. At this time, in Equation 6

Is

Is the effective value of

Has (tension, temperature, magnetic field)

In

The effective value of.

이 가해지는 상황에서 상기 장력 센서의 출력 전압에 대하여 정리하면 다 음 수학식 7과 같다. Next, the tension, temperature and fixed magnetic field in the steel cable using the equation (6)

In this applied situation, the output voltage of the tension sensor is summarized as in Equation 7 below.

Next, when the tension sensor is installed in the steel cable, and the steel cable equipped with the tension sensor is connected to the standard tensile tester shown in FIG. 4, the secondary coil 16 of the tension sensor according to the tension applied to the steel cable. You can measure the voltage output from

For reference, as shown in FIG. 4, the standard tensile tester is provided with a load cell or other tension measuring means that can be directly connected to the tension sensor and the steel cable, and a tension means that can pull the steel cable from both sides. It is possible to measure in real time the tension applied to the steel cable while pulling.

Next, when the output voltage measurement results according to the tension is applied to Equation 6, the permeability curve according to the tension of the steel cable can be obtained.

At this time, the permeability curve according to the tension of the steel cable is changed non-linearly according to the tension and the magnetic field, and constantly changes with respect to the temperature.

라 정의한다. Therefore, the fixed bias magnetic field applied to the primary coil of the tension sensor in the measurement of the tension of the steel cable can operate the tension sensor most stably.

It is defined as

Next, if we summarize the specific permeability in a certain magnetic field can be expressed as a quadratic equation for the tension as shown in Equation (8).

은 자기장

A/m이고, 장력=0 MN이며, T=0도일 때의 비투자율이고, 상기 수학식 8의

는 상기 강재 케이블의 장력에 따른 투자율 곡선을 회귀 분석(curve fitting)함으로써 구해진 값이며,

은 온도 계수이다. In Equation 8

Silver magnetic field

A / m, tension = 0 MN, specific permeability when T = 0 degrees,

Is a value obtained by curve fitting the permeability curve according to the tension of the steel cable,

Is the temperature coefficient.

라 하면 상기 수학식 8은 다음 수학식 9와 같이 표현된다. At this time, the reference temperature is set to 20 degrees when the tension is measured and the fixed bias magnetic field is

Equation 8 is expressed as Equation 9 below.

Next, by substituting Equation 9 into Equation 7, the following Equation 10 can be obtained.

= 0)이고, 일정한 자기장에서 측정하였으므로 이를 수학식 10에 적용하면, 다음 수학식 11을 얻을 수 있다. At this time, the output voltage of the compensation tension sensor 4 has a tension of 0 MN (that is,

= 0) and measured in a constant magnetic field, the following equation (11) can be obtained by applying this equation (10).

By subtracting Equation 11 from Equation 10 using the equation derived as described above, Equation 12 can be obtained.

When the output voltage of the compensating tension sensor 4 is subtracted from the equation 12 for the measurement tension sensor 2, the measurement steel cable 1 has no influence on permeability and ambient temperature, and the measurement steel cable It can be seen that only the influence of the tension applied to (1) is affected.

The control process of the first embodiment operated with the above structure and principle of operation will be described in more detail.

First, according to the first embodiment of the present invention, by operating the AC tension measuring program while the power amplifier 5 is OFF, the measuring tension sensor 2 and the compensating tension sensor are operated. Automatic zero adjustment is performed on the analog signal input from (4) and the current signal output from the shunt 10, and the noise signal and drift input from the measuring tension sensor 2 and the compensation tension sensor 4 are performed. Automatically remove the signal.

Next, when the automatic operation start switch provided in the central control device 6 is pressed by the user, the central control device 6 operates the control start switch to operate the power amplifier 5.

에 따라 상기 측정용 장력 센서(2) 또는 보상용 장력 센서(4)의 1차 코일(14)에 고정 바이어스 자기장과 교류 자기장을 공급하여 상기 측정용 강재 케이블(1) 또는 보상용 강재 케이블(3)에 자기장을 발생시킨다.Next, the power amplifier 5 is an analog signal output through the central control unit 6 and the DAQ board (7)

According to the supply of a fixed bias magnetic field and an alternating magnetic field to the primary coil 14 of the measuring tension sensor 2 or the compensation tension sensor 4 according to the measuring steel cable (1) or the compensation steel cable (3) To generate a magnetic field.

