2.3.7
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NOTE: Polyphase motors shall be selected based on
requirements of the driven equipment, service
conditions, motor power factor, life cycle cost, and
high efficiency in accordance with NEMA MG 10.
Use Motor Master software program to identify the
most efficient and cost effective polyphase motor
for a specific application. Motor Master is located
in the "TOOLS" section of Construction Criteria Base
(CCB). For additional guidance contact Charlie
Mandeville of the NAVFAC Criteria Office at (757)
322-4208. Another source of information on energy
efficiency is E-source, accessible to Navy, users on
the Naval Facilities Engineering Service (NFESC)
energy home page http://energy.navy.mil/.
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Efficiency and losses shall be determined in accordance with IEEE Std 112.
Unless otherwise specified horizontal polyphase squirrel cage motors rated
one to 125 horsepower shall be tested by dynamometer Method B as described
in Section 6.4 of IEEE Std 112. Motor efficiency shall be calculated using
Form B of IEEE Std 112 calculation procedure.
Polyphase motors larger than 125 horsepower shall be tested in accordance
with IEEE Std 112 with stray load loss determined by direct measurement or
indirect measurement (test loss minus conventional loss).
The efficiency shall be identified on the motor nameplate by the caption
NEMA Nominal efficiency or NEMA Nom eff.
2.3.7.1
Main Electric Drive Motor
The main drive motor for each compressor shall be a polyphase [induction]
[or] [synchronous] motor, [_____] kW horsepower, with a continuous service
factor of 1.0. Size the motor so that the nameplate kW horsepower rating
is not exceeded under the entire range of operating conditions specified.
[Design of induction motor shall be high efficiency type, rated not less
than 95 percent, based on IEEE Std 112 testing and labeling.] Electrical
service will be as specified. Motor shall be designed for reduced voltage
starting [at [50] [65] [80] percent of full voltage], allowing for
characteristics of the connected load, and shall start without undervoltage
tripping. Provide resistance temperature detectors (RTD) attached to or
imbedded in motor winding for control system. The motor shall meet the
requirements of NEMA MG 1 with Class F insulation. Provide space heaters
for protection of windings during motor shutdowns.
2.3.7.2
Accessory and Related Equipment Motors
Motors less than 3/8 kW 1/2 horsepower shall be single phase induction
motors and shall conform to NEMA MG 1. Motors 3/8 through 3.75 kW 1/2
through 5 horsepower shall be three-phase induction motors and shall
conform to NEMA MG 1. Single-phase and three-phase motors shall have
bimetallic disk thermostats attached to or imbedded in the motor winding.
Motors shall have NEMA MG 1, Class B insulation.
SECTION 15214N
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