Maintenance - HPS DH Serie Guía De Instalación, Operación Y Mantenimiento

WARNING
Failure to identify and correct the root causes for the
transformer overheating can result in death or
personal injury, property damage or severely reduced
transformer life expectancy.

Maintenance

DANGER
HAZARD OF ELECTRIC SHOCK, EXPLOSION OR
ARC FLASH
Failure to de-energize, isolate and ground the
transformer terminals and to verify the ground
potential on all terminals before performing any
work on the transformer will result in serious
personal injury or death.
Inserting any objects through the ventilation
openings while the transformer is energized will
result in serious personal injury or death.
Short time overload as it relates to time and temperature

and the corresponding loss of life of the transformer.
Overload that results in a reduction of life expectancy of

the transformer.
If the transformer is experiencing increased operating
temperatures, the following contributing factors should be
considered and immediately corrected:
Rigorous motor starting loads or other impact type

loading. For this type of applications a specific
transformer type is required.
Over-excitation of unit due to excess supply line voltage or

current.
Ambient temperatures above standard.

Overload beyond ANSI C57.96 guidelines.

Harmonic distortions of the supply line voltage and

currents.
If overheating is noted, any attempt to add supplemental
fan cooling must be in accordance with factory installation
guidelines. Incorrectly installed fans can misdirect the airflow
and cause serious deterioration of the insulation life expectancy
in a transformer coil.
Dry-type transformers may be shut down and stored for
extended periods of time without any deterioration. Care must
be exercised to clean and dry units prior to energization, as
previously outlined. Proper packaging and moisture prevention
measures during storing are essential.
Under normal operating conditions and environments,
dry-type transformers require periodic care and inspection.
This is essential if the unit is installed in harsh environmental
conditions (for ex. outside, environments with high levels of
pollutants and dust, etc.).
Peripheral inspection and external dust removal may be
performed while the transformer is in operation. However,
access covers must not be opened or any objects inserted
through the transformer ventilation openings under energized
conditions.
Internal maintenance must be performed only with the
transformer de-energized, isolated and with all the
terminals grounded.
Maintenance typically includes internal cleaning,
tightening of links and bolted connections to prescribed torque
levels, servicing and inspection of auxiliary devices and an
infrared scan or thermal image of the transformer.
Air ducts should be maintained free of any accumulation
of dust and debris and all bolted connections at terminals must
be in good condition. We recommend under scheduled annual
maintenance or at shorter regular intervals that connections be
11
IOMGDDI / September 2017