GE Industrial Solutions Fan Assisted Cooling (FAC) Dry-Type Transformers - Manual (Page 7)

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Problem: Three-phase disconnect is being activated and power turned off
Possible causes:
Transformer is running over temperature limits (see above).
NOTE
TRANSFORMERS RUN HOT! UNITS LOCATED IN 40C AMBIENT, CAN HAVE ENCLOSURE TEMPERATURES CLOSE
TO 90C/194F WHEN FULLY LOADED.
10. Maintenance
Under normal environments and operating conditions, dry type transformers are virtually maintenance free. However, they do
require occasional internal cleaning, care and inspection. Fans may fail after life expectancy is reached, so they need to be inspected
regularly depending on load cycles. The frequency of inspection will depend on atmospheric and/or environmental conditions at a
given transformer installation or location.
CAUTION
ANY INTERNAL INSPECTION, ADJUSTMENT, CLEANING OR MAINTENANCE MUST BE DONE WITH THE
TRANSFORMER DE-ENERGIZED AND THE WINDINGS GROUNDED.
A continuously energized transformer needs periodic cleaning and maintenance only to remove accumulations of dust or dirt from
cooling ducts and other surfaces. Large accumulations may reduce cooling efficiency and lead to overheating. Cleaning is
recommended at least once a year in relatively clean installations and at more frequent intervals in more heavily contaminated
atmospheres.
Transformers that are de-energized for long periods of time generally require more frequent maintenance and cleaning to ensure
removal of contamination. Accumulation of dirt on insulating surfaces becomes a hazard when a considerable amount of moisture
is absorbed. Vacuuming is the recommended method for cleaning. Special attention should be given to cooling ducts within the
windings. Low-pressure dry air can be used if care is taken to avoid driving the contamination into the insulation.
Moisture is detrimental to most insulation systems. It is advisable to dry out any transformer that has been exposed for long periods
of time to high humidity. Whenever moisture is visible on insulation surfaces, the unit must be dried before being energized. If
moisture is evident, the unit should be dried out by placing it in an oven or by blowing heated air over it. The temperature of the
heated air should not exceed 110C/230F. Transformers may be subjected to flooding, direct rain or similar applications of water.
In such cases, normal drying techniques may not be adequate and the factory should be consulted. Additionally, if heavy moisture
and or direct contact with water has been allowed, the fans may no longer be functional.
Maintenance would include dust removal and/or drying, tap changing if applicable, tightening of bolted connections, inspection for
fan obstruction and general servicing and inspection of auxiliary devices. Additional information related to the installation and
maintenance of transformers can be found in ANSI publication C57.94, “Guide for Installation and Maintenance of Dry Type
Transformers”.
11. Storage
Condensation and moisture absorption must be prevented during storage. FAC units should be stored in a warm dry location having
a uniform temperature to prevent condensation. Openings should be covered to keep out dust. If outdoor storage cannot be
avoided, the transformer must be protected to prevent the entrance of water, moisture, dust, birds and other foreign material. If unit
is stored for extended periods of time, fans must be inspected to ensure they are functional.
12. Renewal Parts
The core-coil assembly precludes replacement parts. In most cases, field repairs are not recommended, are not economical and can
be dangerous. Renewal parts are available for all enclosure parts surrounding the core and coil assembly. Fan assemblies and
disconnects can also be replaced. Please contact the factory for replacement kits as well as for ordering a bottom panel for wall
mounting.
NOTE
These instructions do not purport to cover all details or variations in equipment or to provide for every possible contingency to be
met in connection with installation, operation or maintenance. Should further information be desired or should particular problems
arise which are not covered sufficiently for the purchasers purpose, the matter should be referred to the manufacturer.