What is a cable trace?

When upgrading or repairing telecommunications and other systems, it is not always easy to find the location of the laid communications. The cable trace is the search for the place where the cable passes.

Even if it is clearly visible, sometimes it is required to track the location of the others in the beam. Often, documentation with layouts is missing or of poor quality.

Not every user understands the trace of the cable: what it is and how to produce it. In the process of performing this operation, the following tasks are solved:

• Determination of the location and depth of the signal and power cables;
• Finding faults in the lines;
• Survey of terrain before excavation to avoid damage to engineering communications.

The principle of the cable finder

The cables are searched using devices that work by the principle of the tone generator of the signal in the wires and its reception, amplification and playback through headphones or speakers.

Search, where a generator with a locator is used, is called active. The installer traces the route from the point of signal delivery along the line in accordance with the volume level. The device registers not the conductor itself, but the electromagnetic field created in it by the induced signal.

First of all, the sensor with the generator is selected with the same parameters - corresponding to the type of lines tested: underground communications, cables in buildings, power lines, metal channels. In the arsenal of installers there is a set of instruments with advanced functions, among which there is a dial, resistance measurement, etc.

The sensor can detect fields created by other signal sources:

• Lines of force;
• Telephone cables;
• Radio broadcast networks;
• Conductive lines at 140-300 kHz.

In these cases, you can do without the generator, where the search is carried out in the passive mode.

Parameters of signal generators

The main parameters are the power and frequency of the induced signal, which can be constant or in the form of several alternating (up to four) values of 0.2-130 kHz. The signal is fed in different ways:

• Direct connection to the veins by means of clamps;
• Coverage from the outside with an inductive clamp or clip without breaking the shell (in accessible places);
• Outside the antenna when the cable is placed under the ground.

Usually, the cable is traced when it is disconnected. With direct connection, the signal level is high. Some models can detect lines that are live. In this case, a direct connection is not possible. To eliminate interference from power lines, filters are used that do not pass the frequency of 50 Hz.

The disadvantage of using inductive antennas is the guidance of the signal in all nearby passing cables. However, the convenience of using the method outweighs its disadvantages. Often it is used in places where direct connection is impossible. The range of the generator is limited and sometimes its connection has to be done several times until the circuit is over.

In addition, the method with an inductive antenna is used to find communications that cross the path of the main line with the transmitter. To do this, two people move along the cable with the receivers at a distance of 20 m.

In addition to the antenna, other inductive couplers are used, which do not need to be connected to conductors. In this case, the signal is applied to only one cable.

Choice of instruments

At purchase it is necessary to select the device most suitable to a certain kind of work. The main element of the inductive probe is a sensor in the form of an antenna (pin or magnetic) of a combined device or contact device. In addition to sound indication, visual is used so that it is possible to work in the presence of noise. Sensors regulate the sensitivity.

Special models are available for tracing air and coaxial cables. When buying the product, you should read the instruction, which details the method of application.

Tracing cable lines

The underground locators of narrow specialization are widely used to detect cables laid open way or in channels at a depth of up to 2 m. Their functions may include determining the depth of occurrence and the place of closure of the braid or veins on the ground. Devices are used for tracing under the ground or in buildings.

The cable routing in the rooms is performed by universal devices with a full set of functions. With their help, you can find the conductor under the plaster, behind the panels, in the concrete floor and behind the suspended ceiling. The signal is supplied from an inductive clamp with detection at a distance of 1.5 km. It is well recognized by hearing, if it consists of two alternately fed frequencies. For the whip antenna, the conductors are kept open or closed for a high resistance load. To detect the cable with a magnetic coil, its conductors are short-circuited or through a low-resistance resistor.

Features of the search for communications

Tracing the cable requires the development of certain skills that allow you to locate the places of breaks or shorts of veins. By adjusting the sensitivity of the probe, the required wires are in the beam for a stronger signal. If his auditory perception is not always obtained in noisy places, you can use a visual indicator.

If the magnetic field is distorted by the action of adjacent conductors, the sensor reading may differ with repeated measurements. The adjusted value is found as the averaged value.

Checking the depth of the route is done at different distances from the ground. In this case, the values obtained must differ by the amount of displacement of the probe.

Tracing systems

Instruments for finding underground and overhead lines should include a full set of equipment. An example is the cable tracing kit cts 132j, designed to identify cables and pairs in telecommunications systems.

The system is used to search for underground and overhead lines and detect faults in them.

Reviews about the device cable routing cts 132j is contradictory: sometimes you have to buy accessories, which is more expensive. Here it is important to choose the right service.

Test set 701K

A cable trace set serves to search for wires on a line or in bundles, to determine breaks and short circuits.

The main elements are a tone generator and an inductive probe. The device works with any wiring: single conductors, twisted pairs, coaxial cables. There is an audible and visual indication of the signal. Upgrading the device is a set of 711K, where 3 sounds are added .

Cable tracing kit TEMPO CTS 132j

The system includes a tone generator with varying frequency of the signal being fed. To find the magnetic field, a coil is used, and the electric field is an inductive probe. In the first case, obtaining a strong signal is provided by closing the pair at the far end, and in the second - it is opened. The presence of an outer shell of the foil shields the electric field, but the magnetic field is easily detected. When tracing a cable, the signal can be fed through a shield braid. The kit is designed to find pairs in couplings, search for wires on lines and in switch cabinets, detect short circuits and breaks.

IntelliTone Trace Set

The kit is designed for tracking and finding cables in active networks. The generation of digital signals excludes the guidance of foreign signals, ensures the determination of the necessary strands in the bundles, determines the defects. An analog mode is also allowed.

Cable tracing kit MT 8200 60A

The system makes it possible to search for telephone, coaxial cables, twisted pairs, other types for security systems and television. Also, there is the use of digital signals that reduce the influence of interference.

Optical cable search

The fiber optic cable may contain metal elements. Here you should use them similarly to the screen of a conventional wire. The optical cable is routed by connecting the generator to the metal shell in any known way, after which it can be searched using a probe.

If the cable does not contain metal elements, it is marked during installation. To do this, a resonance circuit is installed on the cable from the inductive coil and the capacitor. The so-called passive cable marker, for which no power is required, receives and reflects the signal from the emitter. This is the location of the line.

Conclusion

Tracing allows you to determine the direction and location of hidden long objects, mainly - cables. It is important to correctly adjust the volume level of the signal on the transmitter and receiver. Particular attention is drawn to the places of its sharp change. These can be pick-ups from metal parts under the ground, the formation of branches, changing direction, the end of the cable, changing the depth of occurrence, the appearance of a parallel parallel conductor.