Tracing a cable line along the bottom of a reservoir

After the completion of the construction of communication lines from the contractor, as a rule, it is always a problem to achieve high-quality as-built documentation. The documentation that I had to deal with on duty was a very sad sight. The outlined line with an approximate reference to the terrain is not very informative when you need to find a cable line with at least an accuracy of 1 meter. As a result, a lot of time is spent looking for the location of the laid cable line.

The task becomes more complicated if the cable is laid along the bottom of the reservoir. There is such a way of laying FOCL, when the cable is laid on the bottom and gradually sinks into the silt, where it then works for years.

And then the day came when they decided to drain, clean and deepen the bottom of this same reservoir. Needless to say, such work is accompanied by the use of special equipment and damage to the cable line could not be avoided.

You can’t do without tracing a communication line. This process includes measuring the depth of the cable and its location. Since the cable has been lying in the muddy bottom for many years, the route wags from side to side, and the depth is different everywhere. Therefore, for more accurate tracing results, milestones had to be placed much more often than usual.

The first surprise was not long in coming. A lot of interesting things can be found at the bottom of the reservoirs, and unfortunately this is not a treasure, but an optical coupling. It will be the starting point of our tracing.

locator POISK-410 Masteran indispensable tool for these cases.

The device consists of two parts: generator and receiver. It has two modes of operation: active and passive. Everything is just an active mode with a generator connected, and a passive one without a connection. We will use the active mode, this method is the most accurate. So let’s connect the generator to the cable line. Since we are dealing with an optical armored cable, we will make the connection to the armor. An alternating current will flow through the cable, which will create a magnetic field and the trace detector will catch it.

The picture shows the GK-310A-2 generator manufactured by SvyazPribor
The picture shows the GK-310A-2 generator manufactured by SvyazPribor
locator
locator

When searching for a cable route, one should be guided by the display readings and a characteristic sound that indicates the minimum and maximum of the magnetic field created in the cable armor.

From the device manual POSTIK 410 SVYAZPRIBOR
From the device manual POSTIK 410 SVYAZPRIBOR

A bit of theory.

Direct connection to the cable line is the key to successful routing. When grounded at the other end of the cable line, the signal level is the highest.

If you pay attention to the picture above, we will see that the maximum signal level will be exactly at the moment when we are directly above the cable. An audible indicator on the device will notify us of this event.

Very important!!!

The correct connection of the generator to the cable is equal to a successful search. If there is no current in the cable, which will create a magnetic field, then you will not find a cable, no matter how hard you try.

To organize a loop for signal propagation, you need to bring the armor to the ground shield at the far end of the cable, and also connect the ground to the connector on the generator.

Armor output to the ground shield at the far end of the cable.
Armor output to the ground shield at the far end of the cable.
Generator connection diagram.
Generator connection diagram.

In general, the circuit should look like this: a red connector to the armor of the routed cable, a blue connector to ground.

You can search for a cable both at the maximum and at the minimum of the signal. The display shows information about the signal level, depth, current strength and battery level. In addition, there is a scale for setting the sensitivity of the receiver.

Peak values ​​or even an “overload” signal will notify you that the cable line is directly below you. The “overload” signal occurs if a high sensitivity of the receiver is set.

Using this data, we set marks (pegs) directly above the cable. They will be reference points for special equipment during earthworks. Such landmarks are shown in the photo.

Our expeditionary corps overcame difficult mud obstacles to the tracing site and reliable assistants such as UAZ Patriot, UAZ Bukhanka, UAZ Farmer helped us in this. We were still waiting for obstacles on the way in the future, but the harsh domestic auto industry easily overcame them without the help of a tractor.

As they say, there are three types of weather in our country: mud, mud dried up and mud froze! The third state has come, winter has come. It was in winter that large-scale work began on cleaning and deepening the bottom.

The trace completed successfully. The cable line remained intact and unharmed.

Well, we got a unique experience in tracing a line along the bottom of a reservoir.

I hope you have read to the end. If you have any questions let me know in the comments.

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