GE Industrial Solutions Seconday Substation Transformer - Manual (Page 5)

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9. Are all fans and control circuits (if
supplied) operational?
10. Is insulating dielectric strength of
insulating liquid at least 27.5 kV? If
tests are less, filter the liquid.
11.Are all personnel in the clear?
After energizing, watch transformer closely for
the first three hours of operation for evidence
of abnormal conditions.
LOADING
Transformers are suitable for full-load
operation at rated temperature rise without
shortening of useful life, providing the
following conditions are met:
1. Ambient temperature does not
exceed 40°C or average more than
30°C in one 24-hour period.
2. Installed elevation does not exceed
that shown on the nameplate and
stenciled on the transformer tank.
Consult a representative of the
manufacturer for instructions for
operating at higher altitudes.
PERIODIC INSPECTION
1. Sample and test insulating/cooling
liquid for dielectric strength
CAUTION: If a vacuum is indicated
on the pressure vacuum gauge, care
must be used to eliminate it prior to
insulating liquid sampling. Failure to
do so may result in air being pulled
into the tank through the drain valve
which may lead to insulation failure if
energized or upon re-energization.
Contact factory for specific
instructions.
2. Check level of liquid in main tank
and liquid-filled compartments. Add
clean liquid if necessary.
3. Check fan operation on Forced Air
units.
CAUTION: Before entering a
transformer that has been in service,
BE SURE to lock open the line
switches on both the HV and LV
side, then connect a grounded line to
transformer terminals in order to
discharge any stored energy in the
windings.
DO NOT ENTER THE UNIT UNTIL
THE GAS SPACE ABOVE LIQUID
HAS BEEN PURGED WITH DRY
AIR. BREATHING THE NITROGEN
ABOVE THE TRANSFORMER
LIQUID CAN CAUSE
ASPHYXIATION.
MAINTENANCE DURING PERIODS
OF SHUTDOWN
The transformer does not generally require
particular cares for attendance or
maintenance. Anyway, in order to ensure a
safe and reliable operation, it will be
necessary to effect at regular intervals a
series of checks, the frequency of which
depends on ambient and operating
conditions.
Clean any contamination from bushings.
Rotate the tap hanger handle back and forth a
few times. This will clean the contacts. Be
sure to return the handle to its original
position if no change in voltage ratio is
desired.
CHECKING FOR LEAKS: