Oil analysis and transformer diagnosis

Sea Marconi has developed the Deosvision service for analysis and diagnosis, which is aimed at preventing the catastrophical failure of electrical equipment linked to critical issues,
In fact, it is very similar to what happens in clinical diagnostics, as one can monitor the health status of the transformer by analyzing a sample of oil taken from it and then make the subsequent diagnosis.

Deosvision involves the following steps:

  1. Sending the client a kit to sample the fluid
  2. Extracting the sample from the transformer and sending it to the Sea Marconi laboratory
  3. Completeing the required laboratory analysis
  4. Issuing the diagnostic report, which clearly highlights both the problems identified, and the course of action to take.

What analysis is there to do on the different transformers? How often is it necessary to repeat the analysis? How can one be sure that the transformer does not have, for example critical corrosion issues or gas dissolved in the oil?

Diagnostic packages

Based on the investigation’s aim Sea Marconi can suggest a specific diagnostic package (with a series of targeted analysis), for example to know the state of health of a transformer at a specific point in its life cycle (LCM) or to identify/expand on a particular critical “disease” that the oil or transformer has.

Below are the main packages:

Objective: evaluation of the occurrence of thermal or electrical faults during factory tests (heat or other tests).

Application: applied to all insulating liquids.

Tests include:

Dissolved Gas: (DGA) (IEC 60567) A

 

Diagnostic interpretation: This package does not include diagnostic assessments, which are delegated to the manufacturer or in general to the client requiring the test.

A Test accredited by Accredia

Note:
The measured value of dissolved gas depends on the nature and duration of the test run, and it is usually agreed between the equipment supplier and the purchaser.

Objective: Evaluation of the oil’s functional deterioration, and its main dielectric properties

Application: applied to all insulating liquids.

Tests include:

  Appearance (visual)

  Colour (ASTM D 1500 or ISO 2211)

  Dissolved Water (IEC 60814) A

  Dielectric Dissipation Factor – DDF – Delta tangent (IEC 60247)

  Relative permittivity – Relative dielectric factor (IEC 60247)

  Neutralization number – TAN (1) (IEC 62021-1)

  Particles in suspension, number and dimension >4, >6, >14 µm (IEC 60970)

  Hydrocarbons in the askarel (2) (CEI 10-6)

 

Diagnostic Interpretation: Included

A  An ACCREDIA accredited test

Note:
(1) do not apply to chlorinated insulating liquids (Askarels)
(2) Apply only to chlorinated synthetic insulating liquids (Askarel)

Objective: Targeted evaluation of some of the oil’s and transformer’s functional deterioration factors:
Functional deterioration of the insulating liquid by a reduction in its main dielectric properties and the possible presence of physical contaminants;
Functional deterioration of the transformer by dissolved gas analysis (DGA), to identify and classify the presence of any incipient functional defects in the machine, before they develop into failures and interruptions in service: electrical anomalies (high or low energy discharges , partial discharges, corona effect), thermal anomalies (thermal oxidation, hot spots), solid insulation deterioration.

Application: applied to all insulating liquids

Tests include:

  Appearance (visual)

  Colour (ASTM D 1500 or ISO 2211)

  Dissolved Water (IEC 60814) A

  Dielectric Dissipation Factor – DDF – Delta tangent (IEC 60247)

  Relative permittivity – Relative dielectric factor (IEC 60247)

  Neutralization number – TAN (1) (IEC 62021-1)

  Particles in suspension, number and dimension >4, >6, >14 µm (IEC 60970)

  Hydrocarbons in the askarel  (2) (CEI 10-6)

  Dissolved Gas (DGA)  (IEC 60567) A

 

Diagnostic Interpretation: Included

An ACCREDIA accredited test

Note:
(1) do not apply to chlorinated insulating liquids (Askarels)
(2) Apply only to chlorinated synthetic insulating liquids (Askarel)

Objective:
– The insulating liquid’s state of functional deterioration;
– the machine’s state of functional deterioration (any thermal or electrical faults);
– the state of corrosion or erosion, by dissolved metal and element analysis as well as external contamination factors (calcium, silicon, potassium), the quality of the refining and desulphurisation of petrol (total sulphur);
– the state of deterioration for solid insulation, through 2-furfuraldehyde and furan compounds analysis, related to the concentration and rate of water, CO2 and CO formation.

Application: applied to all insulating liquids.

