with the fuse manufacturer's recommendation.]]
]2.2.2
Primary Transition Section
**************************************************************************
NOTE: Transition section should only be specified
where absolutely necessary.
**************************************************************************
Provide transition section for insulated copper [cable][bus-bar]
connections to the transformer primary terminals. Support [bus][cable]
connections between high-voltage [switch][breaker] and transformer primary
by porcelain insulators[ spaced no more than 610 mm 2 feet apart]. Size
and brace [bus][cable] to withstand the specified available fault.
2.2.3
Transformer Sections
**************************************************************************
NOTE: Indicate and specify the type of transformers
required for the project.
1. Use mineral oil filled transformers and locate
transformers at least 7.6 meters 25 feet from
buildings wherever possible. Where adequate
distance from structures cannot be attained, consult
NAVFAC design manuals and MIL-HDBK-1008, "Fire
Protection for Facilities Engineering, Design, and
Construction." Caution should be used in specifying
less-flammable liquid filled transformers. A
thorough analysis should be made by the designer
prior to using silicone filled transformers due to
the concern over operation of tap changers within
the silicone liquid.
2. Use the following option(s) when additional
capacity is required. This involves special
coordination with transformer KVA rating, as well as
sizes and ratings of fuses and secondary breakers.
a. If it is anticipated that future load
requirements will necessitate increasing the
capacity of the transformer, the specification for
the transformer should require the provision of
components and brackets for future forced air
cooling. Forced-air-cooling increases capacity by:
15 percent (750-2000 KVA); 25 percent (2500-5000
KVA).
b. On rare occasions, change "... insulation system
rated for a 65 degrees C rise..." to read
"...insulation system rated for a 55/65 degrees C
rise to allow transformer(s) to have a continuous
overload capacity of 12 percent at rated voltage
without exceeding 75 degrees C winding temperature
rise."
3. Use IEEE C57.12.00, Figure 3(b), voltage
designations, such as "13200 V - 4160Y/2400 V".
SECTION 16361N
Page 17
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