GE Industrial Solutions Seconday Substation Transformer - Manual (Page 4)

4
Self-cooled transformers depend entirely upon
the surrounding air for carrying away their
heat. For this reason, care must be taken to
provide adequate ventilation.
For indoor installation, the room in which the
transformers are place must be well ventilated
so that heated air can escape readily and can
be replaced by cool air. Inlet openings
should be near the floor and distributed so as
to be most effective. The outlet opening(s)
should be as high above the apparatus as the
construction of the building will permit. The
number and size of air outlets required will
depend on their distance above the
transformer and on the efficiency and load
cycle of the apparatus. In general, about 60
square feet of outlet opening or openings
should be provided for each 1000 kVA of
transformer capacity. Air inlets should be
provided with the same total area as the
outlets.
Self-cooled transformers should always be
separated from one another and from
adjacent walls, partitions, etc., in order to
permit free circulation of air about the tanks.
This separation should not be less than 30
inches.
SERVICE SET UP
PRELIMINARY INSPECTION: Before any
work is done on a transformer in preparation
for service, a careful inspection of all external
parts is needed to disclose any evidence of
mistreatment or damage. This inspection
should include a check of all parts required to
complete the installation, making certain that
all parts have arrived and are in first-class
condition. Accessible bolted parts should be
checked for tightness. Pressure test should
be taken and the liquid checked to determine
both its physical level and dielectric strength.
Any indication of leaks, which may have
resulted in moisture entering the transformer,
should be noted and appropriate action taken.
NOTE: Pressurized and sealed at ambient
temperature at time of manufacture. It is
common that a pressure vacuum gauge, if
supplied, could read negative due to lower
temperature at the site of installation. This is
not an indication of an abnormality, but in fact
an indication that the tank is properly sealed.
SERVICE START UP
Before applying voltage to transformer, check
the following items:
1.The feeder cables on bus
connected to bushing terminals are
not stressing the porcelains.
2.The winding neutral terminal is
properly grounded or ungrounded as
required by system operation.
3.The tank is solidly grounded at
grounding pads located near bottom
of tank.
4.All current transformers are
connected to a load or in short
circuit.
CAUTION: Open secondaries can
produce voltages dangerous to
humans and connected equipment.
5.The the tap changer is set in
desired position to give desired
voltage ratio.
6. All tools and foreign objects have
been removed from transformer.
7. All openings and joints are
sealed
8. Is insulating liquid at proper level in
tank? Also level in liquid-filled
compartments (if supplied).