2.1.1
Rating
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NOTE: The local electric utility should be consulted
for the expected average and maximum values of
percentage voltage unbalance, as defined in NEMA MG
1 paragraph 21.81.2, that will be present at the
pumping station. If either value exceeds 1 percent
as recommended in NEMA MG 1 paragraph 21.81, the
utility should be requested to furnish their plans
to improve the voltage unbalance. If they are
unable to do so, then the motor should be derated
where the voltage unbalance exceeds 1-2 percent.
Voltage unbalance should never exceed 5 percent.
Motor manufacturers should be consulted for voltage
unbalance limits whenever motors have specified
limits on locked-rotor currents, particularly the
500 percent limit.
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Each motor shall be wound for three-phase, 60 Hz, alternating current, and
for the respective operating voltage listed below:
PLANT
PUMP
PUMP SERVICE
MOTOR OPERATING VOLTAGE
[_____]
[_____]
[_____]
[_____]
[_____]
[_____]
[_____]
[_____]
The motor shall be designed for operation in a 40 degrees C 104 degrees F
ambient temperature, and all temperature risers shall be above this ambient
temperature. The rated horsepower of the motor shall be not less than 110
percent of the determined maximum load requirement of the pump. [Supply
voltage unbalance will be [_____] percent. The motor rated horsepower will
be further derated according to NEMA MG 1 paragraph 21.81 for a voltage
unbalance above [1.5 percent] [2 percent].] Motors shall have a power
factor and service factor of 1.0. The temperature rise above the ambient
temperature for continuous rated full load conditions and for the class of
insulation specified shall not exceed the values given in NEMA MG 1
paragraph 21.40.
2.1.2
Operating Characteristics
2.1.2.1
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NOTE: This guide specification identifies closed
transition autotransformer-type reduced voltage
starters. These starters provide the most
flexibility during installation, when exact load and
line characteristics are not determined, since both
input voltage and inrush current may be adjusted.
This specification is not meant to limit the
selection of reduced voltage starter to only
autotransformer type. The use of wye-delta type
starter may be appropriate in certain situations.
The reduced starter cost must be weighed against the
increase cost in motor designs; however each design
should be evaluated for the most suitable type
SECTION 16222A
Page 13
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