External arrester
External surge arresters ordered with the transformer
must be installed and connected in the field before the
transformer is put into service.
Arrester and tank ground connections must be completed
before the transformer is connected to the high-voltage or
low-voltage lines. Proper connection places the arrester in a
direct shunt relationship to the transformer insulation.
Maintenance
Exterior maintenance
On an annual or more frequent interval, inspect all exposed
surfaces for evidence of tampering, battered metal, gouges,
etc. Dents or deformities should be repaired at once.
Scratched or weathered paint or protective coatings should
be touched up promptly.
Keep the area around the transformer clean. Do not store
tools, materials or equipment on or against the transformer.
Cabinet interior maintenance
Periodically inspect the terminal compartment interior and
all operating equipment. Check all gauges and controls for
proper operation. Repair or replace damaged or defective
equipment.
Inspect drain cocks, plugs, fuse mountings, and switches.
Look for evidence of insulating liquid seepage around tank-
wall gaskets, seals, etc. Repair as required.
Replacement of gaskets or seals in the tank wall may
require that the tank be opened and the insulating liquid
lowered to the appropriate level. For instruction on opening
the tank and for draining and replacing the insulating liquid,
refer to the
Insulating Liquid Maintenance
section in this
manual.
Tank internal maintenance
(For Envirotran
®
Transformers see the Envirotran
Transformers section of this manual before continuing)
Service to bushings or equipment inside the transformer
tank will require that the tank be opened and the insulating
liquid lowered to the appropriate level. Before opening the
transformer tank, read the
Insulating Liquid Maintenance
section in this manual. The
Liquid Maintenance
section
explains safety precautions that should be taken and
gives instructions on how to prevent insulating liquid
contamination. Precautions must be taken to prevent dirt
or moisture from entering the opened transformer tank.
Contamination of the insulating liquid will prevent the
transformer from operating properly and may cause serious
damage to the transformer.
Three-phase pad-mounted transformers may have either
bolt-on or weld-on main tank covers. Bolt-on covers can be
removed to access the tank interior. Access to the interior
of a transformer with a weld-on tank cover is typically
through a manhole/handhole. To gain additional internal
access to tanks with weld-on tank covers, the tank cover
must be cut open.
Tank cover removal and installation
(For Envirotran Transformers see the Envirotran
Transformers section of this manual before continuing)
WARNING
Hazardous voltage. Can cause severe injury, death, or
damage to equipment. De-energize transformer from
a remote upstream source before opening cabinet
and doing cabinet interior inspection or maintenance.
Check that all transformer terminals and bushings have
zero voltage. Ground transformer following industry
accepted safe grounding practices.
CAUTION
Elevated Pressure. Can cause personal injury or damage
to transformer. Release internal pressure with pressure
relief device before removing tank cover, manhole cover
or handhole cover.
WARNING
Hazardous voltage. Can cause severe injury, death, or
damage to equipment. De-energize transformer from
a remote upstream source before opening cabinet
and doing internal tank inspection or maintenance.
Check that all transformer terminals and bushings have
zero voltage. Ground transformer following industry
accepted safe grounding practices.
CAUTION
Elevated Pressure. Can cause personal injury or damage
to transformer. Release internal pressure with pressure
relief device before removing tank cover, manhole cover
or handhole cover.
WARNING
Hazardous voltage. Can cause severe injury, death, or
damage to equipment. De-energize transformer from
a remote upstream source before opening cabinet
and doing internal tank inspection or maintenance.
Check that all transformer terminals and bushings have
zero voltage. Ground transformer following industry
accepted safe grounding practices.
19
Three-phase pad-mounted compartmental type installation and maintenance instructions
MN202001EN August 2015
