Cable fault pipeline locatorPanel Introduction

① Key ② Output Port ③ LCD Display Area ④ Frequency Composite Key ⑤ Power Adjustment Composite Key ⑥ Menu Composite Key

⑦ Charging port

Feature Overview

① Key: This switch is a self-locking switch; Press to turn on the power, the transmitter is in working state; Pop up and disconnect the power, the transmitter is in a shutdown state.

② Output port: This interface is a multi-core dedicated aviation socket; Used to change the output mode of a signal. Connect directly to the direct connection mode; The connection of the coupling clamp is in coupling mode; Not wired for induction mode.

③ LCD display area: displays the required basic information.

④ Frequency key: This key is a jog soft switch; Pressing once can change the frequency of the output signal; The initial startup frequency is 577Hz. In induction mode, the initial frequency is 8KHz. When in the frequency setting menu interface, press this button to select or cancel the frequency covered by the light bar; When setting up multi frequency mode, pressing this key can select to change the output frequency path.

⑤ Power key: This key is a jog soft switch; Press once to change the output power, and switch between low, medium, high, and full gears. The initial startup is in low gear; When in the frequency setting menu interface, press this button to scroll up and down the frequency menu; When setting up multi frequency mode, press this key to select the output frequency.

⑥ Menu key: This key is a jog soft switch; Press this key to cycle through the frequency setting menu, resistance measurement mode, and multi frequency mode settings.

⑦ Charging port: This interface is a Φ 2.1 charging dock; Used to connect a dedicated charger to charge the battery.

Interface Introduction

Normal output interface

Frequency: Display the current output frequency.

Power: Display the current output power; It can display low gear, medium gear, high gear, and full gear separately.

Mode: Display the current working mode; It can display direct connection, coupling, and induction separately.

Current: Display the current loop current value; The effective display is 0-999 milliamps.

Impedance: Display the current loop impedance value; The effective display is 00001-20000 ohms.

Battery level: Indicates the current battery level; Represented by battery symbol, all black indicates full charge, and the left side displays the current battery percentage.

Matching prompt: When the circular ring below the image starts rolling, it indicates that the transmitter is working stably.

working principle

Cable fault pipeline locatorIt is a high-tech product designed based on the reflection principle and electromagnetic induction principle of electromagnetic waves during transmission, combined with digital filtering, wireless reception, and software control.

Electromagnetic induction: Its basic working principle is that the transmitter generates electric and magnetic waves and transmits the transmitted signal to the underground detected cable through different transmission connection methods. After the underground cable senses the electromagnetic waves, an induced current is generated on the surface of the underground cable, and the induced current will propagate along the cable to a distance. During the propagation of the current, electromagnetic waves will be radiated to the ground through the underground cable. In this way, when the underground cable detector receiver detects on the ground, the electromagnetic wave signal will be received on the ground directly above the underground cable, and the position and direction of the underground cable can be determined by the changes in the strength of the received signal.

The conditions for implementing this principle are: firstly, there must be a signal source capable of generating sufficient electrical energy to form a current in the line capable of transmitting electrical energy, and the current will generate a magnetic field around the line during the flow process; Secondly, there should be a circuit that can receive this specific magnetic field and display the process of magnetic field changes in the form of electrical signals.

Signal output mode - transmitter working mode

The transmitter can output different AC signals and can be applied to the target cable in three ways (direct connection, coupling, induction). To ensure reliable transmission of signals on the target cable, there must be a reliable circuit in the line. It can be an indirect circuit composed of the earth, a capacitive circuit composed of distributed capacitance formed between sufficiently long cables and the earth, or a direct circuit composed of short-circuit fault points between lines. Different circuits meet different tests

Direct connection method

The signal from the transmitter is directly applied to the target cable (power outage cable) using a direct connection method. Directly connect the dividend and black wires, connect the red wire to one of the cables, and the black wire is the working ground wire of the instrument, which should be reliably grounded separately. To ensure reliable one-way transmission of signals in the line, it is required to disconnect at least the target cable

One end of the ground wire allows the signal to flow back through the earth in an indirect or capacitive loop, as shown in the figure.

The direct connection method uses cables to directly transmit signals, with minimal attenuation, strong signal strength, and long transmission distance. It is the best method for signal application and is suitable for the transmission of any type of signal. It is a testing method.

Coupling method

The signal from the transmitter is applied to the target cable using coupling clamps, which is known as coupling method. To ensure reliable transmission of coupled signals in the line, it is required that the clamp must be closed and there must be ground related contact points at both ends of the cable, as shown in the figure.

The strength of cable coupling to the signal is directly related to the frequency of the signal, with weak coupling at low frequencies and strong coupling at high frequencies; Sometimes it is also related to whether the line is running. At the same frequency, the signal coupled to the running cable is stronger than that of the non running cable. So the coupling method is particularly suitable for live path measurement and live recognition.

