The output of the [closed transition auto-transformer-type reduced
voltage] [_____] starter supplied at rated and 90 percent of rated
motor voltage [and connected on its 65 percent and 80 percent taps].
[The pump torque curve shall be plotted for starting and accelerating
against maximum head. Computations shall be furnished to demonstrate
that the motor furnished will carry the pump load under all the
foregoing conditions.]
g. Coils of all windings shall be fully braced so that vibration is
virtually eliminated during repeated starts as required by the duty
cycle specified as well as during normal operation. If a tied system
is used it shall be such that no tie depends upon the integrity of any
other tie within the system.
2.1.6
Thermal Protection
For motors rated 500 hp or greater, resistance temperature detectors (two
per phase) shall be provided in accordance with NEMA MG 1, paragraph 20.63.
Detectors shall have a copper resistance element having a resistance of 10
ohms at 25 degrees C 76 degrees F. Leads shall be terminated on the
terminal blocks specified in paragraph MOTOR TERMINALS AND BOXES. For
motors rated less than 500 hp, positive-temperature-coefficient thermistors
(one per phase) shall be embedded in the windings. The thermistors with
all necessary additional equipment, as required, shall open a normally
closed contact when the critical temperature is reached. All outgoing
wiring shall terminate on the terminal blocks specified in paragraph MOTOR
TERMINALS AND BOXES.
2.1.7
Winding Heaters
**************************************************************************
NOTE: The inclusion or omission of "Winding Space
Heaters" will depend upon the decision reached after
giving due consideration to the problem of
prevention of moisture condensation on the station
equipment. If winding space heaters are not
required, this paragraph, including all
subparagraphs, shall be deleted.
**************************************************************************
Heaters shall be wrapped around the winding end turns. They shall be
designated for operation on 120 volts, 1-phase, 60 Hz, alternating current
and of sufficient capacity or wattage that, when energized, they will hold
the temperature of the motor windings approximately 10 degrees C above the
ambient temperature. They shall be designed for continuous operation and
to withstand at least 10 percent overvoltage continuously. The rate of
heat dissipation shall be uniform throughout the effective length of the
heater. Heaters installed around the winding end turns shall consist of
the required turns of heating cable wrapped around the end turns and
secured in place before the winding is impregnated.
2.1.7.1
Heating Element
Heating element shall conform to the requirements of ASTM B 344 for an 80
percent nickel and 20 percent chromium alloy.
2.1.7.2
Sheath
Sheath shall be of a corrosion-resisting, nonoxidizing metal and shall have
SECTION 16221A
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