In order to verify the general condition of the transformer and to program the preventive or corrective measures, electrical and dielectric tests are carried out.

The service consists of cleaning, physical inspection of the transformer, as well as insulation resistance tests, transformation ratio, ohmic resistance and inductance measurement.

The above is done with measurement and test equipment designed for that purpose, following the guidelines established by the IEEE C57.12.00-2010 standard; IEEE C57.12.90-2010 inherent to test methods for distribution and power transformers.

Service description

- Transformer data record.

- Maneuvers de-energization and grounding.

- Review of the oil level indicator, temperature, maximum temperature.

- External revision and cleaning of the transformer tank.

Image showing three transformers placed in their respective pole and in correct operation

- Transformer preparation (identification and disconnection of the primary and secondary side).

- Measurement of insulation resistance (megohmmeter).

- Sampling and Physical-Electro-Chemical Analysis to Insulating Oil Dielectric strength (kV).

- Measurement of transformation ratio (TTR).

- Measurement of ohmic resistance (micro-ohmmeter).

- Subjection and verification of external connections on the primary and secondary terminals of the transformer.

- Change of packages if necessary.

- Sampling and Analysis for Detection of Polychlorinated Biphenyls

- Removal of grounding and energization of the transformer.

- Delivery of the report in digital form of the service performed.

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- Qualified technical personnel.

- Properly calibrated measuring and testing equipment.

- Use of personal protective equipment.

- The equipment operates in better safety conditions, since its status and operation are known.

- Digital results report.

Set of transformers placed on a pallet as part of inventory in stock


The test service is applicable to medium voltage distribution, pedestal or dry transformers.


It is recommended to perform preventive maintenance to the transformer periodically to ensure its proper functioning and general condition.

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Contact us

For more information:

- Phones: 2295-1167 / 2295-1178

- Email: This e-mail address is being protected from spambots. You need JavaScript enabled to view it.

- Or by means of the following form

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Contact Information

  • Address:

    5 Avenue, 1 and 0 Street, Central Offices, San José, Costa Rica

  • Phone:

    (506) 2295-5000 / Monday to Friday from 7 am to 6 pm

  • Ext:

    10026-1000 San José, Costa Rica

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