Document 2.4.126, Revision 4
October 2017
25
Three-Phase Padmounted Distribution Transformers
These instructions are intended as a general
guide for the maintenance of Howard three-
phase compartmental padmounted distribution
transformers, when used in typical applications
and operated in normal environments. Although
efforts have been made to ensure accuracy and
completeness, these instructions do not address
every conceivable application or circumstance that
might be encountered.
Transformers should be inspected periodically while
in service, with the frequency determined by service
conditions. Transformers operating in unusual
service conditions should be inspected more
frequently. Refer to IEEE Standard C57.12.00 for a
discussion of usual and unusual service conditions.
Accessories such as a pressure relief device,
temperature gauge, fluid level gauge, pressure-
vacuum gauge and drain valve typically require no
maintenance, except replacement in the event of
damage. Gauges should be checked periodically to
make sure they are operating properly.
Periodic Inspection
The transformer’s terminal compartment interior,
all exterior surfaces and the transformer’s
surroundings should be inspected. Inspection
frequency should be governed by operating
conditions at the installation site. More severe
conditions indicate the need for more frequent
inspection.
SECTION 7: MAINTENANCE
WARNING
The transformer must be de-energized
before performing any maintenance
work. FAILURE TO FOLLOW THIS
INSTRUCTION MAY RESULT IN SEVERE
PERSONAL INJURY OR DEATH, AND/OR
DAMAGE TO THE EQUIPMENT.
WARNING
FAILURE TO FOLLOW THE INSTRUCTIONS
BELOW MAY RESULT IN DEATH OR SEVERE
PERSONAL INJURY, AND /OR DAMAGE TO
THE EQUIPMENT.
• De-energize transformer from a remote
location before opening cabinet to
perform inspection or maintenance.
• Make sure all transformer terminals and
bushings have zero voltage.
• Make sure that the transformer is
properly grounded.
• Fluid leaks should be repaired as soon as
they are discovered.
