Panama has developed underground electrical supply systems in the installations of power generators, especially wind and solar plants. Their implementation greatly increases business opportunities and client acquisition. But it is worth noting that, although underground systems have operative and safety advantages over overhead power lines, they become a disadvantage when repairs are needed. Direct and simple visual inspection of faults and flaws is basically non-existent, which means that every failure turns into a challenge to restore the service quickly, efficiently, and safely.

Modernisation of the capital and hard legislation enacted by the regulatory body, along with topology changes carried out to meet quality and reliability standards in the electrical supply, have forced companies in the field to find adequate alternatives at short notice to face failures in commercial, industrial and residential areas, to reestablish service. They found their best solution in Applus+.

Applus+ in Panama has been locating flaws in the underground electrical medium voltage system since 2007. This service is focused on Panama City, with more than 800 km of underground network divided in 82 circuits, which supply over 100,000 clients. Our extensive experience over the years and our pursuit to always be a trusted partner for our clients, has led us to gather a team of carefully chosen experts and all necessary technology.

The workforce receives regular training in:

  1. Technical concepts, use of equipment, and analysis of results to identify the point of failure in the underground system.
  2. Risk analysis, use of equipment, and interpretation of results to assess potential hazards.

The steps to detect an underground failure are as follows:

  1. Adaptation of the work area and risk assessment.
  2. Determination of the failing wire/cable.
  3. Location of failure.
  4. Final testing to guarantee the network is fully operational.

 

Adaptation of the work area and risk assessment

We follow a rigorous process, starting with the adaptation of the work area after a risk assessment and control. We follow at all times the sequence of protocols for electric networks and apply basic unchanging concepts like the Five Golden Rules. We constantly monitor small spaces, adapting ventilation and employing rescue equipment for a safe and quick intervention.


Determination of the failing wire/cable:

To determine which are the failing wires/cables, we test insulation resistance; we conduct VLF (Very Low Frequency) withstand testing and continuity testing of conductors. A wire/cable in good condition will yield high readings in insulation resistance and will sustain voltage with a low leakage current. It will also maintain electrical continuity along its length, with parameters according to its conductors’ sections.

 

Location of failure:

Once we know which wires/cables are failing, we apply radar technology specifically to the time-domain reflectometer (TDR), which enables us to measure the rough distance to where the wire/cable’s characteristics drastically changed, the point of failure. Knowing the wire/cable’s trajectory, it is possible to get the precise location of the failure with the application of shock waves and their resulting acoustic and electromagnetic impulses.

 

Final testing: 

The next step is cutting to insulate the underground failure section and preparing the wire/cable on both ends. Finally, we test it to verify that the rest of it is in good condition, going through the first sequence of tests, only this time expecting positive results.