Howard HI-104 Single-Phase Pad Transformer - Manual (Page 10)

Document 2.4.96, Revision 0
March, 2013
10
Single-Phase Pad-Mounted Compartmental-Type Distribution Transformers
assembled transformer. The transformer should sit
flush with the mounting surface, so that there are no
gaps that might compromise tamper resistance of
the terminal compartment. The installed transformer
should not tilt in any direction more than three
degrees. Greater tilt may compromise insulating
fluid coverage of live parts within the tank and may
prevent insulating fluid from circulating properly
through the cooling radiators. Improper circulation of
insulating fluid may cause overheating and reduced
transformer life.
The transformer should be located at least 24 inches
from any obstruction and have adequate clearance
to allow the terminal compartment hood or doors to
open fully. Avoid locating the transformer in corrosive
areas. Remove any shipping braces and packing
material that may have been installed at the factory.
Hold-down cleats or brackets should be used to
securely fasten the transformer to the mounting
surface.
Verifying Enclosure Integrity
Howard single-phase compartmental-type pad-
mounted transformers are designed and constructed
to be tamper resistant according to the requirements
of IEEE Standard C57.12.28 Pad-Mounted
Equipment—Enclosure Security, or C57.12.29 Pad-
Mounted Equipment—Enclosure Security for Coastal
Environments, as applicable, and therefore need not
be installed in a restricted area. Do not modify the
tank or terminal compartment in such a way that it
will compromise tamper resistance. If for any reason
modifications must be made to the tank or terminal
compartment that compromise tamper resistance,
the transformer must then be located in a restricted
area. Such modifications of may void the warranty.
Consult with the Howard Industries Transformer
Division before making any modifications to the
transformer.
▲
! WARNING
FAILURE TO FOLLOW THE INSTRUCTIONS
BELOW COULD RESULT IN DEATH OR SERIOUS
PERSONAL INJURY, AND COULD ALSO RESULT
IN DAMAGE TO THE EQUIPMENT.
Do not modify the transformer in any way that
might compromise its tamper-resistant con-
struction.
Grounding
The transformer must be permanently grounded
according to applicable local and national codes.
Ground the transformer by using ground pads or
nuts located inside the terminal compartment at
the base of the front panel. Do not use hold-down
bolts, pipe connections or any other fittings for
ground connections. A proper low-resistance ground
connection is necessary for safe operation.
In addition to proper tank grounding as stated above,
transformers designed for use on a grounded-wye
system must also have all winding neutrals securely
and effectively grounded to the system neutral.
▲
! WARNING
FAILURE TO FOLLOW THE INSTRUCTIONS
BELOW COULD RESULT IN DEATH OR SERIOUS
PERSONAL INJURY, AND COULD ALSO RESULT
IN DAMAGE TO THE EQUIPMENT .
The transformer must be properly grounded at
all times.
High-Voltage and Low-Voltage Connections
Before making high-voltage and low-voltage line
connections, check to make sure that all mating
connector surfaces are clean and smooth.
Connections must be tightened appropriately to
prevent overheating and possible failure of the
connection. Refer to the nominal torque guidelines
contained in Table 3. Connections should be made
with care to avoid placing undue cantilever stress on
the bushings.
High-Voltage Terminals
Dead-front transformers are designed to use the
separable insulated high-voltage connector system
defined in IEEE Standard 386. These dead-front
transformers come equipped with universal bushing
wells only, one-piece (integral) bushings or universal
bushing wells with factory-installed bushing inserts.
Either loadbreak-rated or non-loadbreak-rated
bushings can be provided as specified by the user.
When transformers are provided with universal
bushing wells only, bushing inserts must be installed
in the field by the user before cable connections can
be made. Bushing well inserts must be compatible