Induction method

1. Induction conditions

1) There must be grounding points or points associated with the ground at both ends of the cable

2) The placement of the transmitter requires that the induction test line must be aligned with the cable direction

3) The burial depth cannot exceed 20 meters

2. Induction signal application

Press the power switch of the transmitter to select high frequency or full RF power When the icon at the bottom right of the LCD appears, it indicates that the transmitter is working properly

The transmitter is placed above a known point on the cable, and the induction test line is aligned with the direction of the cable at this point

Extension of Induction Detection - Blind Testing

1. Blind testing principle

Blind testing is a testing method that uses the induction mode of instruments to measure unknown metal pipelines and various cables. It uses the built-in antenna of the transmitter to emit high-frequency or radio frequency electromagnetic signals in a certain direction underground (and also in the air). When the electromagnetic signal touches the underground metal pipeline, it will be transmitted by the metal pipeline in the form of current. At the same time, a secondary magnetic field will be radiated from the pipeline. The receiver can receive this secondary magnetic field signal above the pipeline, locate a point of the pipeline position, and connect the measured pipeline position points to obtain the specific location and direction of the pipeline. This is the principle of blind measurement.

The use of instrument induction blind measurement is an effective method for detecting pipelines, but it is also affected and constrained by factors such as the site environment, the material of the pipeline, and the depth of burial. Therefore, surveying an area must be combined with the surrounding area and existing drawing data, as well as various methods such as investigating local users and conducting field observations.

2. Blind testing method:

1) Preparation before testing: Before blind testing, the receiver must be placed within a certain distance range from the transmitter, usually between 5-10 meters, preferably around 7 meters. The closer one carries the transmitter to the ground, the better (try to be as close to the ground as possible). Do not connect any wires, turn on the transmitter, select high frequency or radio frequency (radio frequency is recommended), and choose high power. The other person is holding a receiver with the head pointing towards the front panel of the transmitter, and the two machines are about 7 meters apart. At this time, turn on the receiver, select the frequency corresponding to the transmitter, and then adjust the gain so that the receiver is not affected by the magnetic field signal radiated from the transmitter in the air as much as possible. Generally, reduce the gain (about 50DB) so that the signal strength of the receiver is displayed at about 500. With this signal strength as the base, keep the gain unchanged, maintain this distance, and then conduct blind testing. (Note: The distance between the two machines is close. The receiver gain drops very low, resulting in a loss of detection depth and a reduction in testing blind spots. The distance between the two machines is far, and the receiver distance is far, resulting in less receiver gain drop and ensuring testing depth. However, the secondary signal radiated is relatively weak compared to the near point, while the blind spot increases.)

a) Blind testing method one: surface testing

(1) Operation: Based on the preparation before the test, the two machines should be facing each other and moved parallel. The movement speed should not be too fast, but should be slow to allow sufficient reaction time for the instrument to test. Take the transmitter as the active and the receiver as the passive, always keeping the receiver head pointing towards the front of the transmitter and the two machines in the same state. When the signal strength of the receiver suddenly increases (with no change in gain, greater than the baseline set before measurement), it indicates that there is a metal pipeline between the transmitter and receiver points. At this point, you can lift the receiver up a bit to check if the signal strength decreases, and stick it down to the ground to see if the signal strength increases. If so, it is certain that there is a pipeline below. In this way, all metal pipelines within a depth of 2.5 meters perpendicular to the direction of movement (with a deviation angle of ± 10 °) can be measured. Once a known point is measured, the path of the metal pipeline can be determined using induction method. Then, by changing the direction of movement, the pipeline perpendicular to the direction of movement can be identified, and the pipeline within this working face can be identified.

(2) Advantages: Fast testing speed.

(3) Disadvantage: There is a blind spot on a test surface due to the inability to divide angles too finely during parallel movement, as well as the presence of pipelines that suddenly turn.

(4) Characteristics: This method is fast, effective, and suitable for finding pipelines with clear directions but unknown specific locations.

b) Blind testing method 2: point testing

(1) Operation: Based on the preparation before the test, the two machines face each other and maintain a distance. One machine (transmitter) rotates around a human axis (center) at the measured point, while the other machine (receiver) rotates synchronously on a circle with a radius of about 7 meters between the two machines (note: the two machines must rotate face to face, with the receiver head pointing towards the front of the transmitter). When rotating, be sure to slow down as much as possible to give the instrument enough reaction display time. When turning to a certain position, the receiver signal strength suddenly increases (the gain remains unchanged, greater than the pre measurement baseline), indicating that there is a metal pipeline between this point on the circumference and the two points at the center of the circle. At this point, you can lift the receiver up a bit to see if the signal is weakened, and then stick it down to the ground to see if the signal is enhanced. If so, it is certain that there is a pipeline below. By rotating once in this way, pipelines buried within 2.5 meters of the measured point (R ≤ 0.5 meters) can be measured. (Suggestion: During the rotation process, the instrument on the circumference should be the active one, and the instrument on the center of the measured point should be the passive one, synchronously rotating face to face. Because the amount of rotation on the circumference is large, the center of the circle rotates very little, so it rotates around the human axis.). After measuring the two known points of the pipeline, the path of the pipeline can be determined using induction methods.

(2) Advantages: For a certain point, the testing speed is fast, accurate, and there are no blind spots.

(3) Disadvantage: The testing area is small, less than the range of R=0.5 meters.

(4) Features: Suitable for testing on point work surfaces.