Tests include:

  Appearance (visual)

  Colour (ASTM D 1500 or ISO 2211)

  Dissolved Water  (IEC 60814) A

  Dielectric Dissipation Factor – DDF – Delta tangent (IEC 60247)

  Relative permittivity – Relative dielectric factor  (IEC 60247)

  Neutralization number – TAN (1) (IEC 62021-1)

  Particles in suspension, number and dimension  >4, >6, >14 µm (IEC 60970)

  Hydrocarbons in the askarel  (2) (CEI 10-6)

  Dissolved Gas (DGA)  (IEC 60567) A

  Dissolved Metals (ASTM D 7151)

  2 – Furfural and furan compound derivatives  (IEC 61198) A

 

Diagnostic Interpretation: Included

A An ACCREDIA accredited test

Note:
(1) do not apply to chlorinated insulating liquids (Askarels)
(2) Apply only to chlorinated synthetic insulating liquids (Askarel)

Objective: Targeted evaluation of the critical factors related to the state and rate of thermal decay in solid insulating materials (Kraft paper), by means of analysing and studying the trend in the card’s main thermal degradation markers.

PThis provides an annual or biennial monitoring plan, completing a minimum program of four samples taken on a regular basis (quarterly or biannually) to identify the card’s state and relative rate of decay, compared to the same types of transformers and equipment in typical conditions.

Application: applied to all insulating liquids.

Tests include:

  Dissolved Water  (IEC 60814) A

  Dissolved Gas –DGA ( IEC 60567) A

  2 – Furfural and furan compound derivatives  (IEC 61198) A

At the end of the monitoring plan the Kraft card’s state of thermal decay is evaluated as well as the related life consumption, and where possible, an estimate of the equivalent DP range based on different algorithms and interpretative models.

 

Diagnostic Interpretation: Included

 

A An ACCREDIA accredited test

DEOS CORROSIVE BASE

Objective: Evaluation of the insulating liquids’ corrosiveness, according to the Report Cigre WG A2.32.

Application: Applied only to mineral insulating oils.

Tests included:

  Potentially Corrosive Sulphur – CCD teston conductors wrapped in paper (IEC 62535) (IEC 62535)

  TTAA (Toluil-triazolammina) – Irgamet®39 (IEC 60666)

Diagnostic interpretation: The package includes a general comment on the corrosive conditions of the oil as highlighted by the test results..

DEOS CORROSIVE COMPOUND

Objective: Quantitative evaluation of the presence different corrosive compounds in insulating liquids.

Application: Applied only to mineral insulating oils.

Tests include:

  DBDS – dibenzyl sulphide (SMT internal method – GC/AED)

  Total Mercaptans and disulphides (SMT internal method – potentiometric titration)

Diagnostic interpretation: the package includes a general comment on the corrosive conditions of the oil highlighted by the test results.

DEOS CORROSIVE SCREENING

Objective: Targeted evaluation of the corrosiveness of insulating liquids and the interaction of any present additive, in order to determine the deterioration mechanisms correlated to:

– the formation of copper sulphate on bare copper conductors
– the formation of copper sulphate deposits on Kraft paper in the reels
– the presence of additives that can alter or mask the intrinsic reactivity of the oil.

Application: Applied only to mineral insulating oils..

Tests include:

  Corrosive Sulphur on copper specimens (ASTM D 1275 B)

  Potentially Corrosive Sulphur – CCD test, on conductors wrapped in paper (IEC 62535)

  DBDS – dibenzyl sulphide (SMT internal method – GC/AED)

  Passivating triazole additives – BTA + TTAA (IEC 60666)

  Phenolic antioxidant additives – DBPC + DBP (IEC 60666)

 

Diagnostic interpretation: the package includes a general comment on the corrosive conditions of the oil highlighted by the test results.

DEOS CORROSIVE DELUXE

Objective: Targeted evaluation of the corrosiveness of insulating liquids and the interaction of any present additive, in order to determine the deterioration mechanisms correlated to:

– the formation of copper sulphate on bare copper conductors, qualitative and quantitative evaluation
– the formation of copper sulphate deposits on Kraft paper in the windings
– the presence of additives which may alter or mask the intrinsic reactivity of the oil
– evaluation of DBDS decomposition by-products.
BDS.

Application: Applied only to mineral insulating oils.

