Howard HI-104 Single-Phase Pad Transformer - Manual (Page 28)

Document 2.4.96, Revision 0
March, 2013
28
Single-Phase Pad-Mounted Compartmental-Type Distribution Transformers
These instructions are intended as a general guide
for the maintenance of Howard single-phase pad-
mounted distribution transformers, when used in
typical applications and operated in normal envi-
ronments. Although every effort has been made to
ensure accuracy and completeness, these instruc-
tions do not address every conceivable application or
circumstance that might be encountered.
▲
! WARNING
FAILURE TO FOLLOW THE INSTRUCTIONS
BELOW COULD RESULT IN DEATH OR SERIOUS
PERSONAL INJURY, AND COULD ALSO RESULT
IN DAMAGE TO THE EQUIPMENT.
• De-energize transformer from a remote
location before performing any inspection or
maintenance work.
• 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.
Periodic Inspection
Transformers should be inspected periodically while
in service, with the frequency determined by service
conditions. Transformers operating in unusual ser-
vice 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 pressure relief valves, tempera-
ture gauges, fluid level gauges, pressure-vacuum
gauges and drain valves typically require no mainte-
nance, except replacement in the event of malfunc-
tion or damage. Gauges should be checked periodi-
cally to make sure they are operating properly.
Inspection Checklist
Observing the safety instructions above, open the
terminal compartment and perform the following
checks.
1. De-energize the transformer and ground all termi-
nals
2. Inspect for dents or other damage to metal sur-
faces and make the necessary repairs.
3. Inspect the cabinet for evidence of tampering
and immediately repair any damage to ensure
cabinet integrity and prevent unauthorized entry.
4. Inspect the paint finish for damage, corrosion or
weathering that exposes the primer coat or bare
metal. Repair any paint damage that might be
found. Refer to “Exterior Paint Finish” for instruc-
tions.
5. Inspect all surfaces thoroughly for evidence of
fluid leaks, including tank, radiators, bushings,
gauges, switches, valves, fuse holders and all
other accessories and fittings. Check the fluid
level gauge or sight glass (if either of these is
present) to determine the fluid level. Check the
pressure-vacuum gauge (if present) for a zero
reading, which indicates the possibility of a tank
leak. The pressure-vacuum gauge may indicate
zero occasionally, but normally indicates a slight
positive or negative pressure, as a function
of fluid and ambient temperatures. Perform a
pressure test according to the instructions in the
“Pre-Energization Inspection and Tests” section.
Add fluid as necessary to ensure that the proper
fluid level is maintained. Repair as necessary.
Fluid leaks should be repaired immediately to
prevent serious damage to the transformer and
an unsafe operating condition. Refer to “Fluid
Leaks” for instructions.
6. Visually check all gaskets for cracking or other
signs of deterioration, and replace as necessary.
When replacing a gasket, carefully clean mating
surfaces to remove any rust, dirt, transformer
fluid, old gasket material, or other contamination
that might prevent a good seal. Use appropriate
gasket cement when installing new gaskets. Do
not reuse old gaskets. Six months after replac-
ing a gasket, check and re-tighten, if necessary.
7. Maintain a clean and unobstructed area around
the transformer, including sufficient clearance
around radiator panels, to ensure adequate cool-
ing of the transformer.
8. Inspect the base of the transformer tank and
terminal compartment and make sure that there
is no accumulated dirt or other debris that might
promote corrosion.
SECTION 7: MAINTENANCE AND REPAIR