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6/2011
INSTALLATION
This transformer is to be installed in such a manner and location as to
minimize the hazards to all those who have access to it.
SURGE PROTECTION
The successful operation of any transformer depends on various
factors such as installation, loading, service conditions, and
maintenance. Electrical systems in which transformers, along with
vacuum or SF circuit breakers, are used are capable of high
frequency over voltages which will not be suppressed by lightning
arresters. These medium voltage systems may require a detailed,
high frequency over voltage system analysis and/or the addition of
high frequency over voltage protection. The transformer should be
installed in conditions as specified in ANSI/IEEE Section C57.12.01
Usual Service Conditions, unless the transformer is designed
specifically for operation in conditions other than the usual service
conditions.
INDOOR (CATEGORY C)
Follow all local and national codes when locating the transformer.
Make sure the ventilated openings, on the top and bottom of the
enclosure, are clear. The transformer must have proper clearances
from walls or other obstructions to allow circulation of air through and
around each unit (refer to nameplate for specific clearances).
For indoor installations, consult local and national codes to ensure all
applicable requirements are satisfied. If the transformer is located
near combustible materials, make sure the transformer meets or
exceeds the minimum clearances as required by the National
Electrical Code® (NEC) or other applicable local codes.
RESTRICTING ACCESS
Ventilated dry type transformers are not designed or constructed to
be tamperproof. Install the transformer in an area that is secure and
that only allows access to qualified personnel.
OUTDOOR (CATEGORY B)
For outdoor installations, consult local and national codes to ensure all
applicable requirements are satisfied. If the transformer is located
near combustible materials, make sure the transformer meets or
exceeds the minimum clearances as required by the NEC or other
applicable local codes. The transformer must have proper
clearances from walls or other obstructions to allow circulation of air
through and around each unit (refer to nameplate for specific
clearances). Ventilated outdoor substation transformers and pad-
mounted unit substations are designed for installation on a well-
drained, concrete pad. Unless specified otherwise, the transformer is
supplied without a bottom plate in the enclosure. If installing the
transformer in a elevated position where the bottom is exposed, add a
bottom plate (for rodent resistance) with provisions for drainage to
the enclosure.
Proper drainage is mandatory.
ATMOSPHERIC CONDITIONS
Atmospheric
conditions
and
accessibility
are important
considerations when locating the transformer outdoors.
Install outdoor ventilated transformers in locations that are
free from unusual dust or chemical fumes. The enclosure helps
protect the transformer from atmospheric conditions such as dust,
rain, or snow. Also, the enclosure is designed to divert water from
energized parts, insulation, and wiring. However, it may not protect
against internal condensation or ice, or completely stop snow
from entering. If possible, locate the transformer in a shielded
area such as in the corner of a building or landscaped
windbreak to provide extra protection from driving wind, rain, or
snow. When subjected to severe weather, outdoor dry type
transformers should be inspected to determine if added protection is
necessary.
VENTILATION
For core and coil transformers, consult with factory for necessary
case dimensions to allow proper ventilation.
For adequate cooling the unit should be installed with proper
clearances from walls and other obstructions which might prevent
free circulation of air through and around the unit (refer
to nameplate for specific clearances). Mechanical clearances
should be taken into consideration in installing the transformer.
Sufficient room should be allowed for removal of panels for
cleaning and, with reverse arrangement of units, for changing of
taps.
If the transformer is to be installed in a vault, provide ventilation
adequate to keep the room temperature from exceeding that of the
incoming air by more than 5°C. The number and size of air outlets
required will depend on their distance above the transformer, and
on the efficiency and load cycle of the apparatus. See ANSI Guide
C57.94, “Guide for Installation and Maintenance of Dry-Type
Transformers”.
Arrange air inlets and outlets so that they are permanently open.
Do not use as ventilators, windows or doors which may be opened
and closed by attendants because of the danger of
excessive heating in case they are inadvertently left closed during
periods of heavy load or high temperature. If forced ventilation
is used, supply about 5000 cubic feet of air per minute (141
cubic meters per minute) for each 1000 kVA of transformer
capacity, and deliver the incoming air uniformly around the
transformer at floor level and low velocity.
MIT100-15A
Locate
the
transformer
on
a
level
foundation
strong
enough
to
support
the
weight
of
the
transformer,
preferably
of
reinforced
concrete.
MADDOX
recommends
that
you
do
not
place
the
transformer
directly
on
an
earthen
surface.
Ensure
the
foundation
has
adequate
drainage.
Seismic
regulations
may
require
that
the
transformer
be
anchored
to
the
pad
or
foundation.