Tests include:

  Potentially Corrosive Sulphur – CCD test, on conductors wrapped in paper  (IEC 62535)

  DBDS – dibenzyl sulphide (SMT internal method – GC/AED)

  Passivating triazole additives – BTA + TTAA (IEC 60666)

  Phenolic antioxidant additives – DBPC + DBP (IEC 60666)

  BBZ – Bibenzyl (test method: SMT internal GC/MS)

  TCS – Total Corrosive Sulphur (SMT internal method)

 

Diagnostic interpretation: the package includes a general comment on the corrosive conditions of the oil highlighted by the test results.

Obiettivo: valutazione mirata di PCB/PCT/PCBT nei liquidi isolanti e prodotti petroliferi,oli nuovi ed usati, in conformità alla Direttiva 59/96/CE (Art. 2) del 16/09/1996, allo stato dell’arte (BAT).

Applicazione: si applica su tutti i liquidi isolanti.

Prove incluse:

  Policlorobifenili in conformità a IEC EN 61619:1997 A

  Policlorotrifenili (PCT) e Policlorobenziltolueni (PCBT) in conformità a EN 12766:2005 (Parte 3). A

Prevede il riconoscimento della miscela commerciale che costituisce la contaminazione dell’olio (ad esempio: miscele Aroclor di PCB, miscele Ugilec per i PCBT).

Qualora dalle misure risulti che il campione esaminati è costituito da PCB puro (Askarel), la quantificazione dei PCB non sarà eseguita, e verrà fornita evidenza mediante spettro FT-IR nel campo degli infrarossi

Interpretazione diagnostica: include pareri ed interpretazioni circa la conformità alle Direttive e Leggi vigenti.

A prove accreditate da ACCREDIA

What makes our service so effective?

Firstly, the Sea Marconi laboratory is an international leader in insulating fluid and electrical equipment deterioration diagnostics: powerful and scaled transformers, reactors, rectifiers, drives and loops.Furthermore we are known for the following key points:

Complying fully with industry standards

We are state of the art regarding industry standards, thanks to our help in writing them.In fact Sea Marconi takes a active in improving international standards (egIEC).Sea Marconi played an key role, for example; the discovery of DBDS in 2005; the study of particles since 1976 and metals since 1982; PCBs identification methods in fluids using the gas chromatography technique with high resolution capillary column (1979).

The certification of our tests

The work of our laboratory is constantly monitored and periodically certified (as well as ISO 17025) by the Italian accreditation ACCREDIA.Thanks to agreements between ACCREDIA and ILAC (International Laboratory Accreditation Cooperation), Sea Marconi’s accreditation is internationally valid.Certification guarantees controls on the work done by the laboratory, which occurs periodically by inter-laboratory testing, Round Robin Test (RRT).

Profound subject knowledge

Due to our experience in the industry since 1968, Sea Marconi has developed particular expertise in the field, i.e. monitoring critical issues (illnesses) for each type of transformer, by analysing the oil in order to identify specific indicators (markers)

Nonstop research and development

leads to new solutions for problems which are yet to be regulated, as well as new analytical techniques and new ways of launching them on the market

The development of an unparalleled diagnostic tool

i.e. a single process that examines not only the signs and symptoms of a transformer, but correlates them with similar ones to identify trends within particular parameters, and risk factors of, enabling us to predict the way the current problem will develop (prognosis)

The largest data bank in the private sector

which allows us to derive statisitics for every problem’s (functional or environmental) standard, warning and alarm values depending on the type of transformer and insulating oil

In an emergency, the Sea Marconi laboratory provides an analytical response in just 4 working hours

  • 17.500 – fluid samples analyzed in 2017
  • 10.000 – Transformers analyzed in 2017
  • 85.000 – Laboratory tests carried out in  2017
  • > 75.000 – Transformers in our database
  • > 240.000 – Total diagnoses are in our database

The dielectric fluid industry is becoming ever more sophisticated.Imagine that just among the category of new mineral oils one can now count more than 30 different oils (See.IEC 60296), then there are natural or synthetic esters that further complicate the task of identifying the state of deterioration.As for less common oils there is not a great number of case studies and often there is not even a reference standard.

Sea Marconi can boasts plenty of experience even with “niche”oils. With natural esters for example, which currently are preferred from an environmental aspect due to their biodegradability and fire risk, not only when doing diagnostics it is necessary to adopt very different interpretive criteria compared to mineral oils, but also during the treatment phase, when totally different considerations need to be taken in to account.

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