2.1.3.3
Overspeed Alternate
**************************************************************************
NOTE: NEMA MG 1 paragraphs 12.48 and 20.44 specify
that overspeeds are for emergencies lasting no
longer than one minute. Using this option will
insure additional costs due to requirements well
beyond standard limits.
**************************************************************************
Each motor shall be designed to withstand indefinitely, without injury, the
maximum overspeed to which the motor will be subjected when the pump to
which it is connected is acting as a hydraulic turbine under the maximum
head with the pump discharge pipe open.
2.1.3.4
Antireverse Device Alternate
A self-actuated backstop device or antireversing ratchet, to prevent
reverse rotation of the pump due to loss of power or failure of the
electric prime mover, shall be installed as an integral part of the motor.
The design of the device shall be submitted to and approved by the
Contracting Officer. It shall have sufficient capacity to prevent reverse
rotation with a back-flow through the pump due to a [_____] foot
differential head. If the device requires a lubrication system, an oil
reservoir independent of the one used for the thrust bearing and complete
with visible oil level gauge and 120-volt a.c. rated high and low level
contacts shall be provided. All electrical leads shall be terminated in
the accessory terminal box specified in paragraph MOTOR TERMINALS AND
BOXES. The lubricant for the antireverse device shall contain a corrosion
inhibitor whose type and grade shall be shown on a special nameplate
attached to the frame adjacent to the lubricating filling device.
2.1.3.5
Eyebolts
Eyebolts, lugs, or other approved means shall be provided for assembling,
dismantling, and removing the motor, if required, from above using an
overhead crane. All lifting devices required for use in conjunction with
the crane shall be provided with the motor.
2.1.4
Cores
The cores for the stators and rotors shall be built up of separately
punched thin laminations of low-hysteresis loss, nonaging, annealed,
electrical silicon steel, assembled under heavy pressure, and clamped in
such a manner as to insure that the assembled core is tight at the top of
the teeth of the laminated core. Laminations shall be properly insulated
from each other. Only laminations free from burrs shall be used, and care
shall be taken to remove all burrs or projecting laminations from the slots
of the assembled cores. Cores shall be keyed, dovetailed, or otherwise
secured to the shaft or frame in an approved manner. Treatment against
corrosion shall be as specified in paragraph GENERAL REQUIREMENTS.
2.1.5
Insulated Windings
**************************************************************************
NOTE: If motor temperature rise is of particular
concern, the designer may specify Class F insulation
with a Class B temperature rise instead of Class F
insulation with 110 percent continuous overload
SECTION 16221A
Page 14
Previous Page
