Insulation diagnostic and on-site testing

LCOE has different mobile test generators, some of which are of its own design and development, and pioneers in Spain. With them, it has been providing the service of on-site testing of high voltage equipment to the electrical industry since 2005.

The most advanced technologies are also used to diagnose the insulation of high voltage equipment by measuring partial discharges, today the most effective technique for evaluating the insulation of these equipment.

The measurements are carried out in the tests prior to the commissioning of the equipment (off-line techniques) and also during their normal operation (on-line techniques), in this case by periodically monitoring the activity of partial discharges in isolates.

“Off-line” trials

The LCOE has the following mobile facilities for off-line testing:

  • “Off line” tests for Cables: There are three resonant generators installed in mobile laboratories for PD measurement: 36 kV-17 A generator, 265 kV-82 A generator and 680 kV-3 A generator to test cables of lengths from 10 m to 10 km.
  • Testing “off line” of Power Transformers. There are two mobile facilities for induced voltage testing of power transformers: the facility for testing medium power transformers of up to 120 MVA (installed in a 6 m long container) and the facility for testing high power transformers of up to 700 MVA (installed on a 13 m long trailer).
  • GIS “off line” tests. There is a specific installation for GIS tests, composed of a 680 kV-3 A resonant generator with three reactances of 250 kV, each one.

On-line tests

The LCOE uses the Partial Discharge measurement technology appropriate for “on-line” measurements.

Depending on the installation, different types of sensors are used (HF, VHF and UHF), different filtering technologies (filtering by selection of the measurement frequency, Wavelet filtering, etc.) to discriminate the electrical noise from the PD signals, different techniques for locating the position of the discharges (reflectometry, GPS, etc.), and different ways of identifying each PD source with the type of defect or cause that originates it.

The LCOE provides itinerant insulation monitoring services on a continuous basis, by measuring PDs in electrical installations, which makes it possible to analyze the evolution of PDs over time and assess their criticality.

Tests and measurements according to IEC 60060-3

Commissioning of high voltage lines

  • 260 kV – 83 A Resonant generator.
  • 680 kV – 3 A resonant generator.
  • Main insulation test.
  • PD measurement.
  • Dielectric test of the cover.
  • Measurement of resistance of the conductor and screen.
  • Delta tangent and capacity measurement.

On-site tests on power transformers

  • Transformers up to 500 MVA.
  • Testing of complete installations (GIS + lines).
  • Induced surge test.
  • Measurement of partial discharges.

Measurement of overvoltages on screens in GIS substations

  • Measurement of overvoltages in p.a.t of substations.
  • Transient modeling using ATP

Diagnosis of insulation systems

  • Continuous or itinerant monitoring through partial downloads.
  • Comprehensive systems for GIS lines or substations
  • Periodic reports of diagnosis and evolution of discharges.