On-Site maintenance is recommended when the transformer feeds a critical load which due to production or availability is not possible to take out of service. To perform a on-line maintenance the transformer and its insulating oil are required to meet certain standard characteristics which are checked once the client requests the service.

In on-site maintenance we offer the following services:

On-site treatment to remove humidity

This procedure consists in taking full advantage of the heat within the transformer to free the moisture trapped in the windings paper insulation, which is then transferred to the insulating oil, and is finally released by the filtering system through thermal-vacuum.

Passive drying with Drymax online

This procedure consists of removing the moisture from the paper insulation of the windings. A transformer with a humidity by dry weight [up to 5% or more] can be dried to acceptable levels with the use of an on-line Drymax equipment. This piece of equipment is key to dry the humid insulation in a transformer that cannot be removed from service for normal drying procedures.

The result is that with time the moisture in the transformer is reduced to acceptable levels, which increases the reliability of the transformer and its life expectancy is extended.

Immediate results reveal a decrease in the water concentration (ppm) and saturation %.

Characteristics of the equipment:

• Has the ability to effectively dry the transformer whilst still in service, helping obtain a maximum efficiency, cost reduction and extended life expectancy.
• Saves time and money, compared to having to dry it various times with other methods, this method, if done thoroughly, gives long lasting low moisture results.
• Tested technology
• Passive – the improvement is slow and gradual which guarantees long lasting results.
• Portable – easy installment allows to move it from one apparatus to another.
• On-line process (energized) – there is no need to remove the transformer from service.
• Security for your transformer – only removes the humidity and does not affect dissolved gas tendencies.
• Change of filters is fast and safe.
• There are no wastes – environmentally friendly – each column can be regenerated.
• Efficient operation – low energy consumption (110 V, 15 amps).

Off-line Maintenance

Off-line maintenance is recommended when the transformer is able to be removed from service and when the conditions of the oil have deteriorated to a point that it would be too risky to perform a on-line treatment on the transformer.



Oil leak correction in man holes, tubing and Buchholz relay.






Crane placement to perform tank lid gasket replacement






Tank lid gasket replacement






Tank lid gasket replacement





Off-line maintenance consists of the following services:

OIL CHANGE

If the acid number, ASTM color and interfacial tension are beyond acceptable parameters and theres no time to perform an oil regeneration procedure, an oil change is recommended.

The oil change on-site consists in draining all the oil from the tank, removal of a high voltage bushing and rinsing of the windings through the opening with new hot oil to remove sludge that causes blockage in the refrigeration ducts. All gaskets are changed and the unit is filled with new processed oil.

OIL REGENERATION

Oil regeneration is recommended when the acid number is higher than 0.06 mgKH/g, Interfacial tension is below 27.9 mN/m and the ASTM color is above 4.0. The process of regeneration is done with Fuller Earth Ultra Clear 30/60 heated up to the aniline point, redissolving sludge in the oil once again. If the transformer oil, at the aniline point, is recirculated various times, the oil will clean the windings, clamps, core, tap changer etc. Once this cleaning process is finished, the oil is transferred to the tanks filled with Fuller Earth. This process removes a great part of the decomposition products of the oil, polishes and restores the oil to "as" new.

ON-SITE OIL FILTERING

Oil filtering through thermal-vacuum is recommended when the moisture content, dielectric strength and percent moisture in oil saturation are beyond the acceptable parameters. If moisture is ignored, in time the oxidation process will begin to deteriorate the insulating oil giving way to the formation of sludge that in time will obstruct the cooling ducts overheating the windings and shortening the transformers life expectancy.