Transformer Tank Sections

ARRANGEMENT

DESCRIPTION OF

SWITCH POSITION

#

SWITCH

LINE A SW

LINE B SW

XFMR SW

ARRANGEMENT

OPEN CLOSE

lines connected to

transformer

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2

Transformer connected

X

to Line A only

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3

Transformer connected

X

to Line B only

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4

Transformer open and

X

loop closed

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5

Transformer open and

X

loop open

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2.9.2.3

Transformer Tank Sections

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NOTE: For 480Y/277 volt secondaries, 2 primary taps

above and 2 primary taps below are standard. For

208Y/120 volt secondaries, 4 primary taps below are

standard. Normally, the design should use standard

impedances in conjunction with circuit breakers

having adequate interrupting ratings. ANSI

C57.12.26, Table 2, lists 5.75 percent for 750 kVA -

2500 kVA. For 75 kVA - 500 kVA, use manufacturer's

standard.

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Transformers shall comply with IEEE C57.12.00, ANSI C57.12.21, and ANSI

C57.12.26 and shall be of the [mineral oil-insulated type] [less-flammable,

liquid-insulated type with [high molecular-weight hydrocarbon] [or]

[dimethyl silicone] liquid]. Transformers shall be suitable for outdoor

use and shall have 2 separate windings per phase. Standard NEMA primary

taps shall be provided. Where primary taps are not specified, 4, 2-1/2

percent rated kVA high-voltage taps shall be provided [2 above and 2 below]

[below] rated, primary voltage. Operating handles for primary tap changers

for de-energized operation shall be located within high-voltage

compartments, externally to transformer tanks. Adjacent to the tap changer

operating handle, a nameplate or equivalent stenciled inscription shall be

provided and inscribed "DO NOT OPERATE UNDER LOAD." Transformer ratings at

60 Hz shall be as follows:

Three-phase capacity.....................................[_____] kVA.

Impedance....................................................[_____].

Temperature Rise........................................65 degrees C.

High-voltage winding...................................[_____] volts.

SECTION 16375A

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