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Impedance voltage of a transformer |
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|  MIL-T-15108C(NAVY)
3.2.2 Dry type transformer. A dry type transformer is a transformer cooled by the
natural circulation of air.
Primary winding is the winding on the input side.
3.2.3 Primary winding.
Secondary winding is the winding on the output side.
3.2.4 Secondary winding.
A tap in a transfer-r is a connection brought out of a
3.2.5 Tap in a transformer.
winding at some point between its extremities, usually to permit changing the voltage ratio.
Rated kVA of a transformer is the
3.2.6 Rated kilovoltampere kVA of a transformer.
output which can be delivered for the time specified at approximately rated secondary voltage
and rated frequency without exceeding the specified temperature limitations.
Ratio of a transformer is the turn ratio of the trans-
3.2.7 Ratio of a transformer.
former.
Regulation of a transformer is the change in
3.2.8 Regulation of a transformer.
secondary voltage, expressed in percent of rated secondary voltage, which occurs when rated
kVA output at a specified power factor is reduced from rated value to zero, with the primary
impressed terminal voltage maintained constant.
Impedance voltage of a transformer is the
3.2.9 Impedance voltage of a transformer.
voltage required to circulate rated current through a winding of the transformer when another
winding is short-circuited, with the respective windings connected for rated voltage operation
and is expressed in percent of the rated voltage of the winding in which the voltage is
measured.
Exciting current of a transformer is the
3.2.10 Exciting current of a transformer.
current which flows in any winding used to excite the transformer when all other windings are
open-circuited, and is expressed in percent of the rated current of the winding in which it
is measured.
3.2.11 Lead polarity of a transformer. Lead polarity of a transformer is a designation
of the relative instantaneous directions of currents in its leads. Primary and secondary
leads are said to have the same polarity when at a given instant the current enters the
primary lead in question and leaves the secondary lead in question in the same direction as
though the two leads formed a continuous circuit. The lead polarity of a single-phase
distribution or power transformer may be either additive or subtractive. If one pair of
adjacent leads from the windings in question is connected together and voltage applied to
one of the windings:
(a) Lead polarity is
additive if
the voltage across the other two leads
of the windings
in question
is greater than that of the higher
voltage winding
alone.
(b) Lead polarity is
subtractive
if the voltage across the other two leads
of the windings
in question
is less than that of the higher voltage
winding alone.
#
3.3 General requirements. Transformers shall comply with the requirement of MIL-E-917
and the requirements of this specification, except as otherwise specified in the contract
or order. If any requirement specified herein conflicts with the requirements of MIL-E-917,
the requirements of this specification shall govern.
#
3.4 Insulation system. The insulation system shall be class 130 as specified in
MIL-E-917 or higher. The whole core and coil of each transformer shall have varnish applied
by the dipping process or vacuum-pressure process specified in MIL-E-917.
#
3.5 Painting Painting shall comply with the requirements of MIL-E-917, except that
only one coat of gray enamel need be applied. Marks or scratches made due to handling dur-
ing fabrication and testing shall be repainted by either complete repainting of equipment
or by touchup method. Parts to be painted shall consist of those not having a corrosion-
resisting treatment or not fabricated of corrosion-resisting materials of the types speci-
fied in MIL-E-917 and shall include exterior and interior surfaces of the enclosure.
#
3.6 Enclosure. Unless otherwise specified in the contract or order, transformers shall
be driproof (45 degree), in accordance with class I of MIL-E-2036 for electric equipment and
with MIL-STD-108. Enclosure shall provide for the entrance of the ship's cables. Ready
accessibility shall be provided with clearance in the vertical direction for installation
and maintenance or electrical connections (see table III). Sufficient space shall be provided
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