The fixed bias magnetic field has the largest change in output voltage depending on the tension applied to the measuring steel cable 1 or the compensating steel cable 3 by the measuring tension sensor 2 and the compensating tension sensor 4. It can be obtained by a tension test as a magnetic field that can be operated under optimal conditions with less heat.

Next, the first embodiment transmits and displays the fixed bias magnetic field and the alternating magnetic field of the measuring steel cable 1 and the compensating steel cable 3 to the central control unit 6, and displays the measuring tension sensor. Cable vibration signals and the like included in (2) and the compensating tension sensor 4 are removed through signal processing.

Next, the central control unit 6 synthesizes the signals output from the measuring tension sensor 2 and the compensating tension sensor 4 and converts them into RMS (root meansqure = effective value) values, and then the RMS value. Will be displayed to the user.

Next, the central control unit 6 receives the signals input from the measurement tension sensor 2 and the compensation tension sensor 4 for a predetermined time in accordance with the control signal of the measurement start switch 12 and averages them. Then, it is displayed and stored to the user, and the measurement standby state is maintained until the control signal of the measurement start switch 12 is received.

Next, the first embodiment entering the measurement standby state is the data measured so far according to the measurement completion control signal of the central control device 6, that is, the measurement tension sensor 2 and the compensation tension sensor 4 ), A combined value of the measurement tension sensor 2 and the compensation tension sensor 4, a fixed bias magnetic field, an alternating magnetic field, or a temperature and the like, and the measured data are shown in FIG. To the user.

On the other hand, the second embodiment, unlike the first embodiment, does not use the compensation tension sensor 4, the temperature sensor 8 and the measurement tension sensor 2 mounted on the measurement steel cable 1 By using only the bar can measure the tension applied to the measurement steel cable (1), the measurement process is as follows.

를 얻는다.First, in order to use the temperature correction coefficient applied to the second embodiment, as shown in Figure 7, the output voltage of the measurement tension sensor 2 according to the temperature is shown in a graph, and the measurement tension sensor output according to the temperature Curve fitting of the voltage to the next temperature correction factor

Get

Therefore, the temperature correction equation in which the temperature correction coefficient is applied to the output voltage derived from the measurement tension sensor 2 of the second embodiment is expressed by Equation 13 below.

는

로 환산된 측정용 장력 센서(2)의 출력 전압이고,

는 임의의 온도에서 검출된 측정용 장력 센서(2)의 출력 전압이며,

는 임의의 온도이다. At this time, the equation (13)

Is

Is the output voltage of the measurement tension sensor 2 converted into

Is the output voltage of the measurement tension sensor 2 detected at an arbitrary temperature,

Is any temperature.

Next, when the tension measurement results of the measurement steel cable (1) according to the result of the equation (13) using the equation 13 and the standard tensile tester shown on the graph, as shown in Figure 7, the tension for measurement The tension characteristic curve of the measuring steel cable 1 with respect to the output of the sensor 2 can be obtained.

Next, when the tension characteristic curve shown in FIG. 7, that is, the tension characteristic curve of the measuring steel cable 1 with respect to the output of the measuring tension sensor 2 is expressed by the equation, Equation 14 is obtained. Can be.

At this time, Y in the equation (14) is the tension applied to the measurement steel cable (1), X is the output voltage derived from the measurement tension sensor (2).

Therefore, as a result, by applying the derived equations (13) and (14) to the second embodiment, it is possible to measure the tension of the measuring steel cable (2) in which the influence of temperature is corrected from the second embodiment. .

On the other hand, the process of operating the second embodiment according to the present invention is similar to the operation process of the first embodiment presented above, so the detailed description of the operation of the second embodiment will be omitted in order to avoid redundant description.

The tension measuring device of the steel cable using the alternating magnetism of the present invention having such a structure is provided with a tension sensor for measuring the magnetic field can be changed in accordance with the tension applied to the steel cable on one side of the steel cable mounted on a large bridge If only a cycle is given, the tension of the steel cable can be measured within a range that does not damage the steel cable.

Therefore, the apparatus for measuring the tension of a steel cable using alternating magnetism according to the present invention can easily measure the tension of the steel cable without installing load cells at both ends of the steel cable to measure the tension of the steel cable. There is a number.

The present invention described above is capable of various substitutions, modifications, and changes without departing from the technical spirit of the present invention for those skilled in the art to which the present invention pertains. It is not limited.

