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Laboratory for Equipment and Electrical Facility Diagnostic


The Laboratory for Equipment and Electrical Facility Diagnostic (Labdig), implemented by Cepel in 1998, develops projects, studies, technical analyses and investigations on the causes of failures, equipment and facility assessments with the aim of reducing maintenance costs, increasing electrical system reliability and also extending equipment service life.

Located in the Fundão Unit, Labdig develops, implements and applies techniques for projects of electricity utilities, mainly Eletrobras companies. The laboratory also interacts with some universities providing support for applied research and the development of specific tools needed for models and diagnoses.

The laboratory has cutting-edge instruments and masters state-of-the-art diagnostic techniques which, allied to a multidisciplinary team, allow identifying a variety of situations and indicating the most adequate techniques to be applied in each event and facility.

The laboratory's instruments and trained staff allow dealing with the following techniques:

• Partial Discharges (Electromagnetism)

• Acoustic Emissions

• Return Voltage (Polarization Spectroscopy)

• PDC – Polarization Depolarization Current

• Frequency-Domain Characterization (up to 10 MHz)

• Remote monitoring for characterization of voltage transients produced by switching equipment (conventional and SF6 substation circuit breakers and isolation switches) on power transformers

• Chromatography of gases dissolved in insulating oil (in the field and online)

• Thermography

• Leakage current

All information resulting from field measurements and assessments is stored in a database with data relative to over 100 power transformers and 3,000 power station lightning arresters. Algorithms and computational intelligence techniques can be applied to increase the reliability of diagnoses (neural networks, fuzzy, wavelets).

Current laboratory activities are related to:

• real-time monitoring of On-Load Tap Changers (OLTCs)

• development of a method for field assessment of 500 kV TCs

• monitoring displacements of large transformer coils

• development of techniques for assessment of the electric insulation of transformers and reactors

• integration of diagnosis methods for the assessment of lightning arresters and instrument transformers in the field

• assessment of interactions in power transformers and electrical system (Tijuco Preto - Furnas Substation).

Some of the laboratory's clients are: electricity utilities such as the Eletrobras companies, Furnas, Eletrosul, Chesf, Eletronorte and Eletronuclear.

See below further information on the software programs developed by Labdig. For the services provided by the laboratory, please click on the "Services" tab.


In addition to a set of cutting-edge instruments, Labdig has at its disposal special power supplies (200 kV AC power supply free of partial discharges, and 1000 kV impulse generator) necessary for high voltage experiments and for validation of the techniques being developed.


• Software programs
• Services
 CDF – Frequency- Domain Characterization

• Software Programs
• Services
 Transient Measurement
 Frequency- Domain Characterization
 Acoustic Emission Technique
 Field Analysis of Gases Dissolved in Isolating Mineral Oil
 Application of the Acoustic Methodology for Diagnosis of SF6 Gas Insulated Systems
 Assessment of Equipment State and Investigation of the Causes of Failures
 Remote Measurement of Electromagnetic Transients in Substations
 Characterization of Transformers and Reactors in the Frequency Domain up to 10 MHz
 Monitoring of Power Transformers and Reactors by Acoustic Emissions



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