Factory test

The factory test is the phase in which the behaviour of the new transformer (just built or following major revision) is assessed; the transformer is filled with oil and undergoes thermal and/or electrical testing (e.g. partial discharge test, heating test, insulation tests, chopped-lightning, impulse test) in line with the reference standards.
When the tests have been completed, the impreganting/filling oil is drained from the transformer. After emptying the oil from the casing, the latter is filled with a protective gas (nitrogen) and then pre-transport activities are carried out.

It should be noted that 10/15% of the oil used for the tests (even after emptying) remains impregnated in the solid insulation, and is deposited in the form of films on the inner surfaces of the transformer, the bottom of the casing and in the dead points of the radiators.

During the factory tests, Sea Marconi is able to support the owners in the activities of supervision of the oil-transformer system in relation to what was agreed between the manufacturer, the owner and the third party operator.

In concrete terms, Sea Marconi performs:

A. sampling activities, oil analysis, certification of analytical results. The types of control vary based on the type of machine-oil and the critical issue diagnosed.

Specific indicators to be monitored are mainly dissolved gases: hydrogen, hydrocarbon gases (methane, ethane, ethylene, acetylene), carbon monoxide, carbon dioxide, oxygen and nitrogen, based on the detection limits required for the acceptance test (see Table 5, p. 47 IEC 60567).
For factory tests, the limits of detection of dissolved gases are much stricter than those required for the analysis of gas in operation (also in view of rapid changes in values); for some gases, the value is 10 times lower. This obviously requires greater precision in execution of the test (and sampling) and a correct expression of measurement uncertainty, which is why it is recommended that accreditation of the test of dissolved gases be requested.

Factory Test

B. diagnosis of critical issues in the oil-transformer system.

In particular, it is necessary to verify the absence of cross-contamination (possible contaminants include: water, particles, PCB, DBDS, corrosive compounds, polar compounds, dissolved metals, DBPC, Irgamet 39, Irgamet 30, BTA) that may result from the use of low-quality oil, or failure to wash the impregnation/treatment systems* properly;

C. final report recommending appropriate corrective actions (solutions) to eliminate or mitigate any critical issues that have been identified. Some of the most important corrective actions regard the oil itself (impregnation, transformer filling, physical treatment, selective depolarisation, and integrated treatment of the oil-transformer system), or the electro-mechanical activities on the machine.

 

Sea Marconi can also assist transformer manufacturers to select the appropriate impregnating oil and to identify potentially critical issues with the oil during factory testing.

Before factory testing, transformers are normally filled with oil by the manufacturers, using their own equipment such as storage tanks, tubes and oil treatment systems .

? Can I trust the oil used for factory tests? Can I request that the factory tests be carried out using the oil specified and ordered for use in the field?

​Contact us to find out more

? Are you familiar with the critical issue of "cross contamination" and when it may occur?
Contact us to find out more. Sea Marconi has recently dealt with a series of cases of this type.

 

Why choose Sea Marconi?

 

- Sea Marconi is a third party supplier operating independentlyof transformer manufacturers and oil producers.
- In 2017 alone, Sea Marconi performed over 11,400 dissolved gas tests, the main test involved in the factory testing phase. The dissolved gas test is one of the tests that Sea Marconi is accredited to carry out, and represents both a guarantee of analytical quality and a benefit to the customer.
- Availability of a complete field kitset for initial screening of the oil directly in the field (PCB, acidity and total corrosive sulphur screening)

 

Regulatory requirements

 

IEC 60422 ed. 4.0 - 2013 -> Mineral insulating oils in electrical equipment - Supervision and maintenance guidance
IEC 61181 ed. 2.0 - 2007 -> Mineral oil-filled electrical equipment - Application of dissolved gas analysis (DGA) to factory tests on electrical equipment
IEC 60567 ed. 4.0 - 2011 -> Oil-filled electrical equipment - Sampling of gases and analysis of free and dissolved gases – Guidance


More details on the IEC website

 

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