1 is a control block diagram of a first embodiment of an apparatus for measuring tension of a steel cable using alternating magnetism according to the present invention;

2 is a control block diagram of a second embodiment of a tension measuring device of a steel cable using alternating magnetism according to the present invention;

3 is a cross-sectional view of the measurement tension sensor and compensation tension sensor provided in the present invention,

4 is a state in which the tension sensor and the steel cable is mounted on a standard tensile tester,

Figure 5 is a state diagram showing the results measured from the components provided in the present invention in the central control device provided in the present invention,

6 is a graph showing the output value of the measurement tension sensor according to the temperature of the steel cable from the measurement tension sensor provided in the second embodiment,

7 is a graph showing the tension applied to the measurement steel cable to the voltage output from the measurement tension sensor

* Explanation of symbols on the main parts of the drawings

1. Steel cable for measurement 2. Tension sensor for measurement

3. Compensation steel cable 4. Compensation tension sensor

5. Power amplifier 6. Central controller

7.DAQ board 8.Temperature sensor

9. Control start switch 10. Shunt

11. Pre-amp 12. Measurement Start Switch

13. Bobbin 14. Primary Coil

15. Secondary coil fitting 16. Secondary coil

Claims (5)

A measuring steel cable 1 supporting the structure; A measurement tension sensor (2) capable of measuring the tension applied to the measurement steel cable (1); A steel cable for compensation in a no-load state for compensating for environmental requirements applied to the measurement steel cable (1); A compensation tension sensor (4) capable of measuring the tension applied to the compensation steel cable (3); A power amplifier (5) for applying a fixed bias magnetic field or an alternating magnetic field to the measurement tension sensor (2) and the compensation tension sensor (4); The information collected from the measurement tension sensor 2 and the compensation tension sensor 4 is monitored, and the measurement is performed using the resultant values of the measurement tension sensor 2 and the compensation tension sensor 3. A central control device (6) capable of deriving the tension of the steel steel cable (1) and controlling the power amplifier (5); And converts an analog signal input from the measuring tension sensor 2 and the compensating tension sensor 4 into a digital signal, connected to the central control device 6, and transmitted to the central control device 6. Tension of steel cable using alternating current magnet; consisting of: DAQ board (7) converting the digital control signal transmitted from the central controller (6) to the power amplifier (5) to an analog signal and transmitting it to the power amplifier (5) Measuring device. A measuring steel cable 1 supporting the structure; A measurement tension sensor (2) capable of measuring the tension applied to the measurement steel cable (1); A power amplifier (5) for applying a fixed bias magnetic field or an alternating magnetic field to the measurement tension sensor (2); A temperature sensor 8 capable of measuring the temperature of the measuring steel cable 1; While monitoring the information collected from the measuring tension sensor 2 and the temperature sensor 8, and using the resultant values of the measuring tension sensor 2 and the temperature sensor 8, the measuring steel cable ( Derive the tension of 1), A central control unit (6) capable of controlling the power amplifier (5); Connected to the central control unit 6 and converts the analog signal input from the measuring tension sensor 2 and the temperature sensor 8 to a digital signal to transfer to the central control unit 6, the central control unit A device for measuring tension of steel cables using alternating magnetism comprising a DAQ board (7) for converting a digital control signal transmitted from (6) to the power amplifier (5) to an analog signal and transmitting the analog signal to the power amplifier (5). The method according to claim 1 or 2, A control start switch capable of controlling the power amplifier 5 according to a control signal input from the central controller 6 and the DAQ board 7 between the power amplifier 5 and the DAQ board 7; 9) is an additional device for measuring the tension of the steel cable using alternating magnetism. The method according to claim 1 or 2, The primary coil 14 of the measurement tension sensor 2 or the compensation tension sensor 14 directly connected to the power amplifier 5 may accurately sense the current flowing through the primary coil 14. The shunt 10 is directly connected, The output signal branched from the shunt 10 is combined with the preamplifier stage 11 to amplify a very small current signal input from the shunt 10 to an appropriate magnitude, and then to the DAQ board 7. Tension measuring device of steel cable using alternating magnetism, characterized in that the transmission. The method according to claim 1 or 2, An input / output terminal of the DAQ board 7 may be equipped with a measurement start switch 12 which may be operated when the tension of the measurement steel cable 1 reaches a target value or when the tension measurement condition is satisfied. Tension measuring device of steel cable using alternating current magnetism.

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