Document 2.4.128, Revision 3
October, 2017
13
Network Transformer Instruction Manual
Post-Energization Inspection and Tests
After the transformer is energized, the following tests
and inspections should be performed.
1. Verifying Correct Voltage
Before supplying voltage from the transformer
to the load, verify that the secondary voltage
is correct. Using a suitable AC voltmeter,
measure the voltage of the secondary
windings and make sure they agree with the
secondary voltages listed on the transformer
nameplate.
2. Checking for Leaks
Check the main tank, high-voltage switch
chamber and terminal chamber to make sure
there are no fluid leaks.
3. Observing Operation
After the transformer is initially energized,
visually inspect it occasionally for a few hours,
to make sure that no abnormal conditions are
observed.
4. Checking Gauges
Observe the fluid level and fluid temperature
gauges to confirm the proper fluid level and
temperature.
5. Audible Sound
It is normal for transformers to emit an
audible humming sound, which is primarily
caused by alternating magnetic flux in the
transformer core. Amplitude and harmonic
content of the sound is influenced by
transformer size, the energizing voltage level
and sinusoidal purity, load conditions and
acoustic conditions at the installation site.
Refer to NEMA Standards Publication TR-1,
Transformers, Regulators and Reactors
, and
IEEE Standard C57.12.90,
IEEE Standard
Test Code for Liquid-Immersed Distribution,
Power, and Regulating Transformers
, for
more information about design sound levels
and factory sound testing. Unusual sounds
should be investigated, as this might indicate
a potential problem.
WARNING
FAILURE TO FOLLOW THE INSTRUCTIONS
BELOW COULD RESULT IN DEATH OR
SERIOUS PERSONAL INJURY AND MAY ALSO
RESULT IN DAMAGE TO THE EQUIPMENT.
• Do not energize the transformer
using single-phase switches or fuses.
Use only gang-operated three-phase
switches to energize a three-phase
transformer
• Do not operate the transformer with
any of the primary phases open.
• Only qualified personnel with
appropriate equipment should
measure transformer voltages.
• Wear personal protective equipment
to prevent injury from potential arc-
flash or contact with dangerous
voltages.
• Make sure the transformer is securely
and effectively grounded at all times.
• CT leads must be connected to the
metering load or shorted together
and grounded to prevent dangerous
voltages at the CT terminals.
DANGER
FAILURE TO FOLLOW THE INSTRUCTIONS BELOW
WILL RESULT IN DEATH OR SERIOUS PERSONAL
INJURY AND MAY ALSO RESULT IN DAMAGE TO
THE EQUIPMENT.
Be aware of dangerous voltages and avoid
personal contact with live terminals
